METHOD FOR OBTAINING FINE-CRYSTALLINE FORM OF CALCIUM CIS-2,3-EPOXYSUCCINATE Russian patent published in 2021 - IPC C07D303/48 C07B61/00 C07D301/12 

FIELD: chemistry.

SUBSTANCE: invention relates to the field of production of metal carboxylates. In particular, the invention relates to the field of obtaining a new crystalline form of calcium cis-2,3-epoxysuccinate (salt of 2,3-epoxy-1,4-butanedioic acid), which can be raw material for the production of L-(+)-tartaric acid. A method for obtaining a fine-crystalline form of calcium cis-2,3-epoxysuccinate includes following stages: incomplete neutralization of maleic anhydride or maleic acid with the first portion of a calcium compound to obtain acid calcium maleate; epoxidation of acid calcium maleate with hydrogen peroxide in the presence of an epoxidation catalyst to obtain acid calcium cis-2,3-epoxysuccinate; neutralization of acid calcium cis-2,3-epoxysuccinate by adding the second portion of the calcium compound in the presence of a surfactant added in the amount from 0.0001 to 10 wt.% of the weight of the final product of calcium cis-2,3-epoxysuccinate; and the retention of calcium cis-2,3-epoxysuccinate for 24 to 240 h to obtain a fine-crystalline form of calcium cis-2,3-epoxysuccinate, crystals of which belong to a spatial group P21/n, and parameters of a crystal lattice at 22°C are a=15.1916(2), Å, b=8.9121(1), Å, c=7.4724(1), Å, beta=103.309(1)°.

EFFECT: obtaining a new crystalline form of calcium cis-2,3-epoxysuccinate.

92 cl, 5 dwg, 4 tbl, 5 ex