JP2007202563A - METHOD FOR PRODUCING OPTICALLY ACTIVE alpha-TRIFLUOROMETHYLLACTIC ACID AND ITS CHIRAL ESTER AND METHOD FOR PURIFYING THE COMPOUND - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing optically active α-trifluoromethyllactic acid and its chiral ester, and to provide a method for purifying the compound (method for improving optical purity). <P>SOLUTION: This method for producing the optically active α-trifluoromethyllactic acid and its chiral ester comprises asymmetrically hydrolyzing a racemic α-trifluoromethyllactate represented by the general formula (I) (R is a substituted or non-substituted 1 to 12C hydrocarbon group) in the presence of an enzyme, an enzyme-immobilized product, a microbial cell culture solution or a microbial cell-treated product. The method for purifying the compound comprises recrystallizing the optically active α-trifluoromethyllactic acid obtained by the method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing optically active α-trifluoromethyl lactic acid and its enantiomer ester useful as raw materials or intermediates for pharmaceuticals, agricultural chemicals and the like.

  Racemic α-trifluoromethyl lactic acid and its ester have been reported to be synthesized from 1,1,1-trifluoroacetone and sodium cyanide as raw materials (Journal of Chemical Society, 2329, 1951). In the same report, a method for producing optically active α-trifluoromethyl lactic acid from racemic α-trifluoromethyl lactic acid by an optical resolution method using brucine is reported. Furthermore, WO93 / 23358 reports a method for producing optically active α-trifluoromethyl lactic acid from racemic α-trifluoromethyl lactic acid by optical resolution using (S)-(-)-α-methylbenzylamine. ing.

  However, either method requires an expensive resolving agent to increase the optical purity, and the production cost is high. Furthermore, in these methods, it is necessary to carry out the de-resolving agent treatment after repeating recrystallization several times in the form of a salt with the resolving agent, and the operation is complicated.

  In addition, the above-mentioned document does not mention anything about purification of optically active α-trifluoromethyllactic acid by recrystallization (improvement of optical purity), and whether or not optical purity can be improved by recrystallization. It was completely unknown.

  An object of the present invention is to provide an optically active α-trifluoromethyllactic acid useful as a raw material or intermediate for pharmaceuticals, agricultural chemicals, etc. The object is to provide a simple purification method (an optical purity improving method) of a body.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found an enzyme having an activity of optically hydrolyzing racemic α-trifluoromethyl lactate, and further, optically active α-trifluoro. The inventors have found that optical purity is improved by recrystallizing methyl lactic acid, and the present invention has been completed.

  That is, the present invention includes the following inventions.

（式中、Ｒは置換又は非置換の炭素原子数１〜12の炭化水素基である。）
で表されるラセミ体α−トリフルオロメチル乳酸エステルを、エステル不斉加水分解能力を有する酵素、酵素固定化物、微生物、菌体培養液、又は菌体処理物の存在下で不斉加水分解することを特徴とする、光学活性α−トリフルオロメチル乳酸及びその対掌体エステルの製造方法。 (1) General formula (I):

(In the formula, R is a substituted or unsubstituted hydrocarbon group having 1 to 12 carbon atoms.)
Is asymmetrically hydrolyzed in the presence of an enzyme having an asymmetric hydrolysis ability, an enzyme-immobilized product, a microorganism, a cell culture broth, or a cell-treated product. A process for producing optically active α-trifluoromethyl lactic acid and its enantiomer ester.

  (2) Enantiomer optics obtained by hydrolyzing the optically active α-trifluoromethyl lactic acid obtained by the method described in (1) above or the enantiomer ester obtained by the method described in (1) above. A method for purifying optically active α-trifluoromethyl lactic acid, comprising recrystallizing active α-trifluoromethyl lactic acid and recovering the crystals.

  According to the present invention, optically active α-trifluoromethyl lactic acid and its esters useful as raw materials for pharmaceuticals, agricultural chemicals and the like or synthetic intermediates can be produced without using an optical resolution agent. Moreover, if the optically active α-trifluoromethyllactic acid obtained by the present invention is recrystallized, purification (improvement of optical purity) can be achieved by a simple technique.

