Question

Which from following amines on heating with chloroform and ethanolic potassium hydroxide produces foul smell?

• A. $(CH_3)_3N$
• B. $(CH_3)_2NH$
• C. $(CH_3CH_2)_2NH$
• D. $CH_3CH_2NH_2$

Hint:

The carbylamine test is highly specific and is the standard laboratory qualitative analysis technique used to easily distinguish primary amines from secondary and tertiary amines.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The reaction described is the Carbylamine test (isocyanide test). This test is positive only for primary ($1^\circ$) amines.

Step 2: Formula Application:
$R-NH_2 + CHCl_3 + 3KOH \xrightarrow{\Delta} R-NC + 3KCl + 3H_2O$.

Step 3: Explanation:
The foul smell is due to the formation of an alkyl isocyanide (carbylamine). (a) is a tertiary amine. (b) and (c) are secondary amines. (d) Ethylamine ($CH_3CH_2NH_2$) is a primary amine and will undergo this reaction to produce ethyl isocyanide.

Step 4: Final Answer:
The amine is $CH_3CH_2NH_2$.