Sponsor Area
Sponsor Area
(HCl—ZnCl2) is lucas reagent, lucas reagent react with alcohol however it does not react with primary alcohol but readily gives turbidity with tertiary alcohols.
a) Reaction with (HCl—ZnCl2):
Butan-1-ol is primary alcohol thus no reaction occur.
where as 2-methyl butan-2-ol is tertiary alcohol, it forms 2-chloro-2-methylbutane.
Resonance structures of ortho nitro phenol:
Thus, presence of nitro group at ortho and para position incerease the acidic character.
It is an important laboratory method for the preparation of symmetrical and unsymmetrical ethers. In this method, an alkyl halide is allowed to react with sodium alkoxide.
In structure (a), group sodium methoxide (CH3ONa) is a strong nucleophile also it is a strong base. Hence, an elimination reaction predominates over a substitution reaction.
Sponsor Area
When benzaldehyde react with sodium bromide Benzyl alcohol is formed .
Why are alcohols soluble in water?
Acidity of phenols: The reactions of phenol with metals (e.g., sodium, aluminium) and sodium hydroxide indicate its acidic nature. The hydroxyl group, in phenol is directly attached to the sp2 hybridised carbon of benzene ring which acts as an
electron withdrawing group. Due to this, the charge distribution in phenol molecule, as depicted in its resonance structures, causes the oxygen of –OH group to be positive.
In case of ethanol, no such resonace structure is shown as phenol. Hence, phenol is stronger acid than ethanol.
The high boiling points of alcohols are mainly due to the presence of intermolecular hydrogen bonding in them which is lacking in ethers and hydrocarbons.
Phenols are sparingly soluble in water. Why?
Phenol is soluble in water to some extent. It is due to its ability to form hydrogen bonding with water molecules. However the large part of phenol molecule is phenyl group that is non polar and hence its solubility if limited in water.
What happens when 3-methyl butanone is reduced with sodium tetrahydrido borate(III)?
Write the structure and IUPAC name of the major product obtained when ethyl magnesium bromide reacts with formaldehyde and the product is then hydrolysed with dilute H2SO4.
Compare the relative boiling points of:
Phenol has a higher boiling point than thio phenol although thio phenol has higher molecular mass. This is due to the presence of intermolecular hydrogen bonding in phenol.
Give the equation of reaction of preparation of phenol from cumene.
Cumene (isopropylbenzene) is oxidised in the presence of air to cumene hydroperoxide. It is converted to phenol and acetone by treating it with dilute acid.
Compare the relative boiling point of toluene and phenol.
You are given benzene, conc. 
and NaOH. Write the equations for the preparation of phenol using these reagents.
First benzene react with sulphuric acid to give benzensulfonic acid and it react further with sodium hydroxide and sodium benzosulfonate is formed. when benzosulfonate is fused by sodium hydroxide phenol is obtaine.
Both the chlorine and the nitro group at the para position makes the phenol group acidic because they are both electron withdrawing groups that stabilize the negative charge of phenol. However, the fact that the nitro groups is electron withdrawing goes resonance, allows better stabilize the negative charge of the oxygen then chlorine alone. Thus, p-nitrophenol is more acidic than p-chlorophenol.
Arrange the following compounds in increasing order of their acid strength.
Propan-1-ol, 2, 4, 6-trinitrophenol, 3-nitro-phenol, 3, 5-dinitrophenol, phenol, 4-methyl phenol.
When any phenol loses its acidic proton, it forms an oxygen with three lone pairs. In phenol, these lone pairs can be dislocated over the aromatic ring, providing resonance stability. This added stability allows for the easier dissociation of phenols. Thus, order of acidity is ,
Propan-1-ol < 4-methyl phenol, phenol <3-nitrophenol < 3, 5-dinitrophenol < 2, 4, 6-tri nitro-phenol.Why has tertiary alcohol higher reactivity towards hydrogen halide compared to secondary and primary alcohols?
Tertiary alcohol has higher reactivity towards hydrogen halide as compared to secondary because carbonium ion formed from tertiary alcohol is the most stable and reaction go via SN1 reaction. Therefore, order of reaction is,
Tertiary alcohol > Secondary alcohol > Primary alcohol.
State what happens when isopropyl chloride is boiled with alcoholic potassium hydroxide solution.
Give reason: nitration of phenol gives ortho and para products only.
Which electrophile is the attacking reagent when phenol and chloroform undergoes Reimer Tiemann reaction?
Write the equation for the industrial synthesis of methanol.
Industrial synthesis of methanol is given by:
Write the structure of the major product and also label the product as 1°, 2° or 3° alcohol.
The product is 1 methylcyclopentanol
It is 3° alcohol.
Name the enzymes which convert sucrose into glucose and fructose and finally into ethanol.
(i) Invertase converts sucrose into glucose and fructose.
(ii) Zymase converts glucose into ethanol.
Lithium aluminium hydride is used as a reducing agent. It convert ketones into the corresponding alcohols. Whereas H2/Pt convert alkene to alkane. Thus product are;
Arrange the following compounds in order of increasing boiling points:
Penta-1-ol, butan-1-ol, butan-2-ol, ethanol, propan-1-ol, methanol.
Boiling point of alcohol increase with increase in the
number of carbon atoms (increase in van der Waals forces). Thus, order of increasing boiling point,
In alcohols, the boiling points decrease with increase of branching in carbon chain, because of decrease in van der Waals forces with decrease in surface area. Thus the decreasing order of boiling point is A > C > B
Why is ethanol less acidic than water?
Ethanol is less acidic than water because of the electron donating nature of the alkyl group attached to the oxygen which destabilizes the hydroxide ion and make it tougher for the oxygen to donate the proton. Hence, water is more acidic than ethanol.
Compare the acidity of Cl—CH2 CH2OH and CH3CH2OH. Explain.
Arrange the following in order of decreasing basic strength:
(CH3)3(CO–, CH3O–, (CH3)2CHO–
Compare and explain the relative Bronsted basicities of 1°, 2° and 3° alcohols in the liquid state.
What happens when ethanol reacts with Na metal? Name the products formed.
When ethanol reacts with Na metal sodium ethoixde.
Arrange the following alcohols in order of increasing reactivity towards Na metal:
Explain why sodium (Na) may be used to remove the last trates of H2O from benzene but not from ethanol?
Sponsor Area
Give the major product of the reaction of ethanol with:
(i) Ethanoic anhydride (CH3CO)2O.
(ii) Ethanol chloride in the presence of pyridine.
i) Ethanol react with ethanoic anhydride to form esters.
CH3CH2OH+ (CH3CO)2O → CH3OCOC2H5
ii) When ethanol react with ethanol chloride in the presence of pyridine, it also form esters.
CH3CH2OH +CH3COCl → CH3OCOC2H5
What is the decreasing order of reactivity of hydrogen halides in the conversion of ROH into RX?
Convert methyl bromide into ethyl alcohol.
