Phenylisocyanate is an organic compound typically abbreviated PhNCO. The molecule consists of a phenyl ring attached to the isocyanate functional group. It is a colourless liquid that reacts with water. Phenylisocyanate has a strong odor and tearing vapours, therefore it should be handled in the fumehood. Characteristic of other isocyanates, it reacts with amines to give ureas. Similarly, reacts with alcohols to form carbamates. It is used in addition with triethylamine to activate nitro groups to undergo (C,O) 1,3-dipolar cycloaddition (as opposed to O,O). The nitro group (RCH2NO2) is converted to RCNO in the reaction, with CO2 as one of the by products.