question_answer

Which of the following statements about primary amines is false?                      [AIPMT (S) 2010]

A) Alkyl amines are stronger bases than aryl amines

B) Alkyl amines react with nitrous acid to produce alcohols

C) Aryl amines react with nitrous acid to produce phenols

D) Alkyl amines are stronger bases than ammonia

Correct Answer: C

Solution :

[c] Key Idea (i) Presence of electron withdrawing substituent decreases the basicity while the presence of electron releasing substituent like,  etc increases the acidity.

(ii)  converts  group of aliphatic .      amine into —OH while that of aromatic      amines into

Since, phenyl group is a electron withdrawing

group, it decreases the basicity. Alkyl group, on the other hand, being electron releasing, increases the basicity. Thus, alkyl amines are more basic as compared to aryl amines as well as ammonia.  Thus,  (nitrous acid) converts alkyl amines to alcohols.

But

Thus, does not convert aryl amines into phenol.