Question

a) Aromatic and aliphatic amines are basic in nature like ammonia. Arrange the following compounds in the increasing order of their basic strength:

CH₃NH₂,(CH₃),NH,NH₃,C₆H₅ -NH₂

b) How will you carry out the following reactions?

i) Hoffmann bromamide reaction

ii) Carbylamine reaction (Chemical equations not required)

Answer 1

a) C₆H₅-NH₂<NH₃<CH₃NH₂<(CH₃)₂NH

b) i) Hoffmann bromamide reaction – When an amide is treated with bromine in an aqueous or ethanolic solution of NaOH an amine with one carbon atom less than that present in the amide is formed. In this degradation reaction, migration of an alkyl or aryl group takes place from carbonyl carbon of the amide to the nitrogen atom.

ii) Carbylamine reaction – Aliphatic and aromatic primary amines on heating with chloroform and ethanolic KOH form isocyanides or carbylamines which are foul smelling substances.

R – NH₂ + CHCI₃ + 3KOH → R – NC + 3KCI + 3H₂O