Chemistry Ii Chapter 13 Amines
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    NCERT Solution For Class 12 Chemistry Chemistry Ii

    Amines Here is the CBSE Chemistry Chapter 13 for Class 12 students. Summary and detailed explanation of the lesson, including the definitions of difficult words. All of the exercises and questions and answers from the lesson's back end have been completed. NCERT Solutions for Class 12 Chemistry Amines Chapter 13 NCERT Solutions for Class 12 Chemistry Amines Chapter 13 The following is a summary in Hindi and English for the academic year 2021-2022. You can save these solutions to your computer or use the Class 12 Chemistry.

    Question 1
    CBSEENCH12008839
    Question 2
    CBSEENCH12008840
    Question 5
    CBSEENCH12008843

    Write structures of different isomeric amines corresponding to the molecular formula C4H11N.

    Solution

    a) CH3-CH2-CH2-CH2-NH2
    Butanamine (primary)


    b) Buta-2-amine (sec.)

    c) 2-methyl propamine (pri)

    d) 2-methylpropan-2-amine (pri)

    e) CH3-CH2-CH2-NH-CH3
    N-methylpropanamine (sec.)


    f) CH3-CH2-NH-CH2-CH3
    N-ethyl ethanamine (sec.)

    (g) N-Methyl propan-2-amine (sec.)

    h) N,N Dimethylethanamine (tert)

    Question 6
    CBSEENCH12008844

    Write IUPAC names of all the isomers.

    Solution
    Eight isomeric amines are possible.


    Question 7
    CBSEENCH12008845

    What type of isomerism is exhibited by different pairs of amines?

    Solution

    a) CH3-CH2-CH2-CH2-NH2
    Butanamine (primary)


    b) Buta-2-amine (sec.)

    c) 2-methyl propamine (pri)

    d) 2-methylpropan-2-amine (pri)

    e) CH3-CH2-CH2-NH-CH3
    N-methylpropanamine (sec.)


    f) CH3-CH2-NH-CH2-CH3
    N-ethyl ethanamine (sec.)

    (g) N-Methyl propan-2-amine (sec.)

    h) N,N Dimethylethanamine (tert)

    (iii) The pairs (a) and (b) and (e)and (g) exhibit position isomerism.
    The pair (a) and (c); (a) and (d); (b) and (c); (b) and (d) exhibit chain isomerism.
    The Pairs (e) and (f) and (f) and (g) exhibit metamerism.

    All primary amines exhibit functional isomerism with secondary and tertiary amines and vice versa.

     

    Question 8
    CBSEENCH12008846

    How will you convert Benzene into aniline.

    Solution
    Benzene into aniline:
    stack straight C subscript 6 straight H subscript 6 with Benzene below space rightwards arrow with HNO subscript 3 divided by straight H subscript 2 SO subscript 4 on top space straight C subscript 6 straight H subscript 5 NO subscript 2 space rightwards arrow with Sn divided by HCl on top space stack straight C subscript 6 straight H subscript 5 NH subscript 2 with Aniline below
    Question 9
    CBSEENCH12008847

    How will you convert Benzene into N, N-dimethylaniline?

    Solution
    Benzene into N, N-dimethylaniline:

    Question 10
    CBSEENCH12008848

    How will you convert Cl minus left parenthesis CH subscript 2 right parenthesis subscript 4 minus Cl into hexan - 1.6-diamine?

    Solution

    Conversion of Cl minus left parenthesis CH subscript 2 right parenthesis subscript 4 minus Cl into hexan - 1.6-diamine.

    Question 11
    CBSEENCH12008849

    Arrange the following in increasing order of their basic strength:
    C2H5NH2, C6H5NH2, NH3, C6H5CH2NH2 and (C2H5)2NH

    Solution
    The increasing order of basic strength of the above amines and ammonia follows of following order:
    (C2H5)2NH > C2H5NH2 > C6H5CH2NH2 > NH3 > C6H5NH2
    Question 12
    CBSEENCH12008850
    Question 13
    CBSEENCH12008851

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    Question 18
    CBSEENCH12008856

    Write structures of different isomers corresponding to the molecular formula C3H9N. Write IUPAC names of the isomers which will liberate nitrogen gas on treatment with nitrous acid.

    Solution

    (a) CH3-CH2-CH2-NH2
    Propan-1-amine (pri)

    b) Propan -2-amine (pri)

    (c) CH3-CH2-C2H5
    N-methylethanamine (Sec)

    (d) N,N-Dimethyl methanamine (tert)

    primary amine, (a) Propan-1-amine, and (b) Propan-2-amine will liberate nitrogen gas on treatment with nitrous acid.

    Question 19
    CBSEENCH12008857

    Convert 3-Methylaniline into 3-Nitrotoluene .

    Solution

    3-methyl aniline is converted to 3-nitrotoluene by nitration reaction.

    Question 20
    CBSEENCH12008858

    Convert Aniline into 1, 3, 5-tribromobenzene.

    Solution

    Conversion of aniline to 1,3,5 -tribromobenzene.

    Question 21
    CBSEENCH12008859

    Define amines.

    Solution
    Amines is derivatives of ammonia obtained by replacement of hydrogen atom with alkyl or aryl groups.
    Question 22
    CBSEENCH12008860

    Classify the following amines as primary (1°), secondary (2°), or tertiary (3°).


    Solution
    i) Primary amine.
    ii)Primary amine.
    iii)Secondary amine.
    iv)Tertiary
    Question 23
    CBSEENCH12008861

    Give the common names of the following compounds:

    Solution
    The common name of given compound is Sec-butyl amine.
    Question 24
    CBSEENCH12008862

    Give the common names of the following compounds:

    begin mathsize 16px style bold left parenthesis bold italic C bold italic H subscript bold 3 bold right parenthesis subscript bold 3 bold N end style

    Solution
    The common name of given compound is trimethylamine.
    Question 25
    CBSEENCH12008863

    Give the common and IUPAC names of:


    Solution

    Common name: o-toluidine
    IUPAC name: 3-methyl benzenamine or 2- aminotoluene.

    Question 26
    CBSEENCH12008864

    Write the IUPAC and common name of


    Solution
    Common name: α- phenyl ethylamine
    IUPAC name: 1-phenyl ethanamine
    Question 29
    CBSEENCH12008867

    Give IUPAC name to the compound


    Solution
    2- (4'-bromophenyl) ethanamine.
    Question 30
    CBSEENCH12008868

    Write the IUPAC name of aniline.

    Solution
    Benzenamine or Phenylamine.
    Question 31
    CBSEENCH12008869

    Write the IUPAC name of CH3NH C2H5.

    Solution
    N-Methyl ethanamine.
    Question 32
    CBSEENCH12008870

    Write the IUPAC name of:


    Solution
    3, N, N- trimethyl -3-pentanamine.
    Question 33
    CBSEENCH12008871

    Write an equation of Hoffmann Bromamide reaction.

    Solution

    Hoffmann bromamide reaction is given as:
    R C O N H subscript 2 space plus B r subscript 2 space plus 4 N a O H space stack rightwards arrow R minus N H subscript 2 with space space space space space space space space on top space space space plus N a subscript 2 C O subscript 3 space plus 2 N a B r plus 2 H subscript 2 O

    Question 34
    CBSEENCH12008872

    Write the major product of the reaction when amide  is reduced with LiAlH4

    Solution

    Lithium aluminium hydride yield amines.

    Question 36
    CBSEENCH12008874

    How is aniline obtained on a large scale?

    Solution
    Aniline can be obtained on a large scale by reducing nitrobenzene with scrap iron turnings and hydrochloric acid.
    begin mathsize 16px style space space stack bold 4 bold C subscript bold 6 bold H subscript bold 5 bold N bold O subscript bold 2 with bold n bold i bold t bold r bold o bold space bold b bold e bold n bold z bold e bold n bold e below bold plus bold 9 bold italic F bold italic e bold plus bold 4 bold H subscript bold 2 bold O bold space bold rightwards arrow bold space bold space stack bold 4 bold C subscript bold 6 bold H subscript bold 5 bold N bold H subscript bold 2 with bold a bold n bold i bold l bold i bold n bold e below bold space bold plus bold space bold 3 bold italic F bold italic e subscript bold 3 bold O subscript bold 4 end style
    Question 38
    CBSEENCH12008876

    Convert benzyl bromide to β-phenyl ethylamine.

    Solution

    Conversion of benzyl bromide to β-phenyl ethylamine.

    Question 39
    CBSEENCH12008877

    Give the name of the product along with its structure when CH3NH2 reacts with an excess of CH3I.

    Solution
    The product obtained is (CH3)4 N+I- and its IUPAC name is tetramethyl ammonium iodide.

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    Question 40
    CBSEENCH12008878

    How can a carboxylic acid be converted to an amine having one carbon atom less than the carboxyl acid used?

    Solution
    The reaction of the carboxylic acid with ammonia gives amide. which on Hoffman reaction gives amine. 
    In this reaction, migration of an alkyl or aryl group takes place from carbonyl carbon of the amide to the nitrogen atom. The amine so formed contains one carbon less than that present in the amide. 
    Question 41
    CBSEENCH12008879

    Arrange the following in decreasing order of their basic strength.
    C6H5NH2, C2H5NH2, (C2H5)2NH, CH3NH2, C6H5CH2NH2, NH3

    Solution
    The decreasing order of basic strength of the above amines and ammonia follows the following order:(C6H5)2NH > C2H5NH> CH3NH2 > NH3 > C6H5CH2NH> C6H5NH2.
    Question 42
    CBSEENCH12008880

    Why are amines basic in nature?

    Solution
    Amines are basic in nature because the lone pair of electrons on the nitrogen atom (R-NH2) can be donated to electron-deficient species (acids).

    Question 43
    CBSEENCH12008881

    Why are aromatic amines weaker bases than aliphatic amines?

    Solution
    The phenyl group (C6H5) withdraws electron density from the nitrogen atom and this makes aromatic amine a weak base (mesomeric effect).
    Question 44
    CBSEENCH12008882

    Why are amines soluble in dilute mineral acids?

    Solution
    An amine forms ionic crystalline salts with dilute mineral acids..

    Question 45
    CBSEENCH12008883

    Why sulphanilic acid has high melting point?

    Solution
    Sulphanilic acid exists in zwitter ion form and hence behaves as a salt and hence has a high melting point as expected of a salt.

    Question 46
    CBSEENCH12008884

    What happens when silver chloride is treated with aqueous ethylamine?

    Solution
    Silver chloride dissolves in aqueous ethylamine due to the formation of the complex.
    AgCl + 2NH2 C2H→ [Ag (NH2 C2H5)2]+ + Cl-
    Question 47
    CBSEENCH12008885

    What is diazotization?

    Solution

    Diazotization is a process of converting aromatic amine by nitrous acid below 5° to a diazonium salt.
    NaNO2 + HCl → HNO3 + NaCl
    C6H5NH2 + HNO→ [C6H5N+ = N] Cl-

    Question 49
    CBSEENCH12008887

    How acetanilide obtained from aniline?

    Solution
    Acetanilide obtained from aniline by reacting aniline with acetic anhydride


    Question 51
    CBSEENCH12008889

    Which amine in the following pair is stronger base?

    Solution
     because isopropyl group is electron releasing whereas -COOCH3 is electron withdrawing.
    Question 52
    CBSEENCH12008890

    Which amine is the following pair is a stronger base?
    CH3CH2CH2—NH2; CH3—NH—CH2CH3

    Solution

     CH3—NH—CH2CH3 is stronger base because of greater inductive effect.

    Question 53
    CBSEENCH12008891

    Which test is used to detect the presence of primary amine?

    Solution
    Carbylamine test uses to detect the presence of a primary amine.

    Question 54
    CBSEENCH12008892
    Question 55
    CBSEENCH12008893

    Why aqueous ethylamine turns red litmus blue?

    Solution
    Aqueous ethylamine is basic in nature because of the presence of free OH- ions, hence it turns red litmus blue.
    straight C subscript 2 straight H subscript 5 straight N with.. on top straight H subscript 2 plus straight H subscript 2 straight O space rightwards arrow space space open square brackets straight C subscript 2 straight H subscript 5 NH subscript 3 close square brackets to the power of plus space plus space OH to the power of minus
    Question 56
    CBSEENCH12008894

    Why aniline dissolves in hydrochloric acid?

    Solution
    Aniline dissolves in hydrochloric acid because of the basic nature of aniline it forms salt with HCl.
    stack straight C subscript 6 straight H subscript 5 NH subscript 2 with Aniline below plus space HCl space rightwards arrow space space space stack open square brackets straight C subscript 6 straight H subscript 5 NH subscript 3 close square brackets to the power of plus Cl to the power of minus with stack Anilinium space chloride with left parenthesis Soluble space salt right parenthesis below below
    Question 57
    CBSEENCH12008895

    What happens when ethylamine is treated with methyl magnesium bromide?

    Solution
    When ethyl amine is treated with methyl magnesium bromide, methane is formed.

    Question 58
    CBSEENCH12008896

    What happens when aniline is treated with bromine?

    Solution
    2, 4, 6-Tri bromoaniline is formed, when aniline is treated with bromine.


    Question 59
    CBSEENCH12008897

    Give one test to distinguish Aniline and N-methyl aniline.

    Solution
    Aniline will give the bad smell of isocyanide when it is heated with chloroform and ale. KOH (carbylamine reaction), while N-methyl aniline does not give this test.
    stack straight C subscript 6 straight H subscript 5 NH subscript 2 with Aniline below space plus space CHCl subscript 3 plus space 3 KOH space left parenthesis aq right parenthesis space rightwards arrow space space stack straight C subscript 6 straight H subscript 5 NC with Phenyl space iso minus cyanide below space plus space 3 KCl space plus space 3 straight H subscript 2 straight O
    Question 60
    CBSEENCH12008898

    Give one use of quaternary ammonium salt.

    Solution
    Quaternary ammonium salts containing long carbon chains are used as detergents, e.g.,
    [CH2 (CH2)15N(CH3)2]+Cl-.
    Question 61
    CBSEENCH12008899

    What would be the product of controlled oxidation of aniline with K2Cr2O7 + H2SO4 ?

    Solution

    when aniline oxidised in a controlled manner in the presence ofK2Cr2O7 + H2SO4 , p Benzoquinone is formed. 

    Question 62
    CBSEENCH12008900

    Arrange the following in order of increasing basic strength. 
    Aniline, ethylamine, ethane, phenol.

    Solution
    The order of increasing basic strength:
    Phenol,< ethane,< aniline <ethylamine.
    Question 63
    CBSEENCH12008901

    Why cyclohexylamine is stronger base than aniline?

    Solution
    In aniline the electron pair of nitrogen is delocalized due to resonance, hence, it is less available for protonation, while in cyclohexylamine no delocalization of electron pair, hence it is more available for a proton.
    Question 66
    CBSEENCH12008904
    Question 67
    CBSEENCH12008905

    Write the chemical reaction of preparation of aniline from benzene ?

    Solution

    Benzene reacts with the nitric acid in presence sulphuric acid to form nitrobenzene and further reaction with S2/HCl to give aniline.

