Diethylene glycol (DEG) is an organic compound with the formula (HOCH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>O. It is a colorless, practically odorless, poisonous, and hygroscopic liquid with a sweetish taste. It is miscible in water, alcohol, ether, acetone and ethylene glycol.
DEG is produced by the partial hydrolysis of ethylene oxide. Depending on the conditions, varying amounts of DEG and related glycols are produced. The resulting product is two ethylene glycol molecules joined by an ether bond.
"Diethylene glycol is derived as a co-product with ethylene glycol and triethylene glycol. The industry generally operates to maximize MEG production. Ethylene glycol is by far the largest volume of the glycol products in a variety of applications. Availability of DEG will depend on demand for derivatives of the primary product, ethylene glycol, rather than on DEG market requirements."