Haloalkanes and Haloarenes

Haloalkanes and Haloarenes

Question

Answer the following question:

(i) What is meant by the chirality of a compound? Give an example.

(ii) Which one of the following compounds is more easily hydrolyzed by KOH and why?

CH3CHCICH2CH3 or CH3CH2CH2Cl

(iii) Which one undergoes S N 2 substitution reaction faster and why?

Answer

(i)Chirality: It is a geometrical property of a rigid object ( or molecules ) by which it gets such spatial arrangement of points or atoms that, the molecule becomes non-super imposable of its mirror image.

The chiral molecule of the object does not have any element of symmetry like, a mirror image, centre of inversion (i) etc.

3-bromopent-1-ene is represented as

 

The centre of chirality is designated as *. It is due to the presence of four different groups.

(ii) Due to +I effect of alkyl groups the 2° carbonium ion CH3—CH+ —CH2—CH3 derived from sec. butyl chloride is more stable than the 1° carbonium ion CH3—CH2—C H2+ derived from n-propyl chloride. Therefore sec. butyl chloride gets hydrolyzed more easily than n-propyl chloride under SN1 conditions.

(iii) Undergoes SN2 substitution reaction faster.

This is because; iodine is a better leaving group due to its large size. So, it will be released at a faster rate in the presence of an incoming nucleophile

More Chapters from Haloalkanes and Haloarenes