    Question 68
    CBSEENCH12008906
    Question 69
    CBSEENCH12008907
    Question 70
    CBSEENCH12008908

    An organic compound ‘A’ having the molecular formula C2H7N on treatment with nitrous acid gave an oily yellow substance. Identify ‘A’.

    Solution


    'A' is N-methyl methenamine which on reaction with nitrous acid gave yellow oil called a nitrosamine.
    Question 71
    CBSEENCH12008909

    Account for the fact that ‘before nitration, aniline is converted to acetanilide’.

    Solution
    Aniline is converted to acetanilide because aniline gets easily oxidised and nitric acid is a strong oxidising agent.
    Question 73
    CBSEENCH12008911

    Why lower aliphatic amines are soluble in water?

    Solution

    Lower aliphatic amines are soluble in water because they can form hydrogen bonds with water molecules.

    Question 76
    CBSEENCH12008914

    Tertiary amines do not undergo acylation. Why?

    Solution
    Tertiary amines, R3N, do not contain any replaceable hydrogen atom and thus cannot be acylated.
    Question 77
    CBSEENCH12008915

    Sulphanilic acid has high m.p. as well as insoluble inorganic solvent why?

    Solution
    Sulphanilic acid exists as Zwitter ion and thus due to ionic (dipolar nature) it has high m.p. as well as insoluble in inorganic solvent. 

    Question 78
    CBSEENCH12008916

    (C2H5)4N+ is neither an electrophile nor a nucleophile. Why?

    Solution
    In (C2H5)4N+, there is no electron pair on N as well as N cannot accept electrons since all the orbitals are occupied. Thus, it is neither an electrophile nor a nucleophile.
    Question 79
    CBSEENCH12008917

    The amino group in ethyl amine is basic, whereas that in acetamide, it is not basic. Why?

    Solution
    In acetamide, delocalization of lone pair of an electron on N due to resonance gives rise to lesser availability of a lone pair of the electron for coordination whereas in amines no such resonance exists.

    Thus, amino group in ethyl amine is basic.

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    Question 80
    CBSEENCH12008918

    Aniline undergoes bromination in ortho and para position but in presence of strong acid it gives m-bromo aniline. Explain.

    Solution
    -NH2 group is o- and p-directing and thus bromination of aniline gives o- and p-bromo aniline. However, in presence of strong acid, aniline combines with H+ to give C6H5NH3+ and -NH3+ m-directing and thus m-bromo products are formed.
    Question 81
    CBSEENCH12008919

    What is the correct order of decreasing boiling point of the following compounds?
    CH3 CH2 CH2 OH, CH3 CH2 CH2 NH2, CH3 CH2OCH3, CH3 CH2 NHCH3

    Solution

    The correct order is:
    CH3CH2CH2OH > CH3CH2CH2NH2 > CH3CH2NHCH3 > CH3CH2OCH3.

    Question 82
    CBSEENCH12008920

    Why is ethylamine has lower boiling point than ethyl alcohol?

    Solution
    N is less electronegative than oxygen. Therefore, the hydrogen bonds in the amine are weaker than those in ethyl alcohol. Hence, ethyl amine has lower boiling points than ethyl alcohol.
    Question 83
    CBSEENCH12008921

    Describe the hybridization and shape of (CH3)3N.

    Solution
    N in (CH3)3 N is sp3 hybridised and a bonded to the carbon of the CH, group. N also has one lone pair of electron present on it. The shape is trigonal pyramidal.

    Question 84
    CBSEENCH12008922

    Why do quaternary ammonium salts having four different group attached to nitrogen show optical activity?

    Solution
    In quaternary ammonium salts, N-has no line pair of electrons present, there is no rapid inversion. N atom is σ bonded to four alkyl group and shows optical activity.

    Question 85
    CBSEENCH12008923

    Arrange the following in decreasing basicity.

    CH3CH2NH2, CH2 = CH—NH2, (CH3CH2)2NH

    Solution
    The correct order of decreasing basicity is (CH3CH2)2NH > CH3CH2NH2 > CH2 = CH—NH2
    Question 86
    CBSEENCH12008924

    What is the evidence of basic nature of aniline?

    Solution
    Aniline (C6H5NH2) forms a salt with a concentrated hydrochloric acid, which is an evidence of the basic nature of aniline.
    straight C subscript 6 straight H subscript 5 NH subscript 2 plus HCl space left parenthesis conc. right parenthesis space rightwards arrow space space stack straight C subscript 6 straight H subscript 5 NH subscript 2. HCl with Aniline space hydrochloride below
    Question 87
    CBSEENCH12008925

    Write the reaction between aniline and benzaldehyde.

    Solution

    When aniline reacts with benzaldehyde, it forms benzylidene aniline.

    Question 90
    CBSEENCH12008928

    Give the structure and IUPAC name of the product obtained when formic acid reacts with dimethylamine .

    Solution
    The product obtained is   and its IUPAC name is N, N—Dimethyl methana-mide.
    Question 91
    CBSEENCH12008929

    Prepare methylamine from ethylamine.

    Solution

    Preparation of methylamine from ethylamine.

    Question 93
    CBSEENCH12008931

    Why is base needed in the following reaction:

    Solution

    The acid generated in the reaction can form a salt of the amine which thus will lose nucleophilic character and the reaction will not proceed to completion.

    (CH3)2NH + HCl → (CH3)2NH2⊕ClΘ
    So, a base is needed to facilitate the reaction.

    Question 94
    CBSEENCH12008932

    Phenylamine is more soluble in dilute hydrochloric acid than in water. Explain.

    Solution
    Phenylamine is more soluble in dilute hydrochloric acid than in water because it reacts with dilute hydrochloric acid to give a water soluble salt.
    Question 95
    CBSEENCH12008933

    Aniline cannot be prepared by Gabriel synthesis. Give reason.

    Solution

    Aniline cannot be prepared by this method because aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.

    Question 96
    CBSEENCH12008934
    Question 97
    CBSEENCH12008935

    Why are primary amines have higher boiling point than tertiary amines?

    Solution
    It is because primary amines are associated with intermolecular H-bonding whereas 3° amines are not.
    Question 98
    CBSEENCH12008936

    How is the basic strength of aromatic amines affected by the presence of an electron releasing group on the benzene ring ?

    Solution
    The presence of electron releasing group increases basic character of aromatic amines.
    Question 99
    CBSEENCH12008937

    Which compound is formed when benzene diazonium chloride reacts with phenol in basic medium?

    Solution
    p-Hydroxy azo benzene compound is formed, when benzene diazonium chloride reacts with phenol in basic medium.
    Question 100
    CBSEENCH12008938
    Question 101
    CBSEENCH12008939

    Name the product of the reaction of HNO2 with the CH3CH2NH2.

    Solution

    When a primary amine reacts with nitrous acid, it forms alcohol.
      CH subscript 3 CH subscript 2 NH subscript 2 space plus HNO subscript 2 rightwards arrow space stack CH subscript 3 CH subscript 2 OH with Ethanol below

    Question 102
    CBSEENCH12008940
    Question 103
    CBSEENCH12008941

    What happens when t-butylamine is treated with potassium permanganate?

    Solution
    t-Butylamine gets oxidised to form a nitro compound.


    Question 104
    CBSEENCH12008942

    Write the structures of compounds A and B.


    Solution

    Nitrobenzene on reaction with H2/pd gives aniline which on further reaction with benzaldehyde gives benzaniline.


    Question 105
    CBSEENCH12008943

    Given the reaction:
    straight R subscript 2 NH space rightwards arrow with NaNO subscript 2 plus HCl on top straight R subscript 2 straight N minus straight N space equals space straight O space plus space NOCl space plus space straight H subscript 2 straight O 

    Why is the productstraight R subscript 2 straight N space minus space NO insoluble in aqueous HCl?

    Solution
    The line pair on amine nitrogen is delocalized with the nitroso group. As a result R2N—NO does not show basic properties and hence insoluble in aqueous HCl.
    Question 106
    CBSEENCH12008944

    Complete the following:

    Solution
    The product obtained is

    Question 107
    CBSEENCH12008945

    Write the product of the following reaction:


    Solution
    The product obtained is

    Question 109
    CBSEENCH12008947

    Explain coupling reaction giving example.

    Solution

    When benzene diazonium chloride reacts with phenol in which the phenol molecules at its para position is coupled with the diazonium salt to form p-hydroxyazobenzene. This reaction is known as coupling reaction.

    Question 110
    CBSEENCH12008948

    Explain Sandmeyer’s reaction giving example.

    Solution

    The Cl–, Br– and CN– nucleophiles can easily be introduced in the benzene ring in the presence of Cu(I) ion. This reaction is called Sandmeyer reaction.

    Question 111
    CBSEENCH12008949

    Write the structure of the Zwitter ion of sulphanilic acid.

    Solution
    The Sulphanilic acid is   and the structure of Zwitter ion is .
    Question 112
    CBSEENCH12008950

    What happens when n-pentyl nitrite reacts with aniline in the presence of HCl in ice-cold solution?

    Solution
    Benzene diazonium chloride is formed, when n-pentyl nitrite reacts with aniline in the presence of HCl in ice-cold solution.

    Question 113
    CBSEENCH12008951

    Convert aniline into chlorobenzene.

    Solution

    Conversion of aniline into chlorobenzene is as follow;

    Question 114
    CBSEENCH12008952
    Question 115
    CBSEENCH12008953

    What is the structure of compound A?
    2 comma space 4 space nitro space benzene rightwards arrow from left parenthesis ii right parenthesis space anisole to left parenthesis straight i right parenthesis space NaNO subscript 2 plus HCl space 0 minus 4 degree straight C of straight A

    Solution

    The structure of compound A is

    Question 116
    CBSEENCH12008954

    How does the formation of 2° and 3° amines can be avoided during the preparation of 1° amine by alkylation?

    Solution
    Use of excess ammonia reduces chances of reaction of 1° amine with alkyl halide to form 2° and 3° amines.
    Question 117
    CBSEENCH12008955

    Compare the reactions of MeN and Ph3N with BF3.

    Solution
    Trimethylamine acts as a Lewis base and reacts with BF3 (A Lewis acid), while triphenylamine does not react with BF3 because the electron pair of N needed to react with B is delocalised to three benzene rings.
    Question 118
    CBSEENCH12008956

    Why is it preferred to use methanol (and not methyl iodide HCHO or HCOOH) for preparing C6H5N(CH3)2 from aniline ?

    Solution

    Use of CH3I forms C6H5—N+ (CH3)3I- as a by-product. While the use of CH2O and HCOOH forms the intermediate electrophile, CH2OH which in turn can attack the activated benzene ring to give
    p-NH2, C6H4, CH2OH.

    Question 119
    CBSEENCH12008957

    Sulphanilic acid is insoluble in water and organic solvents. Explain. 

    Solution
    Sulphanilic acid is ionic in nature and therefore, it is insoluble in organic solvents. Its insolubility in water is typical of dipolar salts. Not all such salts dissolve in water.

    Sponsor Area

    Question 120
    CBSEENCH12008958

    Account for the correct order of decreasing basicity of ethylamine, 2-amino ethanol and 3-amino-1-propanol.

    Solution

    The correct order of decreasing basicity is:
    CH3CH2NH2 > HO(CH2)3NH2 > HO(CH2)2NH2
    The electron withdrawing group -OH decreases the electron density on N, lowering its basicity. This effect decreases when the distance from amino group increases.

    Question 121
    CBSEENCH12008959

    Why the order of boiling of isomeric amines are Primary > Secondary > Tertiary ?

    Solution

    Primary amines and secondary amines are engaged in intermolecular association due to hydrogen bonding between the nitrogen of one and hydrogen of another molecule. This intermolecular association is more in primary amines than in secondary amines as there are two hydrogen atoms available for hydrogen bond formation in it. Tertiary amines do not have intermolecular association due to the absence of hydrogen atom available for hydrogen bond formation. Therefore, the order of boiling points of isomeric amines is as.
    Primary > Secondary > Tertiary

     

    Question 122
    CBSEENCH12008960

    Give industrial application of diazotization.

    Solution
    In preparing azo dyes and  as a indicators (e.g., methyl orange).
    Question 124
    CBSEENCH12008962

    Giving a reason, arrange the following amines in order of decreasing basicity.

    Solution
    The correct order is:

    The -I effect of F decreases the electron density of N atom and decreasing the basicity of amines. But the -I effect of F decrease as it moves always from the amine group and therefore increases the basicity.
    Question 125
    CBSEENCH12008963

    Write the conjugate acid and conjugate base of:


    Solution
    Conjugate acid:

    Conjugate base:

    Question 126
    CBSEENCH12008964

    Complete the reaction:
    CH3NH2 + H2O →

    Solution
    CH3NH2 + H2O ⇌ CH3NH3+ + OH-
    Question 127
    CBSEENCH12008965

    Complete the reaction:
    CH3CHNH2 + HCl(g) →

    Solution
    CH3CH2NH2 + HCl(g) → CH3CH2NH3+Cl-
    Question 128
    CBSEENCH12008966

    How will you purify aniline containing non-basic impurities ?

    Solution
    Aniline is of basic nature. In order to remove non-basic impurities, it is treated with dilute HCl when aniline forms non-volatile hydrochloride. The impurities can be removed by distillation. From the hydrochloride, aniline can be regenerated by reacting with a base such as sodium hydroxide.
    Question 129
    CBSEENCH12008967

    Write the structure of the isomeric aromatic amines with formula C7H9N and give their IUPAC names.

    Solution
    Five Isomeric aromatic amines are possible. These are given below.

    Question 131
    CBSEENCH12008969
    Question 132
    CBSEENCH12008970
    Question 133
    CBSEENCH12008971

    Give IUPAC names of the following compounds according to IUPAC system:



    Solution
    N-Ethyl-N-Methyl propan-1-amine.
    Question 134
    CBSEENCH12008972
    Question 135
    CBSEENCH12008973

    Write common name of the following compounds:



    Solution
    o-amine benzoic acid.
    Question 136
    CBSEENCH12008974

    Write common name of the following compounds:





    Solution
    p-methoxy aniline (or p-anisidine).
    Question 137
    CBSEENCH12008975

    Write common name of the following compounds:
    left parenthesis CH subscript 3 right parenthesis subscript 3 CCH subscript 2 NH subscript 2



    Solution
    neopentylamine
    Question 138
    CBSEENCH12008976

    Write common name of the following compounds:






    Solution
    Sec-butyl dimethylamine.
    Question 139
    CBSEENCH12008977

    Draw structures for the following compound:
    N-isopropylaniline.

    Solution

     Structure of N-isopropylaniline is;

    Question 140
    CBSEENCH12008978

    Draw structures for the following compound:
    p-toluidine

    Solution

    Structure of p-toluidine is given below.

    Question 141
    CBSEENCH12008979

    Draw structure for the following compound:
    t-butylamine

    Solution

    Structure of t-butylamine is,

    Question 142
    CBSEENCH12008980

    Draw structures for the following compound:
    p-amino acetophenone.

    Solution

    Structure of p-amino acetophenone is given as,

    Question 143
    CBSEENCH12008981

    Write IUPAC names of the compounds given below:

    Solution
    N-(1-methylethyl)-Aniline.
    Question 144
    CBSEENCH12008982

    Write IUPAC names of the compounds given below:
    p-toluidine

    Solution
    4-Methyl benzenamine
    Question 145
    CBSEENCH12008983

    Write IUPAC names of the compounds given below:
    t-butylamine.

