PRODUCTION OF ALKALI METAL SALT OF LACTIC ACID IN HIGH CONCENTRATION

PURPOSE:To produce the titled compound with a low impurity content suitable for preparing a pharmaceutical transfusion solution in a process practicable at a low temperature, by neutralizing a concentrated aqueous solution of lactic acid with a bicarbonate, sesquicarbonate or carbonate of alkali metal added thereto. CONSTITUTION:A bicarbonate, sesquicarbonate or carbonate (especially the solid, wet or aqueous suspension state is preferred) is added to a concentrated aqueous solution of lactic acid. Since the reaction is an endothermic reaction, it proceeds with almost no generation of heat while maintaining its temperature at about room temperature. Further, since carbon dioxide gas is generated in the progress of the reaction, the viscosity of the reaction mixture is decreased to achieve good stirring and mixing and to obtain a highly concentrated alkali metal salt of lactic acid (preferably >=50wt.%) easily. EFFECT:Since the amount of water formed in neutralization reaction is small, a high concentration of the salt is achieved.