Hereinafter, the present invention will be described in detail.
In general formula (I), R is a substituted or unsubstituted hydrocarbon group having 1 to 12 carbon atoms. Specifically, alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, n-hexyl group; vinyl group, propenyl group, isopropenyl group, butenyl An alkenyl group having 2 to 12 carbon atoms such as a group, isobutenyl group and hexenyl group; an alkynyl group having 2 to 12 carbon atoms such as ethynyl group, propynyl group and butynyl group; 3 to 12 carbon atoms such as cyclohexyl group; Preferable examples include 3 to 7 cycloalkyl groups; aryl groups such as phenyl group, tolyl group and naphthyl group; aralkyl groups such as benzyl group and the like. In this hydrocarbon group, the hydrogen atom bonded to the carbon atom may be substituted with a substituent such as halogen.

  The racemic α-trifluoromethyl lactate used as a raw material can be synthesized by a known method described in, for example, Journal of Chemical Society, 2329 (1951). That is, to the 1,1,1-trifluoroacetone aqueous solution, sodium cyanide aqueous solution was added dropwise under cooling, and then sulfuric acid was added to react at room temperature for one day to synthesize α-trifluoromethyl lactonitrile, Subsequently, this is hydrolyzed with a strong acid such as sulfuric acid to synthesize α-trifluoromethyl lactic acid, which can then be produced by esterification according to a conventional method.

  The ester asymmetric hydrolase used in the present invention is an ester having the ability to asymmetrically hydrolyze racemic α-trifluoromethyl lactic acid ester to produce optically active α-trifluoromethyl lactic acid and its enantiomer ester. The type of enzyme and the production source thereof are not particularly limited as long as they are asymmetric hydrolases. Among them, enzymes generally called lipases, esterases, and proteases are particularly effective.

  As the ester asymmetric hydrolase, for example, a racemic α-trifluoromethyl lactic acid ester is asymmetrically hydrolyzed to isolate optically active α-trifluoromethyl lactic acid and its enantiomer ester from microorganisms capable of producing the same. Crude or purified enzyme can be used. Examples of such microorganisms include Bacillus, Aspergillus, Candida, Pseudomonas, Rhizopus, Mucor, and Humicola. And microorganisms belonging to

  Examples of microorganisms belonging to the genus Bacillus include Bacillus subtilis, Bacillus licheniformus, Bacillus polymixa, etc. As the microorganisms belonging to the genus Candida, Candida rugosa, Candida antarcia, Candida utilus, etc., and the microorganisms belonging to the genus Pseudomonas include Pseudomonas fluorescence, Pseudomonas antarcia, Pseudomonas sp. MR-2301 (FERM BP-4870), etc. However, examples of the microorganism belonging to the genus Rhizopus include Rhizopus juponicus and the like, examples of the microorganism belonging to the genus Mucor include Mucor juponicus and Mucor miehei, and examples of the microorganism belonging to the genus Humicola include Humicola lanuginosa and the like.

  Moreover, a commercially available thing can be used as ester hydrolase used in this invention. Representative enzymes produced by microorganisms include, for example, NOVO Alcalase (derived from the genus Bacillus), NOVO Durazyme (derived from the genus Bacillus), NOVO Esperase (derived from the genus Bacillus), NOVO Savinase (Derived from Bacillus genus), NOVO neutrase (derived from Bacillus genus), NOVO lipolase (derived from Humicola genus), NOVO flavozyme (derived from Aspergillus genus), Nagase Seikagaku Corporation biolase conch (Bacillus genus) Origin), Nagase Seikagaku Corporation Denateam AP and AP-15 (both Aspergillus genus), Nagase Seikagaku Corporation lipase 2G (Pseudomonas genus), Amano Pharmaceutical lipase P (Pseudomonas genus), Amano Pharmaceutical Lipase PS (derived from the genus Pseudomonas), Amase Pharmaceutical Co., Ltd. Newase F (derived from the genus Rhizopus), Amano Pharmaceutical Co., Ltd. lipase MFL, Amano Pharmaceutical Co., Ltd. lipase M (derived from the genus Mucor), Amano Pharmaceutical Co., Ltd. lipase AY (Candi) genus da), Amano Pharmaceutical lipase A (from Aspergillus genus), Amano Pharmaceutical lipase M-AP-10, Asahi Kasei Kogyo LP-015-S, etc. Examples of degrading enzymes include porcine or bovine pancreatin, trypsin and the like.

