CN103981248B - A kind of leucic method of resolution of racemic - Google Patents

Abstract

The present invention is a kind of leucic method of resolution of racemic, the method prepares left-handed leucine and dextrorotation leucine with Enzymatic Resolution racemize leucine and DL-LEUCINE, specifically comprise the following steps: the first step: with racemize leucine for raw material, prepare DL-LEUCINE methyl ester hydrochloride according to thionyl chloride method; Second step: DL-LEUCINE methyl ester hydrochloride is dissolved in alkaline aqueous solution, adds lipase, enzymatic hydrolysis 5 ~ 10 hours at 30 ~ 40 DEG C of temperature, cool to room temperature gradually again, filter out insolubles, obtain left-handed leucine and L-Leu, and retain filtrate; 3rd step: second step gained filtrate continues hydrolysis in the basic conditions, terminates the neutralization of rear diluted acid, filters to obtain dextrorotation leucine and D-Leu.Splitting solvent for use is water, and production cost is low, and environmental pollution is little; Preparation technology is simple, process is purified conveniently, equipment requirements is not high.

Description

A kind of leucic method of resolution of racemic

Technical field

The present invention is a kind of technology of preparing of chiral organic compound, the leucic method of especially a kind of resolution of racemic.

Background technology

L-Leu, in trophology, belongs to the indispensable amino acid of human body.L-Leu can be used as accessory substance, as preparing amino acid transfusion and comprehensive amino acid preparation, with other amino acid actings in conjunction, repairing muscle, controlling blood sugar, to bodily tissue supplying energy.Research shows, leucine can affect the mechanism controlling people's energy i (in vivo) balance ^[1]; Leucine to human body resistance to fatigue and control muscle and liver starch degraded have remarkable effect ^[2]; Improve the oxidation capacity of body by the oxidation completing carbohydrate and increase skeletal muscle cell Mitochondria density ^[3].In addition, leucine also can be used for seasoning sweetener.D-Leu is a kind of alpha-non-natural amino acid, contributes to Perception In Man Before And After Laser stimulation produced analgesia, is expected to the adjuvant as improving Perception In Man Before And After Laser stimulation produced analgesia effect; With D-phenylalanine acting in conjunction, the amino acid composite preparation obtained can be used as the good anodyne for the treatment of horse pain ^[4], comprise the pain after preoperative, rheumatic arthritis, sprain and pain that overwork etc. causes; Leu derivatives can the aqueous phase aldol reaction of effectively catalyze fatty ketone and aldehyde ^[5]; With the rare fatty acyl-leucine of N-of leucine preparation synthesis, there is anti-microbial property [6]; Derivative N-acyl group-D-Leu may be used for chiral separation.

About the preparation of D-Leu, the method for bibliographical information mainly contains chemical resolution method, enzyme process and induced crystallization method.

Chemical resolution is correlated with, the combination AES resolving agent formed with the substituted-phenyl ethyl sulfonic acid with optically active 1-Phenyl-ethanesulfonic acid and racemization in patent (a kind of fractionation prepares light amino acid whose method .CN102241555A alive) [7], in aqueous fractionation is carried out to DL-Leu and obtain D-Leu, optical purity 98.2%.And acetonitrile/water ratio be split in the solution of 9:1 time, filter cake in acetonitrile/water solution (9:1) dissolve, drip ammoniacal liquor be 5.98 to pH, obtain D-Leu, optical purity 99.6%.Patent (a kind of method for splitting .CN101659623A of DL-Amino Acid) ^[8]be resolving agent with D-DBTA, obtain D-Leu, optical purity 98.8%.Document TheResolutionofAminoAcids.II.Isoleucine, Alloisoleucine, LeucineandNorleucine ^[9]racemize leucine acidylate obtains N-acyl group-DL-LEUCINE; Product and (-)-α-fenchylamine add in hot water, are obtained by reacting double salt; Above-mentioned double salt is purified through fractional crystallization and is obtained N-acyl group-D-Leu (-)-α-fenchylamine double salt in methyl alcohol; the latter's decomposition obtains N-acyl group-D-Leu; then reflux in 3N hydrochloric acid; reaction solution concentrates; after evaporate to dryness; resistates dissolves in methyl alcohol, and adjust pH to iso-electric point with ammoniacal liquor, filtering and obtaining filter cake is D-Leu.Above method, the price comparison of some resolving agents is high, and some intermediates are not easy to carry out aftertreatment, and the then reactions steps had is more, operating process relative complex, inconvenient suitability for industrialized production.

Patent (preparation of N-acyl group-DL-Leu and purposes .CN102617384A) ^[10]in first by L-Leu racemization in organic acid, obtain DL-Leu, racemize leucine generates N-acyl group-DL-Leu with acylating reagent effects such as diacetyl oxides in inorganic alkali solution; be dissolved in basic solution, added D-L-Aminoacylase, through enzymic hydrolysis; neutralization, is separated, and purifies and obtains D-Leu.This method, reaction conditions is gentle, concise in technology; But D-L-Aminoacylase more not easily obtains, and price comparison is high, in reaction system, L-Leu is not easy to reclaim.

