Anhydride

Anhydride, oxide that forms an acid or base when it reacts with water. Metal oxides such as calcium oxide produce hydroxides (bases) and are termed basic anhydrides. Oxides of nonmetals such as phosphorus, carbon, and sulfur produce acids on being dissolved in water and are acid anhydrides. Organic anhydrides are used in the manufacture of solvents, paints, and dyes. Acetic anhydride is used in large quantities during the production of acetic acid and various plastics.