A

Acid Anhydride

R-CO-O-CO-R' (general)
Quick Reference
Formula / NotationR-CO-O-CO-R' (general)
Also Known AsCarboxylic acid anhydride; organic anhydride; RCO-O-COR

What is Acid Anhydride?

An acid anhydride is a compound formed by the condensation of two carboxylic acid molecules with the loss of one water molecule. The resulting compound contains two acyl groups joined by an oxygen atom. Acid anhydrides react readily with water (hydrolysis), alcohols (esterification), and amines (amide formation).

Formula & Notation

R-CO-O-CO-R' (general)

Other Names / Synonyms: Carboxylic acid anhydride; organic anhydride; RCO-O-COR

Properties & Characteristics

General formula: (RCO)₂O; highly reactive; undergo hydrolysis to form two carboxylic acid molecules; acetic anhydride is the most commercially important example; more reactive than corresponding carboxylic acids

Uses & Applications

Acylating agents in organic synthesis; production of esters, amides, and pharmaceuticals; synthesis of aspirin (acetylation of salicylic acid); as dehydrating agents; manufacture of dyes and polymers

Safety Information

Corrosive and reactive — acetic anhydride causes severe skin and eye burns. Reacts vigorously with water. Flammable (flash point: 54°C). Use in a fume hood with appropriate PPE. Some acid anhydrides are highly toxic.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Acid Anhydride
Formula R-CO-O-CO-R' (general)
Synonyms Carboxylic acid anhydride; organic anhydride; RCO-O-COR

Frequently Asked Questions

An acid anhydride is a compound formed by the condensation of two carboxylic acid molecules with the loss of one water molecule. The resulting compound contains two acyl groups joined by an oxygen atom. Acid anhydrides react readily with water (hydrolysis), alcohols (esterification), and amines (amide formation).

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