question_answer

Which one of the following amines cannot be prepared by Gabriel's synthesis?

A)  Butylamine

B)  Isobutylamine

C)  2-phenylethylamine

D)  N-methylbenzylamine

Correct Answer: D

Solution :

 Gabriel synthesis is used for the preparation of primary amines. Butylamine, isobutylamine and 2-phenyl ethylamine are primary amine  hence these can be prepared by Gabriel's synthesis but N-methyl benzylamine is a secondary amine and therefore, it cannot be prepared by Gabriel's synthesis. \[\underset{\text{butyl}\,\text{amine(}{{\text{1}}^{\text{o}}}\,\text{amine)}}{\mathop{C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}C{{H}_{2}}N{{H}_{2}},}}\,\] \[\underset{\begin{smallmatrix}  2-\text{phenyl}\,\text{ethyl}\,\text{amine} \\  ({{1}^{o}}\,amine) \end{smallmatrix}}{\mathop{\underset{{{C}_{6}}{{H}_{5}}}{\mathop{\underset{|}{\mathop{C{{H}_{2}}}}\,}}\,-C{{H}_{2}}-N{{H}_{2}},}}\,\]