Acid anhydrides are chemical compounds formed by the removal of water from an acid. They typically consist of two acyl groups bonded to the same oxygen atom. Common examples include acetic anhydride and phthalic anhydride, which are used in various industrial applications, such as the production of plastics and pharmaceuticals. These compounds can react with water to regenerate the original acid, making them important in organic synthesis. Acid anhydrides can also react with alcohols to form esters, which are widely used in flavorings and fragrances. Their reactivity and versatility make them valuable in chemical manufacturing.