Any of a class of organic compounds of the alcohol family in which two hydroxyl groups (―OH; see functional group ) are attached to different carbon atoms.
The term is often used for the simplest of the class, ethylene glycol (1,2-ethanediol). Propylene glycol (1,2-propanediol), much like ethylene glycol but not toxic, is used extensively in foods, cosmetics, and oral hygiene products as a solvent, preservative, and moisture-retaining agent. Other important glycols include 1,3-butanediol and 1,4-butanediol, used as raw materials for plastics and other chemicals; 2-ethyl-1,3-hexanediol, an insect repellent; and 2-methyl-2-propyl-1,3-propanediol, the raw material of the tranquilizer meprobamate.