Di Ethylene Glycol (DEG), also known as diglycol or digol, is a clear, colorless, and odorless liquid with the chemical formula C4H10O3. It is a dihydric alcohol and belongs to the class of glycols. DEG has a variety of industrial applications, primarily as a chemical intermediate and as a component in the production of various products.

One of the key uses of DEG is as a feedstock in the manufacture of polyester resins, which are used in the production of plastics, fibers, and films. It is also employed as a dehydrating agent in natural gas processing and as a coolant in the petrochemical industry. DEG has applications in the production of antifreeze formulations, where it helps lower the freezing point of water-based solutions. Additionally, it is utilized in the formulation of brake fluids, solvents, and as a humectant in the cosmetics and pharmaceutical industries. While DEG has various industrial applications, it is crucial to handle it with care due to its potential toxicity and health risks when ingested or absorbed through the skin.