The Carbylamine Test (or Isocyanide Test) is extremely specific for Primary ($1^{\circ }$) Amines, both aliphatic and aromatic.

• Reaction: $R-N{H}_2+CHC{l}_3+3KOH(alc)\stackrel{\Delta }{\to }R-NC+3KCl+3H_{2}O$
• Observation: The formation of an Alkyl Isocyanide ($R-NC$) which has an intensely foul or unpleasant smell.
• Secondary and tertiary amines do not contain the necessary two hydrogen atoms on the nitrogen to form the isocyanide and thus do not give this test.