Triethylene

Triethylene, commonly referred to as triethylene glycol (TEG), is a polyether diol consisting of three ethylene glycol units linked by ether bonds. Its chemical formula is C6H14O4, and its structural formula is HO-CH2-CH2-O-CH2-CH2-O-CH2-CH2-OH. It is a colorless, odorless, viscous liquid that is highly hygroscopic.

TEG is miscible with water and many organic solvents. It has a high boiling point and low vapor pressure, which contributes to its stability as a heat-transfer fluid in industrial systems. The compound is thermally stable under ordinary processing conditions and is typically handled as a high‑boiling, viscous liquid. It is soluble in water and interacts with various solvents and resins, making it useful in several formulations.

Industrial production of triethylene glycol involves the controlled condensation or sequential alkoxylation of ethylene oxide with glycols, commonly starting from ethylene glycol and building up the ether chain. This produces a family of glycol ethers, of which TEG is a member.

Applications are diverse. A major use is as a desiccant in natural gas dehydration systems, where TEG removes water from gas streams and is regenerated by vacuum stripping. It is also employed as a heat‑transfer fluid, a solvent and plasticizer in coatings and inks, and as a humectant in cosmetics and pharmaceuticals. It can serve as an intermediate in the synthesis of polyurethane polyols and other derivatives.

Safety and handling notes: TEG has relatively low acute toxicity compared with some glycols but can cause irritation upon contact or ingestion. Standard industrial hygiene practices are recommended, including appropriate personal protective equipment and containment to prevent spills.