An aromatic compound 'A' on treatment with aqueous ammonia and heating forms compound 'B' which on heating with `Br_2` and KOH forms a compound 'C' of molecular formula `C_6H_7N`. Write the structures and IUPAC names of compounds A,B and C.

Explanation

(i) Since the compound .C.having M.F, `C_6_7N` is formed from compound .B. on treatment with `Br_2` and KOH (Hofmann bromamide reaction), therefore, compound .B. must be an amide and compound .C. must be an amine. The only aromatic amine having the M.F. `C_6H_7N" is " C_6H_5NH_2` (aniline or benzenamine).
(ii) Since . C. is aniline is formed must be benzamide. The reaction involved in the conversion of .B. to .C. are :

(iii) Since .B. is formed from .A. by treatment with aqueous ammonia followed by heating, therefore, compound .A. must be benzoic acid or benzenecarboxylic acid. Reactions involved are:
`underset("Benzoic acid")(C_6H_5COOH + NH_3(aq))to C_6H_5COONH_4 underset(-H_2O)overset(Delta)to underset("Benzamide")(C_6H_5CONH_2)`
Thus, `A = C_6H_5COOH`
Benzamide Benzoicacid or Benzenecarboxylic acid