Question

Gabriel phthalimide synthesis is used for the preparation of

• A. Primary amines
• B. Secondary amines
• C. Tertiary amines
• D. Quaternary amines

Answer 1

The correct option is A

Primary amines

The explanation for the correct answer:-

Option (A) Primary amines:

Step 1: Forming Potassium salt of Phthalimide

When Phthalimide is reacted with ethanolic Potassium hydroxide the Potassium salt of Phthalimide which is the imide ion is formed:

Step 2: Forming N-Alkylphthalimide

After the formation of the imide ion, it is then reacted with an Alkyl halide to form N-Alkylphthalimide:

Step 3: Forming the $1°$amine.

After getting the N-Alkylphthalimide, it is then hydrolysed by reacting it with aqueous Sodium hydroxide $\left(\mathrm{NaOH}\right)$to form the required $1°$amine:

This entire process of formation of primary amines ($1°$amine) is called Gabriel phthalimide synthesis.

The explanation for the incorrect answer:-

Option (B) Secondary amines:

1. Secondary amines do not show reaction with alkyl agents, as a result over alkylation is not possible.
2. Therefore Gabriel phthalimide synthesis cannot be used to prepare secondary amines.

Option (C) Tertiary amines:

1. Tertiary amines do not show a reaction with an alkyl agent, due to this factor alkylation cannot be possible.
2. Therefore Gabriel phthalimide synthesis cannot be used to prepare tertiary amines.
3. Hence incorrect option.

Option (D) Quaternary amines:

1. Gabriel phthalimide synthesis is used only for the preparation of primary amine ($1°$amine), not quaternary amines.
2. Also, quaternary amines are highly unstable.
3. Hence incorrect option.

Therefore, Gabriel phthalimide synthesis is used for the preparation of option (A) Primary amines.