a. During the electrophilic substitution reaction of haloarenes, para substituted derivative is the major product.

Question

Give reason for the following:

a. During the electrophilic substitution reaction of haloarenes, para substituted derivative is the major product.

b. The product formed during S_N¹ reaction is a racemic mixture.

Answer 1

a. At the ortho position, higher steric hindrance is there, hence para isomer is usually predominate and is obtained in the major amount.

b. During the S_N¹ mechanism, intermediate carbocation formed is sp² hybridized and planar in nature. This allows the attack of nucleophile from either side of the plane resulting in a racemic mixture.