Patent ID: 7247747

Claim:
A process for the preparation of S-(−)-chlorosuccinic acid comprising reacting S-(=)-aspartic acid and sodium nitrite in a hydrochloric acid-aqueous milieu in which said S-(+)-aspartic acid is suspended in demineralized water in a w/w ratio ranging from 1 kg/L to 0.5 kg/L, and concentrated hydrochloric acid is added in a ratio of S-(+)-aspartic acid to hydrochloric acid ranging from 0.35 kg/L to 0.55 kg/L in the presence of sodium chloride, said S-(+)-aspartic acid and said sodium chloride being in a molar ratio ranging from 1:0.3 to 1:0.5, the improvement consisting in isolating by precipitation of the reaction product by cooling the reaction mixture at a temperature ranging from −10° C. to −20° C.