Primary amine (both aliphatic and aromatic) when warmed with chloroform and alcoholic KOH, gives isocyanides (carbylamines). This is called carbylamine reaction. Carbylamines has an offensive smell. This reaction is answered only by primary amine and hence to distinguish primary amine from other classes of amines.
R-NH2 + CHCl3 + 3KOH ———> RNC (carbylamine) + 3KCl + 3H2O