  Furthermore, not only the crude enzyme or purified enzyme separated from the microorganism as described above, but also the culture obtained by culturing the microorganism in a medium as it is or by collecting the microorganism from the culture by centrifugation or the like. Optically active α-trifluoro is obtained by asymmetric hydrolysis of the racemic α-trifluoromethyl lactate represented by the general formula (I) in the presence of the obtained culture supernatant, cells, or treated cells. Methyl lactic acid and its enantiomer ester can also be produced. Examples of the treated microbial cells include microbial cells treated with acetone, toluene, etc., crushed microbial cells, cell-free extracts crushed microbial cells, and the like.

  In the production method of the present invention, when the ester asymmetric hydrolase is used for the reaction, the form of use is not particularly limited as long as the enzyme exhibits activity, and the enzyme may be used by immobilizing the enzyme on a suitable carrier. it can. By immobilizing the enzyme, separation and recovery of the optically active α-trifluoromethyl lactic acid, its enantiomer ester, and the enzyme after the reaction is facilitated, and the enzyme can be reused.

  In the present invention, optically selective hydrolysis of racemic α-trifluoromethyl lactate can be carried out by the following method. Racemic α-trifluoromethyl lactate as a substrate is dissolved or suspended in the reaction solvent. In addition, the enzyme, enzyme-immobilized product, microorganism, cell culture solution, or cell-treated product having the ability to perform asymmetric hydrolysis, which becomes a catalyst, is added before or after the substrate is added to the reaction solvent. Then, the reaction is carried out until about half of the α-trifluoromethyl lactate is hydrolyzed while controlling the reaction temperature and, if necessary, the pH of the reaction solution. In some cases, the reaction may be interrupted or excessively reacted at an early stage of the reaction.

The substrate concentration of the reaction solution is not particularly limited between 0.1 and 80% by weight, but it is preferably carried out at a concentration of 1 to 50% by weight in consideration of productivity.
The enzyme concentration of the reaction solution is usually 0.01 to 10% by weight, preferably 0.05 to 5% by weight.

The pH of the reaction solution depends on the optimum pH of the enzyme used, but is generally in the range of pH 4-11. It is preferable to carry out the reaction at a pH of 5 to 9 in that a decrease in optical purity and a decrease in yield due to a chemical hydrolysis reaction can be suppressed. Further, the pH decreases as the reaction proceeds. In this case, it is desirable to adjust to an optimum pH by adding an appropriate neutralizing agent such as sodium hydroxide or potassium hydroxide aqueous solution.
The reaction temperature is preferably 5 to 70 ° C, more preferably 10 to 50 ° C.

  As the reaction solvent, an aqueous medium such as ion-exchanged water or a buffer solution is usually used, but the reaction can also be performed in a system containing an organic solvent. Examples of the organic solvent include alcohol solvents such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, t-butyl alcohol, and t-amyl alcohol, and aliphatic hydrocarbon solvents such as pentane, hexane, heptane, and octane. , Aromatic hydrocarbon solvents such as benzene, toluene and xylene, halogenated hydrocarbon solvents such as methylene chloride, chloroform, carbon tetrachloride and dichloroethane, ether solvents such as diethyl ether, diisopropyl ether, tetrahydrofuran and dioxane, acetic acid Ester solvents such as ethyl, propyl acetate and butyl acetate, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, acetonitrile, N, N-dimethylformamide and the like can be used as appropriate. It is also possible to carry out the reaction in a two-layer system by adding these organic solvents beyond the solubility in water. By allowing the organic solvent to coexist in the reaction system, the selectivity, conversion rate, yield, etc. are often improved.

