The amine / salt of amine which gives positive test with a mixture of chloroform and alcoholic KOH solution is
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To identify the degree of an amine, count the number of carbon atoms directly attached to the nitrogen.
\(1^\circ\): \(R-\text{NH}_2\) (1 C attached).
\(2^\circ\): \(R-\text{NH}-R'\) (2 C's attached).
\(3^\circ\): \(R-\text{N}(R')-R''\) (3 C's attached).
Carbylamine test is exclusive to \(1^\circ\) amines.
Step 1: Identify the Chemical Test
The reaction with chloroform (\(\text{CHCl}_3\)) and alcoholic Potassium Hydroxide (\(\text{KOH}\)) is known as the Carbylamine Test or Isocyanide Test.
Step 2: Condition for Positive Test
This test is characteristic of primary amines only (both aliphatic and aromatic). Secondary and tertiary amines do not undergo this reaction.
Reaction:
\[ \text{R-NH}_2 + \text{CHCl}_3 + 3\text{KOH (alc)} \xrightarrow{\Delta} \text{R-NC} \text{ (Bad smelling Isocyanide)} + 3\text{KCl} + 3\text{H}_2\text{O} \]
Step 3: Analyze the Options
(A) \(\text{C}_6\text{H}_5\text{-NH-CH}_3\) (N-methylaniline): This is a secondary ($2^\circ$) amine. Negative test.
(B) \(\text{C}_6\text{H}_5\text{-N(CH}_3)_2\) (N,N-dimethylaniline): This is a tertiary ($3^\circ$) amine. Negative test.
(C) \(\text{C}_6\text{H}_5\text{-N}^+\text{(CH}_3)_3\text{X}^-\): This is a quaternary ammonium salt. Negative test.
(D) \(\text{C}_6\text{H}_5\text{-CH}_2\text{-NH}_2\) (Benzylamine): The Nitrogen is attached to only one Carbon atom (the benzylic carbon). It contains the \(-\text{NH}_2\) group. This is a primary ($1^\circ$) amine. Positive test.
Conclusion:
Only Benzylamine is a primary amine and will give a positive Carbylamine test.
Final Answer: Option (D).
