Carbylamine reaction is used as a test for (A) aromatic primary amine…

The correct answer is Option (4) → (A) and (B) only

The Carbylamine reaction (also known as the Isocyanide test) is a distinctive chemical test used to identify a specific class of amines.

The Carbylamine Reaction

• Reactants: The reaction involves heating the amine with chloroform ($CHCl_3$​) and an alcoholic solution of potassium hydroxide (KOH).
• Product: The characteristic product is an isocyanide (or carbylamine, R-NC), which has a foul and offensive odor.
• General Equation:

$R-NH_2​+CHCl_3​+3KOH\overset{Heat}{\longrightarrow}​R-NC+3KCl+3H_2​O$

Scope of the Reaction

This reaction is only given by Primary Amines.

1. Aromatic Primary Amine ($Ar-NH_2$​): E.g., Aniline.
• Result: Gives the test, forming a foul-smelling aryl isocyanide (Ar-NC).
• (A) Aromatic primary amine → Yes
2. Aliphatic Primary Amine ($R-NH_2$​): E.g., Ethylamine.
• Result: Gives the test, forming a foul-smelling alkyl isocyanide (R-NC).
• (B) Aliphatic primary amine → Yes
3. Aliphatic Secondary Amine ($R_2​NH$): E.g., Diethylamine.
• Result: Does not give the Carbylamine reaction.
• (C) Aliphatic secondary amine → No
4. Substituted Aromatic Secondary Amine (Ar-NH-R): E.g., N-methylaniline.
• Result: Does not give the Carbylamine reaction.
• (D) Substituted aromatic secondary amine → No

Conclusion

The Carbylamine reaction is a specific test for both aromatic primary amines (A) and aliphatic primary amines (B).