| 摘要 |
FIELD: chemical technology, namely production of monochloroacetic acid being half-finished product for production of carboxymethyl cellulose, herbicides, ETDA and pharmaceutical preparations. SUBSTANCE: purification of monochloroacetic acid against dichloroacetic acid is carried out by crystallization. Said crystallization takes place in hydrogen halide solvent having boiling point lower than crystallization point of monochloroacetic acid, said crystallization being carried out at boiling point of solvent. If ethyl chloride is used as said hydrogen halide solvent then crystallization is carried out at 12-16 C, if 1,1,2-trifluorotrichloroethane is used as said hydrogen halide solvent then crystallization is carried out at 46-50 C. Crystals of monochloroacetic acid are separated of mother solution by filtration or by settling followed by washing and by drying, said washing is carried out with the help of solvent being previously used. Mother solution is evaporated, steams of solvent are then condensed and removed in the process. Yield of desired monochloroacetic acid being purified is 90-97 %, content of main substance in it being 99.2-99.7 %, content of dicholoroacetic acid in it being 0.1-0.2 %. EFFECT: improved efficiency of the method. 6 cl |
