Question

The correct increasing order of basic strength is

• A. \(NH_3<C_2H_5NH_2<C_6H_5NH_2<C_6H_5CH_2NH_2\)
• B. \(C_6H_5NH_2<NH_3<C_6H_5CH_2NH_2<C_2H_5NH_2\)
• C. \(C_6H_5NH_2<C_6H_5CH_2NH_2<NH_3<C_2H_5NH_2\)
• D. \(C_6H_5CH_2NH_2<NH_3<C_2H_5NH_2<C_6H_5NH_2\)
• E. \(C_6H_5NH_2<NH_3<C_2H_5NH_2<C_6H_5CH_2NH_2\)

Hint:

Basic strength in amines is influenced by the nature of substituents: electron-donating groups increase basicity while electron-withdrawing groups decrease it.

Answer 1

The Correct Option is B

Step 1: Aniline (\(C_6H_5NH_2\)) is less basic than ammonia (\(NH_3\)) due to the electron-withdrawing nature of the phenyl group via resonance. 
Step 2: Benzylamine (\(C_6H_5CH_2NH_2\)) is more basic than aniline because the benzyl group is less electron-withdrawing compared to a direct phenyl attachment. 
Step 3: Ethylamine (\(C_2H_5NH_2\)) is more basic than both benzylamine and ammonia due to the electron-donating effect of the ethyl group, enhancing the electron density on the nitrogen atom. 
Step 4: The correct order of increasing basicity, considering the electronic effects, is therefore aniline, ammonia, benzylamine, and ethylamine.