    Solution
    2-Methyl propan-2-amine
    Question 146
    CBSEENCH12008984

    Write IUPAC names of the compounds given below:
    p-amino acetophenone.

    Solution
    1-(4-amino phenyl) ethanone
    Question 147
    CBSEENCH12008985

    Write IUPAC names of the compounds given below:

    Solution
    Trimethyl phenyl ammonium nitrate
    Question 148
    CBSEENCH12008986

    Write IUPAC names of the compounds given below:
    left parenthesis CH subscript 3 right parenthesis subscript 4 straight N to the power of plus Cl to the power of minus

    Solution
    Tetra methyl ammonium chloride
    Question 149
    CBSEENCH12008987

    Write IUPAC names of the compounds given below:


    Solution
    Ethyl trimethyl ammonium hydroxide.
    Question 150
    CBSEENCH12008988
    Question 152
    CBSEENCH12008990

    Explain Gabriel phthalimide synthesis.

    Solution
    Gabriel phthalimide synthesis is used for preparing only primary amines. Phthalimide is first treated with KOH and then with an alkyl halide to form N-alkyl phthalimide. N-alkyl phthalimide on hydrolysis gives primary amine.

    Question 153
    CBSEENCH12008991
    Question 156
    CBSEENCH12008994

    Write structure and IUPAC name of the amide which gives propanamine by Hoffmann bromamide reaction.

    Solution
    Propanamine contains three carbons. Hence, the amide molecule must contain four carbons. Structure and IUPAC name of the starting amide with four carbon atoms is given below:

    Question 157
    CBSEENCH12008995

    Write structure and IUPAC name of the amide produced by the Hoffmann degradation of benzamide.

    Solution
    Benzamide is an aromatic amide containing seven carbon atoms. Hence, the amine formed from benzamide is aromatic primary amine containing six carbon atoms.

    Question 158
    CBSEENCH12008996

    Why is aniline weaker base than cyclohexylamine?

    Solution
    In aniline (C6H5NH2), the phenyl group (C6H5) is an electron withdrawing group and therefore decreases electron availability on the nitrogen of - NH2 group and thus makes it a weaker base. In cyclohexylamine, the cyclohexyl group (non-aromatic) is an electron releasing group and thus increases electron density on the nitrogen of - NH2 group and makes it a stronger base than aniline (Inductive effect).


    Question 160
    CBSEENCH12008998

    How will you make the following conversions?
    Ethanoic acid to Dimethylamine

    Solution

    Conversion of ethanoic acid to dimethylamine.

    Question 164
    CBSEENCH12009002
    Question 165
    CBSEENCH12009003
    Question 166
    CBSEENCH12009004
    Question 167
    CBSEENCH12009005
    Question 168
    CBSEENCH12009006

    Explain what happens when aniline reacts with a mixture of sulphuric acid and nitric acid?

    Solution
    Being a strong oxidising agent, HNO3 oxides aniline into tert oxidation product on treating it with conc. H2SO4 and HNO3. However, under controlled conditions, m-nitroaniline is formed along with some amount of p-nitroaniline. This is due to the reason that under strongly acidic conditions — NH, a group of aniline is converting into —NH3+(anilinium ion) which is m-directing, thus the major product is m-nitroaniline.

    Question 169
    CBSEENCH12009007

    Identify compound A to D:

    Solution

    Question 173
    CBSEENCH12009011

    Account for the following:
    Aqueous solution of methyl amine reacts with iron (III) chloride to precipitate iron (III) hydroxide.

    Solution
    Methalamine is basic in nature, therefore, forms OH- which gives radish brown ppt. with FeCl3 to form Ferric hydroxide.

    Question 174
    CBSEENCH12009012

    Why it is not possible to separate the enantiomers?

    Solution
    It is not possible to separate the enantiomers due to rapid nitrogen inversion. This inversion does not involve bond breaking or bond formation.
    Question 175
    CBSEENCH12009013
    Question 177
    CBSEENCH12009015

    Arrange the following set of amines in order of increasing pKa values:


    Solution
    Basicity and the pKvalues are directly related

    Question 178
    CBSEENCH12009016

    Arrange the following set of amines in order of increasing pKa values:




    Solution
    Basicity and the pKvalues are directly related

    Question 179
    CBSEENCH12009017
    Question 180
    CBSEENCH12009018

    Illustrate  the following with an example of reaction:
    Diazotization reaction.

    Solution
    Diazotization reaction: The conversion of primary amine aromatic amines into diazonium salts is known as diazotisation. in this reaction primary amine react with nitrous acid with hydrochloric acid in presence of 0-50 C.

    Question 182
    CBSEENCH12009020

    Identify the substances A and B in each of the following sequences of reactions:
    CH3CONH2 is a weaker base than CH3CH2NH2

    Solution
    In CH3CONH2 the lone pair on N is delocalized with the carbonyl group. As a result, electron density on N decreases basicity decreases.


    While in CH3CH2—NH2, ethyl group is electron releasing makes the amine more basic than CH3CONH2.
    Question 183
    CBSEENCH12009021

    ROH is a stronger acid than RNH2.

    Solution
    O is more electro negative than N, therefore, electron density around H of RO—H group is less as compared to H of RNH—H. Hence, H from alcohol can easily be removed as H+ and is more acidic than RNH2.
    Question 184
    CBSEENCH12009022

    Show how p-amino azobenzene can be prepared from aniline?

    Solution

    Conversion of p-amino azobenzene from aniline.

    Question 185
    CBSEENCH12009023

    Explain the following reactions by taking one suitable example in each case:
    Hoffmann's bromamide reaction.

    Solution
    Hoffmann’s Bromamide Reaction. When an amide (aliphatic or aromatic) is treated with bromine in an alkali solution, it is converted to a primary amine that has one carbon atom less than the starting amide.

    This reaction is extremely useful for stepping down (or descending) homologous series.
    Question 186
    CBSEENCH12009024

    Explain the following reactions by taking one suitable example in each case:
    Gattermann’s reaction.

    Solution
    Gatterman’s reaction: When benzene diazonium salt is treated with Cu/HCl or Cu/HBr, chlorobenzene or bromobenzene is formed. The yield is about 40%.

    Question 187
    CBSEENCH12009025

    How is ethylamine prepared from acetonitrile? Compare its basic character with that of ammonia.

    Solution
    Ethylamine can be obtained from acetonitrile by its reduction.

    Ethylamine is a stronger base than ammonia. This is due to the fact that methyl group is electron donating group, and it tends to increase the electron density a N—atom (+I effect). This leads to an increase in the basic strength of ethylamine as compared to ammonia.
    Question 188
    CBSEENCH12009026

    How is aniline prepared commercially? Describe carbylamines test for primary amines.

    Solution
    Aniline is prepared commercially by the reduction of nitrobenzene using iron and hydrochloric acid.

    Because of the presence of hydrochloric acid in the reaction mixture actually aniline hydrochloride (C6H5NH3+Cl-) is obtained. This on treatment with aqueous sodium carbonate gives aniline.

    Carbylamine test for primary amines:
    Primary amines, both aliphatic and aromatic, give carbylamines having a pungent smell, when heated with chloroform and alcoholic potash.
    Question 189
    CBSEENCH12009027

    Describe the method for the identification of primary, secondary and tertiary amines. Also write chemical equations of the reactions involved.

    Solution

    The three types of amines can be distinguished by Hinsberg method. The sample is treated with benzene sulphonyl chloride, C6H5SO2Cl (Hinsberg’s reagent) followed by treatment with aqueous KOH (5%) solution. Based upon the observations, the following conclusions may be drawn:
    (i) If a clear solution is obtained , then it is a primary amine.
    (ii) If the solution is turbid or ppt appears and remains unaffected by the addition of an acid, the given amine is a secondary amine.
    (iii) If the sample remains insoluble in alkali and dissolves in an acid, then it is a tertiary amine.

    The secondary amine forms dialkyl sulphonamide which is insoluble in alkali

    Tertiary amine do not react with Hinsberg’s reagent. They do not dissolve in alkali, but dissolve in acid.

    Question 190
    CBSEENCH12009028
    Question 191
    CBSEENCH12009029
    Question 192
    CBSEENCH12009030
    Question 193
    CBSEENCH12009031
    Question 194
    CBSEENCH12009032

    Write IUPAC names of following and classify them into primary, secondary, tertiary amines:
    C6H5NHCH3

    Solution

    N-Methylbenzamine or N-methylaniline (20 amine)

    Question 195
    CBSEENCH12009033

    Write IUPAC names of following and classify them into primary, secondary, tertiary amines:
    (CH3CH2)2NCH3

    Solution

    (CH3CH2)2 NCH3

    N-Ethyl-N-methylethanamine (30 amine)

     
    Question 196
    CBSEENCH12009034
    Question 197
    CBSEENCH12009035

    Give one chemical test to distinguish between the following pairs of compounds.
    Methylamine and diethylamine.



    Solution
    Heat both these amines with chloroform and alcohol KOH solution. The compound which gives unpleasant (offensive) smell is methylamine while the compound which does not give any smell is diethylamine.

    Question 198
    CBSEENCH12009036

    Give one chemical test to distinguish between the following pairs of compounds.
    Secondary and tertiary amines.

    Solution

    Shake the given amines separately with Hinsberg’s reagent (benzene sulphonyl chloride) in the presence of an excess of aqueous KOH solution.
    A secondary amine forms N,N—dialkyl benzene sulphonamide which remains insoluble in aqueous KOH and even after acidification with dilute HCl.

    A tertiary amine does not react with benzene sulphonyl chloride and remains insoluble in aqueous KOH.

    Question 199
    CBSEENCH12009037

    Give one chemical test to distinguish between the following pairs of compounds.
    Ethylamine and aniline 

    Solution

    Ethylamine and aniline: To the ice cold solution of both these compounds prepared in excess of dilute HCl, add ice cold solution of sodium nitrite in water and of β—Naphthol (2—Naphthol) prepared in diluted in sodium hydroxide solution.
    Further, cool the reaction mixture in both the cases. The mixture which forms a brilliant orange dye (azodye) contains aniline while the one in which no dye is formed has ethylamine present in it.

    Question 200
    CBSEENCH12009038

    Give one chemical test to distinguish between the following pairs of compounds.
    Aniline and benzylamine

    Solution
    Aniline and benzylamine: Add NaNO2 and HCl to each separately. Cool, it to 0-5°C. Then add an alkaline solution of phenol. Orange azo dye is formed in aniline. Benzylamine (C6H5CH2NH2) does not form an azo dye. 
    Question 201
    CBSEENCH12009039

    Give one chemical test to distinguish between the following pairs of compounds.
    Aniline and N — methlyaniline.

    Solution
    Aniline and N—Methylaniline Carbylamine test: Heat both the compounds separately with chloroform and alcoholic KOH. The compound which gives an unpleasant or offensive smell in aniline while the compound which does not give any smell is N-Methylaniline.

    Question 202
    CBSEENCH12009040

    Account for the following:
    pKb of aniline is more than that of methylamine.

    Solution
    It is because, in aniline, the NH2 group is attached directly to the benzene ring. It results in the unshared electron pair of the nitrogen atom to be in conjugation with the benzene ring and thus making it less available for protonation.
    on another hand, in the case of methylamine (due to the +I effect of a methyl group), the electron density on the N-atom is increased. As a result, aniline is less basic than methylamine. Thus, pkb of aniline is more than that of methylamine 
    Question 203
    CBSEENCH12009041

    Account for the following:
    Ethylamine is soluble in water, whereas aniline is not.

    Solution
    In C2H5NH2, the C2H5 group has a + I effect and increases the electron density on N atom. This results in stronger intermolecular H-bonding. While in C6H5NH2 due to resonance, N acquires a +ve charge and electron density on N decreases. The tendency to form H-bonding diminishes. Hence, ethylamine is soluble while C6H5NH2 is insoluble.
    Question 204
    CBSEENCH12009042

    Account for the following:
    Methylamine in water reacts with ferric chloride to precipitate ferric hydroxide.

    Solution

     

    Due to the +I effect of -CH3 group, methylamine is more basic than water. therefore, in water methylamine produces OH- ions by accepting H+ ions form water.

    Methyl amine is a base and dissolves in water to produce hydroxide ions.
    CH3 NH2 + H2O ⇌ CH3 NH3 + OHΘ
    FeCl3 combines with OH- ions to give reddish brown precipitate of Fe (OH)3
    FeCl3 + 3OH→ Fe(OH)3

     

    Question 205
    CBSEENCH12009043

    Account for the following:
    Although amino group is o- and p-directing for aromatic electrophilic substitution reaction, aniline on nitration gives a substantial amount of m-nitro aniline.

    Solution
    The nitration of aniline is carried out using conc. HNO3 and H2SO4. However, in the presence of conc. H2SO4, aniline forms aniline hydrogen sulphate in which the anilinium ion, C6H5NH3+ is meta directing because the positive charge on the nitrogen attracts electrons from the benzene ring.
    Question 206
    CBSEENCH12009044

    Account for the following:
    Aniline does not undergo Friedel Craft's reaction.

    Solution

    a Friedel -crafts reaction is carried out in the presence of AlCl3. but AlCl3 is acidic in nature, while aniline is a strong base. Thus, aniline reacts with AlCl3 to form a salt. Due to the positive charge on the N-atom, electrophilic substitution in the benzene ring is deactivated.Hence, aniline does not under go the Friedel-crafts reactions.

    Aniline does not under Friedel-Craft reaction (alkylation and acetylation) due to the salt formation with aluminium chloride, the Lewis acid which is used as a catalyst. Due to this, the nitrogen of aniline acquires a positive charge and hence acts as a strong deactivating group for further reaction.
    Question 207
    CBSEENCH12009045

    Account for the following:
    Diazonium ions of aromatic amines are more stable than those of aliphatic amines.

    Solution
    Primary aliphatic amines form a highly unstable alkyl diazonium salts. Primary aromatic amines form arene diazonium salts which are stable for a short time in solution at low temperature (273— 278 K). The stability of diazonium ions of aromatic amines is explained on the basis of resonance.

    Question 208
    CBSEENCH12009046

    Account for the following:
    Gabriel phthalimide synthesis is preferred for the synthesizing amines.

    Solution
    Gabriel phthalimide synthesis results in the formation of primary amine only. secondary or tertiary amines are not formed in this synthesis. thus, the pure primary amine can be obtained. Therefore, Gabriel phthalimide synthesis is preferred for synthesising primary amines.
    Phthalimide is alkylated with alkyl or benzyl halide and then hydrolysed or hydrazinolysis to get pure primary amine. In this method, phthalic acid is produced which can be again converted into phthalimide and used over and over again.
    Question 209
    CBSEENCH12009047
    Question 210
    CBSEENCH12009048

    Arrange the following:
    In decreasing order of basic strength:
    C
    6H5NH2, C6HsN(CH3)2, (C2H5)2NH and CH3NH2

    Solution
    CH3NH2 > (C2H5)2 NH > C6H5N(CH3)> C6H5 NH2
    Question 211
    CBSEENCH12009049

    Arrange the following:
    In increasing order of basic strength:
    (a) Aniline, p-nitroaniline and p-toluidine
    (b) C6H5NH2, C6H5NHCH3, C6H5CH2NH2

    Solution

    (i) p-nitro aniline < aniline < p-toluidine.
    (ii) C6H5NHCH3 < C6H5NH2 < C6H5CH2NH2.

