Question

The correct increasing order of basic strength of following amines, $C_2H_5NH_2, NH_3, (C_2H_5)_2NH, C_6H_5NH_2$ in gaseous state is

• A. $(C_2H_5)_2NH < C_2H_5NH_2 < NH_3 < C_6H_5NH_2$
• B. $C _6 H _5 NH _2<\left( C _2 H _5\right)_2 NH < C _2 H _5 NH _2< NH _3$
• C. $C _6 H _5 NH _2< NH _3< C _2 H _5 NH _2<\left( C _2 H _5\right)_2 NH$
• D. $\left( C _2 H _5\right)_2 NH < C _2 H _5 NH _2< C _6 H _5 NH _2< NH _3$

Answer 1

Answer: (C)

Aniline is far less basic than ammonia and aliphatic amines due to delocalization of lone pair of electrons on the benzene ring. Aliphatic amines are stronger bases than ammonia due to +/ effect of alkyl group: More the number of alkyl groups stronger is the base. Hence basic strength will follow the order: $(C_2H_5)_2NH > C_2H_5NH_2 > NH_3 > C_6H_5NH_2 $