Question

Among the following amines, the one which will give carbylamine test is

• A. Trimethylamine
• B. Dimethylamine
• C. Aniline
• D. Triethylamine

Hint:

Carbylamine test is given only by primary amines: \[ 1^\circ \text{ amines } \rightarrow \text{Positive} \] \[ 2^\circ \text{ and } 3^\circ \text{ amines } \rightarrow \text{Negative} \]

Answer 1

The Correct Option is C

Step 1: Recall the carbylamine test.
When a primary amine is warmed with chloroform and alcoholic KOH, it makes a foul-smelling isocyanide. Only primary amines give this. \[ RNH_2 + CHCl_3 + 3KOH \rightarrow RNC + 3KCl + 3H_2O \]

Step 2: Check trimethylamine.
$(CH_3)_3N$ has three groups on nitrogen, so it is a tertiary amine. It gives no test.

Step 3: Check dimethylamine.
$(CH_3)_2NH$ has two groups on nitrogen, so it is a secondary amine. It gives no test.

Step 4: Check aniline.
$C_6H_5NH_2$ has one $-NH_2$ group, so it is a primary amine. It will give the carbylamine test.

Step 5: Check triethylamine.
$(C_2H_5)_3N$ is a tertiary amine, so it gives no test.

Step 6: Pick the primary amine.
Among all the choices only aniline is a primary amine, so only it responds to the test.

Step 7: State the final answer.
The amine that gives the carbylamine test is:
\[ \boxed{\text{Aniline}} \]