13.10 An aromatic compound ‘A’ on treatment with aqueous ammonia and heating forms compound ‘B’ which on heating with Br2 and KOH forms a compound ‘C’ of molecular formula C6H7N. Write the structures and IUPAC names of compounds A, B and C.

Hint: The second reaction is an example of Hoffmann bromamide reaction

Step 1: 

It is given that compound ‘C’ having the molecular formula, C6H7N is formed by heating compound ‘B’ with Br2 and KOH. This is a Hoffmann bromamide degradation reaction. 

Therefore, compound ‘B’ is an amide, and compound ‘C’ is an amine. The only amine having the molecular formula, C6H7N is aniline, (C6H5NH2). 

Step 2:

Therefore, compound ‘B’ (from which ’C’ is formed) must be benzamide, (C6H5CONH2).

Further, benzamide is formed by heating compound ‘A’ with aqueous ammonia.

Therefore, compound ‘A’ must be benzoic acid.

Step 3:

The given reactions can be explained with the help of the following equations: