anhydride(redirected from acyl anhydride)
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anhydride(ănhī`drīd, –drĭd) [Gr.,=without water], chemical compound formed by removing water, H2O, from another compound; the anhydride can also react with water to form the original compound. An acid anhydride reacts with water to form an acid; e.g., sulfur trioxide, SO3, reacts with water to form sulfuric acid, H2SO4. A basic anhydride reacts with water to form a base; e.g., calcium oxide, CaO, reacts with water to form calcium hydroxide, Ca(OH)2. Anhydrides of organic acids have many uses. They react with alcohols to form esters; e.g., acetic anhydride, (CH3CO)2O, reacts with ethanol, C2H5OH, to form ethyl acetate, CH3COOC2H5, a useful solvent. They also react with ammonia and primary or secondary amines to form amides. Other important acid anhydrides include maleic anhydride and phthalic anhydride.
A compound formed from an acid by removal of water.
1. a compound that has been formed from another compound by dehydration
2. a compound that forms an acid or base when added to water
3. any organic compound containing the group -CO.O.CO- formed by removal of one water molecule from two carboxyl groups