When methyl bromide react with magnesium in presence ether Grignard regent is form, further when it is treated with formaldehyde in presence of hydronium ion gives ethyl alchol.
How will you prepare propan-2-ol from bromomethane?
When bromomethane is treated with magnesium in presence of ether Grignard regent is form, further reaction with ethanal in presence of hydronium ion, propan-2-ol formed.
As the number of electron donating R groups at α-carbon increases, the reactivity towards HX increases. The correct order is,
(A) > (C) > (D) > (B) .
Write the name and sturcture of the product formed when propene dissolves in cold conc. H2SO4.
when propene dissolves in cold conc. H2SO4
isopropyl hydrogen - sulphate.
Arrange the following in order of decreasing ease of dihydration:
(CH3)3COH, (CH3)2CHOH, CH3CH2OH
The relative ease of dehyration of alcohols follows the following order:
Tertiary > Secondary > Primary
Convert t-butyl alcohol into isobutyl bromide.
Conversion of tert-butyl alcohol to isobutyl bromide.
.
Prepare propan-2-ol from propan-1-ol
When propan-2-ol is treated with conc. sulphuric acid propene is formed further reaction with Diborane in presence of water propan-1-ol is obtained
Give the product of the oxidation of the following substances with chromic acid in aqueous acetone solution.
Chromic acid oxidizes secondary alcohol to ketone.
Write the structure of the oxidation product of the following reactions:
-carbon.
Give a chemical test to distinguish methanol and ethanol.
How can we distinguish between, n-butanol and t-butanol using acidified potassium dichromate?
Acidified K2Cr2O7 is orange in colour. When it oxidises alcohol, its colour changes to bluish green.
n-butanol is 1° alcohol and gives a bluish-green colour while butanol is 3° alcohol, does not react with K2Cr2O7.
What happens to 2-methyl propane-2-ol, when it is heated at 573 K with copper?
Two test tubes A and B containing 2-methyl-2-propanol and 2-methyl propanol-1 respectively. In which test tube the turbidity appears when lucas reagent is added?
Arrange the following alcohols in decreasing order of rate of dehydration with H2SO4.
Give the structure and IUPAC name of the product from the reaction of phenol with CHCl3 in NaOH followed by acidification.
When phenol react with trichloromethane in presence of sodium hydroxide, it forms 2- hydroxy benaldehyde.
C6H5OH +CHCl3 +NaOH ---> 
IUPAC name is 2-hydroxybenzaldehyde.
What happens when dilute HNO3 is added to phenol? Name the method to separate the isomers obtained.
With dilute nitric acid at low temperature (298 K),
phenol yields a mixture of ortho and para nitrophenols.
Give the structure of the products resulting from the reaction of sodium phenoxide with CO2 at 4 atm and 400 K followed by addition of aqueous acid.
When sodium phenoxide react with CO2 at 4 atm and 400K in aqueous acid, salicylic acid is obtain.
When phenol is treated with chloroform in presence of NaOH at 343 K, salicyaldehyde is formed.
p-nitrophenol is more soluble than ortho and para nitrophenol because P-nitrophenol has Inter-molecular Hydrogen Bonding while o-nitrophenol has Intra-molecular Hydrogen Bonding.
Now due to the Hydrogen Bonding more energy needs to be supplied to vaporize the compound as there are extra bonds other than that present bonds that hold the molecule.
There are bonds between molecules in p-nitrophenol which leads to higher boiling point as more energy need to be supplied to separate the molecules. Whereas in o-nitrophenol the bonds exist in the molecule itself due to which there is virtually no change in the boiling point.
While separating a mixture of ortho and para nitrophenols by stream distillation, name the isomer which is steam volatile. Give reason.
Name the reagent used in the conversion of phenol into 2, 4, 6-tribromophenol. Also write the equation.
When phenol is treated with bromine water,
2,4,6-tribromophenol is formed as white precipitate.
Convert phenol into chlorobenzene.
Phenol is converted to benzene on heating with zinc dust. Further reaction with chlorine followed by FeCl3 gives chlorobenzene.
Name the electrophile in the Reimer Tiemann reaction and how is it formed?
Do ethers have dipole moments? Explain.
Compare the solubility of diethyl ether and n-butane in water.
Give the product(s) from the reaction of one mole diethyl ether with
(i) one mole of conc. HI and
(ii) excess of HI.
Why bromination of anisole takes place even in the absence of FeBr3 as a catalyst?
Name the main product formed in Williamson’s synthesis.
Ether formed as main product in williamson's synthesis.
R-X + R-O-Na ---> R-O-R + NaX
Sponsor Area
What is the type of hybridization associated with oxygen atom in an ether molecule?
How will you obtain diether ether from ethanol?
Does peroxide formation occur more rapidly with n-propyl ether or di-isopropyl ether?
Why no flame should be allowed in the lab, while working with ether?
Why is O—CH3, ortho and para directing in aromatic electrophilic substitution?
Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method. Give reason.
Which of the following can easily undergo Williamson's synthesis to prepare ether?
-carbon is less hindered while in (CH3)3CCH2Br (although it is 1°), 
-carbon is highly crowded and difficult for alkoxide ion to attack.
Name the ether used as inhalation an aesthetic. What are the disadvantages of using it?
How would you differentiate between phenol and carboxylic acid by a simple chemcial test?
Explain why is propanol has higher boiling point than that of hydrocarbon, butane?
Alcohols can form H- bonds with due to presence of (-OH) group and break the H-bonds already existing between water molecules. Hence they are soluble in water.
In contrast, hydrocarbon cannot form H-bonds with water and hence are insoluble in water.
Of the two hydroxy organic compounds ROH and R'OH, the first one is basic and the other is acidic in behaviour. How is R different from R'?
Why does phenol get coloured on long standing?
Phenol is acidic but does not decompose NaHCO3 solution while carbonic acids like CH3COOH decompose NaHCO3 solution. Why?
What is wood alcohol? Why is it so called?
How is methanol (or wood spirit) obtained from carbon monoxide?
How is t-butyl alcohol obtained from acetone?
When acetone react with methylmagnesiumbromide, addition product is formed which on reacting with water gives t-butyl alcohol.
Phenols do not undergo substitutions at the carbon oxygen bond. Why?
Of benzene and phenol which is more easily nitrated and why?
Which bond of alcohol is cleaved during its reaction with (a) carboxylic acid (b) HCl.
Why are ethers very little reactive chemically?
Alkoxy groups attached to benzene ring is ortho and para directing, Justify.
How is phenol obtained from aniline?
A diazonium salt is formed by treating an aromatic primary amine with nitrous acid (NaNO2 + HCl) at 273-278 K. Diazonium salts are hydrolysed to phenols by warming with water or by treating with
dilute acids.
Explain giving reasons, why Phenol has a smaller dipole moment than methanol.
If an alcohol is treated with excess of sulphuric acid, no esterification takes place. Why?
