The chemical name of propylene glycol is "1,2-propanediol". There is one chiral carbon atom in the molecule. The racemate is a hygroscopic viscous liquid with a slightly pungent taste. It is miscible with water, acetone, ethyl acetate, and chloroform. It can dissolve in many essential oils but is immiscible with petroleum ether, paraffin, and fats. It is relatively stable to heat and light, and more stable at low temperatures. At high temperatures, propylene glycol can be oxidized to propionaldehyde, lactic acid, pyruvic acid, and acetic acid.

Chinese NamePropylene GlycolEnglish NamePropylene glycolOther Names1,2-PropanediolChemical FormulaCH3CHOHCH2OHMolecular Weight76.10CAS Registry Number57-55-6EINECS Registry Number200-338-0Melting Point-60 ℃Boiling Point187 ℃Density1.036 kg/m3

Physical and Chemical Properties

Specific gravity 1.036 (25/4°C), freezing point -59°C. Boiling point 188.2°C, 83.2°C (1,333 Pa), miscible with water, acetone, ethyl acetate, and chloroform. It can dissolve in many essential oils but is immiscible with petroleum ether, paraffin, and fats. It is relatively stable to heat and light, and more stable at low temperatures.

Preparation Method

Direct hydration of propylene oxide: a pressurized non-catalytic hydrolysis method. Propylene oxide and water are directly hydrated at 150-160°C and 0.78-0.98 MPa pressure to produce the product, which is then evaporated and distilled to obtain the final product.