Amongst the given compounds, which will give Carbylamine reaction?
A. Aniline
B. p-toluidine
C. Ethylamine
D. Diphenylamine
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A, B and C only
The carbylamine reaction (isocyanide test) is given only by primary amines, aliphatic as well as aromatic. The carbon from chloroform replaces both hydrogens of the –NH2 group, so the amine needs two N–H hydrogens; the isocyanide formed has a very unpleasant smell:
\( \displaystyle \ce{R-NH2 + CHCl3 + 3KOH} \xrightarrow[\Delta]{\text{ethanol}} \ce{R-NC + 3KCl + 3H2O} \)
A. Aniline — Correct. \( \ce{C6H5NH2} \) is a primary aromatic amine; it forms phenyl isocyanide.
\( \displaystyle \ce{C6H5NH2 + CHCl3 + 3KOH} \xrightarrow{\Delta} \ce{C6H5NC + 3KCl + 3H2O} \)
B. p-toluidine — Correct. \( \ce{CH3C6H4NH2} \) is a primary aromatic amine.
\( \displaystyle \ce{CH3C6H4NH2 + CHCl3 + 3KOH} \xrightarrow{\Delta} \ce{CH3C6H4NC + 3KCl + 3H2O} \)
C. Ethylamine — Correct. \( \ce{C2H5NH2} \) is a primary aliphatic amine; it forms ethyl isocyanide.
\( \displaystyle \ce{C2H5NH2 + CHCl3 + 3KOH} \xrightarrow{\Delta} \ce{C2H5NC + 3KCl + 3H2O} \)
D. Diphenylamine — Incorrect. \( \ce{(C6H5)2NH} \) is a secondary amine with only one N–H hydrogen.
NCERT (2026-27 edition):
Carbylamine Reaction