    Question 212
    CBSEENCH12009050
    Question 213
    CBSEENCH12009051

    Arrange the following:
    Increasing order of boiling point C2H5OH, (CH3)2NH, C2H5NH2

    Solution
    Increasing order of given :
    (CH3)2NH < C2H5NH2 < C2H5OH
    Question 214
    CBSEENCH12009052
    Question 215
    CBSEENCH12009053

    How will you convert:
    Ethanoic acid into methanamine.

    Solution
    Ethanoic acid into methanamine.
    stack CH subscript 3 COOH with Ethanoic space acid below plus space stack HN subscript 3 with Hydrazoic space acid below space rightwards arrow from warm to conc. space straight H subscript 2 SO subscript 4 of space stack CH subscript 3 NH subscript 2 with Methanamine below plus CO subscript 2 plus straight N subscript 2
    Question 216
    CBSEENCH12009054

    How will you convert:
    Hexanenitrile into 1-aminopentane

    Solution
    Hexane nitrite into 1-amino pentane

    Question 217
    CBSEENCH12009055

    How will you convert:
    Methanol to Ethanoic acid.

    Solution
    Conversion of methanol to Ethanoic acid.

    Question 218
    CBSEENCH12009056

    How will you convert:
    Ethanamine into methanamine.

    Solution
    Conversion of Ethanamine into Methanamine.

    Question 219
    CBSEENCH12009057

    How will you convert:
    Ethanoic acid into propanoic acid.

    Solution
    Conversion of Ethanoic acid into Propanoic acid

    Question 220
    CBSEENCH12009058

    How will you convert:
    Methanamine into ethanamine.

    Solution
    Conversion of Methanamine into Ethanamine.

    Question 221
    CBSEENCH12009059

    How will you convert:
    Nitromethane into dimethylamine

    Solution
    Nitromethane into dimethylamine

    Question 222
    CBSEENCH12009060

    How will you convert:
    Propaonic acid into ethanoic acid?

    Solution
    Propanoic acid into ethanoic acid.

    Question 223
    CBSEENCH12009061

    Write short notes on the following:
    Carbylamine reaction.

    Solution
    Carbylamine reaction: The carbylamines reaction test used for detection of primary amines. In this reaction, the analyte/given compound is heated with alcoholic potassium hydroxide and chloroform. If a primary amine is present, the isocyanide(carbylamines) is formed which gives unpleasant smell.

    Question 224
    CBSEENCH12009062

    Write short notes on the following:
    Diazotization.

    Solution
    Diazotization: It is a process of treating primary aromatic amine with nitrous acid at 273 — 278 K to get diazonium salts which are very useful compounds.

    They are used to prepare benzene, phenol, halo-arenes, cyano benzene, dyes, etc.
    Question 225
    CBSEENCH12009063

    Write short notes on the following:
    Hoffmann’s bromamide reaction

    Solution
    Hoffmann bromamide degradation reaction: Hoffman develops a method for preparation of primary amines by treating an amide with bromine in an aqueous or ethanolic solution of sodium hydroxide.
    In this reaction migration of an alkyl or aryl group takes place from carbonyl carbon of the amide to the nitrogen atom. The amine so formed contains one carbon less than that present in the amide.

    Question 226
    CBSEENCH12009064

    Write short notes on the following:
    Coupling reaction

    Solution

    Coupling reaction: When benzene diazonium chloride reacts with phenol in which the phenol molecule at its para position is coupled with coupled with the diazonium salt to form p-hydroxyazobenzene. This is known as coupling reaction.

     
    Question 227
    CBSEENCH12009065

    Write short notes on the following:
    Ammonolysis

    Solution

    Ammonolysis: Alkyl halide reacts with ammonia to form primary amine. The reaction of ammonia with alkyl halide is known as ammonolysis.
    CH3Cl + NH→ CH3NH2.HCl
    CH3NH2.HCl + NH→ CH3NH2 + NH4Cl

    Question 228
    CBSEENCH12009066

    Write short notes on the following:
    Acetylation 

    Solution
    Acetylation: The process, in which acetyl group   is introduced, is called acety lation. It is done by reaction with acetyl chloride or acetic
    anhydride.
    Aliphatic and aromatic primary and secondary amines undergo acetylation reaction by nucleophilic substitution when treated with acid chlorides, anhydrides or esters. 

    Question 229
    CBSEENCH12009067

    Write short notes on the following:
    Gabriel phthalimide synthesis

    Solution
    Gabriel phthalimide synthesis: Primary amines can be prepared by this process. In this process, phthalimide is reacted with alcoholic KOH to get potassium phthalimide which reacts with an alkyl halide to form N-alkyl phthalimide which on basis hydrolysis gives primary amine and phthalic acid. Phthalic acid can be reused to get phthalimide.

    Question 231
    CBSEENCH12009069

    Accomplish the following conversions:
    Benzene to m-bromophenol

    Solution
    Benzene to m-bromophenol

    Question 232
    CBSEENCH12009070

    Accomplish the following conversions:
    Benzoic acid to aniline

    Solution
    Benzoic acid to aniline


    Question 233
    CBSEENCH12009071

    Accomplish the following conversions:
    Aniline to 2, 4, 6-tribromo aniline

    Solution
    Aniline to 2, 4, 6-tribromo aniline


    Question 234
    CBSEENCH12009072

    Accomplish the following conversions:
    Benzyl chloride to 2-phenylethanamine.

    Solution
    Benzyl chloride to 2-phenyl ethanamine.

    Question 235
    CBSEENCH12009073

    Accomplish the following conversions:
    Chlorobenzene to p-chloroaniline

    Solution
    Chlorobenzene to p-bromo aniline

    Question 236
    CBSEENCH12009074

    Accomplish the following conversions:
    Aniline to p-bromoaniline

    Solution
    Aniline to n-bromo aniline

    Question 237
    CBSEENCH12009075

    Accomplish the following conversions:
    Benzamide to toluene

    Solution

    Conversion of Benzamide to toluene;

    Question 238
    CBSEENCH12009076

    Accomplish the following conversions:
    Aniline to benzyl alcohol.

    Solution

    Aniline to benzyl alcohol

     
    Question 251
    CBSEENCH12009089
    Question 253
    CBSEENCH12009091

    Why cannot aromatic primary amines be prepared by Gabriel pthalimide synthesis?

    Solution
    Aromatic primary amines cannot be prepared by Gabriel phthalimide synthesis because it used for the preparation of aliphatic primary amines. It involves nucleophilic substitution (SN2) of alkyl halides by the anion formed by the phthalimide. But aryl halides do not undergo nucleophilic substitution with the anion formed by the phthalimide.
    Hence, aromatic primary amines cannot be prepared by  Gabriel pthalimide synthesis.
    Question 254
    CBSEENCH12009092

    Write the reactions of (i) aromatic, (ii) aliphatic primary amines with nitrous acid.

    Solution
    (i) Primary aromatic amines such as aniline react with nitrous acid under ice cold conditions (273-278 K) to form benzene diazonium salt. The reaction is known as diazotization reaction.

    (ii) Primary aliphatic amines react with nitrous acid at low temperature to form primary alcohol and nitrogen gas accompanied by risk effervescence. For example
     
    Question 255
    CBSEENCH12009093

    Give plausible explanation for each of the following:
    Why are amines less acidic than alcohols of comparable molecular masses?

    Solution

    Oxygen in alcohol is more electro negative than nitrogen in amines. RC —H bond in alcohol is more polar with δ+ charge on
    ROδ-Hδ+ as compared to RN—H bond in Alcohols can loose proton to some extent but are proton acceptors.

    Question 256
    CBSEENCH12009094

    Give plausible explanation for each of the following:
    Why are primary amines higher boiling than tertiary amines?

    Solution
    Amines are polar compounds and can form H-bonds as proton acceptors. Only primary and secondary amines can form intermolecular H-bonding due to the presence of H atom at N atom. Tertiary amines cannot form intermolecular in-bonding. Primary amines are higher boiling due to the presence of a stronger intermolecular force of attraction due to H-bonding.

    Question 257
    CBSEENCH12009095

    Give plausible explanation for each of the following:
    Why are aliphatic amines stronger bases than aromatic amines? 

    Solution
    In aliphatic amines, alkyl groups are electron releasing and increases the electron pair availability at N atom while aryl group in aromatic amines are electron withdrawing decreasing the availability of electron pair at N atom.

    Question 258
    CBSEENCH12009096
    Question 259
    CBSEENCH12009097
    Question 260
    CBSEENCH12009098
    Question 261
    CBSEENCH12009099
    Question 262
    CBSEENCH12009100
    Question 263
    CBSEENCH12009101

    Account for the fact that:
    Sulphanilic acid is feebly basic.

    Solution
    Sulphanilic acid exists largely in the form of an internal salt or Zwitter ion in which the hydrogen ion from the sulphonic acid group has been transferred to the amino group. As a result, the basicity of the amino group is lost.


    Question 264
    CBSEENCH12009102

    Account for the fact that:
    p-nitroaniline is a weak base.

    Solution
    There is an important resonance interaction between the amino and nitro groups in p-nitroaniline as shown.

    Because of the contribution of this structure to the actual state of the molecule, there is a greater loss of resonance energy when p-nitro aniline is converted to its conjugate base p-NH3.C6H4.NO2 than when aniline is converted to the anilinium ion, NH3+C6H5. Hence, p-nitroaniline is a weaker base than aniline which itself is a weak base.
    Question 265
    CBSEENCH12009103

    How will you convert aniline to chlorobenzene.

    Solution

    Conversion of chlorobenzene from aniline.
    straight C subscript 6 straight H subscript 5 NH subscript 2 space rightwards arrow with NaNO subscript 2 divided by HCl on top space straight C subscript 6 straight H subscript 5 straight N subscript 2 to the power of plus Cl to the power of minus space rightwards arrow with Cu subscript 2 Cl subscript 2 divided by HCl on top space straight C subscript 6 straight H subscript 5 Cl

    Question 267
    CBSEENCH12009105

    How will you convert aniline to iodobenzene .

    Solution

    Conversion of Iodobenzene from aniline.

    Question 268
    CBSEENCH12009106
    Question 269
    CBSEENCH12009107
    Question 270
    CBSEENCH12009108
    Question 271
    CBSEENCH12009109

    Explain how does the presence or absence of hydrogen on N of amines affect the modes of their reactions with nitrous acid?

    Solution

    If‘N’ is attached with 2 atoms of hydrogen, we get alcohol and nitrogen gas.
    If ‘N’ is attached to 1 atom of hydrogen, we get the yellow oily compound , nitroso amines by replacing one H by NO.
    If nitrogen is not attached with hydrogen, this protonation of tertiary amines will take place to form salt soluble in water.

    Question 272
    CBSEENCH12009110

    Why does bromination of aniline, even under very mild conditions give 2, 3, 5-tribromo aniline instantaneously?

    Solution
    NH2-group of aniline greatly activates the benzene ring, because of which the electron density at ortho positions correct (at 2 and 6) and para position (at 4 positions) increases appreciably. Thus, under very mild conditions, even in the absence of a catalyst, aniline instantaneously get brominated at both the ortho position and para position to give a white precipitate.

    Question 273
    CBSEENCH12009111

    Why is an amide more acidic than an amine?

    Solution
    Amides are less basic than amine because unlike amines the lone pair of nitrogen in amide is not always available with nitrogen due to the following resonating structures:

    In structure (II), a positive charge is developed on nitrogen because of which it can liberate a proton and shows acidic character.
    2CH3CONH2 + HgO → (CH3CONH)2 + HgO

    Question 274
    CBSEENCH12009112

    mention the chief use of quaternary ammonium salts derived from long chain amines.

    Solution

    The quaternary ammonium salts derived from long chain aliphatic amines are used as detergents. i.e. CH3(CH2)15N+(CH3)2Cl-

    Question 276
    CBSEENCH12009114

    Arrange the isomeric compounds:
    (i) Ethyldimethyl amine
    (ii) n-butyl amine
    (iii) diethyl amine
    in order of decreasing boiling point and give reason.

    Solution

    The correct order is II > III > I
    (II) is a 1° amine (III) is 2° amine and can associate via intermolecular hydrogen bonding. But 1° amine has two H present at N-atom, therefore, more hydrogen bonding. Hence, (II) has a higher boiling point than (III)
    (I) is a 3° amine, there is no H present on N atom, no H-bonding present. Hence, (I) has a lowest boiling point.

    Question 277
    CBSEENCH12009115

    Explain the following general order of basicity in aqueous solution:
    R2NH > RNH> R3N > NH3

    Solution

    Two effects: inductive and the solvation effect determines the basicity of alkyl amines.
    As the number of alkyl group (electron releasing group with +I effect) increases, making the amine more basic. So, in terms of inductive effect, increasing the number of R's should increase the basicity.
    Solvation is present only in the conjugate acid, more the number of H present in the conjugate acid more the H-bonding and more the stabilisation. Therefore the R' increases, the number of H-s in the conjugate acid decreases, solvation decreases. Hence, basicity should decrease.
    The inductive and solvation effect both works in opposite direction. Inductive effect dominates to make all three amines stronger bases than NH3.
    While in R3N solvation effect dominates over the inductive effect.

    Question 278
    CBSEENCH12009116

    Explain the following general order of basicity in aqueous solution:
    R3N ,R2NH , RNH2
    What will be the basic strength order of these amines in gas phase?

    Solution

    In the gas phase there is no solvation effect, only the number of R's and their inductive effect determines the basicity.
    More the number of R's, more the basicity. The basicity order will be their,
    R3N > R2NH > RNH2

    Question 279
    CBSEENCH12009117

    How can you find out whether a given amine is a primary amine? Write the chemical reaction involved in the test you perform.

    Solution
    Primary amines when warmed with chloroform and an alcoholic solution of KOH, forms isocyanide or carbylamines which have very unpleasant smell.

    Question 280
    CBSEENCH12009118

    How can you separate a mixture of primary, secondary and tertiary amines? Write chemical reactions involved in the process.

    Solution

    Hinsberg test is employed to separate primary, secondary and tertiary amines from a mixture. In this test the mixture of amines is treated with benzene sulphonyl chloride C6H5SO2Cl (Hinsberg’s reagent) followed by treatment with aqueous KOH (5%) solution and then shaken with ether in a separatory funnel.
    (a) The primary amine reacts forming mono alkyl sulphonamide which is soluble in alkali forming a potassium salt which forms the lower aqueous layer.
    straight C subscript 6 straight H subscript 5 SO subscript 2 Cl plus RNH subscript 2 space rightwards arrow space space stack straight C subscript 6 straight H subscript 5 SO subscript 2 NHR plus HCl with Monoalkylsulphonamide below
straight C subscript 6 straight H subscript 5 SO subscript 2 NHR space plus space KOH space rightwards arrow space space stack straight C subscript 6 straight H subscript 5 SO subscript 2 NKR plus straight H subscript 2 straight O with Potassium space salt below
    (b) The secondary amine reacts forming dialkylsulphonamide which is insoluble in alkali.
    straight C subscript 6 straight H subscript 5 SO subscript 2 Cl plus straight R subscript 2 NH space rightwards arrow space space stack straight C subscript 6 straight H subscript 5 SO subscript 2 NR subscript 2 space plus space HCl with Dialkyl space sulphonamide below
    The tertiary amines does not react at all.
    Both dialkyl sulphonamide and tertiary amine go into the upper ether layer. While the monoalkyl sulphonamide remains in the lower aqueous layer. The two layers are separated, the aqueous layer containing the potassium salt of mono-alkyl sulphonamide is hydrolysed with concentrated hydrochloric acid when primary amine is regenerated as its hydrochloride.

