question_answer

Which one of the following amines cannot be prepared by Gabriels 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 Gabriels synthesis but N-methyl benzylamine is a secondary amine and therefore, it cannot be prepared by Gabriels synthesis. \[\underset{butyl\text{ }amine\text{ }(1{}^\circ amine)}{\mathop{C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}C{{H}_{2}}N{{H}_{2}},}}\,\] \[\underset{\begin{smallmatrix}  2-phenyl\text{ }ethyl\text{ }amine \\  \,\,\,\,\,\,\,(1{}^\circ \text{ }amine) \end{smallmatrix}}{\mathop{\underset{\begin{smallmatrix}  | \\  {{C}_{6}}{{H}_{5}} \end{smallmatrix}}{\mathop{C{{H}_{2}}}}\,-C{{H}_{2}}-N{{H}_{2}},}}\,\]