The Encyclopedia Americana (1920)/Ac′etyl

AC′ETYL, the radical of acetic acid, its formula being CH$2$CO. Acetic acid may be regarded as the hydrate of this radical, its formula being CH$2$COOH. Acetyl chloride, CH$2$COCl, is obtained by the action of phosphorus trichloride upon acetic acid. Acetyl chloride evolves hydrochloric acid when it is heated with any substance containing the radicals hydroxyl, amidogen or imidogen, and hence it is of importance as a test for these substances.