KR20050103691A - Process for preparation of alkyl s-(l)-lactate and alkyl r-(d)-o-acyllactate using lipase - Google Patents

Abstract

The present invention provides a method of reacting a racemic alkyl lactate of Formula 1 with a carbonyl donor under a lipase enzyme catalyst to stereoselectively carbonylate only the hydroxyl group of an alkyl R -lactate alkyl S- (L)- In the process for preparing lactate and / or alkyl R- (D) -O-acyl lactate, the present invention provides higher yield and optical purity of alkyl S- (L) -lactate and alkyl R- ( D) -O-acyl lactate can be prepared, and thus may be useful industrially.

<Formula 1>

In Formula 1, R means C ₁ to C ₁₀ saturated or unsaturated alkyl, or alkyl substituted aryl or heteroaryl.

Description

PROCESS FOR PREPARATION OF ALKYL S- (L) -LACTATE AND ALKYL R- (D) -O -ACYLLACTATE USING LIPASE}

The present invention relates to a process for preparing alkyl S- (L) -lactate and / or alkyl R- (D) -O-acyltate from racemic alkyl lactate using lipases.

Lactic acid and its derivatives are widely used in industrial fields such as food, medicine, leather, and textiles. Recently, lactic acid and its derivatives have important significance as a raw material of polylactic acid, which is mainly used in specialty medicines and eco-friendly biodegradable materials. Have. Therefore, studies on industrially available methods for producing lactic acid and its derivatives are being actively conducted (Jong-sun Yun et al., Enzyme and Microbial Technology , 33, 416-423, 2003).

Acid is divided into L- and D- optical isomers or in the S- and R-, S - (L) - lactic acid derivative may be easily obtained by the fermentation of microorganisms. However, R a natural - (D) - lactic acid derivatives that Very difficult to manufacture R- (D) -lactic acid derivatives have high yield and optical purity because of the increasing demand as a starting material for making a formulation which cannot be substituted with S- (L) -lactic acid derivatives in the above various industrial fields. There is a need for the development of a process for the preparation of R- (D) -lactic acid derivatives.

Looking at a variety of previously reported manufacturing methods of R- (D) -lactic acid derivative, screening (D) -lactic acid-producing strain among the mutants of the lactic acid-producing strain (Demirci, J. Indus, Microbial, 11, 23-28, 1992), a method for chemically degrading racemic lactic acid to separate D-lactic acid, and L-2-chloropropionic acid (Hydrohydrolase) L-2-chloropropionic acid) has been reported to replace D-lactic acid (Goldman, J. Biol. Chem. , 243, 428-434, 1968), but these have low yields and complicated procedures. There is a disadvantage that the growth rate of the production strain is slow. In addition, D-lactic acid is produced by reducing pyruvic acid with D-lactate dehydrogenase (Simon, Appl. Biochem. Biotech. , 22, 169-179, 1989), L- Substitution of L-lactic acid with D-lactic acid using lactate dehydrogenase (Biade, J. Am. Chem. Chem., 114, 893-897, 1992) also yielded low or used enzymes and coenzymes (coenzyme). ) The high price of NAD (nicotinamide adenine dinucleotide) has low industrial utility.

Meanwhile, lipases are used to separate carboxyl ester groups of racemic alkyl lactates by stereoselective hydrolysis (US Pat. No. 5,605,833), or sterically selective hydrolysis of hydroxy ester groups (Kazulauskas, J. Org.Chem ., 56, 2656-2665, 1991; Scilimati, Tetrahedron Lett. , 29, 4927-4930, 1989), but these methods are susceptible to environmental pollution due to the use of surfactants and per substrate. The amount of lipase used is disadvantageous. In addition, the separation efficiency of the carbonylation RS optical isomer is low except that the alkyl group of racemic alkyl lactate is t -butyl.

Accordingly, the present inventors have diligently researched to solve the problems of the conventional method for preparing R- (D) -O-lactic acid derivatives, which are inexpensive, low-purity, and inexpensive. The present invention was completed by developing a method for preparing and purifying alkyl S- (L) -lactate and alkyl R- (D) -O-acyltate with high optical purity.

