The Carbylamine reaction (also known as the isocyanide test) is a chemical test for the detection of primary amines. When a primary aliphatic or aromatic amine is heated with chloroform ($CHCl_3$) and alcoholic potassium hydroxide (KOH), it leads to the formation of an alkyl or aryl isocyanide (carbylamine), which is characterised by a highly unpleasant, foul smell.

The general reaction is: $R-NH_2 + CHCl_3 + 3KOH \xrightarrow{\Delta} R-NC \text{ (Isocyanide)} + 3KCl + 3H_2O$