Question

Which of the following amines on heating with chloroform generate foul smelling product?

• A. Ethanamine
• B. Ethylmethylamine
• C. Ethyldimethylamine
• D. Diethylmethylamine

Hint:

Primary amines react with chloroform to form foul-smelling carbylamines.

Answer 1

The Correct Option is A

Concept:
The reaction of an amine with chloroform ($CHCl_3$) and alcoholic KOH producing a foul-smelling isocyanide is called the Carbylamine reaction. General reaction: \[ RNH_2 + CHCl_3 + 3KOH \rightarrow RNC + 3KCl + 3H_2O \] This test is given only by: \[ \text{Primary amines } (1^\circ) \] Secondary and tertiary amines do not give this reaction.
Step 1: Check Option A: Ethanamine
\[ CH_3CH_2NH_2 \] Nitrogen is attached to one alkyl group and two hydrogens. \[ \Rightarrow \text{Primary amine} \] Hence gives carbylamine test.
Step 2: Check Option B: Ethylmethylamine
\[ CH_3CH_2NHCH_3 \] Nitrogen attached to two alkyl groups. \[ \Rightarrow \text{Secondary amine} \] Does not give test.
Step 3: Check Option C: Ethyldimethylamine
\[ CH_3CH_2N(CH_3)_2 \] Nitrogen attached to three alkyl groups. \[ \Rightarrow \text{Tertiary amine} \] Does not give test.
Step 4: Check Option D: Diethylmethylamine
\[ (CH_3CH_2)_2NCH_3 \] Nitrogen attached to three alkyl groups. \[ \Rightarrow \text{Tertiary amine} \] Does not give test.
Step 5: Final Answer
The compound which gives foul smell with $CHCl_3$ and KOH is: \[ \boxed{\text{Ethanamine } (CH_3CH_2NH_2)} \] Quick Tip:
Carbylamine test is used to identify only primary amines.