  The reaction time is usually 1 hour to 1 week, preferably 1 to 72 hours, and it is preferable to select reaction conditions for completing the reaction in such a time.

  The substrate concentration, enzyme concentration, pH, temperature, solvent, reaction time, and other reaction conditions as described above are the most targeted optically active compounds in consideration of the reaction yield, optical yield, etc. under the conditions. It is desirable to appropriately select the conditions for collection.

  By the above reaction, racemic α-trifluoromethyl lactic acid ester is asymmetrically hydrolyzed to produce optically active α-trifluoromethyl lactic acid. The remaining substrate becomes the enantiomer ester of the optically active α-trifluoromethyl lactic acid produced.

  Isolation of the produced optically active α-trifluoromethyl lactic acid and optically active α-trifluoromethyl lactic acid ester (that is, the enantiomer of optically active α-trifluoromethyl lactic acid) from the reaction mixture is extraction, distillation, It can be performed by a usual isolation method such as column separation.

  For example, optically active α-trifluoromethyl lactate is prepared by adjusting the pH of the reaction solution to near neutral, and then ethers such as diethyl ether and diisopropyl ether; esters such as ethyl acetate; hexane, octane, benzene, It can be extracted and separated by a general organic solvent such as hydrocarbons such as toluene; halogenated hydrocarbons such as methylene chloride.

  On the other hand, optically active α-trifluoromethyl lactic acid can be extracted and separated with the same general organic solvent as described above after adding a strong acid such as sulfuric acid or hydrochloric acid to the above extraction residue.

  Furthermore, the optically active α-trifluoromethyl lactic acid ester can be converted to α-trifluoromethyl lactic acid while maintaining the optical activity by hydrolysis by a usual method. Further, optically active α-trifluoromethyl lactic acid can be converted to α-trifluoromethyl lactic acid ester while maintaining optical activity by esterification by a usual method. Therefore, α-trifluoromethyl lactic acid and esters thereof having an arbitrary configuration can be obtained.

  The optically active α-trifluoromethyl lactic acid obtained as described above can be further purified by recrystallization to improve its optical purity. Hereinafter, purification by recrystallization will be described in detail.

  In the present invention, the optically active α-trifluoromethyl lactic acid to be used for recrystallization may be either an R-form or an S-form optically active form. The optical purity is not 0% e.e., that is, as long as any one of the R-form and S-form is contained more than the other, there is no particular limitation, but a 10% e.e. or higher is preferable. In the present specification, the optical purity is expressed as an enantiomeric excess (% e.e.).

  The optically active α-trifluoromethyl lactic acid obtained by asymmetric hydrolysis according to the present invention can be used for recrystallization as it is. On the other hand, the enantiomer ester produced at the same time as the optically active α-trifluoromethyllactic acid needs to hydrolyze the ester bond by a conventional method before being subjected to recrystallization.

  The solvent used for recrystallization of the optically active α-trifluoromethyllactic acid is not particularly limited as long as it does not react with the optically active α-trifluoromethyllactic acid, and the optical purity of the raw material used, the target optical purity, etc. Depending on the situation, it can be appropriately determined in consideration of the recovery rate of the object. Examples of the solvent include aliphatic hydrocarbon solvents such as pentane, hexane, heptane, and octane; aromatic hydrocarbon solvents such as benzene, toluene, and xylene; halogens such as methylene chloride, chloroform, carbon tetrachloride, and dichloroethane. Hydrocarbon solvents; ether solvents such as diethyl ether, isopropyl ether, tetrahydrofuran and dioxane; ester solvents such as ethyl acetate, propyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; and acetonitrile , N, N-dimethylformamide and the like. Among them, toluene, n-hexane, ethyl acetate, methylene chloride, chloroform, isopropyl ether, acetone and acetonitrile are preferable in terms of versatility and economy. Among them, toluene, freezing point to the boiling point (under 1 atmosphere, -95 ℃ ~110.6 ℃) is in the range easily handled range, and therefore the range is wide, particularly preferred. These recrystallization solvents can be used alone or in combination.

