Glycols

Abstract

Glycols or diols are hydrocarbons that have two hydroxyl groups attached to separate carbons in an aliphatic chain or alicyclic ring. They are used as antifreeze agents, heat transfer agents, deicing agents, cryoprotectants, humectants, solvent carriers, chemical intermediates, components of polymers and resins, and vehicles in a number of chemical formulations including cosmetic and pharmaceutical preparations. They vary from slightly viscous liquids to waxy solids, are soluble in water, alcohols, and ketones, and are insoluble in hydrocarbons. They have low vapor pressures; therefore inhalation of vapors and aerosols is of little concern unless they are heated, agitated, or sprayed. They have little or no odor; thus only their irritancy at high concentrations is a warning property. Because of the irritant properties and the potential for central nervous system (CNS) depression at high concentrations, the occupational exposure limit (OEL) for glycols is generally set as a ceiling limit. The chemical and physical properties of several of the more common glycols are given.