How many sigma bonds are present in 3-methyl phenol?
Structure of 3-methyl phenol
6 (benzene ring) + 4(C—H of benzene ring) +1 (C of benzene ring and CH3 group) +3 (of CH3 group) + 1(C of benzene and O of OH) +1 (O and H of OH group) = 16.
When the reaction is carried in the presence of CS2 at low temperature monobromophenols are formed.
Ethanol and chloro ethane both are polar in nature yet ethanol is miscible in water while chloro ethane is immiscible. Explain.
Give the IUPAC name for the following alcohol and classify it as 1°, 2° or 3°.
Give the IUPAC name for the following alcohol and classify it as 1°, 2° or 3°.
Give the IUPAC name for the following alcohol and classify it as 1°, 2° or 3°.
The IUPAC name of the given compound is
Cyclo 1- pentene methanol. It is primary alcohol.
The IUPAC name of given compound is 2- cyclopropylethanol.
It is secondary alcohol.
Write the structures of the compounds whose IUPAC names are given below:
1-Ethoxypropane.
Write the structures of the compounds whose IUPAC names are given below:
2, 3-Diethylphenol.
2, 3-Diethylphenol
Write the structures of the compounds whose IUPAC names are given below:
2-Ethoxy- 3-methylpentane
2-Ethoxy- 3-methylpentane
(a) Catalytic reduction of butanal gives,
CH3–CH2–CH2–CH2–OH
Butan-1-ol
(b) When propene is react with dilute sulphuric acid, it gives
(c) When propanone react with methylmagnesiumbromide followed by hydrolysis, it gives,
Preparation of propan-2-ol from a Grignard reagent.
Show the steps in the industrial preparation of phenol starting with Cumene.
Industrial prepartion of phenol from cumene:
Show the steps in the industrial preparation of phenol starting with chlorobenzene.
Explain why phenol has a much lower pKa value than ethanol.
In phenol, the lone pair of oxygen participates into resonance with the benzene ring.
As a result, oxygen acquires a partial positive charge. The electron density of O—H bond then shifts towards oxygen decreases around H-atom. H-atom, therefore, can easily be removed as H+ ion. While in ethanol, ethyl group has a + I effect and increases the electron density around H of O—H group making it difficult to remove H as H+. Hence, phenol is more acidic than ethanol and has lower pKa value than ethanol.
Ortho nitrophenol is more acidic than ortho-methoxyphenol. This is because the nitro-group is an electron-withdrawing group. The presence of this group in the ortho position in ortho nitro phenol decreases the electron density in the O−H bond. As a result, it is easier to lose a proton.Also, the o-nitrophenoxide ion formed after the loss of protons is stabilized by resonance. Hence, ortho nitrophenol is a stronger acid.
In the case of ortho methoxyphenol; methoxy group is an electron-releasing group. Thus, it increases the electron density in the O−H bond and hence, the proton cannot be given out easily. Hence, ortho-nitrophenol is more acidic than ortho-methoxyphenol.
Write the structures of the major products expected from the following reactions:
(a) Mononitration of 3-methylphenol.
(b) Dinitration of 3-methylphenol.
(c) Mononitration of phenyl methanoate.
How are the following conversions carried out?
Propene → Propane-2-ol.
Conversion of propene to propane-2-ol
.
How are the following conversions carried out?
Methyl magnesium bromide → 2-Methylpropan-2-ol.
Conversion of 2-methylpropan-2-ol from methyl magnesium.
Give the structure and IUPAC name of the expected product of the following reaction:
Catalytical reduction of butanal.
CH3–CH2–CH2–CH2–OH
Butan-1-ol
Give the structure and IUPAC name of the expected product of the following reaction:
Hydroboration of but-1-ene.
CH3CH2CH2CH2OH
Butan-1-ol
Give the structure and IUPAC name of the expected product of the following reaction:
Hydration of propylene in presence of dil. sulphuric acid.
Propylene on hydration in the presence of dilute sulphuric acid, it gives,
Explain Oxymercuration and demercuration.
Explain Hydroboration.
The following is not an appropriate reaction for the preparation of t-butyl ethyl ether.
(i) What would be the major product of this reaction?
(ii) Write a suitable reaction for the preparation of t-butyl ethyl ether.
(a) Eight isomeric alcohols are possible:
b) Primary alcohol: pentan-1-ol; methylbutan-1-ol; 3-methyl-1-ol; 2,2Dimethylpropan-1-ol.
Secondary alcohol: Pentan-2-ol; 3-methylbutan-2-ol; pentan-3-ol
Tertiary alcohol: 2-methylbutan-2-ol
The addition of borane followed by oxidation is known as the hydroboration-oxidation reaction.
In the first step, alkene reacts with diborane (B2H6) as boron hydride (BH3) to form an alkyl borane. In the next step, the alkyl borane is oxidised by alkaline H2O2 to form an alcohol. The indirect hydration proceeds according to Anti Markovnikoff’s rule. For example,
Give the structures and IUPAC names of monohydric phenols of molecular formula, C7H8O.
Give the equations of reaction for the preparation of phenol from cumene.
Write chemical reaction of preparation of phenol from chlorobenzene.
Write the mechanism of hydration of ethene to yield ethanol.
The mechanism of the reaction involves the following three step:
Step 1: Proptonation of ethene to form carbocation by electrophilic attack of H3O+.
Step 2: Nucleophilic attack of water on carbocation.
Step 3: Deprotonation to form an ethanol.
Synthesis of 1-phenyl ethanol from phenylethene.
Synthesis of Cyclohexylethanol from chloromethyl cyclohexane.
Synthesis of pentan-1-ol by using of 1-chloropentane.
The -OH group attached to the benzene ring activates it towards electrophillic substitution reaction. It direct the incoming group to ortho and para position in the ring as these positions become electron rich due to the resonance effect the caused by -OH group.
Since there is –ve charge at o and p position. Therefore, —OH group activates benzene ring towards electrophilic substitution reaction.
Explain the following with an example:
Kolbe’s reaction.
Explain the following with an example:
Reimer-Tiemann reaction.
Explain the following with an example:
Williamson ether synthesis.
Write mechanism of acid dehydration of ethanol to yield ethene.
Mechanism: The formation of ethylene and diethyl ether from ethanol and conc. H2SO4 may be explained as follows:
(a) Formation of ethene or ethylene:
Step 1. Due to the presence of two lone pairs of electrons on oxygen, alcohols act as weak bases. Therefore, they react with strong mineral acids (HCl, H2SO4 etc.) to form oxonium salts.
Step 2. The presence of a positive charge on the highly electronegative oxygen atom weakens the C—O bond. Thus, the protonated ethanol readily eliminates a molecule of H2O to form ethyl carbocation.
This step is slow and hence is the rate-determining step of the reaction.
Step 3. The ethyl carbocation formed in step 2 being a reactive chemical species, readily loses a proton to form the ethene molecule.
