PROCESS FOR PURIFYING MONOCHLOROACETIC ACID Russian patent published in 1997 - IPC

FIELD: chemical technology, more specifically manufacture of monochloroacetic acid semiproduct for preparation of carboxylmethyl cellulose, ethylenediamine tetracetic acid and pharmaceuticals. SUBSTANCE: process for purifying monochloroacetic acid from dichloroacetic acid comprises crystallization in halogen hydrocarbon solvent having boiling temperature lower than crystallization temperature of monochloroacetic acid. Crystallization is carried out at solvent boiling temperature. The solvent is preferably ethyl chloride and crystallization is carried out at 12-16 C or 1,1,2- trifluorotrichloroethane (coolant 113), and crystallization process is carried out 46-50 C. Monochloroacetic acid crystals are separated from mother liquor by filtration of settling followed by washing with the solvent used and drying. The mother liquor is evaporated. Solvent vapors are condensed are recycled to the process. Yield of purified monochloroacetic acid is 90-97%. The content of main substance therein is 99.2-98.7% and content of dichloroacetic acid is 0.1-0.2%. Equipment need not be incrustated in the claimed process. EFFECT: more efficient purification process. 6 cl