Write the structure of the principal organic product obtained on nitration of each of the...

Write the structure of the principal organic product obtained on nitration of each of the following:

(a) p-Methylbenzoic acid

(b) m-Dichlorobenzene

(c) m-Dinitrobenzene

(d) p-Methoxyacetophenone

(e) p-Methylanisole

(f) 2,6-Dibromoanisole

Sample Solution (a) Of the two substituents in p-methylbenzoic acid, the methyl group is more activating and so controls the regioselectivity of electrophilic aromatic substitution. The position para to the ortho, para-directing methyl group already bears a substituent (the carboxyl group), and so substitution occurs ortho to the methyl group. This position is meta to the m-directing carboxyl group, and the orienting properties of the two substituents reinforce each other. The product is 4-methyl-3-nitrobenzoic acid.

p-Methylbenzoic acid 4-Methyl-3-nitrobenzoic acid