91Ó°ÊÓ

• Both the given compounds are disubstituted benzene derivatives.

• The electrophilic substitution reactions on these compounds depend on the directing effects of the two substituents on the benzene ring.

• The substituents are an o-isopropyl group which is an ortho-para director, and a CHO group, which is a meta director.

• If the directing effect of one substituent opposes the directing effect of another substituent, then the position of the incoming electrophile is determined by the dominant activator group. Therefore, the isopropyl group determines the position of the incoming electrophile.

• Also, no substitution can take place between two meta substituents due to crowding.

a. The given reagent is ${\text{Br}}_{\text{2}}$,${\text{FeBr}}_{\text{3}}$. This reagent is used in the bromination of aromatic compounds. The product formed on bromination of compounds A and B are:

b. The given reagents are ${\text{HNO}}_{\text{3}}{\text{,H}}_{\text{2}}{\text{SO}}_{\text{4}}$. This reagent is used in the nitration of aromatic compounds. The product formed on nitration of compounds A and B are:

c. The given reagents are ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{COCl, AlCl}}_{\text{3}}$. This reagent is used in Friedel-Craft’s acylation of aromatic compounds. The product formed on Friedel-Craft’s acylation of compounds A and B are: