Question

R–NH$_2$ + CHCl$_3$ + 3KOH (alc.) $\longrightarrow$ RNC + 3KCl + 3H$_2$O. The above reaction is:

Hint:

Carbylamine test is used to detect primary amines; the product is an isocyanide (R–NC) with a foul odour.

Answer 1

Step 1: Recall the carbylamine reaction.
In the carbylamine reaction, a primary amine (R–NH$_2$) reacts with chloroform (CHCl$_3$) and alcoholic KOH to form isocyanides (R–NC), which have a foul smell.

Step 2: Match with the given reaction.
The given equation: \[ R–NH_{2} + CHCl_{3} + 3KOH \longrightarrow RNC + 3KCl + 3H_{2}O \] fits exactly with the carbylamine test.

Step 3: Analyzing options.
- (A) Coupling reaction: Involves diazonium salts, not applicable here.
- (B) Carbylamine reaction: Correct. Forms isocyanides (R–NC).
- (C) Hoffmann bromamide reaction: Converts amides to amines, not relevant here.
- (D) Schmidt reaction: Reaction of hydrazoic acid with carboxylic acids, different case.

Step 4: Conclusion.
Therefore, the given reaction is the carbylamine reaction.

Final Answer: \[ \boxed{\text{(B) Carbylamine reaction}} \]