KR0150592B1 - Separation method of racemic (r,s)-1,2-phenylethandiol by using enzymes - Google Patents

Abstract

The present invention relates to a method for efficiently optically dividing 1,2-phenylethanediol, and more particularly, to apply lipase and acetate to a 1,2-phenylethanediol racemic mixture represented by the following formula (I). The present invention relates to a method for optically dividing (R, S) -1,2-phenylethanediol by preparing an ester having high optical purity.

According to the present invention, it is possible to complete the reaction while maintaining high optical purity within a short time under mild conditions of room temperature and atmospheric pressure, and there is an advantage that the post-reaction treatment process is very simple.

Description

Optical cleavage method of (R, s) -1,2-phenylethanediol using enzyme

The present invention relates to a method for effectively optically dividing 1,2-phenylethanediol, and more particularly, to a 1,2-phenylethanediol racemic mixture represented by the following formula (I): The present invention relates to a method for optically dividing (R, S) -1,2-phenylethanediol by applying an ester having high optical purity.

1,2-phenylethanediol having high optical temperature is a useful synthetic intermediate that can be used in medicine, pesticides, liquid crystals, etc., and much research has been made to obtain it as a pure optical isomer. Looking at these prior arts, chemical methods include the method by chemical reduction of (S) -mandelic acid, published in JOC 44,1729 (1979) and (D) -mannitol, published in JOC 43,4876 (1978). Although there are methods used, these methods have a long synthesis process and require a large amount of catalyst (such as lead tetraacetylated), which is not suitable for commercial production.

In addition, as a biochemical method, there is a method of separating a diol by selectively metabolizing only one isomer as disclosed in EP-A-317-998, but this yields a low yield and produces only one isomer.

It is therefore an object of the present invention to provide a simple and efficient method for separating racemic mixtures of 1,2-phenylethanediol represented by Formula (I) into their respective isomers.

In the present invention, vinylacetate is used as an acetyl group donor in the optical division of 1,2-phenylethanediol racemic mixture, so that the acetylation reaction proceeds in the presence of a powdered enzyme or an immobilized enzyme. Under the conditions, the reaction can be completed while maintaining high optical purity within a short time, and there is an advantage that the post-reaction treatment is very simple. As a result of this reaction, a monoester represented by the following formulas (II) and (III) is produced first, and an enzyme and an acetyl group donor act on these monoesters again to give a high optical purity represented by the following formula (IV). To esters. This result is because the characteristics of the enzyme used acetylate the primary hydroxy group without optical selectivity, while the second hydroxy group exhibits high optical selectivity.

The diester in the ester mixture represented by the following formulas (II), (III), and (IV) produced as a result of the above reaction can be separated by a well-known method such as column chromatography.

The reaction of the present invention proceeds in various organic solvents, such as ethyl acetate, normal hexane, butyl acetate, diethyl ether, and the like, and vinyl acetate may be used as the acetyl group donor and solvent.

At this time, the molar ratio of 1,2-phenylethanediol and vinyl acetate as an acetyl donor is about 1: 1.6 to about 1:15, preferably about 1: 2.5 to about 1: 3. When vinyl acetate is used as a solvent, it is maintained at 1:25 or more.

The concentration of 1,2-phenylethanediol in the reaction mixture is maintained between 0.01M and 2M, preferably from 0.05M to 1M. In addition, the weight ratio of the enzyme and 1,2-phenylethanediol is maintained at 0.05M to 1M.

The reaction of the ester proceeds with vigorous stirring of the reaction mixture consisting of 1,2-phenylethanediol, vinyl acetate, solvent, powder or immobilized enzyme, and the reaction temperature is maintained at 0 ℃ to 50 ℃, preferably Maintain at 20 ° C. to 30 ° C.

The enzyme used after the reaction is completed can be easily removed by filtration and can be reused without significant degradation of activity.

After the reaction, the excess reactant is removed and the monoester is separated from the diester by column chromatography or the like, and the obtained ester can be converted into 1,2-phenylethanediol by a chemical method.

The enzyme used in the present invention is a microbial-derived lipase, and can be used in powder or immobilized. Immobilization of the enzyme has the advantage of increased activity and stability, and easy recovery and reuse after the reaction. Porous materials having a large surface area such as celite, porous glass, silica and the like are suitable for such applications.

