Question

Which of the following amines cannot be prepared by Gabriel phthalimide synthesis?a) sec — propylamineb) tent - butylaminec) 2 — Phenylethylamined) N — Methylbenzylamine

Answer 1

answer : option (d) N - methylbenzylamine

explanation :-
Gabriel phthalimide synthesis is used for the preparation of primary amines , phthalimide on treatment with ethanolic potassium hydroxide formed salts of phthalimide which in heating with alkyl halide followed by alkyl hydrolysis produce corresponding primary amines.

automatic primary amines cannot be prepared by $\textbf{Gabriel phthalimide synthesis}$ because aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.

hence, answer is option (D)

Answer 2

Explanation:

primary amines react with excess methyl iodide to form quaternary ammonium salts.

The explanation is as follows :

The nitrogen atom of primary amines contains a lone pair of electron. So, primary amines are strongly nucleophilic in nature. Moreover, the hydrogen atoms on nitrogen are easily replaceable. So, primary amines can act as nucleophiles and can react with alkyl halides. In the presence of excess alkyl halides, one amine molecule can repeatedly react with a number of alkyl halide molecules and result in the formation of a quaternary ammonium salt.

The reaction is as follows :

RNH

2

+3CH

3

I→[RN(CH

3

)

3

]

+

(quaternary ammonium salt)

Here, in the options, only option C is a primary amine.

So, C is a correct answer