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Question:

An aromatic compound 'A' of molecular formula C7H6O2 undergoes a series of reactions as shown below. Write the structures of A, B, C, D, and E in the following reactions. OR (a) Write the structures of the main products when benzene diazonium chloride reacts with the following reagents: (i) H3PO2 + H2O (ii) CuCN/KCN (iii) H2O (b) Arrange the following in increasing order of their basic character in an aqueous solution: C2H5NH2, (C2H5)2NH, (C2H5)3N (c) Give a simple chemical test to distinguish between the following pair of compounds: C2H5-NH2 and C6H5-NH-CH3

Solution:

(b) Order of basic strength:
C2H5NH2 < (C2H5)2NH < (C2H5)3N
(c) C6H5-NH2 (Primary amines) and C6H5-NH-CH3 (secondary amines) can be distinguished by Hinsberg's test. In this test, amines are allowed to react with Hinsberg's reagent, benzenesulfonyl chloride (C6H5SO2Cl). Primary amines react with this reagent to form N-alkylbenzenesulfonyl amide, which is soluble in alkali, but secondary amines give sulfonamide, which is insoluble in alkali.