Anhüdriididega

Anhüdriididega is the Estonian term for anhydrides. In chemistry, an anhydride is a compound that can be formed from another compound, typically an acid or base, by removing the elements of water. For instance, an acid anhydride is formed by the dehydration of two molecules of a carboxylic acid. This process often involves heating the acid, sometimes in the presence of a dehydrating agent. The resulting anhydride molecule retains the reactive acyl groups from the original acid.

Anhydrides are important reagents in organic synthesis. They readily react with nucleophiles, such as alcohols, amines, and water, to form esters, amides, and carboxylic acids, respectively. This reactivity makes them useful for introducing acyl groups into other molecules. For example, acetic anhydride is commonly used to acetylate alcohols and amines.

Inorganic anhydrides are often formed by heating metal hydroxides or oxyacids. For example, calcium oxide (CaO) is the anhydride of calcium hydroxide (Ca(OH)2). When calcium oxide reacts with water, it reforms calcium hydroxide. Similarly, sulfur trioxide (SO3) is the anhydride of sulfuric acid (H2SO4). The term "anhydride" can also refer to a substance that readily absorbs moisture from the air, acting as a drying agent. These are sometimes called hygroscopic anhydrides.