Question

Which of the following amine cannot be prepared by the Gabriel phthalimide synthesis method?

• A. Ethylamine
• B. Benzylamine
• C. Phenylamine
• D. Propylamine

Hint:

Gabriel synthesis is for primary amines via $ S_N2 $ on primary alkyl halides. Aryl halides do not work.

Answer 1

The Correct Option is C

Step 1: Understand Gabriel phthalimide synthesis.

Uses S_N2 reaction of potassium phthalimide with primary alkyl halide.

Step 2: Consider the required halides for each amine.

Ethylamine: Ethyl halide (primary).

Benzylamine: Benzyl halide (primary).

Phenylamine (Aniline): Aryl halide (does not undergo S_N2 readily).

Propylamine: Propyl halide (primary).

Step 3: Identify the amine requiring an unsuitable halide.

Phenylamine requires an aryl halide.

Step 4: Conclusion.

Phenylamine cannot be prepared by this method.