    Primary amine is recovered from the hydrochloride by distillation with alkali.
    RNH2.HCl+ KOH → RNH2 + KCl + H2O
    The ether layer distilled when tertiary amine distills over. The residue of dialkyl sulphonamide is hydrolysed with concentrated hydrochloric acid when secondary amine is regenerated as its hydrochloride.
    C6H5SO2NR2 +H2O + HCI → C6H5SO2OH + R2NH.HCl
    The hydrochloride on distillation with alkali gives the free secondary amine
    R2NH.HCl + KOH → R2NH + KCl + H2O

     


    Question 281
    CBSEENCH12009119

    Explain: In aqueous solution order is Et2NH,>Et3N > EtNH2.

    Solution

    In aqueous solution, the Kb order is Et2NH > Et3N > EtNH2
    This may be explained by the following factors:
    (a)    Steric factor: The size of the alkyl group is more than that of hydrogen and, therefore, it hinders the attack of acid on the amine and therefore, basic strength decreases. Now crossing of alkyl group increases from primary to tertiary amines. As a result, their basic strength decreases. This is called steric hindrance. According to this effect, alkyl amines should be least basic.
    (b)    Solvation of ions: When amines are dissolved in water, they undergo hydration through hydrogen bonding. The protonated amines form hydrogen bonds with water molecules and release energy called hydration energy. Now, greater the extent of hydrogen bonding in protonated amine, more will be its stabilization and consequently, greater will be the tendency of amine to change into a cation and greater will be the strength of the corresponding amine. As can be seen below, the hydration of protonated amine due to hydrogen bonding decreases as:
    Et NH3+ > Et2 NH2+ > Et3NH+
    The tertiary ammonium ion is less hydrated than secondary ammonium ion, which is less hydrated than primary ammonium ion. Thus, tertiary amines have less tendency to form ammonium ion and consequently are less basic.
    As a consequence of combining effects of inductive effect and solvation, the secondary amines are the strongest bases among amines and basic strength varies as:
    Et2NH > Et3 N > Et NH2

     
    Question 283
    CBSEENCH12009121
    Question 284
    CBSEENCH12009122
    Question 285
    CBSEENCH12009123
    Question 286
    CBSEENCH12009124
    Question 287
    CBSEENCH12009125

    A substance (X) has a molecular formula C3H9N. This substance gives a unpleasant smell with chloroform and caustic potash. Write the structure of this organic substances (X). Write their IUPAC names also.

    Solution
    As the compound (X) reacts with CHCI3 and KOH (carbylamine reaction) the compound (X) is a primary amine containing NH2 group. There are two structures possible for (X).

    Question 288
    CBSEENCH12009126

    A compound (X) having molecular formula C3H7NO, reacts with bromine and caustic soda to give another compound (Y). The compound (Y) reacts with HNO2 to form alcohol and nitrogen gas. Identify the compounds (X) and (Y) and write the chemical equations of the reactions involved.

    Solution

    As the compound (X) is giving a positive Hoffmann bromamide reaction, the compound (X) contains the CONH2 group. As only three carbons present, the structure of compound (X) is:
    (X) → CH3CH2CONH2
    Hoffmann bromamide reaction give 1° amine with one carbon less, therefore, the structure for compound (Y) is:
    (Y) → CH3CH2NH2
    The reaction involved are:

    Question 290
    CBSEENCH12009128
    Question 292
    CBSEENCH12009130

    Why does bromination of aniline, even under very mild conditions give 2, 4, 6- tribromo aniline instantaneously?

    Solution
    This high reactivity of aniline is due to the fact that, in addition to other resonating structures that stabilizes the intermediate carbonium ion in aromatic electrophilic substitution, the following two structures are also formed due to the interaction of nitrogen lone pair of an electron with the positively charged ring. This also contributes to the stability of the intermediate in o, p-bromination.

    Question 293
    CBSEENCH12009131

    An organic compound (A) with IMF C4H11N, capable of being resolved into optical isomers gives a base soluble product with benzene sulphonyl chloride. What is the structure and IUPAC name of (A)? What happens when this compound (A) is treated with ethanoyl chloride?

    Solution
    As the compound (A) is giving a base soluble product with Hinsberg’s reagent, it means the compound is a primary amine with —NH2 group. As the compound is capable of being resolved into optical isomers, it indicates the presence of chiral carbon. Therefore, the structure of compound (A) is:

    With ethanoyl chloride, compound (A) forms an amide.
    Question 294
    CBSEENCH12009132

    How is benzene diazonium chloride obtained?

    Solution
    Benzene diazonium chloride is obtained by treating aniline with NaNO2 and HCl in ice cold solution. The reaction is called diazotisation.

    Question 295
    CBSEENCH12009133

    Why are aryl diazonium ions more stable than alkyl diazonium ions?

    Solution
    Aryl diazonium ions  are more stable than R-N2+ due to resonance. Aryl diazonium ions have more contributing  structure than alkyl diazonium ions. Hence, aryl diazonium is more stable.

    Question 296
    CBSEENCH12009134

    Explain what is meant by the 'protection of the amino group'.?

    Solution
    Direct nitration of aniline (and other aryl amines) results in oxidized, tarry material. This is prevented by acetylation of the amino group before nitration. The hydrolysis of the o- and p- nitro acetanilide yields the corresponding nitro anilines. Acetylation of arylamines prior to substitution reactions is referred to as the “protection of the amino group.”
    Question 297
    CBSEENCH12009135

    How would you protect the amino group during the nitration of an aromatic amino compound? Give chemical equations.

    Solution
    The equations for the aromatic amino compound aniline are:


    Question 298
    CBSEENCH12009136

    Show by means of equations how an amide may be converted into an amine containing the same number of carbon atoms.

    Solution
    By reduction an amide can be converted into an amine containing the same number of carbon atoms.
    RCONH2 + 4[H] → RCH2NH2 + H2O
    Question 299
    CBSEENCH12009137

    Show by means of equations how an amide may be converted into an amine containing one carbon atom less than the amide.

    Solution
    By bromo amide reaction:
    RCONH2 + Br2 + 4KOH → RNH2 + 2KBr + K2CO3 + 2H2O
    Question 301
    CBSEENCH12009139

    Explain how does the presence or absence of hydrogen on N atom of amines affect the modes of their reactions with nitrous acid.

    Solution

    The three classes of amines react differently with nitrous acid. Nitrous acid is very unstable and is generated only during the course of a reaction using NaNO2/HCl.
    Primary amines have two hydrogens present on N-atoms.
    Aromatic primary amine from diazonium salt with NaNO2/HCl

    While Aliphatic primary amine form diazonium salt which is unstable and decompose to liberate N2 gas and form alcohol,

    Secondary amines contain one hydrogen on N-atom. Both aliphatic and aromatic amines undergo electrophilic substitution reaction with HNO2 to form nitrosamines.

    Tertiary amines have no H present on N-atom. Aliphatic tertiary amine form salt with HNO2 which is water soluble.
    R3N + H—ONO → R3NH⊕®ONOΘ
    Aromatic tertiary amine undergo electrophilic reaction at para position as the ring is highly activated by NR2 group.

    Question 302
    CBSEENCH12009140

    Explain the following:
    Aniline dissolves in aqueous HCl.

    Solution
    The solubility of C6H5NH2 in dil. HCl is due to the formation of water soluble salt.
    straight C subscript 6 straight H subscript 5 NH subscript 2 plus space straight H subscript 3 straight O to the power of plus space plus space Cl to the power of minus space rightwards arrow space stack straight C subscript 6 straight H subscript 5 NH subscript 3 to the power of plus Cl to the power of minus with Anilinium space chloride below plus straight H subscript 2 straight O
    Question 303
    CBSEENCH12009141

    Explain the following:
    Amines are stronger bases than ammonia.

    Solution
    Amines have electron repelling groups which increase the electron density on nitrogen, while ammonia has no such group.
    Question 304
    CBSEENCH12009142

    Explain the following:
    Aniline is a weak base than ethylamine.

    Solution
    In aniline the electron pair of nitrogen atom is delocalised due to resonance and hence lesser available for protonation while ethylamine does not undergo resonance.
    Question 305
    CBSEENCH12009143

    Explain the following:
    The amino group in ethylamine is basic whereas that in acetamide is not basic.

    Solution
    In amides the lone pair of electrons on nitrogen atom is delocalised and hence less available for protonation than in amines where no resonance is possible and thus

    acetamide is a weaker base than ethylamine.
    Question 306
    CBSEENCH12009144

    Explain the following:
    Cyclo hexylamine is a stronger base than aniline.

    Solution
    Aniline is weaker base than cyclohexylamine because of resonance while there is no resonance in cyclohexylamine

    Question 307
    CBSEENCH12009145

    Describe simple tests for distinguishing:
    p-Toluidine and benzyl amine

    Solution
    p-Toluidine, p-CH3C6H4NH2, undergoes diazotisation and coupling reactions to form azo dyes while benzyl amine (C6H5CH2NH2), being aryl substituted aliphatic amine, does not do so.
    Question 308
    CBSEENCH12009146

    Describe simple tests for distinguishing:
    CH3ONHC6H5 and C6H5CONH2

    Solution
    With hot aqueous NaOH, only C6H5CONH2 liberates ammonia.
    Question 309
    CBSEENCH12009147

    Describe simple tests for distinguishing:
    C6HsNH3 +Cl- and p-ClC6H4NH2

    Solution
    Aqueous silver nitrate precipitates from C6H5NH3+Clbut does not forms with p-ClC6H4NH2.
    Question 310
    CBSEENCH12009148

    Describe simple tests for distinguishing:
    (CH3)4N+OH and (CH3)2NCH2OH

    Solution
    CrO3 is reduced to green Cr3+ by (CH3)2NCH2OH.
    (CH3)4N+OH- is strongly basic to litmus.
    Question 311
    CBSEENCH12009149

    Describe simple tests for distinguishing:
    p-CH3COC6H4NH2 and CH3CONHC6H5

    Solution
    Cold dilute HCl dissolves p-CH3COC6H4 which also gives a positive iodoform test with NaOH.
    Question 312
    CBSEENCH12009150

    Arrange the following in the order of decreasing basicity:
    NH3, CH3NH2, C6H5NH2 (C6H5)2NH.

    Solution
    CH3NH2 > NH> C6H5NH2 > (C6H5)2NH > (C6H5)3N.
    Question 313
    CBSEENCH12009151

    Arrange the following in the order of decreasing basicity:
    C6H3NH2, p-NO2C6H4NH2, m-NO2.C6H4NH2, p-CH3 OC6H4NH2.

    Solution

    p-CH3OC6H4NH2 > C6H5NH2 > m-NO2.C6H4. NH2 > p-NO2.C6H4.NH2-NO2 group in m-position weakens the base due to inductive effect while in o- and p- positions it weakens the base due to -I effect and extended straight pi bonding. 

    Question 314
    CBSEENCH12009152

    Arrange the following in the order of decreasing basicity:
    p-Toluidine, N, N-dimethyl-p-toluidine, p-nitro aniline, aniline.

    Solution
    p-Toluidine > aniline > p-nitroaniline > N, N-dimethyi-p-toluidine.
    Question 315
    CBSEENCH12009153

    Arrange the following in the order of decreasing basicity:
    Methyl amine, dimethyl amine, aniline, N-methyl aniline.

    Solution
    Dimethylamine > methylamine > N-methyl aniline > aniline.
    Question 316
    CBSEENCH12009154

    Arrange the following in the order of decreasing basicity:
    C2H5NH2, iso-(C3H7)3N, CH3CONH2, CH3NH-Na+

    Solution

    CH3NH-Na > C2H5NH2 > (iso-C3H7)3N > CH3CONH2
    CH3NH- is the conjugate base of the very weak acid CH3NH2 and therefore is the strongest base. The three bulky isopropyl groups on cause steric strain, but with an unshared electron pair on N, the strain is partially relieved by increasing the normal C—N—C bond angle (109°) to about 112°. If the unshared electron pair forms a bond to H, as in R3NH+, relief of strain by angle expansion is prevented. 3° Amines, therefore, resist forming the fourth bond and suffers a decrease in basicity. In CH3CONH2, the N atom is weakly basic because its electron pair can be delocalised to O of the CH3CO— group by extended straight pi bonding.

    Question 317
    CBSEENCH12009155
    Question 318
    CBSEENCH12009156
    Question 320
    CBSEENCH12009158

    Primary, secondary and tertiary amines can be separated from each other by means of ___________.

    Solution
    benzene sulphonyl chloride or diethyl'oxalate.
    Question 321
    CBSEENCH12009159
    Question 324
    CBSEENCH12009162
    Question 325
    CBSEENCH12009163
    Question 326
    CBSEENCH12009164
    Question 328
    CBSEENCH12009166
    Question 329
    CBSEENCH12009167
    Question 330
    CBSEENCH12009168
    Question 336
    CBSEENCH12009174
    Question 345
    CBSEENCH12009183
    Question 351
    CBSEENCH12009189

    Why are benzene diazonium salt soluble in water?

    Solution

    Benzene diazonium salt is soluble in water because diazonium salt is polar in nature. water is polar solvent, thus polar diazonium salt get dissolved in water. 

    Question 352
    CBSEENCH12009190

    Give IUPAC name of sulphanilic acid.

    Solution

    3-Aminobenzenesulfonic acid. 

    Question 353
    CBSEENCH12009191

    An organic compound 'A' having molecular formula C2H7N on treatment with HNOgave an oily yellow substance- Identify A.

    Solution

    As the organic compounds has N and also it reacts with nitrous acid, it may be an amine.
    CH3CH2NH2 +HNO2-->CH3CH2OH +N2+H2O

    the compound A is ethylamine and the product is ethanol.

    Question 354
    CBSEENCH12009192

    What happens when acetamide is reacted with bromine in the presence of potassium hydroxide?

    Solution

    Acetamide, when treated with bromine and concentrated potassium hydroxide solution methylamine, is formed. This reaction is known as Hofmann bromamide reaction.
    CH3CONH2 + Br2+4KOH --> CH3NH2 +2KBr +K2CO3+2H2O

    Question 355
    CBSEENCH12009193
    Question 356
    CBSEENCH12009194

    Write the IUPAC name for:
     

    Solution

    Propionamide

    Question 357
    CBSEENCH12009195

    Complete the reaction:

    Solution

    Question 358
    CBSEENCH12009196

    Aniline is more soluble in aq. HCl than in water. Explain. 

