Method for recovering and mechanically applying L-(+)-tartrate in D-ethyl ester production

Abstract

The invention discloses a method for recovering and mechanically applying L-(+)-tartrate in D-ethyl ester production, which comprises the following steps: 1)obtaining a L-(+)-tartrate solution; 2)recovering L-(+)-calcium tartrate dehydrate; 3)acidifying; 4)performing pressure reduction and condensation; and 5)crystallizing, separating and drying. The method of the invention employs an inertia organic solvent, takes a solvent method to replace a water phase method to recover L-(+)-tartrate, key points of control temperature, time, centrifugation and vacuum degree are realized, the product yield is high, the purity and specific rotation of the recovered L-(+)-tartrate product accord with quality requirement, quality standard of the L-(+)-tartrate raw material can be reached, and the method can be used for chiral resolution of D-ethyl ester, recovery and mechanical application of L-(+)-tartrate can be realized, production cost is reduced, and the method is suitable for industrial production.

Description

technical field [0001] The invention belongs to the technical field of chemistry and relates to a method for recovering and applying L-(+)-tartaric acid in the production of D-ethyl ester. Background technique [0002] D-(+)-p-thymphenylphenylserine ethyl ester (referred to as D-ethyl ester) is obtained from DL-(±)-p-thymphenylphenylserine ethyl ester through L-(+)-tartaric acid optical resolution Obtained, the intermediate is an important intermediate for the synthesis of thiamphenicol and florfenicol, especially florfenicol is an excellent broad-spectrum antibiotic for veterinary use, with low toxicity, no residue, and no drug resistance. Because the rapid growth of the amount of florfenicol has driven the growth of the demand for intermediates, therefore, a large amount of L-(+)-tartaric acid needs to be consumed in the D-(+)-ethyl ester generation process. [0003] The chiral substance L-(+)-tartaric acid was used to resolve DL-(±)-p-thiamphenicyl phenylserine ethyl est...

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Problems solved by technology

[0016] It has been reported in the literature that methanol and ethanol are used as organic solvents to prepare L-(+)-tartaric acid, but the added calcium chloride reacts with the solvent to form CaCl 2 ·4CH 3 OH, CaCl 2 ·4C 2 h 5 OH and other complex impurities, and even react under strong acid catalysis and a certain temperature to form impurities such as L-(+)-dimethyl tartrate, L-(+)-diethyl tartrate, etc., without special purification and separation, Concentrate under reduced pressure directly, most of the impurities are always present in the L-(+)-tartaric acid, resulting in the quality of the recovered L-(+)-tartaric acid not meeting the resolution requirements

[0017] In above-mentioned aqueous phase method and described alcohol solvent method reaction process, there are many difficult problems, if handle badly, will cause the L-(+)-tartaric acid quality of reclaiming to be unqualified, HPLC content<98.0%, specific rotation [a] D20: <+12° (C=20, aqueous solution) (generally +9.0°~+11.5°), the quality of recovered L-(+)-tartaric acid product is poor, and basically cannot reach L-( +)-tartaric acid raw material quality standards, can not be directly applied to the production of D-ethyl ester

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