Diethylene glycol (DEG) is an organic compound with the structural formula HO-CH2-CH2-O-CH2-CH2-OH. It is a clear, hygroscopic, odorless liquid. It is miscible with water and polar organic solvents such as alcohols and ethers.

Diols and Polyols

Diethylene glycol is one of several diols (hydrocarbons containing two alcohol groups). They are derived from ethylene oxide. Triethylene glycol, TEG or triethylene glycol is also a colorless, odorless, viscous liquid. It is used as a plasticizer for vinyl. It is also used in air disinfecting products such as "Oust" or "Clean and Pure". When atomized, it can be used as a disinfectant. Ethylene glycol is also used as a liquid desiccant for natural gas and air conditioning systems. It is an additive for hydraulic oil and brake fluid.

Product uses

Like ethylene glycol, solutions of diethylene glycol and water are used as coolants. It both lowers the freezing point of the solution and raises the boiling point, making it more suitable for hot climates. DEG is also a building block of organic syntheses, such as morpholine and 1,4-dioxane. It is a solvent for nitrocellulose, resins, dyes, oils, and other organic compounds. It is a humectant for tobacco, cork, printing inks, and glues. It can also be found in some hydraulic fluids and brake fluids.

In personal care products (e.g., skin creams and lotions, deodorants), DEG is often replaced by the much less toxic DEG ethers.

DEG is also illegally used as a pseudoglycerin in some countries and is sold internationally as an ingredient in cough syrups and toothpaste.