Method for producing methyl lactate with high content and high optical purity in two steps

A technology of methyl lactate and optical purity, applied in the field of organic chemical industry, can solve the problem of no methyl lactate

Active Publication Date: 2010-12-15
XIAOGAN ESUN NEW MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, there is no patent related to the synthesis of methyl lactate in China

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0023]The raw material is purchased lactic acid with a content of 88%. The falling film evaporator is used to vacuum distill the raw material lactic acid. The temperature of the material in the falling film evaporator is maintained at 50°C, and the vacuum degree is maintained at 8000Pa. The monomer content of the concentrated lactic acid is Above 99%. Transfer 500Kg of concentrated lactic acid into the polycondensation tank through a delivery pump, add zinc lactate as a catalyst at a weight ratio of zinc lactate to lactic acid of 5 / 10000, and raise the material from 80°C to 120°C within 2 hours. The vacuum degree is maintained at 5000Pa, and the whole reaction is carried out with stirring. The viscosity of the lactic acid oligomer is detected by an online viscometer. According to the relationship between viscosity and molecular weight, determine whether its molecular weight is between 1000 and 2500. Inside, the oligomeric lactic acid is transported into the depolymerization ta...

example 2

[0025] 500Kg of concentrated lactic acid is transported into the polycondensation tank through a delivery pump, and zinc oxide is added as a catalyst according to the weight ratio of zinc oxide and lactic acid as 8 / 10000. Within 2 hours, the material is raised from 80°C to 120°C. The vacuum degree is maintained at 4000Pa, and the whole reaction is carried out with stirring. The viscosity of the lactic acid oligomer is detected by an online viscometer. According to the relationship between viscosity and molecular weight, its molecular weight is determined to be 1600. The oligomeric lactic acid is transported into the depolymerization tank, and zinc oxide is added as a catalyst according to the weight ratio of zinc oxide to lactic acid of 10 / 10000. The whole reaction is carried out under the condition of stirring, and the material is rapidly heated to 185°C, vacuum The temperature is maintained at 1500Pa. After the lactide vapor obtained continuously is condensed, it is enriched ...

example 3

[0027] 500Kg of lactic acid purchased with a content of 95% is transported into the polycondensation tank through a delivery pump, and a mixed catalyst is added in a ratio of 10 / 10000 by weight ratio of the catalyst to lactic acid. The mixed catalyst is zinc oxide, tin oxide and butyl titanate according to A mixture with a weight ratio of 1:1:1. Within 2.5 hours, the material was raised from 80°C to 120°C, the vacuum degree was maintained at 5000Pa ~ 4000Pa, the whole reaction was carried out with stirring, and the viscosity of the lactic acid oligomer was detected by an online viscometer. relationship, confirm that its molecular weight is 2000, and the polycondensation is completed, the oligomeric lactic acid is transported into the depolymerization kettle through the height difference and vacuum pressure difference, and the mixed catalyst is added in a ratio of 8 / 10000 according to the weight ratio of the catalyst to the lactic acid, and the mixed catalyst is oxidation A mix...

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Abstract

The invention relates to a method for producing methyl lactate with high content and high optical purity from lactide and methanol through ester exchange reaction in two steps. The method comprises the following steps of: adding a catalyst to a lactic acid to carry out polycondensation reaction to obtain the lactate oligomer with the molecular weight of 1,000-2,500; adding a catalyst to the lactate oligmer to carry out depolymerization reaction to obtain the crude lactide; refining the lactide, and carrying out full-reflux reaction on the refined lactide and the absolute methanol to obtain the methyl lactate. The process is simple, the content of synthesized methyl lactate is more than 99.5%, and the optical purity can achieve more than 99%.

Description

technical field [0001] The invention belongs to the technical field of organic chemical industry, and specifically relates to a method for producing methyl lactate with high content and high optical purity by using lactide and anhydrous methanol as direct raw materials through a two-step transesterification reaction method. Background technique [0002] Methyl lactate has a special fragrance and is an important fine chemical raw material. Because methyl lactate contains asymmetric carbon atoms, it has two optical isomers and is also an important industrial solvent with optical activity. It can be used as nitrocellulose, cellulose acetate, methanolic acid resin, kauri ester, Manila resin, Solvent for rosin, shellac, vinyl resin, paint, etc., and high-grade solvent for artificial pearls. It is also used as a plasticizer in other industrial fields, used in asymmetric synthesis to synthesize optically active carboxylic acid esters, and widely used in food, wine, chemical, pharm...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C69/68C07C67/03
Inventor 杨义浒徐杰
Owner XIAOGAN ESUN NEW MATERIAL
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