    Solution

    Aniline does not undergo hydrogen bonding because of the presence of the benzene which is highly hydrophobic. therefore aniline is insoluble in water.
    In the HCl the amine group becomes protonated (-NH3+) and the ionic  hence soluble in HCl.

    Question 359
    CBSEENCH12009197

    explain the sandmeyer's reaction?

    Solution

    The Cl-,Br- and CN- nucleophiles can easily be introduced in the benzene in the presence of Cu(I) ion. This reaction is called sand Meyer's reaction.

    Question 360
    CBSEENCH12009198
    Question 362
    CBSEENCH12009200

    What happens when ethylamine is treated with silver chloride.

    Solution

    A soluble product is formed when ethylamine react with silver chloride.

    Question 363
    CBSEENCH12009201
    Question 365
    CBSEENCH12009203
    Question 366
    CBSEENCH12009204
    Question 367
    CBSEENCH12009205
    Question 368
    CBSEENCH12009206

    Complete the following:

    straight C subscript 6 straight H subscript 5 NH subscript 2 space end subscript space rightwards arrow from 453 minus 475 space straight K to conc. space straight H subscript 2 SO subscript 4 of

    Solution
    Question 369
    CBSEENCH12009207

    Complete the following:
    straight C subscript 6 straight H subscript 5 NH subscript 2 space rightwards arrow from left parenthesis Base right parenthesis to CH subscript 3 COCl of

    Solution

    Question 370
    CBSEENCH12009208

    Complete the following:
    straight C subscript 6 straight H subscript 5 straight N subscript 2 Cl space rightwards arrow with straight H subscript 2 straight O on top

    Solution

    Question 371
    CBSEENCH12009209

    Complete the following:
    straight C subscript 6 straight H subscript 5 NH subscript 2 space rightwards arrow with Br subscript 2 divided by straight H subscript 2 straight O on top


    Solution

    Question 372
    CBSEENCH12009210

    Complete the following:

    Solution
    Question 373
    CBSEENCH12009211

    complete the following?

    Solution

    Question 374
    CBSEENCH12009212

    Complete the following ?

    Solution

    Question 375
    CBSEENCH12009213

    Write the reaction of (i)aromatic and (ii) aliphatic primary amines with nitrous acid ?

     

    Solution

    Aromatic primary amines reacts with HNO2 at 273-278K to form aromatic diazonium salts.

    aliphatic Primary amines also react with HNO2 at 273-278 K to form aliphatic diazonium salts. But these are unstable even at this low temperature and thus decompose readily to form a mixture of compounds consisting of alkyl chlorides, alkenes and alcohols,out of which alcohols generally predominates.

    Question 376
    CBSEENCH12009214

    acylation of ethylamine?

    Solution

    ethylamine is readily acetylated by acetyl chloride and acetic anhydride in the cold to give ethyl acetamide.

    Question 380
    CBSEENCH12009218

    Aniline to p-bromoaniline ?

    Solution

    Question 383
    CBSEENCH12009221

    How do you the following substances react?
    Potassium phthalimide + ethyl bromide.

    Solution

    By treating potassium phthalimide with ethyl bromide and hydrolysing the resulting N-ethyl phthalimide by refluxing with 20% HCl under pressure .

    Question 385
    CBSEENCH12009223
    Question 386
    CBSEENCH12009224

    Why are the secondary amines more basic than primary amines?

    Solution

    Amines are bases due to the lone pair of electrons on the nitrogen atom of amines. These react with water to form hydroxyl ions.
    Bases are those species that donate OH- ions (hydroxyl ions). The more easily is the availability of the hydroxyl ions; more is the basicity of the amine. A secondary amine can donate its lone pair more easily, as the extra inductive effect stabilises the charge on the nitrogen atom

    Question 388
    CBSEENCH12009226

    Mention two important uses of Sulphanilic acid.

    Solution

    sulphanilic acid is used in the manufacture of i) dyes ii) sulpha drugs.

    Question 389
    CBSEENCH12009227

    Give reasons:
    C2H5NH2 is soluble in water, whereas C6H5NH2 is insoluble.

    Solution

    Ethylamine is soluble in water because it forms a hydrogen bond with water. Whereas, aniline is hydrophobic to water. hence it is insoluble.

    Question 390
    CBSEENCH12010039
    Question 391
    CBSEENCH12010040

    Name the reagents used in the following reactions ? 

    Solution


    Name of the reagent: Sodium borohydride (NaBH4). It is a good reducing agent useful in the reduction of aldehyde and ketone to alcohol.

     

    Name of the reagent: Alkaline potassium permanganate (KMnO4-KOH). Potassium permanganate is a strong oxidising agent.

     

    Question 393
    CBSEENCH12010078

    Arrange the following in the increasing order of their boiling point: C2H5NH2, C2H5OH, (CH3)3N

    Solution

    Increasing order of boiling point: (CH3)3N < C2H5NH2 < C2H5OH

    Alcohols have a higher boiling point as compared to that of amines because of oxygen, being more electronegative, forms strong hydrogen bond as compared to that of nitrogen. In tertiary amine, there is no hydrogen to form hydrogen bond and hence, has the lowest boiling point.
    Question 394
    CBSEENCH12010079

    Give a simple chemical test to distinguish between the following pair of compounds:

    (CH3)2NH and (CH3)3N.

    Solution

    (CH3)2NH reacts with benzene sulphonyl chloride as follows:

    (CH3)3N does not react with benzene sulphonyl chloride.

     

    Question 395
    CBSEENCH12010092

    Arrange the following compounds in increasing order of solubility in water:

    C6H5NH2, (C2H5)2NH, C2H5NH2

    Solution

    The increasing order of solubility in water of the given compounds is as follows:

     C6H5NH2 < (C2H5)2NH < C2H5NH2

    The more extensive the hydrogen bonding, the higher is the solubility of the compound in water. C2H5NH2 contains two H-atoms, whereas (C2H5)2NH contains only one H-atom. Therefore, C2H5NH2 is more soluble than (C2H5)2NH. The solubility of C6H5NHis least due to its high molecular mass.

    Question 396
    CBSEENCH12010123

    How will you convert the following?

    Nitrobenzene into aniline

    Solution

    i) Nitrobenzene into aniline


    Question 397
    CBSEENCH12010124

    How will you convert the following?

    Ethanoic acid into methanamine

    Solution

    Ethanoic acid into methanamine


    Question 398
    CBSEENCH12010125

    How will you convert the following?

    Aniline into N-phenylethanamide

    Solution

    Aniline into N-phenylethanamide

    Question 400
    CBSEENCH12010227

    Arrange the following compounds in an increasing order of their solubility in water: 

    C6H5NH2, (C2H5)2NH, C2H5NH2

    Solution

    The solubility order of the given amines is as follows:

     C6H5NH2 < (C2H5)2NH < C2H5NH2  

    The more extensive the Hydrogen bonding, the higher is the solubility. C2H5NH2 contains two H-atoms whereas (C2H5)2NH contains only one H-atom. Thus, C2H5NH2undergoes more extensive. Hydrogen bonding than (C2H5)2NH. Hence, the solubility in water of C2H5NH2 is more than that of (C2H5)2NH. 

    Further, the solubility of amines decreases with increase in the molecular mass. This is because the molecular mass of amines increases with an increase in the size of the hydrophobic part.

    The molecular mass of C6H5NH2 is greater than that of C2H5NH2 and (C2H5)2NH.

     

    Question 401
    CBSEENCH12010249

     Explain why an alkylamine is more basic than ammonia.

    Solution

    (a) The basicity of amines depends on the +I effect of the alkyl groups. With increase in alkyl group the +I effect will increase which will increase the ease of donation of lone pair electron. Amine will accept a proton and from cation will be stabilized in water by salvation (by hydrogen bonding).better the salvation by hydrogen bonding higher will be the basic strength.
    Hence, alkyl amine is more basic than ammonia 
    CH3NH2 > NH3

    Question 403
    CBSEENCH12010311

    Write the main products of the following reactions: 

    Solution

    (i) bold C subscript bold 6 bold H subscript bold 5 bold N to the power of bold plus bold Cl to the power of bold minus bold space bold rightwards arrow with bold H subscript bold 3 bold PO subscript bold 2 bold space bold plus bold H subscript bold 2 bold O bold space bold space on top bold space bold C subscript bold 6 bold H subscript bold 6 bold space bold plus bold N subscript bold 2 bold plus bold H subscript bold 3 bold PO subscript bold 3 bold space bold plus bold HCl

     

    Products are Benzene, Nitrogen gas, Phosphorous acid and Hydrochloric acid.

    (ii)

     

     

    Products is 2,4,6-Tribromoaniline

    iii)  bold CH subscript bold 3 bold CONH subscript bold 2 bold space bold plus bold Br subscript bold 2 bold space bold plus bold 4 bold NaOH bold space bold rightwards arrow bold CH subscript bold 3 bold NH subscript bold 2 bold space bold plus bold Na subscript bold 2 bold CO subscript bold 3 bold space bold plus bold 2 bold NaBr bold space bold plus bold 2 bold H subscript bold 2 bold O

    Products are Methanamine, Sodium carbonate, Sodium bromide and Water.

    Question 404
    CBSEENCH12010340

    Complete the following chemical reaction equations:

    (i) C6H5N2Cl + H3PO2+ H2O --->

    (ii) C6H5NH2+ Br2(aq.)--->

    Solution

    (i) C6H5N2Cl + H3PO2+ H2O ---> C6H6 + N2 + H3PO3+ HCl

     

     

    (ii) 

    Question 405
    CBSEENCH12010341

    Describe the following giving the relevant chemical equation in each case:

    (i) Carbylamines reaction

    (ii) Hofmann’s bromamide reaction.

    Solution

    (i) Carbylamines reaction

    Carbylamines reaction is used as a test for the identification of primary amines. When aliphatic and aromatic primary amines are heated with chloroform and ethanolic potassium hydroxide, carbylamines (or isocyanides) are formed. These carbylamines have very unpleasant odours.

    Secondary and tertiary amines do not respond to this test.

      stack straight R minus NH subscript 2 with Primary space amine below space plus stack CHCl subscript 3 with chloroform below space plus stack 3 space KOH space with potassium space hydroxide below left parenthesis alc. right parenthesis space rightwards arrow with increment on top space space stack straight R minus NC with carbylamine below space plus space 3 space KCl space plus 3 space straight H subscript 2 straight O

    For example, 

      CH subscript 3 minus NH subscript 2 space plus CHCl subscript 3 space plus 3 KOH space left parenthesis alc. right parenthesis space rightwards arrow with space increment space space on top space stack CH subscript 3 minus NC with methyl space carbylamine below space plus 3 KCl space plus 3 space straight H subscript 2 straight O

    (b) Hoffmann bromamide reaction

    When an amide is treated with bromine in an aqueous or ethanolic solution of sodium hydroxide, a primary amine with one carbon atom less than the original amide is produced. This degradation reaction is known as Hoffmann bromamide reaction. This reaction involves the migration of an alkyl or aryl group from the carbonyl carbon atom of the amide to the nitrogen atom.

      stack straight R minus CO minus NH subscript 2 with amide below space plus Br subscript 2 space plus 4 NaOH space rightwards arrow stack straight R minus NH subscript 2 with primary space amine below space plus Na subscript 2 CO subscript 3 space plus 2 NaBr space plus straight H subscript 2 straight O

For space example comma

stack CH subscript 3 minus CO minus NH subscript 2 with Ethanamide below space plus Br subscript 2 plus 4 NaOH space rightwards arrow space stack CH subscript 3 minus NH subscript 2 with Methanamine below space plus Na subscript 2 CO subscript 3 space plus 2 NaBr space plus 2 straight H subscript 2 straight O

stack straight C subscript 6 straight H subscript 5 minus CO minus NH subscript 2 with Benzamide below space plus Br subscript 2 plus 4 NaOH space rightwards arrow space stack straight C subscript 6 straight H subscript 5 minus NH subscript 2 with aniline below space plus Na subscript 2 CO subscript 3 space plus 2 NaBr space plus 2 straight H subscript 2 straight O

     

     

     

    Question 406
    CBSEENCH12010363

    Write the IUPAC name of the given compound:

    Solution

    The IUPAC name of the compound is 2,4,6 tribromo aniline.

    Question 407
    CBSEENCH12010378
    Question 409
    CBSEENCH12010400

    Give reasons for the following:
    i) Aniline does not undergo Friedal-Crafts reaction.
    ii) (CH3)3N is more basic than (CH3)3N in an aqueous solution.
    iii) Primary amines have higher boiling point than tertiary amines.

    Solution

    (i) Aniline is a Lewis base while AlCl3 is lewis acid. They combine to form a salt.

    (ii)Due to combined + I and solvation effects.

    (iii)Due to the presence of H-bonding in primary amines.
    Question 410
    CBSEENCH12010419

    Give a chemical test to distinguish between ethylamine and aniline.

    Solution

    Ethylamine and aniline can be distinguished from each other by the azo-dye test.
    A dye is obtained when aniline (an aromatic amine) reacts with HNO2 (NaNO2 + dil.HCl) at 0-5°C, followed by a reaction with the alkaline solution of 2-naphthol.

    Ethylamine (an aliphatic amine) gives a brisk effervescence due (to the evolution of N2 gas) under similar conditions.

    Question 411
    CBSEENCH12010434

    State reasons for the following:

    (i) pKb value for aniline is more than that for methylamine.

    (ii) Ethylamine is soluble in water whereas aniline is not soluble in water.

    (iii) Primary amines have higher boiling points than tertiary amines.

    Solution

    (i) Aniline undergoes resonance and as a result, the electrons on the N-atom are delocalized over the benzene ring. Therefore, the electrons on the N-atom are less available to donate.

    On the other hand, in case of methylamine (due to the +I effect of methyl group), the electron density on the N-atom is increased. As a result, aniline is less basic than methylamine. Thus, pKb of aniline is more than that of methylamine.

    (ii) Ethylamine when added to water forms intermolecular H-bonds with water. Hence, it is soluble in water.

     

    But aniline does not undergo H-bonding with water to a very large extent due to the presence of a large hydrophobic -C6H5 group. Hence, aniline is insoluble in water.

    (iii) The boiling points of compounds depend on the extent of H-bonding present in that compound. The more extensive the H-bonding in the compound, the higher is the boiling point. Tertiary amines [(CH3)3N] does not contain H-atom whereas primary amine (CH3NH2) contains two H-atoms. Then, primary amines undergo more extensive H-bonding than tertiary amines. Hence, the boiling point of primary amines is higher than that of tertiary amines.

    Question 412
    CBSEENCH12010447

    The conversion of primary aromatic amines into diazonium salts is known as __________ .

    Solution

    The conversion of primary aromatic amines into diazonium salts is known as diazotization reaction.

    Question 413
    CBSEENCH12010466

    Account for the following:
    (i) Primary amines (R-NH2) have higher boiling point than tertiary amines (R3N).
    (ii) Aniline does not undergo Friedel - Crafts reactions:
    (iii) (CH3)2NH is more basic than (CH3)3N in an aqueous solution.