Document OpticalResolutionofDL-AminoAcidsbyPreferentialCrystalliz ationProcedure ^[11], DL-Leu and Phenylsulfonic acid are made DL-Leu benzene sulfonate.DL-Leu benzene sulfonate is dissolved in water, adds a small amount of D-Leu-BS and do crystal seed, separate out D-Leu benzene sulfonate, separate Phenylsulfonic acid by ion exchange method, obtain D-Leu.Induced crystallization legal system gets D-Leu, extends the production cycle, adds production cost, and the optical purity of product is relatively low, is not suitable for industrial production.Therefore, be necessary to study new method for splitting.

Summary of the invention

Technical problem: the object of this invention is to provide a kind of method that Enzymatic Resolution DL-LEUCINE prepares L-Leu and D-Leu, the method splits that DL-LEUCINE environmental pollution is little, concise in technology, products obtained therefrom optical purity is high and yield is higher.

Technical scheme: the leucic method of resolution of racemic of the present invention prepares left-handed leucine and dextrorotation leucine with Enzymatic Resolution racemize leucine and DL-LEUCINE, specifically comprises the following steps:

The first step: with racemize leucine for raw material, prepares DL-LEUCINE methyl ester hydrochloride according to thionyl chloride method;

Second step: DL-LEUCINE methyl ester hydrochloride is dissolved in alkaline aqueous solution, adds lipase, enzymatic hydrolysis 5 ~ 10 hours at 30 ~ 40 DEG C of temperature, cool to room temperature gradually again, filter out insolubles, obtain left-handed leucine and L-Leu, and retain filtrate;

3rd step: second step gained filtrate continues hydrolysis in the basic conditions, terminates the neutralization of rear diluted acid, filters to obtain dextrorotation leucine and D-Leu.

Described lipase comprises: acid lipase enzyme, neutral lipase, alkaline lipase.

Described diluted acid comprises dilute hydrochloric acid or dilute sulphuric acid, and the concentration of diluted acid is 0.1-2.0mol/L.

Alkaline aqueous solution in described second step alkali used is: NaOH, KOH, NaHCO ₃, Na ₂cO ₃or ammoniacal liquor.

Alkali required for described 3rd step neutral and alkali condition is LiOH, NaOH, KOH, K ₂cO ₃or Na ₂cO ₃.

Beneficial effect: the solution of the ester after ferment treatment of the present invention is easier than acid amides in buck to be hydrolyzed; Splitting solvent for use is water, and production cost is low, and environmental pollution is little; Preparation technology is simple, process is purified conveniently, equipment requirements is not high.

Accompanying drawing explanation

Fig. 1 is process route chart of the present invention.

Embodiment

The present invention prepares left-handed leucine and dextrorotation leucine with Enzymatic Resolution DL-Leu, take first DL-Leu as raw material, prepares DL-LEUCINE methyl ester hydrochloride according to thionyl chloride method.Then leucine methyl ester hydrochloride is dissolved in alkaline aqueous solution, add and easily obtain cheap lipase, enzymatic hydrolysis for some time at a certain temperature, then cool to room temperature gradually, filter out insolubles, obtain left-handed leucine (L-Leu).Mother liquor continues hydrolysis in the basic conditions, terminates rear acid neutralization, filters to obtain dextrorotation leucine (D-Leu).This uses lipase selective hydrolysis leucine ester to prepare light leucic method alive first, and compared with preparing D-Leu with use D-L-Aminoacylase, lipase source is more extensive, cheaper, and L-Leu is convenient to reclaim.

Utilize lipase can the hydrolysis of the left-handed leucine methyl ester of selective catalysis enantiomorph in the present invention, obtain left-handed leucine and dextrorotation leucine methyl ester, due to left-handed leucine, solubleness be less in the solution, can separate out from solution; And dextrorotation leucine methyl ester solubleness is comparatively large in the solution, then stay in the solution.After balance for some time, they can be separated by filtering.

The dextrorotation leucine methyl ester obtained is hydrolyzed reaction in the basic conditions, obtains dextrorotation leucine sodium salt.Neutralize through rare strong acid again, generate leucine.The pH of regulator solution is to leucic iso-electric point, and now leucic solubleness is minimum, separates out from solution, filters and namely obtains dextrorotation leucine.

2 splitting condition

DL-LEUCINE methyl ester hydrochloride is dissolved in a certain amount of saturated enzyme liquid, and adds a certain amount of sodium bicarbonate, stir 5 ~ 10 hours at 30 ~ 40 DEG C, then be cooled to room temperature, leach white solid.White solid is left-handed leucine.Containing dextrorotation leucine methyl ester in filtrate, at hydrolyzed under basic conditions such as NaOH, then through diluted acid acidifying, adjust ph, namely obtains the higher D-Leu of optical purity.

