A = aniline (reduction)
B = acetanilide (protection)
C = 4-nitroacetanilide (nitration)
D = 4-nitroaniline (de-protection)
E = 4-aminobenzenesulphonic acid (sulphonation)
(b) Arrange the following in the increasing order of their basic strength: CH3NH2, (CH3)2NH, C6H5NH2, C6H5CH2NH2
For methyl substituted amines, the order of basicity is 2°>1°>3°. This order is concluded from considering a subtle interplay of inductive effect, solvation effect and steric hinderance of alkyl group.
Aryl amines are less basic than alkyl amines because the benzene ring acts as EWG and the electron pair on nitrogen will be less available for protonation as it is in conjugation with the ring and this decreases the basicity.
However, in C6H5CH2NH2, it is not directly connected to benzene ring so electron pair on N will be more available for protonation. Hence, it has more basic strength.
Therefore, the increasing order of their basic strength:
C6H5NH2< C6H5CH2NH2< CH3NH2<(CH3)2NH
(c) Chemical test to distinguish between Aniline (aromatic amine) and Ethyl amine (aliphatic amine) is azo dye test.
A dye is produced when aniline is treated with HONO whereas brisk effervescence of N2 gas is obtained whn ethyl amine is treated under same conditions.
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