It is an object of the present invention to provide a process for preparing alkyl S- (L) -lactate and alkyl R- (D) -lactic acid derivatives with high yield and optical purity.

In accordance with the above object, in the present invention, a racemic alkyl lactate of Formula 1 is reacted with a carbonyl donor under a lipase enzyme catalyst as shown in Scheme 1 to stereoselectively select only a hydroxyl group of an alkyl R -lactate. Provided is a method for preparing alkyl S- (L) -lactate of formula (2) and alkyl R- (D) -O-acylactate of formula (3) comprising the step of carbonylating.

In the above scheme, R means C ₁ to C ₁₀ saturated or unsaturated alkyl, or alkyl substituted aryl or heteroaryl, and R ¹ means C ₁ to C ₁₀ saturated or unsaturated alkyl, or aryl.

Hereinafter, the present invention will be described in detail.

As shown in Scheme 1, the alkyl S- (L) -lactate of Formula 2 and the alkyl R- (D) -O-acyl of Formula 3 from the racemic alkyl lactate of Formula 1 according to the present invention The method for preparing lactate comprises the step of stereoselectively carbonylating only the hydroxyl group of the alkyl R -lactate by reacting a racemic form of alkyl lactate with a carbonyl donor using lipase as a catalyst. , Further comprising separating S- (L) -lactate and alkyl R- (D) -O-acylactate from the reaction product.

Lipase enzymes used as catalysts in the present invention are, for example, Pseudomonas cepacia lipase (LPS), Candida antarctica lipase (CAL), Candida lugera lipase known in the art. ( Candida rugosa lipase; CRL, or Candida cylindracea lipase; CCL), Aspergillus niger lipase (ANL), Mucor miehei lipase, Pseudomonas fluorecens lipase; , Rhizopus Perth Ari juice lipase (Rhizopus arrhizus lipase), Rhizopus Perth nibe mouse lipase (Rhizopus niveus lipase), Hog plate Ingress lipase (Hog pancreas lipase), Candida Li poly urticae lipases (Candida lipolytica lipase), Muko jabani kusu lipase (Mucor javanicus lipase, Penicillium roqueforti lipase, or Rhizomucor miehei lipase ), Preferably Candida antartica derived lipase. The lipase may be added in an amount of 0.1 to 10 g per 100 g of the reactor, and may be used in the form of a liquid, a solid and an immobilized formulation.

In addition, the carbonylation reaction may be performed at 0 to 80 ℃, preferably 25 to 70 ℃ for 1 to 100 hours. In this case, the carbonyl donor used in the reaction may include ester ( ) Compounds with functional groups such as vinyl acetate, vinyl propionate, vinyl butyrate, methoxyvinyl acetate, 2,2,2-trifluoroethyl butyrate, vinyl pivalate, acetylacetone oxime, diallyl carbonate and di Organic acid esters such as benzyl carbonate, organic acid anhydrides such as diketene and succinic anhydride, or organic carboxylic acids such as butyric acid and benzoic acid, and the like, and 0.5 to 100 equivalents, preferably 0.6 to 5 equivalents, relative to racemic alkyl lactate. Can be used.

On the other hand, the carbonylation reaction may be carried out in the presence of a solvent or in the absence of a solvent, when carried out in the presence of a solvent as a solvent hexane, diethyl ether, diisopropyl ether, t -butyl methyl ether, acetonitrile, tetra Common organic solvents such as hydrofuran, methylene chloride, ethyl acetate, dichloroethane, benzene, toluene and xylene are used. The amount of the solvent used in the reaction may be used in an amount of 0 to 100 times by weight compared to the racemic alkyl lactate, but the amount thereof is not significantly affected. When the concentration of the alkyl lactate is high, the reaction rate is sufficiently high, and thus the solvent is not used. It is advantageous in terms of economy, eco-friendliness and safety.

