anhydridejen

Anhydridejen is a term used in chemistry to denote the class of compounds known as anhydrides. Anhydrides are formed by the dehydration of acids, removing a molecule of water between two acid units. In organic chemistry most anhydrides have the structure R-CO-O-CO-R' and can be cyclic or acyclic. In inorganic chemistry the term also covers oxide derivatives that arise from the corresponding acids when water is removed.

Anhydridejen are commonly divided into organic and inorganic groups. Organic anhydridejen include symmetric and unsymmetrical acyl anhydrides such as acetic anhydride, phthalic anhydride, succinic anhydride and maleic anhydride. Inorganic anhydridejen include sulfur trioxide, phosphorus pentoxide and related oxide anhydrides that originate from mineral acids.

Preparation methods: most commonly by dehydration of carboxylic acids, often with dehydrating agents or high temperature; alternatively by reaction of acid chlorides with carboxylates to form anhydrides. Industrial production of acetic and phthalic anhydride relies on controlled dehydration of the corresponding acids or using catalysts. Anhydridejen are moisture sensitive and hydrolyze readily in water to the parent acids.

Reactions and applications: Anhydridejen are versatile acylating agents, capable of transferring acyl groups to alcohols, amines, and other nucleophiles to form esters and amides. They are used to prepare polymers with anhydride linkages, pharmaceuticals, dyes, and fragrances. Cyclic anhydrides such as phthalic and maleic anhydride are precursors to polyesters and resins.

Safety and handling: many anhydridejen are corrosive and irritant; they react vigorously with water and air moisture, releasing heat and sometimes fumes. They should be handled in well-ventilated areas with appropriate PPE and stored in moisture-free conditions away from water.