  Also, alcohol solvents such as methanol, ethanol, propanol and butanol can be used as a mixed solvent in combination with other solvents as long as they do not cause esterification with optically active α-trifluoromethyllactic acid. It is also effective in some cases.

  The recrystallization operation can be carried out according to a general method and is not particularly limited. That is, optically active α-trifluoromethyl lactic acid as a raw material is dissolved in the recrystallization solvent under heating, and can be precipitated by cooling after that. Moreover, you may precipitate a crystal | crystallization by adding the poor solvent of optically active alpha-trifluoromethyl lactic acid. Furthermore, in order to precipitate crystals smoothly and efficiently, crystal seeds can be seeded. The crystal seed is not particularly limited, but it is preferable to use a crystal with high optical purity, a racemic crystal, or the like depending on the purpose.

  The temperature conditions for the recrystallization operation can be appropriately determined depending on the boiling point and freezing point of the solvent used. In general, the raw material is dissolved from room temperature (25 ° C.) to the boiling point of the solvent, and crystallized at −80 ° C. to 50 ° C. Can be deposited. When using toluene (under 1 atm, freezing point: -95 ° C., boiling point: 110.6 ° C.) as a solvent, the raw materials are dissolved at 90 ° C. to 110 ° C., and crystals are precipitated at −20 ° C. to 50 ° C. preferable. In addition, the amount relationship between the recrystallization solvent and the optically active α-trifluoromethyl lactic acid used as a raw material is not particularly limited as long as it is within a completely soluble range. Depending on the situation, it can be appropriately determined in consideration of the recovery rate of the object.

  Next, the recovery of the purified optically active α-trifluoromethyl lactic acid can be performed according to a conventional method such as filtration or centrifugation.

  The optical purity of these optically active α-trifluoromethyllactic acids can be easily measured by gas chromatography using a GC capillary column for optical resolution after esterification by a conventional method. The optical purity (enantiomeric excess;% ee) is generally calculated from the peak areas of (S) -α-trifluoromethyllactic acid and (R) -α-trifluoromethyllactic acid by GC using the following formula: can do.

[Equation 1]
If R> S:
Optical purity of R-form (% ee) = (R−S / R + S) × 100
If S> R:
Optical purity of S-form (% ee) = (S−R / R + S) × 100
S: Peak area of (S) -α-trifluoromethyl lactic acid R: Peak area of (R) -α-trifluoromethyl lactic acid

  The optically active α-trifluoromethyllactic acid obtained as described above can be made into an optically active substance with higher optical purity by repeating the purification by recrystallization one or more times in the same manner.

EXAMPLES The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited to the scope of these examples.
[Reference Example 1]
Synthesis of racemic α-trifluoromethyl lactate n-butyl ester
To 65 ml of n-butanol, 60 g of racemic α-trifluoromethyl lactic acid and 1 ml of concentrated sulfuric acid were added and reacted for 15 hours while refluxing. The excess butanol was then removed by distillation. The remaining solution was put into ice water and extracted three times with 60 ml of diethyl ether. The diethyl ether layers obtained by three extraction operations were combined and purified by distillation under reduced pressure to obtain 64 g of racemic α-trifluoromethyl lactate n-butyl ester.

[Example 1]
To a reactor equipped with a pH controller, 300 ml of 0.1 M phosphate buffer, 15 g of racemic α-trifluoromethyl lactate n-butyl ester and 3 g of Denateam AP (manufactured by Nagase Seikagaku Corporation) were added, and 2N hydroxide was added. The reaction was carried out at 30 ° C. for one day while adjusting the pH of the reaction solution to 7.0 with an aqueous sodium solution.

  After completion of the reaction, extraction was performed 3 times using 100 ml of diisopropyl ether. The diisopropyl ether layers obtained by the three extraction operations were combined and dehydrated by adding anhydrous magnesium sulfate, and then diisopropyl ether was removed by distillation. The α-trifluoromethyl lactate n-butyl ester (4.8 g) thus obtained was analyzed by capillary gas chromatography equipped with an optical resolution column (Chirasil-DEX CB column manufactured by Chrome Pack). It was an optically active substance (S form), and its optical purity was 96.5% ee.

