PROCESS FOR PURIFYING d,l-MALIC ACID Russian patent published in 1996 - IPC

FIELD: chemical industry. SUBSTANCE: the product of the empirical formula: C₄H₆O₅. The content of fumaric acid is 0.12-0.18%. Reagent 1: d,l- malic acid. Reagent 2: lower aliphatic ester. Reaction conditions: mixing circulating solution saturated at room temperature and feeding solution saturated at 70-120 C at their weight ratio being from 10 to 15:1. The resulting mixture is thereafter cooled to room temperature to form supersaturated solution which is admitted for crystallization to form layer of crystals through which said supersaturated solution continues circulating in fluized bed mode, and the crystals thus formed are further recovered. EFFECT: more efficient purification process. 1 dwg