propanediols

Propanediols are chemical compounds in which two hydroxyl groups are attached to a three-carbon chain. The term commonly refers to two structural isomers: 1,2-propanediol (propylene glycol) and 1,3-propanediol (trimethylene glycol). Both are colorless, hygroscopic liquids that mix well with water and have relatively high boiling points for small alcohols.

1,2-Propanediol is widely used as a solvent and humectant in cosmetics, pharmaceuticals, and foods, and as an antifreeze component and heat-transfer fluid in industrial applications. It also serves as a versatile building block in the production of polymers, resins, and unsaturated polyesters. 1,3-Propanediol is an important monomer for polytrimethylene terephthalate (PTT), a polyester used in fibers for textiles and carpets as well as in engineering plastics. It is also used as a solvent and humectant, and can be produced by chemical synthesis or by biotechnological fermentation of glycerol.

Production methods for propanediols vary. 1,2-propanediol is typically produced by the catalytic hydration of propylene oxide, with alternative routes including fermentation to some extent. 1,3-propanediol can be manufactured via traditional chemical routes or produced through biotechnological processes that convert glycerol to the diol, expanding the share of bio-based feedstocks in the market.

Safety and environmental considerations are generally favorable for propanediols in moderate use. They have relatively low acute toxicity and are biodegradable, though concentrated solutions can cause irritation and appropriate handling and disposal procedures are followed in industrial settings.