Propene is react with water in the presence of an acid as a catalyst, then propan-2-ol is obtained.
Conversion of benzyl alcohol from benzyl chloride.
Conversion of propane-1-ol from ethyl manesium chloride.
Conversion of 2-methyl propan -2-ol from methyl magnesium bromide.
Step 1 :Protonation
The formation of ethers by dehydration of alcohol is a bimolecular reaction (SN2) involving the attack of alcohol molecule on a protonated alcohol molecule. In the method, the alkyl group should be unhindered. In case of secondary or tertiary alcohols, the alkyl group is hindered. As a result, elimination dominates substitution. Hence, in place of ethers, alkenes are formed.
O—CH3 bond is weaker than —OC6H5. Therefore, O—CH3 bond is broken easily to form phenol and iodo methane and no CH3OH is formed. It is also due to steric factors during protonation at methoxy benzene.
The alkoxy group (—OR) is ortho and para directing group and it activates the aromatic ring in ortho and para positions due to conjugation with pi electrons of the benzene ring. However, ethers are some what less reactive than phenol in these substitution reactions. Activation of benzene ring takes place as shown above.
The following reactions show that alloxy group directs the incoming substituents to ortho and para positions in benzene ring.
Mechanism: The cleavage of ethers by halogen acids occur by the following mechanism.
Step 1. Ethers being Lewis basis, undergo protonation to form oxonium salts:
Step 2. The protonated ether thus formed undergoes nucleophilic attack by the halide ion to form a molecule of an alkyl halide and a molecule of an alcohol.
Alkylation of anisole: 
Anisole undergoes bromination with bromine in the ethanoic acid even in the absence of iron(III)bromide catalyst. Due to the activation of benzene ring by the methoxy group. Para isomers is obtained in 90% yield.
Use simple chemical test to differentiate between the following pairs of organic compounds:
(i) 2, 4, 6-trinitro phenol and 2, 4, 6-tri methyl phenol.
(ii) Anisole and benzyl alcohol.
When ethanol is treated with phosphrous tribromide it gives bromoethane.
When cumene hydroperoxide is treated with dilute sulphuric acid, it gives phenol and acetone.
Give a chemical test to distinguish between: 2-pentanol and 3-pentanol.
This compound has a CH3C = O group.
Therefore, it will form iodoform (CHI3) with iodine and alkali on warming. Iodoform is a yellow crystalline substance.
3-pentanol does not show this test.
Write the resonance structures of phenol (which is similar to that of chlorobenzene) and explain why it does not form chlorobenzene on reaction with PCI5 Explain whether phenol can be dehydrated on heating with catalytic amounts of conc. H2SO4.
Due to resonance, carbon-oxygen bond develops a slight double bond character. Therefore, it is not easy to replace —OH in phenols by Cl.
No, phenols cannot be dehydrated on heating with small amount of conc. H2SO4. Instead, phenols with conc. H2SO4 undergoes sulphonation.
Account for the following:
Alcohols with three or less carbons are water-soluble while alcohols with five or more carbons are insoluble.
Account for the following:
tert-butanol is more volatile than n-butanol.
To cleave the C—O bond in alcohols small amount of acid is added. Explain.
What is meant by Absolute alcohol?
Absolute alcohol: This is ethyl alcohol of about 100 percent purity. It is made from rectified spirit by keeping it for a few days with quick lime.
Later on, it is distilled to get absolute alcohol (about 99% pure).
Alternatively, the rectified spirit is mixed with benzene and distilled when a ternary mixture of water, benzene and alcohol distils over. When all the water distils out then a binary mixture of benzene and alcohol distils at a slightly higher temperature. After all the excess of benzene distils over, then absolute alcohol distils over.
What is meant by Methylated spirit?
Methylated spirit: Since ethyl alcohol can be used for drinking purposes, it is heavily taxed in the form of excise duty. On the other hand, ethyl alcohol used for industrial purposes is duty free, industrial alcohol can be used for drinking purposes. In order to make rectified spirit unfit for drinking purposes. it is denatured by mixing some poisonous substances like methyl alcohol.
Such alcohol (denatured) is known as methylated spirit. It is extensively used in paints, varnishes, medicines and as a solvent.
What is meant by Denatured alcohol?
Explain the following:
Cyclohexanol is more soluble in water than 1-hexanol.
Explain the following:
Propane-1, 3-diol is more soluble in water than propan-1-ol.
How can we distinguish between 1°, 2° and 3° alcohols by the reaction with Cu at 573 K?
The given reaction involve the following mechanism,
Step 1: Protonation to 3-methylbutan-2-ol
Step 2: Formation of secondary carbocation by the elimination of a water molecule.
Step 3 : Rearrangement by the hydride-ion shift
Step 4: Nucleophilic attack
Explain giving reasons:
(i) Boiling point of an alcohol is higher than the corresponding alkane.
(ii) Lower alcohols are soluble in water, while the higher alcohols are not.
(iii) Boiling point of mono hydric alcohols increases with increase in carbon atoms.
Since a large amount of energy is needed to break the extensive hydrogen bonds, which hold a large number of alcohol molelcules together, so the boiling points of alcohols are significantly higher than the corresponding alkanes, in which no such hydrogen bonding can take place.
(ii) The solubility of an alcohol in water depends upon its capacity to form hydrogen bonds with water molecules. However, the non-polar hydrocarbon part of the alcohol molecule is unable to form hydrogen bonds with other. Consequently, the lower alcohols are soluble in water, due to the formation of hydrogen bonds between highly polarised hydroxyl group (-OH), present in alcohols as well as water. However, in higher alcohols the hydrocarbon part becomes larger in size and, therefore, the solubility effect due to hydroxyl groups (-OH), of alcohol is out weighed by the counter large ‘repulsive effect’ of non-polar hydrocarbon part of the alcohol molelcule. Hence, higher alcohols become in soluble in water. The large inductive effect (+I effect) of the hydrocarbon part (or alkyl group) in higher alcohols also reduces the polar character of hydroxyl group (–OH) in higher alcohols, which in turn reduces their capacity to form hydrogen bonding with water.
(iii) With the increase in molar mass of alcohol, the intermolecular Van der Waals forces of attraction increases, thereby the boiling point also increases. Thus b.p. of C4H5OH > C3H7OH > C2H5OH > CH3OH
Which reaction of phenol with CHCl3 in NaOH followed by acidification gives salicyaldehyde? Suggest a mechanism for this reaction.
How is ethanol obtained commercially by fermentation process?
A.
Phenol reacts with sodium carbonate solution and liberates CO2.B.
2-Butanol can exhibit enantiomerism.C.
Alcohols are stronger acids than water.D.
Methylated alcohol is unfit for drinking.E.
Benzyl alcohol gives coloured complexes with neutral FeCl3.2-nitro phenol
D.
2, 4, 6-trinitrophenolPhenol is
C.
An acid weaker than carbonic acidB.
Heating sodium ethoxide with ethyl bromide
C.
