acid anhydride

chemical compound

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July 23, 2026

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An acid anhydride is a chemical compound formed by removing water from an acid. For example, sulfur trioxide (SO₃) is derived from sulfuric acid. Acid anhydrides are a type of anhydride, which are compounds created by eliminating water from another substance.

The most common organic acid anhydride is acetic anhydride, used in manufacturing cellulose acetate and aspirin. Organic anhydrides are valuable in synthesis for introducing the acyl group (RCO). They react with water to form carboxylic acids, with alcohols to create esters, and with ammonia or amines to produce amides.1

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chemical compound
Carboxylic acids
…chlorine or bromine atom; and anhydrides have an attached carboxyl group. Each type of acid derivative has a set of characteristic reactions that qualifies it as a unique functional group, but all acid derivatives can be readily converted to a carboxylic acid under appropriate reaction conditions. Many simple esters are…
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…chlorine or bromine atom; and anhydrides have an attached carboxyl group. Each type of acid derivative has a set of characteristic reactions that qualifies it as a unique functional group, but all acid derivatives can be readily converted to a carboxylic acid under appropriate reaction conditions. Many simple esters are…
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oxide
Oxides of nitrogen
Two oxides of nitrogen are acid anhydrides; that is, they react with water to form nitrogen-containing oxyacids. Dinitrogen trioxide is the anhydride of nitrous acid, HNO₂, and dinitrogen pentoxide is the anhydride of nitric acid, HNO₃.N₂O₃ + H₂O → 2HNO₂
N₂O₅ + H₂O → 2HNO₃ There are no stable oxyacids…
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Two oxides of nitrogen are acid anhydrides; that is, they react with water to form nitrogen-containing oxyacids. Dinitrogen trioxide is the anhydride of nitrous acid, HNO₂, and dinitrogen pentoxide is the anhydride of nitric acid, HNO₃.N₂O₃ + H₂O → 2HNO₂
N₂O₅ + H₂O → 2HNO₃ There are no stable oxyacids…
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anhydride
…an acid are often called acid anhydrides, whereas those such as calcium oxide that are produced by a base upon the loss of water are designated basic anhydrides.
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…an acid are often called acid anhydrides, whereas those such as calcium oxide that are produced by a base upon the loss of water are designated basic anhydrides.
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