    OR
    straight i right parenthesis space straight C subscript 6 straight H subscript 5 space rightwards arrow with Sn space plus HCl on top space straight A space rightwards arrow from 273 space straight K to space NaNO subscript 2 plus HCl of space straight B space space rightwards arrow with straight H subscript 2 straight O on top space straight C

ii right parenthesis space CH subscript 3 CN space rightwards arrow with straight H subscript 2 straight O divided by straight H to the power of plus on top space straight A space rightwards arrow from increment to NH subscript 3 of space straight B space rightwards arrow with Br plus KOH on top space straight C

    Solution

    (i) The greater the extent of intermolecular hydrogen bonding, greater is the boiling point of the compound. Primary amines are involved in intermolecular hydrogen bonding, whereas tertiary amines do not have any available hydrogen atoms, and hence they are not involved in any intermolecular hydrogen bonding. Thus, primary amines (R-NH2) have higher boiling point than tertiary amines (R3N).

    (ii) A Friedel-Crafts reaction is carried out in the presence of a lewis acid such as AlCl3. Aniline being basic in nature reacts with AlCl3 to form a salt (as shown in the following equation).

     

    Due to the positive charge on the N-atom, electrophilic substitution in the benzene ring is deactivated. Hence, aniline does not undergo the Friedel-Crafts reaction.

    (iii) The order of basic strength of aliphatic amines in the aqueous phase, is based on following factors:

    Steric factor: Alkyl group is larger than hydrogen atom that causes steric hindrance to attack of acid. As the number of alkyl group increases from primary to tertiary. The steric hindrance also increases in the same direction.

    Solvation of ions: when amines are dissolved in water, they form hydrogen bonds with a water molecule and release hydration energy; in the process converting themselves to the protonated amines to get stabilized. Greater the extent of hydrogen bonding, greater is the hydration energy released and more is the stability of the protonated amine; thus greater is the tendency of the amine to form cation leading to the greater basic strength of the amine. So, the actual order of basic strength in aqueous phase is found to be:

    Secondary > Tertiary > Primary

    Therefore, secondary amines are the strongest base in aqueous solution.


    Or
    straight i right parenthesis space straight C subscript 6 straight H subscript 5 space rightwards arrow with Sn space plus HCl on top space stack straight C subscript 6 straight H subscript 5 NH subscript 2 with Aniline below space rightwards arrow from 273 space straight K to space NaNO subscript 2 plus HCl of space stack straight C subscript 6 straight H subscript 5 minus straight N subscript 2 superscript plus Cl to the power of minus with Benzediazonium space chloride below space space rightwards arrow with straight H subscript 2 straight O on top space stack straight C subscript 6 straight H subscript 5 OH with phenol below

ii right parenthesis space CH subscript 3 CN space rightwards arrow with straight H subscript 2 straight O divided by straight H to the power of plus on top CH subscript 3 COOH space rightwards arrow from increment to NH subscript 3 of space CH subscript 3 CONH subscript 2 space rightwards arrow with Br plus KOH on top space CH subscript 3 NH subscript 2
    Question 414
    CBSEENCH12010516

    Give reasons:
    Acetylation of aniline reduces its activation effect.

    Solution

    Acetylation of aniline reduces its activation effect Because it result in decrease of electron density on nitrogen. Due to the resonance, the electron pair of nitrogen atom gets delocalised towards carbonyl group therefore so activation effect reduces.

    Question 415
    CBSEENCH12010517

    Give reasons :
    CH3NH2 is more basic than C6H5NH2.

    Solution

    CH3NH2 is more basic than C6H5NH2 due to +I effect in methylamine, electron density in methylamine at nitrogen increases whereas in aniline resonance takes place and electron density on nitrogen
    decreases.

    Question 416
    CBSEENCH12010518

    Give reasons :
    Although –NH2 is o/p directing group, yet aniline on nitration gives a significant amount of m-nitroaniline.

    Solution

    Nitration is carried out in an acidic medium ( a mixture of concentrated HNO3 and concentrated H2SO4). In an acidic medium, aniline is protonated to give anilinium ion (which is meta-directing).

    Question 419
    CBSEENCH12010595

    Give reasons:
    (CH3)2NH is more basic than (CH3)3N in an aqueous solution.

    Solution

    The order of basic strength of aliphatic amines in the aqueous phase is based on the following factors:

    Steric factor: Alkyl group is larger than hydrogen atom that causes steric hindrance to attack of acid. As the number of alkyl group increases from primary to tertiary. The steric hindrance also increases in the same direction.

    Solvation of ions: when amines are dissolved in water, they form hydrogen bonds with a water molecule and release hydration energy; in the process converting themselves to the protonated amines to get stabilized. Greater the extent of hydrogen bonding, greater is the hydration energy released and more is the stability of the protonated amine; thus greater is the tendency of the amine to form cation leading to the greater basic strength of the amine. So, the actual order of basic strength in the aqueous phase is found to be:

    Secondary > Tertiary > Primary

    Therefore, secondary amines are the strongest base in aqueous solution.

    Question 420
    CBSEENCH12010596

    Give reasons:

    Aromatic diazonium salts are more stable than aliphatic diazonium salts.

    Solution

    Aromatic diazonium salts are more stable than aliphatic diazonium salts. The stability of aromatic diazonium salts is due to resonance which is absent in aliphatic diazonium salts.

    Question 422
    CBSEENCH12010598

    Give a simple chemical test to distinguish between Aniline and N, N-dimethylaniline.

    Solution

    Carbylamine test can be used to distinguish.

    Question 423
    CBSEENCH12010599

    Arrange the following in the increasing order of their pKb values:
    C6H5NH2, C2H5NH2, C6H5NHCH3

    Solution

    pKb tells the strength of a base. Lower is pKb value, stronger is the base. Now C6H5NH2 is a weak base because the lone pair is involved in resonance with the benzene and is thus not available for a donation while in C2H5NH2, C2H5 is an electron donating group, which increases the e- density on N thus felicitating the release of lone pair. Hence, C2H5NH2 is a strong base.
    Thus, the correct order is:

    C2H5NH2< C6H5NHCH3< C6H5NH2

    Question 424
    CBSEENCH12010626

    In the Hofmann bromamide degradation reaction, the number of moles of NaOH and Br2 used per mole of amine produced are:

    • Four moles of NaOH and two moles of Br2

    • Two moles of NaOH and two moles of Br2

    • Four moles of NaOH and one mole of Br2

    • One mole of NaOH and one mole of Br2

    Solution

    C.

    Four moles of NaOH and one mole of Br2

    Hofmann-bromamide degradation reaction is given as
    RCONH2 + 4 NaOH + Br2 → RNH2 + Na2CO3 + 2NaBr + 2H2O
    Hence four moles of NaOH and one mole of Br2 are used.

    Question 425
    CBSEENCH12010645

    In the reaction,


    The product E is

    Solution

    C.

    Question 426
    CBSEENCH12010665

    On heating an aliphatic primary amine with chloroform and ethanolic potassium hydroxide, the organic compound formed is

    • an alkanol

    • an alkaneodiol

    • an alkyl cyanide 

    • an alkyl isocyanide

    Solution

    D.

    an alkyl isocyanide

    The reaction is an example of carbylamines reaction which includes conversion of amine to isocyanide.
    straight R minus straight N with minus on top straight H subscript 2 space plus space CHCl subscript 3 space rightwards arrow from KOH to straight C subscript 2 straight H subscript 5 OH of space stack straight R minus straight N with plus on top identical to straight C with minus on top colon with Alkyl space isocyanide below

    Question 427
    CBSEENCH12010670

    Considering the basic strength of amines in aqueous solution, which one has the smallest pKb value?

    • (CH3)2NH

    • CH3NH2

    • (CH3)3N

    • C6H5NH2

    Solution

    A.

    (CH3)2NH

    Order of basic strength of aliphatic amine in aqueous solution is as follows (order of Kb)
    left parenthesis CH subscript 3 right parenthesis subscript 2 straight N with minus on top straight H space greater than thin space CH subscript 3 straight N with minus on top straight H subscript 2 greater than space left parenthesis CH subscript 3 right parenthesis subscript 3 straight N with minus on top space greater than thin space straight C subscript 6 straight H subscript 5 straight N with minus on top straight H subscript 2
As space we space know space pK subscript straight b space equals space minus space log space straight K subscript straight b
    So (CH3)2 NH will have smallest pKb value.
    In the case of phenylamine, N is attached to sp2 hybridised carbon, hence it has highest pKb and least basic strength.

    Question 428
    CBSEENCH12010680

    A compound with molecular mass 180 is acylated with CH3COCl to get a compound with molecular mass 390. The number of amino groups presents per molecule of the former compound is 

    • 2

    • 5

    • 4

    • 6

    Solution

    B.

    5


    Since,each-COCH3  group displaces one H atom in the reaction of one mole of CH3COCl with the one-NH2 group, the molecular mass increases with 42 units.
    Since, the mass increases by (390-180) = 210, hence the number of -NH2
    the group is 210/42 =5
    Question 432
    CBSEENCH12010750

    Which of the following compounds will the significant amount of meta product during mono-nitration reaction?

    Solution

    C.

    (a) Nitration reactions take place in presence of concentrated HNO3+ concentrated H2SO4.
    (b) Aniline acts as a base. In presence of H2SO4, its protonation takes place and anilinium ion is formed
    (c)Anilinium ion is a strongly deactivating group and meta directing in nature so it gives meta nitration product in a significant amount.

    Question 433
    CBSEENCH12010810

    The hydrocarbon which can react with sodium in liquid ammonia is

    • CH3CH2CH2C≡CCH2CH2CH

    • CH3CH2C≡CH

    • CH3CH=CHCH3

    • CH3CH2C≡CCH2CH3

    Solution

    B.

    CH3CH2C≡CH

    CH subscript 3 CH subscript 2 space minus space straight C identical to space CH rightwards arrow from increment to Na divided by Liq. space NH subscript 3 of space CH subscript 3 CH subscript 2 straight C identical to space straight C to the power of minus Na to the power of plus
    It is a terminal alkyne, having acidic hydrogen.
    Note: Solve it as a case of terminal alkynes, otherwise all alkynes react with Na in liq. NH3.
    Question 434
    CBSEENCH12010820

    In the chemical reaction, CH3CH2NH2 + CHCl3 + 3KOH → (A) + (B) + 3H2O, the compounds (A) and (B) are respectively

    • C2H5CN and 3KCl 

    • CH3CH2CONH2 and 3KCl

    • C2H5NC and K2CO3

    • C2H5NC and 3KCl

    Solution

    D.

    C2H5NC and 3KCl

    It is example of carbylamine reaction. so, the product will be C2H5NC and 3KCl

    Question 435
    CBSEENCH12010834

    Which one of the following is the strongest base in aqueous solution?

    • Trimethylamine

    • Aniline

    • Dimethylamine

    • Methylamine

    Solution

    C.

    Dimethylamine

    In aqueous solution basicity order of 1o, 2o and 3o amine with methyl group is 2o>1o>3o
    In case of aniline lone pair of nitrogen is involved in resonance, so it is weaker base than aliphatic amines.

    Question 437
    CBSEENCH12010919

    Amongst the following the most basic compound is

    • benzylamine

    • aniline

    • acetanilide

    • p-nitroaniline

    Solution

    A.

    benzylamine

    -NH2 group is not linked to the benzene ring.

    Question 438
    CBSEENCH12010967

    Which one the following does not have sp2 hybridized carbon?

    • Acetone

    • Acetamide

    • Acetonitrile

    • Acetic acid

    Solution

    C.

    Acetonitrile

    Acetonitrile does not contain sp2 hybridised carbon.

    Question 439
    CBSEENCH12010971

    Consider the acidity of the carboxylic acids

    • PhCOOH

    • p – NO2C6H4COOH

    • o – NO2C6H4COOH

    • m – NO2C6H4COOH

    Solution

    C.

    o – NO2C6H4COOH

    -NO2 group at any position shows electron withdrawing effect thus acid strength is increased. But o -nitro benzoate ion is stabilised by intramolecular H-bonding. Hence its acid strength is maximum. The effect is more at para position.

    Question 440
    CBSEENCH12010972

    Which of the following is the strongest base?

    Solution

    B.

    The basicity of amine group depends on the lone pair present on N atom. If this lone pair involved in the conjugation, the basic character of amine decreases. So, find the molecule in which lone pair of nitrogen does not involve in conjugation.

    Question 441
    CBSEENCH12010983

    Which of the following compounds will be suitable for Kjeldah1’s method for nitrogen estimation?

    Solution

    D.

    Kjeldahl's method is used for Aniline. This method is used for quantitative analysis of N compound in organic substance (NH3/NH4+).

    This method is not used in the case of nitro, azo compounds and also to the compounds containing nitrogen in the ring e.g. Pyridine.

    Question 442
    CBSEENCH12010985

    The increasing order of basicity of the following compounds is:

    • (d) < (b) < (a) < (c)

    • (a) < (b) < (c) < (d)

    • (b) < (a) < (c) < (d)

    • (b) < (a) < (d) < (c)

    Solution

    D.

    (b) < (a) < (d) < (c)

    Order of base nature depends on electron donation tendency.

    It compounds (b) nitrogen is sp2 hybridized so least basic among all given compound

    Compound (c) is a very strong nitrogeneous organic base as a lone pair of one nitrogen delocalize in resonance and make another nitrogen negatively charged and conjugate acid have two equivalent resonating structure.
    Thus it is most basic in given compound.

    (d) is secondary amin more than (a) which is a primary amine.

    Question 443
    CBSEENCH12010997

    The compound that does not produce nitrogen gas by the thermal decomposition is

    • (NH4)2SO4

    • Ba(N3)2

    • (NH4)2Cr2O7

    • NH4NO2

    Solution

    A.

    (NH4)2SO4

    (NH4)2SO4  2NH3 (g) + H2SO4Ba(N3)2 (s)  Ba + 3N2 (g)(NH4)2 Cr2O7 (s)   N2 (g)+ Cr2O3 (s) + 4H2ONH4NO2  N2 (g)+ 2H2O

    Question 444
    CBSEENCH12011028

    The correct statement regarding the basicity of arylamines is

    • Arylamines are generally more basic than alkylamines because the nitrogen lone pair electrons are not delocalized by interaction with the aromatic ring pi-electron system

    • Arylamines are generally more basic than alkylamines, because of aryl group

    • Arylamines are generally more basic than alkylamines because the nitrogen atom in arylamines is sp-hydridized.

    • Arylamines are generally less basic than alkylamines because the nitrogen lone pair electrons are delocalized by interaction with aromatic ring pi-electron system.

    Solution

    D.

    Arylamines are generally less basic than alkylamines because the nitrogen lone pair electrons are delocalized by interaction with aromatic ring pi-electron system.

    In the aryl amines, due to the delocalization of lone pair of electrons of N-atom to the benzene ring, it loses its basicity and becomes less basic than alkyl amine.
    on the other hand, alkyl amines have +I alkyl effect of the alkyl group which increase electron density on N -atom. Hence the availability of free electron on amine as well as +I effects enhances its basic nature.