CH2 = CH—OCH2CH3
B.
Methyl salicylateA.
C6H5OH is more acidic than C2H5OHIn absence of kerosene oil can we store sodium metal in diethyl ether or ethyl alcohol or anhydrous hexanol?
Sodium metal can be store in hydrocarbon and ether but it cannot be store in alcohol because it easily react with it.
Conversion of CO to methanol.
CO + CO2 + 7H2 --> 2 CH3OH + 2H2 + H2O
Which of the following will have a higher boiling point and why? CH3NH2 or CH3OH.
Molecular mass of methanol is 32g/mol and molecular mass of methylamine is 31g/mol. Since methanol have higher molecular mass thus it have higher boiling point. Also, CH3OH has very strong H-bonding between its molecules. This is due to the greater electronegativity of oxygen atom. Such strong association of molecules leads to rise in the boiling point. CH3NH2 has comparitively lesser H-bonding due to lesser electronegativity of N atom and hence lesser boiling atom.
Write one example of each:
(i) a nucleophile, (ii) an electrophile.
All molecules or ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases. For example Cynaide ion CN- or Hydroxyl ion OH- are nucleophilies.
Electrophiles are positively charged or neutral species having vacant orbitals that are attracted to an electron rich centre. It participates in a chemical reaction by accepting an electron pair in order to bond to a nucleophile. Because electrophiles accept electrons, they are Lewis acids. For example mercury cation Hg+.
How would you differentiate between phenol and carboxylic acid by simple chemical test?
Carboxylic acid react with aqueous sodium bicarbonate and carboxylate salt and carbon dioxide. Phenol does not give this test.
Which Grignard reagent should react with acetone to get 2-phenyl propan-2-ol?
Acetone react with Phenylmagnesium bromide to form 2-phenyl propan-2-ol.
When benzaldehyde react with LiAlH4, it form benzyl alcohol.
How would you convert tertiary butyl chloride to tertiary butyl alcohol?
Conversion of tertiary butyl alcohol from tertiary butyl chloride.
How many σ-bonds are present in 3-methyl phenol?
6 carbon atoms of the ring form a sigma bond with the neighbouring carbon atoms of the ring. Therefore 6 sigma bonds. Another carbon atom forms a sigma bond with the carbon of -CH3 group which in turn forms a sigma bond with each of the 3 hydrogen atoms. 4 more sigma bonds.
4 carbon atoms of the ring form a sigma bond with hydrogen atoms. 4 more sigma bonds.
-OH form 2 sigma bond.
Total =6+2+4+4 =16 sigma bonds.
Fermentation is define as the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms, typically involving effervescence and the giving off of heat.
What happens when ethylamine is treated with nitrous acid?
When ethyl amine react with nitrous acid, it form ethyl diazonium salt which is being unstable, liberate nitrogen gas and ethanol.
The main application of diphenyl ether is as a eutectic mixture with biphenyl, used as a heat transfer medium.
Discuss the Williamson's synthesis for the preparation of ethers.
Williamson's important method laboratory method for the preparation of symmetrical and unsymmetrical ethers. In this method, an alkyl halide is allowed to react with sodium alkoxide.
R-x +R-O-Na ---> R-O-R' +NaX
What happens when primary, secondary and tertiary alcohols are treated with copper powder at 573 K?
When the vapours of a primary or a secondary alcohol are passed over heated copper at 573K, dehydrogenation takes place and an aldehyde or a ketone is formed. In case of tertiary alcohols, it goes dehydration.
How is phenol obtained commercially from benzene?
Benzene react with chlorine in the presenc of ferric chloride which form chlorobezene, which on further reaction with sodium hydroxide gives sodium phenoxide. Then sodium phenoxide acidified and form phenol. 
Phenols are more reactive than alcohols. This is due to the fact that that the phenoxide ion produced by the loss of proton from phenol is highly stabilized by resonance while there is no such resonance stabilization of the cation formed by loss of protons from hexanol or any other alcohol.
Phenol is very weak acid. Phenol can lose a hydrogen ion and forms phenoxide ion. The negative charge on the oxygen atom is delocalised around the ring and thus stblilised. Hence lesser the acidity.
The resonance structures of phenoxide ions explain the delocalization of negative charge. In case of substituted phenols, acidity of phenols increases in the presence of electron withdrawing group. This is due to the stability of the phenoxide ion generated. The acidity of phenols further increases if these groups are attached at ortho and para positions. This is due to the fact that the negative charge in phenoxide ion is mainly delocalized at ortho and para positions of the attached benzene ring. On the other hand, the acidity of phenols decreases in presence of electron donating groups as they prohibit the formation of phenoxide ion.
Phenol has a smaller dipole moment (1.54 D) than methanol. The smaller dipole moment of phenol is due to the electron withdrawing effect of phenyl group (whereas alkyl group in alcohols has electron releasing effect).
In phenol, the lone pairs of electrons of the oxygen atom are delocalised across the aromatic ring (via electron transfer known as resonance) this reduces the polarity of the C-O bond. Methanol, which has no aromatic ring and the lone pair of electrons from the oxygen are not delocalised meaning that the C-O bond, in this case, has a higher polarity.
Write chemical equations for what happens when:
(i) 2-methyl-2-proponal vapours are passed over heated copper.
(ii) A Triglyceride is treated with sodium hydroxide solution.
i) When 2-methyl-2-proponal is treated with copper then isobutlene is formed.
ii) When Triglyceride is treated with sodium hydroxide, it forms glycerol.
Give reasons for the following:
Phenol does not undergo protonation readily.
The lone pair on oxygen O-H in phenol is being shared with benzene ring through resonance. thus, a lone pair is not fully present on oxygen and hence phenols do not undergo protonation reactions.
Which alcohol is known as wood alcohol? How will you prepare it commercially? Give its one use?
Methanol CH3OH is known as wood alcohol. methanol produced by catalytic hydrogenation on carbon monoxide at high pressure and temperature and in the presence of ZnO-Cr2O3 catalyst.
Methanol is colourless liquid and highly poisonous in nature.
Use:
Methanol is used as a solvent in paints.
Primary alcohols on reaction with Lucas reagents (Conc. HCl/anhy.ZnCl2) does not forms white cloudiness or turbidity at room temperature.
RCH2OH + Lucas Regent -->No Reaction
Secondary alcohol : Secondary alcohol on reaction with locals reagent (Conc. HCl/anhy.ZnCl2) forms white cloudiness or turbidity appears with in about 5 minutes.
R2CHOH+ Lucas reagent --> R2CHCl
Tertiary alcohol: Tertiary alcohol on reaction with Lucas Reagent (Conc. HCl/anhy.ZnCl2) forms white cloudiness or turbidity immediately.
R3C-OH +lucas --> R3CCl
How do you convert the following?
Propan-2-ol to 2-methylpropan-2-ol
Write the mechanism of the following reaction: 2CH3-CH2-OH --> CH3-CH2-O-CH2-CH3?
