Question

Consider the following statements: I. Aniline does not give Friedel-Crafts reaction. II. Aromatic primary amines cannot be prepared by Gabriel phthalimide synthesis. Choose the correct option.

• A. Both I and II
• B. Neither I nor II
• C. Only II
• D. Only I

Hint:

Gabriel phthalimide synthesis is suitable for preparing aliphatic primary amines but not aromatic primary amines because aryl halides are generally unreactive toward nucleophilic substitution.

Answer 1

The Correct Option is A

Concept: Aniline is an aromatic amine containing an amino group attached directly to a benzene ring. \[ \text{C}_6\text{H}_5\text{NH}_2 \] The presence of the amino group significantly affects the chemical behavior of aniline.

Step 1: Analyzing Statement I. Aniline generally does not undergo Friedel-Crafts alkylation or acylation reactions. Reason: The lone pair on the nitrogen atom coordinates with the Lewis acid catalyst such as \[ \text{AlCl}_3 \] forming a complex. \[ \text{C}_6\text{H}_5\text{NH}_2 + \text{AlCl}_3 \rightarrow \text{Complex} \] This complex formation decreases the electron density of the benzene ring and prevents the Friedel-Crafts reaction from occurring normally. Therefore, \[ \boxed{\text{Statement I is correct}} \]

Step 2: Analyzing Statement II. Gabriel phthalimide synthesis is a useful method for preparing aliphatic primary amines. The reaction involves nucleophilic substitution of alkyl halides. However, aryl halides do not undergo the required nucleophilic substitution reaction under ordinary conditions. Hence aromatic primary amines such as aniline cannot be prepared by Gabriel synthesis. Therefore, \[ \boxed{\text{Statement II is correct}} \]

Step 3: Final conclusion. Both statements are correct. Hence, \[ \boxed{(A)\ \text{Both I and II}} \]