anhydriden

Anhydriden, commonly referred to in English as anhydrides, are chemical species that form when water is removed from a larger molecule. In organic chemistry, organic anhydrides are typically acyl anhydrides produced by dehydration of two carboxylic acid molecules, yielding a structure such as R-CO-O-CO-R' and water. In inorganic chemistry, the term also covers oxide anhydrides, which are oxides that hydrate to give corresponding acids.

Organic anhydrides include examples such as acetic anhydride and cyclic anhydrides like succinic anhydride. They are usually prepared by dehydrating carboxylic acids using dehydrating reagents or by reactions involving acid chlorides and carboxylic acids. Organic anhydrides react with water to revert to the parent carboxylic acids and are widely used as acylating agents in organic synthesis, for example to introduce acetyl groups, and in polymer chemistry.

Inorganic anhydrides include sulfur trioxide (SO3), phosphorus pentoxide (P4O10), carbon dioxide (CO2), dinitrogen pentoxide (N2O5), and chlorine heptoxide (Cl2O7). Upon hydration, they form the corresponding acids such as sulfuric acid (H2SO4), phosphoric acid (H3PO4), carbonic acid (H2CO3), and nitric acid (HNO3). These anhydrides are often produced by dehydration of the acids, by oxidation of elements, or by other dehydration routes, and they are typically highly reactive with water.

Properties and safety: Anhydrides are usually moisture-sensitive and can be strong electrophiles or corrosive. They frequently react with alcohols and amines, and hydration is often exothermic. Handling requires dry, ventilated conditions and appropriate protective equipment, with storage away from moisture. The term “anhydriden” reflects the plurality in some languages and is used to refer to these compounds collectively.