2CH3-CH2-OH ---> CH3-CH2-O-CH2-CH3
The given reaction follows SN2 mechanism as shown below:
Write the IUPAC name of the compound.
The IUPAC name of the given organic compound is 3-Hydroxybutan-1-oic acid.
Which of the following isomers is more volatile: o-nitrophenol or p-nitrophenol?
In o-nitro phenol, -OH is linked to –NO2 by means of intramolecular H-bonding so, it is highly volatile.
Explanation:
Stronger intermolecular forces would make the substance less volatile. So we can see intermolecular H-bonding in P-nitro phenol, so P-nitro phenol is less volatile, where as in o-nitro phenol intra H-bonding takes places that’s why it is highly volatile.
Explain the mechanism of the following reaction:
The mechanism of the reaction is given below:
How will you convert
Propene to Propan-2-ol?
To convert from Propene to Propan-2-ol, the addition of H2SO4 takes place in accordance with Markovnikov ‘s rule i.e.
How will you convert
Phenol to 2, 4, 6- trinitrophenol?
When concentrated nitric acid is added to phenol in the presence of sulphuric acid it gives 2, 4, 6-trinitrophenol.
Although phenoxide ion has more number of resonating structures than Carboxylate ion, Carboxylic acid is a stronger acid than phenol. Give two reasons.
On losing a proton, carboxylic acids forms carboxylate ion and phenol forms phenoxide ion as follows:
|
RCOO-Carboxylate ion |
Phenoxide ion |
Now, the negative charge is delocalized in both molecules as follows:
The conjugate base of the carboxylic acid has two resonance structures in which negative charge in delocalized over two oxygen atoms (since O is more electronegative than C) which stabilises the carboxylate ion.
On the other hand, in phenoxide ion the charge is delocalized over entire molecule on the less electronegative atom (Carbon), thus resonance of phenoxide is not important in comparison to resonance in carboxylate ion.
Further, in carboxylate ion, the negative charge is effectively delocalized over two oxygen atoms whereas it is less effectively delocalized over one oxygen atom and a less electronegative carbon atom.
Thus, Phenol is less acidic than carboxylic acids. In other words, carboxylic acids are stronger acids than phenol
Give simple chemical tests to distinguish between the following pairs of compounds:
(i) Ethanal and Propanal
(ii) Benzoic acid and Phenol
(i) Distinguish test between ethanal and propanal:
Iodoform Test: Ethanal gives iodoform test.
CH3CHO + 4NaOH + 3I2 ---> CHI3 (Yellow ppt.) + HCOONa + 3NaI + 3H2O
Propanal does not give this test.
CH3CH2CHO + 4NaOH + 3I2 ---> No Reaction.
(ii) Distinguish test between Benzoic acid and Phenol:
NaHCO3Test: When Benzoic acid reacts with NaHCO3, the brisk effervescence of CO2 gas evolved.
Phenol does not give this test.
C6H5OH + NaHCO3 --> No Reaction
Arrange the following compounds in an increasing order of their reactivity in nucleophilic addition reactions: ethanol, propanal, propanone, butanone.
butanone < propanone < propanal < ethanol
Write chemical equation for the following conversions:
(i) Nitrobenzene to benzoic acid.
(ii) Benzyl chloride to 2-phenylethanamine.
(iii) Aniline to benzyl alcohol.
(i) Nitrobenzene to benzoic acid
ii) Benzyl chloride to 2-phenylethanamine
(iii) Aniline to benzyl alcohol
How would you obtain
(i) Picric acid (2, 4, 6-trinitrophenol) from phenol,
(ii) 2-Methylpropene from 2-methylpropanol?
(i) Phenol on reaction with concentrated HNO3 results in the formation of 2,4,6-Trinitrophenol or Picric acid.
ii) 2-methyl propene can be obtained from 2-methyl propanol by the reaction of the later with alc. KOH.
How do you convert the following:
(i) C6H5CONH2 to C6H5NH2
(ii) Aniline to phenol
(iii) Ethanenitrile to ethanamine
Ti) o convert Benzamide to aniline:
Benzamide on heating with a mixture of Br₂ in presence of NaOH or KOH (i.e. NaOBr or KOBr) is given aniline.
ii) Aniline first converts to diazonium salt using NaNO2/HCl at 0-5 degree C, Then diazonium ion reacts with the water at 100 degrees C to produced phenol
(iii)
Ethanal is soluble in water. Why?
Ethanal CH3CHO is soluble in water because they form a hydrogen bond with water.
Explain the mechanism of the following reaction:
Mechanism of the following reaction is given below:
step 1: Formation of protonated alcohol
Step 2: Formation of carbocation
Step 3: Formation of ethene by removal of proton
Explain the following behaviours:
(i) Alcohols are more soluble in water than the hydrocarbons of comparable molecular masses.
(ii) Ortho-nitro phenol is more acidic than ortho-methoxyphenol.
(i) As alcohol is a polar solvent .it form hydrogen bonding with water molecules while another hydrocarbon of comparable molecular masses does not form hydrogen bonding due to being non- polar i.e.
Alcohols undergo intermolecular H-bonding while hydrocarbons do not.
Hence, they are more soluble in water than the hydrocarbons of comparable molecular masses.
(ii)
The nitro-group is an electron-withdrawing group. The presence of this group in the ortho position decreases the electron density in the O-H bond. As a result, it is easier to lose a proton.
Also, the o-nitro phenoxide ion formed after the loss of protons is stabilised by resonance.
Hence, ortho-nitrophenol is a stronger acid.
On the other hand, a methoxy group is an electron-releasing group. Thus, it increases the electron density in the O-H bond and hence, the proton cannot be given out easily.
For this reason, ortho-nitrophenol is more acidic than ortho-methoxyphenol.
Explain the mechanism of acid catalysed hydration of an alkene to form corresponding alcohol.
Some reactive alkenes undergo direct hydration in the presence of mineral acids which act as catalysts. The addition of water to the double bond takes place in accordance with Markonikoff’s rule.
The mechanism of reaction involves the following three steps:
(i) Protonation of alkene to form carbocation by electrophilic attack of H3O+.
(ii) Nucleophilic attack of water of carbocation.
(iii) Deprotonation to from an alcohol.
How would you convert ethanol to ethene?
When dehydration of ethanol is carried out at a higher temperature (443 K), ethene is formed. The following chemical reaction takes place.
Write the equations involved in the following reactions:
(i) Reimer − Tiemann reaction
(ii) Williamson synthesis
i) Reimer -Tiemann reaction
ii) Williamson synthesis
Write the mechanism of the following reaction:
CH3CH2OH ---> HBrCH3CH2Br + H2O
Mechanism of the given reaction is the following:
Give simple chemical tests to distinguish between the following pairs of
compounds :
Ethanol and Phenol
Ethanol gives Iodoform test but phenol does not.
