Lactic acid

Physical and chemical properties

The pure product is a colorless liquid, and the industrial product is a colorless to pale yellow liquid. Odorless and hygroscopic. The relative density is 1.2060 (25/4°C). The melting point is 18°C. The boiling point is 122°C (2kPa). Refractive index nD (20°C) 1.4392. It can be miscible with water, ethanol and glycerol, and its aqueous solution is acidic, with pKa=3.85. Insoluble in chloroform, carbon disulfide and petroleum ether. It is heated and decomposed under normal pressure, and when it is concentrated to 50%, part of it becomes lactic anhydride, so the product often contains 10% to 15% lactic anhydride. Due to the hydroxyl and carboxyl groups, esterification reaction can occur under certain conditions, and there are three kinds of products.