    Question 445
    CBSEENCH12011052

    In the reaction,

    straight H minus straight C identical to CH space rightwards arrow from left parenthesis ii right parenthesis space CH subscript 3 CH subscript 2 Br to left parenthesis straight i right parenthesis space NaNH subscript 2 divided by liq. NH subscript 3 of space straight X
space space space space space space space space space space space space space space space space space space straight X space rightwards arrow from left parenthesis ii right parenthesis space CH subscript 3 CH subscript 2 Br to left parenthesis straight i right parenthesis NaNH subscript 2 divided by liq. NH subscript 3 of space straight Y
    X and Y are

    • X=2-butyne; Y= 3-hexyne

    • X=2-butyne;Y=2-hexyne

    • X=1-butyne ;Y = 2-hexyne

    • X=1-butyne; Y =3-hexyne

    Solution

    D.

    X=1-butyne; Y =3-hexyne

    NaNH2/liq.NH3 behaves as a base, so it abstracts a proton from acetylene to form acetylide anion followed by alkylation to give compound (X) i.e 1-butyne (X) further reacts with NaNH2/Liq NH3 followed by alkylation with ethyl bromide yields 3-hexyne (Y).
    straight H minus straight C identical to straight C minus straight H left parenthesis 1 right parenthesis space rightwards arrow with NaNH subscript 2 divided by liq. space NH subscript 3 on top space straight H minus straight C identical to straight C to the power of minus

straight H minus straight C identical to straight C to the power of minus rightwards arrow with stack CH subscript 3 minus CH subscript 2 minus Br with alkylation below on top space stack straight H minus straight C identical to straight C minus CH subscript 2 CH subscript 3 with bold X with bold 1 bold minus bold butyne below space below

stack straight H minus straight C identical to straight C minus CH subscript 2 CH subscript 3 with bold X with bold 1 bold minus bold butyne below space below space rightwards arrow with left parenthesis straight i right parenthesis space NaNH subscript 2 divided by liq. NH subscript 3 on top space CH subscript 3 CH subscript 2 minus straight C identical to straight C to the power of minus
stack CH subscript 3 CH subscript 2 minus straight C identical to straight C to the power of minus rightwards arrow with CH subscript 3 CH subscript 2 minus Br on top space straight H subscript 3 CCH subscript 2 minus straight C identical to straight C minus CH subscript 2 CH subscript 3 space with stack bold left parenthesis bold Y bold right parenthesis with bold 3 bold minus bold hexyne below below plus HBr

    Question 446
    CBSEENCH12011053

    Consider the nitration of benzene using mixed conc. H2SO4 and HNO3. If a large amount of KHSO4 is added to the mixture, the rate of nitration will be

    • slower

    • uncharge

    • doubled

    • faster

    Solution

    A.

    slower

    IN the nitration of benzene in the presence of conc. H2SO4 and HNO3, benzene is formed.
    HNO3 +H2SO4  rightwards harpoon over leftwards harpoon space NO subscript 2 superscript plus space plus HSO subscript 4 superscript minus space plus straight H subscript 2 straight O
    If a large amount of KHSO4 is added to this mixture more HSO4- ion furnishes and hence the concentration of electrophile decreases, rate of electrophilic aromatic reaction slows down.

    Question 448
    CBSEENCH12011080

    The electrolytic reduction of nitrobenzene in strongly acidic medium produces

    • p-aminophenol

    • azoxybenzene

    • azobenzene

    • aniline

    Solution

    A.

    p-aminophenol

    Under weakly acidic conditions nitrobenzene on electrolytic reduction gives aniline but under strongly acidic conditions gives p-aminophenol.

    Question 449
    CBSEENCH12011103

    In the following reaction, the product (A) is 


    Solution

    D.


    The above reaction is coupling reaction of aniline with the diazonium salt to give azo benzene compound. This is coupling reaction takes place at para position to -NH2 group of benzene.
    Question 450
    CBSEENCH12011104

    Which of the following will most stable diazonium salt RN2+X-?

    • CH3N2+X-

    • C6H5N2+X-

    • CH3CH2N2+X-

    • C6H5CH2N2+X-

    Solution

    B.

    C6H5N2+X-

    Diazonium salt containing aryl group directly linked to the nitrogen atom is most stable due to resonance stabilization between the benzene nucleus and N-atom.

    Question 451
    CBSEENCH12011138

    Nitrobenzene on reaction with conc. HNO3/H2SO4 at 80-1000C forms which one of the following products?

    • 1,2-dinitrobenzene

    • 1,3- dinitrobenzene

    • 1,4-dinitrobenzene

    • 1,2,4-trinitrobenzene

    Solution

    B.

    1,3- dinitrobenzene

    NO2 group being electron withdrawing reduces electron density at output positions. Hence, now the meta-position becomes electron rich on which the electrophile (nitronium ion) attacks during nitration.
    HNO3 +H2SO4 ---> H2NO3+ +HSO-4 +H2O +NO2+


    Question 452
    CBSEENCH12011139

    Some meta-directing substituents in aromatic substitution are given. Which one is most deactivating?

    • -C identical toN

    • -SO3H

    • -COOH

    • -NO2

    Solution

    D.

    -NO2

    The deactivation tendency of given groups follows the order

    Thus,-NO2 is the most deactivation group.

    Question 453
    CBSEENCH12011141

    Which of the following compounds will not undergo Friedel -Craft's reaction easily?

    • Cumene

    • Xylene

    • Nitrobenzene

    • Toluene

    Solution

    C.

    Nitrobenzene

    Nitro group being electron withdrawing, deactivates the benzene nucleus to such an extent so that it becomes incapable to give Friedel -Crafts reaction.
    Nitrobenzene because of its unreactivity towards Friedel-Craft's reaction is used as a solvent for this reaction.

    Question 454
    CBSEENCH12011142

    In the reaction,

    • HgSO4/H2SO4

    • Cu2Cl2

    • H3PO2 and H2O

    • H+/H2O

    Solution

    C.

    H3PO2 and H2O

    When diazonium salt is treated with H3PO2 followed by hydrolysis. It diazonium group is replaced by -H resulting to the formation of hydrocarbon. Thus, A must be H3PO2/H2O.

    Question 455
    CBSEENCH12011163

    Among the following compounds, the one that is most reactive towards electrophilic nitration is

    • Benzoic acid

    • Nitrobenzene

    • toluene

    • benzene

    Solution

    C.

    toluene

    The presence of electron releasing group like -R, -OH etc., increases the electron density at o/p position and thus, makes the benzene ring more reactive (at(o/p position) towards electrophile. On the other hand, electron withdrawing group like-COOH,-NO2 etc. If present, reduces electron density and thus, reduces the activity benzene nucleus towards electrophile.Thus, the order of the given compounds towards electrophilic nitration is

    Thus, toluene is most reactive towards electrophilic nitration.

    Question 456
    CBSEENCH12011184

    Which of the following reagents will be able to distinguish between 1-butyne and 2-butyne?

    • NaNH2

    • HCl

    • O2

    • Br2

    Solution

    A.

    NaNH2

    NaNH2 is used to distinguish between 1-butyne and 2-butyne.
    CH subscript 3 CH subscript 2 straight C identical to CH space rightwards arrow with NaNH subscript 2 on top space CH subscript 3 CHC identical to CNa space plus 1 half straight H subscript 2 space upwards arrow
CH subscript 3 minus straight C identical to straight C minus CH subscript 3 space rightwards arrow with NaNH subscript 2 on top space No space reaction

    Question 457
    CBSEENCH12011185

    Consider the reaction,
    RCHO +NH2NH2 →RCH =N-NH2
    What sort of reaction is it?

    • Electrophilic addition elimination reaction

    • Free radical addition-elimination reaction

    • Electrophilic substitution elimination reaction

    • Nucleophilic addition-elimination reaction

    Solution

    D.

    Nucleophilic addition-elimination reaction

    RCHO space plus straight N with bold. bold. on top straight H subscript 2 space rightwards arrow RCH equals straight N minus NH subscript 2 space plus straight H subscript 2 straight O
    In the above reaction  negative space straight N with bold. bold. on top straight H subscript 2acts as nucleophilic species which adds on carbon. Therefore this is the case of the nucleophilic addition reaction. Simultaneously, a mole of H2O also eliminated. Therefore, overall this reaction is a nucleophilic addition-elimination reaction.
    Question 459
    CBSEENCH12011212

    What is the product obtained in the following reaction?

    Solution

    D.

    Reduction of nitrobenzene with Zn/NH4Cl (neutral medium) gives phenyl hydroxyamine.

    Question 460
    CBSEENCH12011226

    Method by which aniline cannot be prepared is 

    • hydrolysis phenyl isocyanide with the acidic solution

    • degradation of benzamide with bromine in alkaline solution

    • reduction of nitrobenzene with H2/Pd in ethanol

    • potassium salt of phthalimide treated with chlorobenzene followed by the hydrolysis with aqueous NaOH solution

    Solution

    D.

    potassium salt of phthalimide treated with chlorobenzene followed by the hydrolysis with aqueous NaOH solution

    Due to resonance in chlorobenzene C- Cl  bond accquires double bond chracter hence, C -Cl bond is inert towards nucleophile (phthalimide ion)

    Question 461
    CBSEENCH12011240

    Which of the following compound is most basic?

    Solution

    B.

     The compound is most basic due to localised lone pair of electrons on nitrogen atom while in other compounds , as result of resonance, the lone pair of electrons on nitrogen atoms gets delocalised over benzene ring and thus is less easily available for donation.
    Question 462
    CBSEENCH12011262

    The following reaction, 


    is known by the name

    • Friedel -Crafts reaction

    • Perkins reaction

    • Acetylation reaction

    • Schotten - Baumann reaction

    Solution

    D.

    Schotten - Baumann reaction

    Schotten- Baumann reaction is a method to synthesise amides from amines and acid chlorides.

    Question 463
    CBSEENCH12011281

    Which of the following statements about primary amines is false?

    • Alkyl amine are stronger bases than aryl amines

    • Alkyl amines reacts with nitrous acid to produce alcohols

    • Aryl amines react with nitrous acid to produce phenols

    • Alkyl amines are stronger base than ammonia

    Solution

    C.

    Aryl amines react with nitrous acid to produce phenols

    i) The presence of electron withdrawing substituent decrease the basicity while the presence of electron releasing substituent like, -CH3 - C2H5 etc increases the acidity.
    ii) HNO2 converts - NH2 group of an aliphatic amine into - OH while that of aromatic amines into - N =NCl.
    Since phneyl group is a electron withdrawing group, it decreases the basicity. Alkyl group, on the other hand, being electron releasing, increases the basicity. Thus, alkyl amines are more basic as compared to arylamines as well as ammonia.
    R-NH2 HNO2 R -OH
    Thus, HNO2 (nitrous acid ) converts alkyl amines to alcohols. But,

    C6H5NH2 HNO2 C6H5N = NClbenzene diazonium chloride

    Thus, HNO2 does not convert aryl amines into phenol.

    Question 464
    CBSEENCH12011316

    Predict the product,


     

    Solution

    A.

    With nitric acid (NaNO2) + HCl), primary aromatic amines give azo compounds and secondary aromatic amines gives nitroso compound

      

    Question 465
    CBSEENCH12011349
    Question 466
    CBSEENCH12011365

    Which one of the following on reduction with lithium aluminium hydride yield a secondary amine?

    • Nitroethane

    • Methylisocyanide

    • Acetamide

    • Methyl cyanide

    Solution

    B.

    Methylisocyanide

    On a catalytic reduction or with nascent hydrogen or with lithium aluminium hydride (LiAlH4) alkyl isocyanide yield secondary amine.

    CH subscript 3 space minus straight N space identical to straight C space plus space 4 space left square bracket straight H right square bracket space rightwards arrow space CH subscript 3 space minus space NH minus CH subscript 3

    Question 467
    CBSEENCH12011407

    Which of the following is more basic than aniline?

    • Diphenylamine

    • Triphenylamine

    • p-nitroaniline

    • Benzylamine

    Solution

    D.

    Benzylamine

    Benzylamine C6H5 - NH2 is more basic than aniline because benzyl group C6H5CH2 is electron donating group due to +I effect. So, it is able to increase the electron density of N of -NH2 group. Thus due to higher electron density rate of donation of a free pair of electron is increased i.e, basic character is higher. Phenyl and nitro group are electron attractive groups. so they are able to decrease the electron density of N of NH2 group. Hence, they are less basic with aniline.

    Question 468
    CBSEENCH12011428

    The correct increasing order of basic strength for the following compounds is 

    • II < III < I 

    • III < I < II

    • III < II < I

    • II < I < III

    Solution

    D.

    II < I < III

    –NO2 has strong –R effect and –CH3 shows +R effect. Therefore, Order of basic strength is 

    Question 471
    CBSEENCH12011448

    Which of the following compounds can form a zwitter ion?

    • Aniline

    • Acetanilide

    • Glycine

    • Benzoic acid

    Solution

    C.

    Glycine

    Amphoteric Nature of Glycine: In aqueous solution, glycine exists as an inner salt or a dipolar ion.
    H2NCH2COOH +H2O  H3N+CH2COO- +H2O

    This doubly charged ion is known as a Zwitterion or an ampholyte. Due to formation of the ampholyte, glycine acts both as an acid or a base.

    In aqueous solution, Zwitter- ion tends to lose a proton. Hence, if electrolyzed, the negative glycine ion will migrate to anode.
    H3N+CH2COO- +H2O [NH2CH2COO-] +H3O+

    The pH value for the isoelectric point of glycine is 6.0.

    Question 472
    CBSEENCH12011450

    Nitration of aniline in strong acidic medium also gives m-nitroaniline because

    • Inspite of substituents nitro group always goes to only m-position.

    • In electrophilic substitution reactions amino group is meta directive.

    • In acidic (strong) medium aniline is present as anilinium ion.

    • In absence of substituents nitro group always goes to m-position.

    Solution

    C.

    In acidic (strong) medium aniline is present as anilinium ion.

    In acidic medium, aniline is protonated to form anilinium ion which is meta-directing.
    Hence besides para (51%) and ortho (2%), meta product (47%) is also formed in significant yield.

    Question 473
    CBSEENCH12011456

    Which of the following carbocations is expected to be most stable?

    Solution

    C.

    -NO2 group is meta-directing group, therefore,

    Less stable due to more e- withdrawing effect of -NO2

    More stable due to the less e-withdrawing effect of NO2

    Question 474
    CBSEENCH12011496

    The main product formed in the following reaction is

     

    Solution

    A.

    As -NH3 group is more reactive than -OH group, CH3COCl will attack -NH3 group and give as the product.

    Question 475
    CBSEENCH12011497

    The correct order of the basic strength of the following are

    • I>II>III>IV

    • IV>II>III>I

    • III>IV>II>I

    • III>II>IV>I

    Solution

    D.

    III>II>IV>I

    Electron releasing groups increases the basic nature while electron withdrawing group decreases the basis strength of amines.

    Therefore, the correct order is III> II> IV>I

    Question 476
    CBSEENCH12011498

    In the reaction,

    Solution

    A.

    Question 477
    CBSEENCH12011502

    Which of the following sodium compound/compound (s) are formed when an organic compound containing both nitrogen and sulphur is fused with sodium?

    • Cyanide and sulphide

    • Thiocyanate

    • Sulphite and Cyanide

    • Nitrate and sulphide

    Solution

    B.

    Thiocyanate

    When an organic compound containing both nitrogen and sulphur is fused with sodium, sodium-thiocyanate is formed as follows,

    Na + S + C + N → NaSCN

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