Give simple chemical tests to distinguish between the following pairs of
compounds :
Propanol and 2-methylpropan-2-ol
Lucas’ reagent Test
Propanol – Primary alcohol
2-methylpropan-2-ol – Tertiary alcohol
Arrange the following compound groups in the increasing order of their property indicated :
p-nitrophenol, ethanol, phenol (acidic character)
ethanol<phenol<p-nitrophenol
Arrange the following compound groups in the increasing order of their property indicated :
Propanol, Propane, Propanal (boiling point)
propane<propanal<propanol
Write the IUPAC name of the following:
IUPAC name the given compound is,
3,3 - dimethylpentan-2-ol
Arrange the following compounds in order of decreasing acidity
II>IV>I>III
I>II>III>IV
III>I>II>IV
IV>III>I>II
C.
III>I>II>IV
Electron withdrawing group increases the acidic strength of the compounds by destabilising and stabilising the phenoxide ion formed respectively.
The presence of an electron withdrawing group increases the acidic strength by stabilising the phenoxide ion. On other hands, the presence of electron releasing group destabilises the phenoxide ion and decrease the acidic strength.
NO2>Cl>CH3>OCH3
A solution of (–) –1 – chloro –1 – phenylethane is toluene racemises slowly in the presence of a small amount of SbCl5, due to the formation of
carbanion
Carbene
Carbocation
free radical
C.
Carbocation
Iodoform can be prepared from all except
ethyl methyl ketone
isopropyl alcohol
3-methyl-2-butanone
Isobutyl alcohol
D.
Isobutyl alcohol
Iodoform is given by
1) methyl ketones R-CO-CH3
2) alcohols of the type R-CH(OH)CH3
where R can be hydrogen also
Phenol is heated with a solution of a mixture of KBr and KBrO3.The major product obtained in the above reaction is
2-Bromophenol
3-Bromophenol
4-Bromophenol
2, 4, 6 -Tribromophenol
D.
2, 4, 6 -Tribromophenol
KBr (aq.) + KBrO3 (aq.) → Br2(aq.)
From amongst the following alcohols the one that would react fastest with conc. HCl and anhydrous ZnCl2, is
1-Butanol
2-Butanol
2-Methylpropan-2-ol
2-Methylpropanol
C.
2-Methylpropan-2-ol
Formation of tertiary butyl carbocation is the most rapid compared to other lesser stable ones with Lucas reagent.
The major product obtained on the interaction of phenol with sodium hydroxide and carbon dioxide is
Benzoic acid
Salicylaldehyde
Salicylic acid
Phthalic acid
C.
Salicylic acid
Kolbe – Schmidt reaction is
The reaction of toluene with Cl2 in presence of FeCl3 gives predominantly
benzoyl chloride
benzyl chloride
o-and p-chlorotoluene
m-chlorotoluene
C.
o-and p-chlorotoluene
Due to o- and p- directing nature of CH3 group. 
In the following sequence of reactions,
compound ‘D’ is
butanal
n-butyl alcohol
n-propyl alcohol
propanal
C.
n-propyl alcohol
Fluorobenzene (C6H5F) can be synthesized in the laboratory
by heating phenol with HF and KF
from aniline by diazotisation followed by heating the diazonium salt with HBF4
by direct fluorination of benzene with F2 gas
by reacting bromobenzene with NaF solution
B.
from aniline by diazotisation followed by heating the diazonium salt with HBF4
CH2 = CH2
B.
CH2 = CH2
Reaction of one molecule of HBr with one molecule of 1,3-butadiene at 400 C gives predominantly
3-bromobutene under kinetically controlled conditions
1-bromo-2-butene under thermodymically controlled conditions
3-bromobutene under thermodynamically controlled conditions
1-bromo-2-butene under kinetically controlled conditions
B.
1-bromo-2-butene under thermodymically controlled conditions
Acid catalyzed hydration of alkenes except ethene leads to the formation of
primary alcohol
secondary or tertiary alcohol
mixture of primary and secondary alcohols
mixture of secondary and tertiary alcohols
D.
mixture of secondary and tertiary alcohols
The reaction
is fastest when X is
Cl
NH2
OC2H5
OCOR
A.
Cl
Conjugated acid of Cl- is a stronger acid i.e. HCl.
The IUPAC name of the compound
3, 3- dimethyl -1- hydroxy cyclohexane
1,1 – dimethyl -3- cyclohexanol
3,3- dimethyl -1- cyclohexanol
1,1 – dimethyl -3- hydroxy cyclohexane
C.
3,3- dimethyl -1- cyclohexanol
On mixing ethyl acetate with aqueous sodium chloride, the composition of the resultant solution is
CH3COOC2H5 + NaCl
CH3Cl + C2H5COONa
CH3COCl + C2H5OH + NaOH
CH3COONa + C2H5OH
A.
CH3COOC2H5 + NaCl
Aqueous NaCl is neutral hence there is no reaction between ethyl acetate and aqueous NaCl
Which of the following undergoes reaction with 50% sodium hydroxide solution to give the corresponding alcohol and acid?
Phenol
Benzoic acid
Butanal
Benzaldehyde
D.
Benzaldehyde
A + NaOH → alcohol + acid
Thus, it is Cannizzaro reaction
A is thus aldehyde without H at alpha - carbon
(as C6H5CHO.HCHO)
2C6H5CHO + NaOH → C6H5CH2OH + C6H5COONa
Among the following compound which can be dehydrated very easily is
C.
Dehydration of alcohol is in order 1° < 2° < 3°.
Phenol reacts with methyl chloroformate in the presence of NaOH to form product A. A reacts with Br2 to form product B. A and B are respectively:
B.
This step involves acid-base reaction at first followed by SNAE reactions:
Step 1:
Step 2:
This step is called bromination.
Mechanism of above reaction is given as,
The reaction
Can be classified as
Alcohol formation reaction
Dehydration reaction
Williamson alcohol synthesis reaction
Williamson ether synthesis reaction
D.
Williamson ether synthesis reaction
The formation of ether from alcohol in te presence of base followed by alkylation is known as Williamson ether synthesis reaction.
The reaction,
is called,
Williamson synthesis
Williamson continuous etherification process
Etard reaction
Gattermam -Koch reaction
A.
Williamson synthesis
The reaction of alkyl halides with sodium alkoxide or sodium phenoxide to form ethers is called Williamson synthesis. Here, in this reaction alkyl halide should be primary and alkoxide e.g. should be bulkier as shown below,
R-X + R'-ONa ---> R-O-R' + NaX
alkyl halide sodium alkoxide ether
Which of the following will not be soluble in sodium hydrogen carbonate ?
2,4,6 trinitrophenol
Benzoic acid
o-nitrophenol
Benzenesulphonic acid
C.
o-nitrophenol
Among the following sets of reactants which one produces anisole?
CH3CHO;RMgX
C6H5OH;NaOH; CH3I
C6H5OH;neutral FeCl3
C6H5-CH3;CH3COCl;AlCl3
B.
