JEE Chemistry 2025 Question with Solution

Given: The compounds A to E are different amines.

Find: Which amine(s) show a positive carbamylamine test.

The carbamylamine test is used to detect primary amines. A positive test involves formation of an isocyanide.

Now check each structure:

• A is phenylamine and is a primary amine, so it gives a positive test.
• B is $\text{(CH}_3)_2\text{NH}$, a secondary amine, so it does not give the test.
• C is $\text{CH}_3\text{NH}_2$, a primary amine, so it gives a positive test.
• D is $\text{(CH}_3)_3\text{N}$, a tertiary amine, so it does not give the test.
• E is methylamine attached to a benzene ring, as described in the solution, but the worked conclusion states the correct options are A and C.

Therefore, the correct option is C.

There is a discrepancy in the solution: one line says E gives a positive result, but the conclusion on the page states A and C, and the page marks the correct option as C. Hence the final accepted answer is taken as A and C Only.

Given: Carbamylamine test distinguishes classes of amines.

Find: Which listed amines are primary amines.

This test is specific to $1^\circ$ amines. Both aliphatic primary amines and aromatic primary amines respond positively. $2^\circ$ and $3^\circ$ amines do not.

So the required classification is:

• primary amine $\rightarrow$ positive carbamylamine test
• secondary amine $\rightarrow$ negative test
• tertiary amine $\rightarrow$ negative test

From the worked solution:

• A is primary
• B is secondary
• C is primary
• D is tertiary

Thus the accepted set is A and C, which matches option C.