CN1332152A

CN1332152A - Synthesis of L-glutamic acid-5-methyl ester

Info

Publication number: CN1332152A
Application number: CN 00135649
Authority: CN
Inventors: 刘德海; 何金兰
Original assignee: ZHANJIANG NORMAL UNIVERSITY
Current assignee: ZHANJIANG NORMAL UNIVERSITY
Priority date: 2000-12-14
Filing date: 2000-12-14
Publication date: 2002-01-23
Anticipated expiration: 2020-12-14
Also published as: CN1163473C

Abstract

L-glutamic acid -5-methyl ester is an important raw material for the synthesis of several amino acids and amino acid medicines. The L-glutamic acid -5-methyl ester product with 98 % over purity is prepared through esterification of glutamic acid in methanol solvent in the presence of H2SO4 as catalyst and under certain reaction conditions. After reaction, excessive H2SO4 is eliminated with Ba(OH)2 and methanol is recovered for reuse. The synthesis process is simple, low in cost, less in environmental pollution and significant in industrial production.

Description

The synthetic method of L-L-glutamic acid-5-methyl esters

The invention belongs to the synthetic method of a kind of L-L-glutamic acid-5-methyl esters.

About the synthetic method of L-L-glutamic acid-5-methyl esters, existing report, as United States Patent (USP) (US2798092), Japanese Patent (day disclosure special permission, clear 46--24888) etc., all there are some problems in these patented methods, and the separation that can not realize that has is purified; What have can not reclaim solvent and environment is had pollution; The technology that has is complicated, and yield is low etc.

The objective of the invention is problem, carry out comprehensive exploitation, the synthetic method of a kind of L-L-glutamic acid-5-methyl esters is provided, can improve yield, and reclaim solvent and utilize again, can protect environment, reduce cost at above-mentioned prior art existence.

Synthetic method of the present invention is: L-L-glutamic acid is joined in the methyl alcohol, and add equimolar dense H ₂SO ₄Make the dissolving of L-L-glutamic acid, add dense H again ₂SO ₄As catalyst levels is the 3%--20% mole number of the mole number of L-L-glutamic acid, and esterification is 1 hour under 30 ℃ of temperature; With Ba (OH) ₂Remove the H of catalyzer ₂SO ₄Redistillation is reclaimed methyl alcohol to oily; Again oily matter is dissolved in water, adds Ba (OH) ₂The aqueous solution is removed H ₂SO ₄, and use BaCl ₂Check is until no SO ^-2Remove by filter BaSO ₄, and water thorough washing filter cake, filtrate decompression has been concentrated into crystallization and has separated out; Put into refrigerator at 10 ℃--subzero 10 ℃ of recrystallize, to filter then, and use the methanol wash crystallization, final drying gets product.

Described reduced vacuum degree is 60mmHg--10mmHg.

Synthetic method of the present invention is used H in methanol solution ₂SO ₄The esterification of catalysis L-L-glutamic acid, single-esterification is used Ba (OH) after finishing again ₂Remove the H of catalytic amount ₂SO ₄, can obtain to contain the L-L-glutamic acid-5-methyl esters product more than 98%, and recyclable 95% methanol solvate.Product yield reaches more than 60%.Synthetic method of the present invention, simple for process, recovered solvent still can be used further to esterification, thereby has protected environment, has reduced cost.

Embodiment 1:

With 25g (～0.13mol) L-L-glutamic acid joins in the 250ml methyl alcohol, and adds 7ml (～0.13mol) dense H ₂SO ₄Make the dissolving of L-L-glutamic acid.Add 1.3ml (～0.02mol) dense H again ₂SO ₄Catalyzer is 30 ℃ of following esterifications 1 hour, with 4g (～0.02mol) Ba (OH) ₂Remove the H of catalytic amount ₂SO ₄, distillation is reclaimed methyl alcohol to oily, and (rate of recovery of methyl alcohol reaches more than 95%) adds the 100ml water dissolution in oily matter, add 22g (～0.13mol) Ba (HO) again ₂The aqueous solution is removed H ₂SO ₄, and use BaCl ₂Check is up to no SO ^-2Remove by filter BaSO ₄, and water thorough washing filter cake, filtrate is to be concentrated into crystallization under the 60mmHg--10mmHg condition to separate out at the reduced vacuum degree, puts into the refrigerator recrystallize, filters then, and uses methanol wash crystallization, final drying to get L-L-glutamic acid-5-methyl esters 17.8g, yield reaches 65%.〔α〕 _D ²⁰＝+28°(C＝2，6N?HCl)。

Embodiment 2:

Increase to 1.4ml (～0.026mol) dense H as catalyst consumption ₂CO ₄, esterification is 4 hours under 25 ℃ of temperature, other reaction conditions, and operation is with embodiment 1.Can obtain L-L-glutamic acid-5-methyl esters 16.4g, yield reaches 60%.〔α〕 _D ²⁰＝+29°(C＝2，6N?HCl)。

Claims

1, the synthetic method of a kind of L-L-glutamic acid-5-methyl esters is characterized in that: L-L-glutamic acid is joined in the methyl alcohol, and add equimolar dense H ₂SO ₄Make the dissolving of L-L-glutamic acid, add dense H again ₂SO ₄As catalyst levels is the 3%--20% mole number of the mole number of L-L-glutamic acid, and esterification is 1 hour under 30 ℃ of temperature; With Ba (OH) ₂Remove the H of catalyzer ₂SO ₄Redistillation is reclaimed methyl alcohol to oily; Again oily matter is dissolved in water, adds Ba (OH) ₂The aqueous solution is removed H ₂SO ₄, and use BaCl ₂Check is until no SO ^-2Remove by filter BaSO ₄, and water thorough washing filter cake, filtrate decompression has been concentrated into crystallization and has separated out; Put into refrigerator at 10 ℃--subzero 10 ℃ of recrystallize, to filter then, and use the methanol wash crystallization, final drying gets product.

2, according to the synthetic method of the described a kind of L-L-glutamic acid of claim 1-5-methyl esters, it is characterized in that: described reduced vacuum degree is 60mmHg--10mmHg.