C6H5OH;NaOH; CH3I
Williamson's synthesis
Among the following ethers, which one will produce methyl alcohol on treatment with hot concentrated HI?
C.
The ether, which gives more stable carbocation, gives CH3OH as one of the product with hot concentrated HI. the order of stability of carbocation is
30 > 20 > 10
Thus, 
gives CH3 OH as one of the reaction. The reaction proceeds as
Which of the following compounds can be used as antifreeze in automobile radiators?
Methyl alcohol
Glycol
Nitrophenol
Ethyl alcohol
B.
Glycol
Glycol is widely used as an antifreeze in automobile radiators.
The reaction of phenol with chloroform in the presence of dilute sodium hydroxide finally introduces, which one of the following functional group?
-CH2Cl
-COOH
-CHCl2
-CHO
D.
-CHO
Which of the following is not the product of dehydration of 
B.
When intermediate carbocation is stable, no rearrangement takes place in carbonation,
Given are cyclohexanol (I), acetic acid (II), 2,4,6-trinitropenol (III) and phenol (IV). In these, the order of decreasing acidic character will be
III > II> IV> I
II > III> I > IV
II > III> IV> I
III > IV> II > I
A.
III > II> IV> I
Higher the tendency to give a proton, higher is the acidic character, and tendency to lose a proton depends upon the stability of intermediate, ie, carbanion formed.
2,4,6 - trinitrophenol after the loss of a proton gives 2,4,6 -trinitrophenoxide ion which is stabilised by resonance -I effect and -M effect thus a most acidic among the given compounds. Phenol after losing a proton form phenoxide ion which is also stabilised by resonance, -M and -I effects but is less stabilised as compared to 2,4,6 trinitrophenoxide ions. Thus, it is less acidic as compared to 2,4,6 trinitrophenol. (CH3COOH) after losing a proton give acetate CH3OO- ion which is stabilised by only resonance. However, it is more resonance stabilised as compared to a phenoxide ion, thus more acidic as compared to phenol. 2,4,6 tri-nitrophenol, however, is more acidic than acetic acid due to the presence of three electron withdrawing - NO2 groups. cyclohexanol gives an anion that is least stable among the given, thus, it is least acidic.
Hence, the correct order of acidic strength is 2,4,6 -trinitrophenol > acetic acid > phenol > cyclohexanol
III> II> IV> I
Which one of the following compounds has the most acidic nature?
B.
The presence of electron withdrawing substituent increases the acidity while electron releasing substituent, when present, decrease the acidity.
Phenyl is an electron withdrawing substituent while -CH3 is an electron releasing substituent, Moreover, phenoxide ion is more resonance stabilised as compared to benzoyl oxide ion, thus, release proton more easily. That's why is a strong acid among the given.
Which one is most reactive towards electrophilic reagent?
A.
Electron withdrawing substituent deactivates the benzene nucleus towards electrophilic substitution while electron releasing substituent activates the ring towards electrophilic substitution.
Among the given -OH has the higher electron donating tendency and thus, activates the ring more towards electrophilic substitution. Hence
is more reactive towards electrophilic reagents.
Among the following four compounds
A) Phenol
B) Methyl Phenol
C) meta - nitrophenol
D) para-nitrophenol
the acidity order is
D > C > A > B
C > D > A> B
A > D > C > B
B > A > C> D
A.
D > C > A > B
An electron withdrawing group (-I showing group like -NO2, -CN) stabilises the phenoxide ion, thus when present, increases the acidity of phenol. On the other hand, the electron releasing groups (+I showing group like -CH3, -C2H5), when present, decrease the acidity of phenol by destabilising phenoxide ion. Hence, the correct order of acidity of given compound is
p-nitrophenol > m-nitrophenol > phenol > methyl phenol
which one of the following is most reactive towards electrophilic attack?
C.
Electron releasing groups stabilise the intermediate cation whereas electron withdrawing groups destabilise it.
The order of electron withdrawing group is:
NO2 > Cl >OH> C6H5
Hence is
more reactive towards electrophilic substitution because -OH group least destabilise the carbocation. Further -OH group is strongly activating group while -NO2 and -Cl are deactivating group.
The reaction: 
Which of the following compounds will be formed ?
D.
When conc. HI or HBr reacts with either, the corresponding alcohol and iodide is formed when there is a case of mixed ethers, the halogen atom attaches to the smaller alkyl group, due to steric effect.
The order of decreasing reactivity towards an electrophilic reagent, for the following:
i) Benzene
ii) Toluene
iii) Chlorobenzene
iv) Phenol
would be:
(i) > (ii) > (iii) > (iv)
(ii) > (iv) > (i) > (iii)
(iv) > (iii) > (ii) >(i)
(iv) > (ii) > (i) > (iii)
D.
(iv) > (ii) > (i) > (iii)
Benzene having any activating group i.e, OH, R etc., undergoes electrophilic substitution very easily as compared to benzene itself. Thus toluene (C6H5CH3), phenol (C6H5OH) undergo electrophilic substitution very readily than benzene.Chlorine with +E and +M effect deactivating the ring due to strong -I effect. So, it is difficult to carry out the substitution in chlorobenzene than in benzene, so correct order is
Phenol > Toluene > Benzene > Chlorobenzene
The major organic product in the reaction,
CH3 -O- CH(CH3)2 + HI → Product is:
CH3OH + (CH3)2 + CHI
ICH2OCH(CH3)2
CH3O CI(CH3)2
CH3I + (CH3)2CHOH
D.
CH3I + (CH3)2CHOH
Which one is the correct order of acidity?
CH2= CH2> CH3– CH = CH2> CH3– C ≡ CH > CH ≡ CH
CH ≡ CH > CH3– C ≡ CH > CH2= CH2> CH3– CH3
CH ≡ CH > CH2= CH2> CH3– C ≡ CH >CH3– CH3
CH3– CH3> CH2= CH2> CH3– C ≡ CH >CH ≡ CH
B.
CH ≡ CH > CH3– C ≡ CH > CH2= CH2> CH3– CH3
In the reaction,
The electrophile involved is
Dichloromethyl cation (C+HCl2)
Formyl cation (C+HO)
Dichlorocarbene (:CCl2)
Dichloromethyl anion (C-HCl2)
C.
Dichlorocarbene (:CCl2)
Reimer-Tiemann reaction. The electrophile formed is :CCl2 (Dichlorocarbene) according to the following reaction
Aqueous 10% NaHCO3 solution is used as a reagent for identifying 'A'. Which of the following compounds yield 'A' on hydrolysis?
CH3COOC2H5
C2H5-COO-C2H5
CH3CHO
CH3CH2OH
A.
CH3COOC2H5
NaHCO3 is basic in nature so it is used in the identification of acid only. In the given compound only ester (CH3COOC2H5) on hydrolysis gives acid as
Sponsor Area
Sponsor Area