Example 1:

Taking 3.62g (0.02mol) leucine methyl ester hydrochloride adds in fine taper bottle, taking 1.68g (0.02mol) sodium bicarbonate again adds in Erlenmeyer flask, and measure 16ml saturated fatty enzyme solution and add in reaction flask, Erlenmeyer flask is put into constant temperature oscillator vibrate, arranging temperature of reaction is 38 DEG C, reaction 8h, then reaction flask Slow cooling cooling, vacuum filtration.Obtaining filter cake is L-Leu 1.02g, and productive rate is 77.86%, specific rotatory power [α] _d ²⁰=+14.6 ° of (C=2,6mol.L ^-1hCl).Containing D-Leu methyl esters in filtrate, in filtrate, add a certain amount of sodium hydroxide, after dissolving, add isopyknic methyl alcohol again, in stirred at ambient temperature 10h, use 1mol.L ^-1the pH of dilute hydrochloric acid regulator solution to 6, then reacts 1h, and filter, wash filter cake with water, drying obtains D-Leu 0.90g, and yield is 68.70%, [α] _d ²⁰=-14.35 ° of (C=2,6mol.L ^-1hCl).

Example 2:

Taking 3.62g leucine methyl ester hydrochloride adds in fine taper bottle, taking 1.68g (0.02mol) sodium bicarbonate again adds in Erlenmeyer flask, and measure 16ml saturated fatty enzyme solution and add in reaction flask, Erlenmeyer flask is put into constant temperature oscillator vibrate, temperature of reaction is 34 DEG C, reaction times is 8h, then reaction flask Slow cooling cooling, vacuum filtration.Obtaining filter cake is L-Leu 0.92g, and productive rate is 70.22%, specific rotatory power [α] _d ²⁰=+14.6 ° of (C=2,6mol.L ^-1hCl).Containing D-Leu methyl esters in filtrate, in filtrate, add a certain amount of sodium hydroxide, after dissolving, add isopyknic methyl alcohol again, in stirred at ambient temperature 10h, use 1mol.L ^-1the pH of dilute hydrochloric acid regulator solution to 6, then reacts 1h, and filter, wash filter cake with water, drying obtains D-Leu 0.94g, and yield is 71.76%, [α] _d ²⁰=-12.52 ° of (C=2,6mol.L ^-1hCl).

Example 3:

Taking 3.62g leucine methyl ester hydrochloride adds in fine taper bottle, taking 1.68g sodium bicarbonate again adds in Erlenmeyer flask, and measure 16ml saturated fatty enzyme solution and add in reaction flask, Erlenmeyer flask is put into constant temperature oscillator vibrate, arranging temperature of reaction is 38 DEG C, react 9 hours, then reaction flask Slow cooling cooling, vacuum filtration.Obtaining filter cake is L-Leu 1.19g, specific rotatory power [α] _d ²⁰=+14.6 ° of (C=2,6mol.L ^-1hCl).Containing D-Leu methyl esters in filtrate, in filtrate, add solid sodium hydroxide, after dissolving, add methyl alcohol again, continuously stirring 10h, use 1mol.L ^-1the pH of dilute hydrochloric acid regulator solution to 6, then reacts 1h, and filter, wash filter cake with water, drying obtains D-Leu 0.83g, and yield is 63.36%, [α] _d ²⁰=-14.40 ° of (C=2,6mol.L ^-1hCl).

Claims (1)

1. the leucic method of resolution of racemic, is characterized in that: the method prepares left-handed leucine and dextrorotation leucine with Enzymatic Resolution racemize leucine and DL-LEUCINE, specifically comprises the following steps:

The first step: with racemize leucine for raw material, prepares DL-LEUCINE methyl ester hydrochloride according to known thionyl chloride method;

Second step: DL-LEUCINE methyl ester hydrochloride is dissolved in alkaline aqueous solution, adds lipase, enzymatic hydrolysis 5 ~ 10 hours at 30 ~ 40 DEG C of temperature, cool to room temperature gradually again, filter out insolubles, obtain left-handed leucine and L-Leu, and retain filtrate;

3rd step: second step gained filtrate continues hydrolysis in the basic conditions, terminates the neutralization of rear diluted acid, filters to obtain dextrorotation leucine and D-Leu;

Wherein:

Described lipase is alkaline lipase;

Described diluted acid comprises dilute hydrochloric acid or dilute sulphuric acid, and the concentration of diluted acid is 0.1-2.0mol/L;

Alkaline aqueous solution in described second step alkali used is: NaOH, KOH, NaHCO ₃, Na ₂cO ₃or ammoniacal liquor;

Alkali required for described 3rd step neutral and alkali condition is LiOH, NaOH, KOH, K ₂cO ₃or Na ₂cO ₃.