Glycols, Propylene Glycols

Abstract The propylene glycol family of chemical compounds consists of monopropylene glycol (PG), dipropylene glycol (DPG), and tripropylene glycol (TPG). These chemicals are manufactured as copoducts and are used commercially in a large variety of applications. They are available as highly purified products which meet well‐defined manufacturing and sales specifications. All commercial production is via the hydrolysis of propylene oxide. The propylene glycols are clear, viscous, colorless liquids that have very little odor, a slightly bittersweet taste, and low vapor pressures. The most important member of the family is monopropylene glycol, also known as 1,2‐propylene glycol, 1,2‐dihydroxypropane, 1,2‐propanediol, methylene glycol, and methyl glycol. All of the glycols are totally miscible with water. Propylene glycol, when produced according to the U.S. Food and Drug Administration good manufacturing practice guidelines at a registered facility, meets the requirements of the U.S. Food, Drug, and Cosmetic Act. It is listed in the regulation as a direct additive for specified foods and is classified as generally recognized as safe (GRAS). In addition, it meets the requirements of the Food Chemicals Codex and the specifications of the U.S. Pharmacopeia XXIII. Because of its low human toxicity and desirable formulation properties it has been an important ingredient for years in food, cosmetic, and pharmaceutical products.