What Is Propanediol?
Propanediol is a divalent alcohol of propane and exists in two isomeric structures. The first, 1,2-propanediol, commonly known as propylene glycol, is a tasteless, colorless, odorless, and hygroscopic liquid at room temperature, with a molar mass of 76.1 g/mol, a melting point of -59°C, a boiling point of 188°C, and a CAS number of 57-55-6. The second, 1,3-propanediol, also known as trimethylene glycol, is a colorless liquid with a molar mass of 76.1 g/mol, a melting point of -27°C, and a boiling point of 211-217°C.
Properties of Propanediol
1,2-Propanediol has a hydroxy group attached to the first and third carbons of propane and is mainly synthesized by hydrolysis of propylene oxide. 1,3-Propanediol, on the other hand, can be produced chemically by reducing organic compounds or by hydrating acrolein. Recent industrial methods include microbial reduction of glycerin and glucose, which also produces lactic acid, acetic acid, and 2,3-butanediol as by-products.
Uses of Propanediol
1. 1,2-Propanediol:
Used as a solvent, antifreeze, heating medium, and refrigerant due to its lower melting point and higher boiling point than water. In the pharmaceutical industry, it serves as a dissolution aid in various medicinal preparations and is an intermediate raw material in resin synthesis. In organic chemistry, it is used for ketone synthesis via the pinacol transfer.
2. 1,3-Propanediol:
Used in cosmetics and personal care products for its moisturizing and antibacterial properties. Industrially, it’s utilized as a solvent, adhesive, and raw material for polyester. It reacts with carbonyl compounds to synthesize six-membered ring acetals, serving as a protective group for carbonyl carbons.
Other Information on Propanediol
Legal Information:
Propanediol is flammable with a flash point of 99°C. It must be handled with care, avoiding proximity to fire.