  To the optically active ester obtained above, 50 ml of 5% aqueous sodium hydroxide solution was added, and a hydrolysis reaction was carried out at room temperature for 2 hours. Subsequently, sulfuric acid was added to adjust the pH to 1.5, and extraction was performed three times with 50 ml of ethyl acetate each time. The ethyl acetate layers obtained by three extraction operations were combined and dehydrated with magnesium sulfate, and then the solvent was removed. The α-trifluoromethyl lactic acid (2.3 g) thus obtained was esterified with diazomethane and then analyzed by capillary gas chromatography equipped with an optical resolution column (Chirasil-DEX CB column manufactured by Chrome Pack). The optical purity was 96.5% ee.

  Further, (S) -α-trifluoromethyllactic acid n-butyl ester extraction residual liquid (aqueous layer) was concentrated to 100 ml. Concentrated sulfuric acid was added to adjust the pH to 1.0, and 50 ml of ethyl acetate was added for each extraction. The ethyl acetate layers obtained by the three extraction operations were combined and dehydrated by adding anhydrous magnesium sulfate, and then the solvent was removed. The α-trifluoromethyl lactic acid (3.3 g) thus obtained was esterified with diazomethane and analyzed by capillary gas chromatography with an optical resolution column (Chirasil-DEX CB column manufactured by Chrome Pack). The optical purity was 58.9% ee.

[Examples 2-45]
In each Example, 10 mg of each of the enzymes shown in Table 1 was added to 0.5 ml of 0.1 M phosphate buffer (pH = 7.0) in which 1% by weight of racemic α-trifluoromethyl lactate n-butyl ester was suspended. After shaking for 24 hours at 30 ° C., 0.5 ml of diisopropyl ether was added and stirred. The optically active α-trifluoromethyl lactate n-butyl ester contained in the diisopropyl ether layer was analyzed by gas chromatography with an optical resolution column (Chirasil-DEX CB column manufactured by Chrome Pack) in the same manner as in Example 1. Table 1 shows the results of measurement of configuration and optical purity.

Example 46
A liquid medium composed of 10 g of peptone (Difco), 5 g of yeast extract (Difco), 5 g of sodium chloride, and 1 L of distilled water was prepared. Steam sterilized at 15 ° C. for 15 minutes. Five platinum flasks were inoculated with 1 platinum ear of Pseudomonas sp. MR-2301 (FERM BP-4870) and cultured with shaking at 30 ° C. for 1 day. Next, the cells were collected from the culture solution in each flask by centrifugation, washed with water, and then suspended in 10 ml of 50 mM phosphate buffer (pH = 7.0). 4.5 ml of 0.1 M phosphate buffer (pH = 7.0) in which 2% by weight of racemic α-trifluoromethyl lactic acid n-butyl ester is suspended is added to 0.5 ml of this cell suspension, and the mixture is heated at 30 ° C. The reaction was carried out with shaking for 24 hours.

  5 ml of diisopropyl ether was added to the reaction solution and stirred. The optically active α-trifluoromethyl lactic acid n-butyl ester contained in the diisopropyl ether layer was analyzed by gas chromatography with an optical resolution column (Chirasil-DEX CB column manufactured by Chrome Pack) in the same manner as in Example 1. As a result of measuring the steric configuration and the optical purity, it was an R form and the optical purity was 30% ee.

[Examples 47 to 61]
In the same manner as in Example 2, 10 mg of each of the enzymes shown in Table 2 was added to 0.5 ml of 0.1 M phosphate buffer (pH = 7.0) in which 1% by weight of racemic α-trifluoromethyl lactate was suspended. Then, after shaking for 24 hours at 30 ° C., 0.5 ml of diisopropyl ether was added and stirred. The optically active α-trifluoromethyl lactate methyl ester contained in the diisopropyl ether layer was analyzed by gas chromatography with an optical resolution column (Chirasil-DEX CB column manufactured by Chrome Pack Co., Ltd.) in the same manner as in Example 1. Table 2 shows the results of measuring the optical purity.