The reaction product obtained in the carbonylation reaction can be separated to obtain alkyl S- (L) -lactate and alkyl R- (D) -O-acylactate separately. According to the present invention, the separation process In consideration of the high water solubility characteristics of the atmospheric pressure or vacuum distillation process or alkyl S- (L)-lactate can be carried out using an extraction process using water. In the vacuum distillation process, the alkyl S- (L) -lactate can be separated at 80 to 82 ° C, and the alkyl R- (D) -O-acyl lactate at 114 to 117 ° C.

The production method of the present invention can prepare alkyl S- (L) -lactate and alkyl R- (D) -O-acyl lactate in higher yield and higher optical purity than the conventional methods, and thus prepared lactic acid Derivatives are not only used in the manufacture of food, medicine, leather and textiles, but also can be usefully applied in various industrial fields because of their high utilization as raw materials for specialty medicines and eco-friendly biodegradable materials.

Hereinafter, the present invention will be described in more detail by the following examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Examples 1-4

As shown in the above scheme, 0.3 mmol of racemic ethyl lactate and 0.6 mmol of vinyl acetate as carbonyl donors in the presence of 3 ml of hexane as a solvent and 10 mg of each lipase shown in Table 1 below at 200 ° C. for 200 hours at 200 rpm After reacting with shaking, the final reaction product was analyzed by gas chromatography using a CycloSil-B column (Agilent) and the results are shown in Table 1 below.

Example Lipase Response time (hours) Ethyl lactate ^a (R: S) Ethyl O-acetyllactate ^a (R: S) One Candida Antartica (Sigma) 26 0: 100 100: 0 2 Rizomuco Miehei (Aldrich) 26 10: 90 97: 3 3 Pseudomonas florence (sigma) 26 19: 81 82: 18 4 Pseudomonas Sephacia (Sigma) 26 15: 85 92: 8 ^a : gas chromatogram area ratio

As shown in Table 1, it can be seen that the reaction rate and chiral selectivity are excellent when reacted under the Candida antartica lipase enzyme catalyst.

Examples 5 to 24

As shown in the above scheme, 0.3 mmol of racemic ethyl lactate and vinyl alkanoate (R ¹ = ethyl (CH) in the presence of 3 ml of each solvent shown in Table 2 and 10 mg of Candida antartica lipase 0.6 mmol of ₂ CH ₃ ) or n -propyl (CH ₂ CH ₂ CH ₃ )) was reacted with shaking at 200 rpm at 25 ° C. for 19 hours, and then the final reaction product was subjected to gas chromatography under the same conditions as in Example 1. The results are shown in Table 2 below.

Example menstruum R ¹ Ethyl lactate ^a R : S Ethyl O-Acylactate ^a R : S 5 Acetonitrile CH ₃ CH ₂ 9.68: 39.15 51.17: 0.00 6 CH ₃ CH ₂ CH ₂ 1.93: 32.65 65.42: 0.00 7 Carbon tetrachloride CH ₃ CH ₂ 7.11: 35.14 57.75: 0.00 8 CH ₃ CH ₂ CH ₂ 0.73: 28.79 70.48: 0.00 9 Diethyl ether CH ₃ CH ₂ 2.40: 36.72 60.88: 0.00 10 CH ₃ CH ₂ CH ₂ 0.00: 23.43 76.57: 0.00 11 Diisopropyl ether CH ₃ CH ₂ 2.17: 36.53 63.16: 0.00 12 CH ₃ CH ₂ CH ₂ 0.02: 29.25 70.73: 0.00 13 Hexane CH ₃ CH ₂ 3.59: 26.29 70.12: 0.00 14 CH ₃ CH ₂ CH ₂ 0.05: 18.82 81.13: 0.00 15 Methylene chloride CH ₃ CH ₂ 14.52: 36.62 48.86: 0.00 16 CH ₃ CH ₂ CH ₂ 3.32: 29.09 67.59: 0.00 17 t -butyl methyl ether CH ₃ CH ₂ 7.95: 37.14 54.91: 0.00 18 CH ₃ CH ₂ CH ₂ 1.38: 31.28 67.34: 0.00 19 Tetrahydrofuran CH ₃ CH ₂ 8.52: 38.09 53.40: 0.00 20 CH ₃ CH ₂ CH ₂ 3.64: 31.51 64.85: 0.00 21 toluene CH ₃ CH ₂ 3.62: 36.02 60.36: 0.00 22 CH ₃ CH ₂ CH ₂ 0.06: 29.02 70.82: 0.00 23 1,4-dioxane CH ₃ CH ₂ 5.01: 38.62 56.37: 0.00 24 CH ₃ CH ₂ CH ₂ 2.90: 33.67 63.43: 0.00 ^a : gas chromatogram area ratio