Immobilization of the enzyme is easily achieved by stirring the phosphate buffer with the enzyme and the selected tin together, and after filtering it, the immobilized enzyme is dried and used at room temperature.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

Example 1

Immobilization of Enzymes

40 g of lipase was clouded in 240 ml of 10 mmol of phosphate buffer (pH 7) and then dissolved by stirring at room temperature for about 30 minutes. 80 g of celite 545 was added to 600 ml of the same buffer solution, stirred at room temperature for 30 minutes, and filtered using a 0.45 μm filtration membrane. Celite sufficiently moistened in the buffer solution is added to the enzyme suspension, stirred for 30 minutes, mixed well, and placed in 1.2L of cold acetone at -20 ° C and stirred for 30 minutes. This was filtered using a filtration membrane and then vacuum dried.

Example 2

Optical division of (R, S) -1,2-phenylethanediol

0.25 g of immobilized PSL (pseudomonas lipase) prepared according to Example 1 and 0.25 g of (R, S) -1,2-phenylethanediol are placed in 12.5 ml of vinyl acetate. When the reaction mixture is stirred vigorously at 25 ° C., the progress of the reaction is determined by gas chromatography. When reacted for about 25 hours, monoester and 50% of monoester are produced. The enzyme used was filtered off, the organic solvent layer was washed with 5% sodium carbonate solution, dried over anhydrous magnesium sulfate, and the solvent was blown off with a rotary evaporator to give a colorless oil. The resulting concentrated reaction mixture was separated by column chromatography (mobile phase; normal hexane; ethyl acetate = 9: 1 volume / volume) and (S) -1,2-propanoyloxy-phenylethane (93% optical purity). (R) -1-propinoyloxy-2-phenylethanol (89% optical purity) was obtained. Physical Properties of (S) -1,2-propanoyloxy-phenylethane:

[α] = + 59.4 ° (c = 1.0 acetone), ee = 93%

¹ H-NMR (CDCl 3, 200 MHz), ppm (δ); 1.2 (t, 3H), 2.4 (q, 1H)

4.4 (m, 2H), 6.1 (m. 1H), 7.4 (s, 5H)

Physical Properties of (R) -1-propanoyloxy-2-phenylethanol:

[α] = + 15.2 ° (c = 1.0 acetone), ee = 89%

¹ H-NMR (CDCl 3, 200 MHz), ppm (δ); 1.2 (t, 3H), 2.4 (q, 1H),

2.9 (s, 1H), 4.2 (m, 2H), 4.95 (m. 1H)

7.4 (s, 5 H)

The optical purity of each product was measured using gas chromatography (Chiraldex G-TA comum, Astec) during the reaction. After each product was separated, it was converted to the respective diol using metalol, and then high pressure liquid chromatography. Optical purity was again confirmed by the graphing method (Chiralcel OB-H Comlum, Daicel Co., Ltd.).

Claims (7)

(R, S)-characterized in that the (R, S) -1,2-phenylethanediol represented by the following formula (1) is separated into a pure optical isomer by reacting with an acetyl group donor in the presence of a microorganism-derived lipase. Optical cleavage method of 1,2-phenylethanediol. The optical cleavage method of (R, S) -1,2-phenylethanediol according to claim 1, wherein the acetylary donor is vinyl acetate. The method of claim 1, wherein the lipase is in powder or immobilized form. The method of claim 1, wherein the weight ratio of the lipase to the diol is maintained at 5: 1 to 1: 100, characterized in that (R, S) -1,2-phenylethanediol. The method of optical separation of (R, S) -1,2-phenylethanediol according to claim 1, wherein the molar ratio of the diol to the acetyl group donor is 1: 1.6 to 1:15. The method of optical separation of (R, S) -1,2-phenylethanediol according to claim 1, wherein the reaction is maintained at a temperature of 0 ° C to 50 ° C. The (R, S) -1,2-phenylethane according to claim 1, wherein after the reaction, the ester is separated by column chromatography and then converted into 1,2-phenylethanediol by a chemical method. Optical division method of diol.