Example 62
10 ml of toluene was added to 1.0 g of 96.5% ee (S) -α-trifluoromethyllactic acid obtained in Example 1, dissolved at 100 ° C., and allowed to stand overnight at room temperature. The precipitated crystals were collected to obtain 0.8 g of (S) -α-trifluoromethyllactic acid having 99% ee or more.

The optical purity was measured as follows. To the obtained crystals, an ether solution of diazomethane is added to form a methyl ester, and this solution is analyzed by gas chromatography (GC) under the following conditions to obtain (S) -α-trifluoromethyllactic acid and (R) -α. -Optical purity (enantiomeric excess) was calculated from the peak area of trifluoromethyllactic acid by the above formula.
Column: CP-Chirasil DEX CB 0.25mm x 25m (made by Chrome Pack)
Column temperature: 70 ° C
Detector: FID

Example 63
50 ml of toluene was added to 1.0 g of 58.9% ee (R) -α-trifluoromethyllactic acid obtained in Example 1, dissolved at 100 ° C, and allowed to stand at 30 ° C for 3 hours. The precipitated crystals were collected to obtain 0.28 g of 79% ee (R) -α-trifluoromethyllactic acid. The optical purity was measured by the method described in Example 62.

[Example 64]
500 g of n-hexane was added to 1.0 g of 58.9% ee (R) -α-trifluoromethyllactic acid obtained in Example 1, and the mixture was dissolved by heating near the boiling point and allowed to stand overnight at room temperature. When the precipitated crystals were recovered, 0.4 g of 70% ee (R) -α-trifluoromethyllactic acid was obtained. The optical purity was measured by the method described in Example 62.

Example 65
Except for halving the reaction time, 2.0 g of 64% ee (S) -α-trifluoromethyllactic acid obtained in the same manner as in Example 1 was dissolved in the solvent shown in Table 3 by heating to room temperature. And allowed to stand for 3 hours to precipitate crystals. Table 3 shows the solvent used, the amount of solvent, the amount of recovered crystals, and the optical purity of the obtained crystals. The optical purity was measured by the method described in Example 62.

Example 66
Except for halving the reaction time, 2.0 g of 64% ee (S) -α-trifluoromethyllactic acid obtained in the same manner as in Example 1 was dissolved in ethyl acetate or isopropyl ether, and n-hexane was further added. Then, the mixture was allowed to stand at −20 ° C. for 5 hours to precipitate crystals. Table 4 shows the solvent used, the solvent amount, the crystal recovery amount, and the optical purity of the obtained crystal. The optical purity was measured by the method described in Example 62.

Example 67
Except for halving the reaction time, 2.0 g of (S) -α-trifluoromethyllactic acid 64% ee obtained in the same manner as in Example 1 was dissolved in acetonitrile or acetone, and toluene was further added at room temperature. Thereafter, the crystals were allowed to stand at −20 ° C. for 5 hours to precipitate crystals. Table 5 shows the solvent used, the amount of solvent, the amount of recovered crystals, and the optical purity of the obtained crystals. The optical purity was measured by the method described in Example 62.

Claims (2)

Formula (I):

(In the formula, R is a substituted or unsubstituted hydrocarbon group having 1 to 12 carbon atoms.)
Is asymmetrically hydrolyzed in the presence of an enzyme having an asymmetric hydrolysis ability, an enzyme-immobilized product, a microorganism, a cell culture broth, or a cell-treated product. A process for producing optically active α-trifluoromethyl lactic acid and its enantiomer ester.   The optically active α-trifluoromethyl lactic acid obtained by the method according to claim 1, or the enantiomer optically active α-trifluoromethyl lactic acid obtained by hydrolyzing the enantiomer ester obtained by the method according to claim 1. A method for purifying optically active α-trifluoromethyl lactic acid, which comprises recrystallizing and recovering the crystals.