As shown in Table 2 above, when the racemic ethyl lactate and the carbonyl donor vinyl alkanoate are reacted in the presence of Candida antartica lipase, only the hydroxyl group of the R -isomer is stereoselectively carbonylated. It can be seen that high optical purity alkyl R- (D) -O-acylactate is produced. In addition, it can be seen that the reaction rate increases as the carbon number of the carbonyl donor increases with ethyl and propyl, even when reacted under the same solvent.

Examples 25-48

As shown in the above scheme, the solvent was fixed with 3 ml of diisopropyl ether and 0.3 mmol of racemic alkyl lactate (R = Me, Et or Bu) and carbonyl donor in the presence of 10 mg of Candida antartica lipase. After reacting 0.6 mmol of canoate (R ¹ = Me, Et or Pr) at 200 rpm at 25, 35, 50 or 65 ° C., the final reaction was analyzed by gas chromatography to detect no alkyl R -lactate. The reaction was terminated at no time and the total reaction time was measured and the results are shown in Table 3 below.

Example R R ¹ Reaction temperature (℃) Response time (h) Alkyl (D) -O-acyl lactate R: S 25 Me Me 50 8 100: 0 26 65 4 100: 0 27 Et 50 6 100: 0 28 65 3 100: 0 29 Pr 50 3 100: 0 30 65 2 100: 0 31 Et Me 25 72 100: 0 32 35 32 100: 0 33 50 15 100: 0 34 65 8 100: 0 35 Et 25 32 100: 0 36 35 20 100: 0 37 50 8 100: 0 38 65 6 100: 0 39 Pr 25 24 100: 0 40 35 12 100: 0 41 50 4 100: 0 42 65 3 100: 0 43 Bu Me 50 14 100: 0 44 65 5 100: 0 45 Et 50 6 100: 0 46 65 4 100: 0 47 Pr 50 4 100: 0 48 65 3 100: 0

As shown in Table 3, according to the method according to the present invention it can be seen that the reaction rate increases as the alkan (R ¹ ) group of the vinyl alkanoate which is a carbonyl donor increases (Examples 21, 23 and 25). ). By performing the reaction for 2 to 72 hours at a temperature in the range of 25 to 65 ℃ can divide the optical isomer with high optical purity, the higher the reaction temperature can be terminated quickly without affecting the stereoselectivity.

Examples 49-52

As shown in the above scheme, the amount of diisopropyl ether as a solvent was kept at a constant ratio of butyl lactate (mmol) / vinyl butyrate (mmol) / lipase (mg) as 10/20/20 as a solvent. The reaction was terminated at the point where no alkyl R -lactate was detected while shaking at 65 ° C. and 200 rpm, and the total reaction time was measured. The results are shown in Table 4 below.

Example Reactor mass (mmol) Lipase amount (mg) Diisopropyl ether (ml) Response time (h) Butyl O-butyryl lactate R : S 49 10 20 0 9 100: 0 50 5 10 One 10 100: 0 51 5 10 2 14 100: 0 52 One 2 3 25 100: 0

As shown in Table 4, it can be seen that the reaction rate increases without increasing the stereoselectivity as the concentration of the reactor is increased even without the solvent.

Example 53

Based on the results of the above example, 73.1 g (0.5 mol) of racemic butyl lactate and 114.1 g (1 mol) of carbonyl donor, vinyl butyrate, in the presence of 200 mg of Candida antartica lipase without solvent were rotated at 65 rpm at 100 rpm. The reaction was carried out. 47 hours after the point when no butyl R -lactate was detected by gas chromatography, Candida antartica lipase was removed by filtration and excess vinyl butyrate was removed using a vacuum evaporator.

