Carbylamine

Carbylamine, also known as isocyanide or isonitrile, is an organic compound with the general formula R−N≡C. The structure consists of a nitrogen atom triple-bonded to a carbon atom, with the nitrogen atom carrying a formal negative charge and the carbon atom carrying a formal positive charge. This arrangement is a resonance structure of the molecule, with another significant contributor being R−N=C=R', where the nitrogen is bonded to the carbon with a double bond. Carbylamines are isomers of nitriles, which have the general formula R−C≡N. The reactivity of carbylamines differs significantly from that of nitriles due to the electropositive nature of the carbon atom in the R−N≡C linkage. They are known for their characteristic foul odor.

Carbylamines are typically prepared through the carbylamine reaction (also known as the Hofmann isocyanide synthesis), which involves the reaction of a primary amine with chloroform in the presence of a strong base, such as alcoholic potassium hydroxide. This reaction is generally used to test for the presence of primary amines. Carbylamines are reactive intermediates and readily undergo various addition reactions, such as polymerization, cycloaddition, and reactions with nucleophiles. They are often used in organic synthesis as building blocks for heterocyclic compounds and other complex molecules. Due to their toxicity and unpleasant smell, they are usually handled with care in laboratory settings.