Question

Ethyl benzene is generally prepared by acetylation of benzene followed by the reduction and not by direct alkylation.Give reason.Also please give the equation of formation of product by direct alkylation.

Answer 1

Preparation of ethyl benzene from acylation of benzene yields acetophenone which on reduction gives ethyl benzene. The complete reactions can be shown as:

The direct alkylation cannot be performed because polysubstitution product is formed. Due to disadvantage of polysubstitution, the Friedel-Crafts alkylation reaction is not used for the preparation of alkyl benzene. Instead of that, Friedel-Crafts acylation is used.