The filtrate thus obtained was vacuum distilled to obtain 35.1 g of butyl S -lactate and 51.9 g of butyl R- O-butyryllactate, the results of which are shown in Table 5 below.

product Distillation temperature yield(%) Optical purity (% ee) Butyl S -Lactate 80 to 82 ° C / 20 mmHg 48 > 99.5 Butyl R- O-Butyryllactate 114 to 117 ° C / 20 mmHg 48 > 99.5

As can be seen in Table 5, according to the present invention, butyl S -lactate and butyl R- O-butyryllactate of high yield and optical purity are produced.

Example 54

Based on the results of the above example, 59.1 g (0.5 mol) of racemic ethyl lactate and 114.1 g (1 mol) of carbonyl donor vinyl butyrate in 100 mg at 100 rpm at 65 ° C. in the presence of 500 mg of Candida antartica lipase without solvent. The reaction was carried out while rotating. This was analyzed by gas chromatography, and after 30 hours at which no butyl R -lactate was detected, the candida antartica lipase was removed by filtration and excess vinyl butyrate was removed using a vacuum evaporator.

The filtrate obtained from this was added 100 ㎖ ethyl acetate and extracted three times with water 100 ㎖ ethyl S - out extracting lactate to the water layer were separated to an aqueous layer and an organic layer. The separated organic layer was dried over magnesium sulfate, solvent was removed from the vacuum evaporator, and the remaining organic material was distilled under vacuum to obtain 43.7 g of ethyl R- O-butyryl lactate (yield 93%, optical purity> 99.5% ee). The water layer containing ethyl S -lactate was extracted with ethyl acetate and vacuum distilled to give 27.3 g of ethyl S -lactate (yield 93%, optical purity> 99.5% ee).

As discussed above, alkyl S- (L) -lactate and alkyl R- (D) -O-acyltate are prepared from racemic alkyl lactate using Candida antartica lipase according to the present invention. The method of preparation can produce alkyl S- (L) -lactate and alkyl R- (D) -O-acylactate with higher yields and optical purity compared to conventional methods, which can also be simply separated Therefore, the method of the present invention can be industrially useful.

Claims (11)

Reacting a racemic alkyl lactate of Formula 1 with a carbonyl donor in the presence of a lipase enzyme catalyst to stereoselectively carbonylate only the hydroxyl group of the alkyl R -lactate, A process for preparing alkyl S- (L) -lactate and alkyl R- (D) -O-acyltate of Formula 3 below. In Chemical Formulas 1 to 3, R means C ₁ to C ₁₀ saturated or unsaturated alkyl, or alkyl substituted aryl or heteroaryl, and R ¹ means C ₁ to C ₁₀ saturated or unsaturated alkyl, or aryl. do. The method of claim 1, Carbonyl donors are esters ( A compound having a functional group. The method of claim 2, The ester functional group-containing compound is an organic acid ester, an organic acid anhydride, an organic carboxylic acid, or a mixture thereof. The method of claim 1, Wherein the carbonyl donor is used in an amount of from 0.5 to 100 equivalents relative to racemic alkyl lactate. The method of claim 1, Using a solvent in an amount of 0 to 100 times by weight relative to racemic alkyl lactate. The method of claim 5, The solvent is at least one selected from the group consisting of hexane, diethyl ether, diisopropyl ether, t -butylmethylether, acetonitrile, tetrahydrofuran, methylene chloride, ethyl acetate, dichloroethane, benzene, toluene and xylene How to. The method of claim 1, The process is characterized in that the reaction is carried out at 0 to 80 ℃ for 1 to 100 hours. The method of claim 1, A lipase enzyme catalyst is a lipase derived from Candida antarctica . The method of claim 1, And separately separating alkyl S- (L) -lactate of formula (2) and alkyl R- (D) -O-acylactate of formula (3) from the reaction product. The method of claim 9, The separation process comprises an atmospheric pressure or vacuum distillation process. The method of claim 9, And the separation process comprises an extraction process using water.