A process for the multistage liquid-liquid extraction resolution of 2-cyclohexylmandelic acid enantiomers

Abstract

The application discloses a method for separating 2-cyclohexyl mandelic acid enantiomers by multistage liquid-liquid extraction, and belongs to the technical field of chiral compound separation. The method comprises the following steps: dissolving a chiral ionic liquid in a phosphate buffer solution to obtain an aqueous phase 1 containing a chiral extractant; dissolving 2-cyclohexyl mandelic acid in an organic solvent to obtain an organic phase 2; mixing, oscillating, standing, layering and separating the organic phase 2 and the aqueous phase 1 to obtain a solution 3; and taking the organic phase in the solution 3 to be subjected to multistage extraction by the aqueous phase 1, so that the extracted organic phase is (R) 2-cyclohexyl mandelic acid and (S) 2-cyclohexyl mandelic acid. The method for separating 2-cyclohexyl mandelic acid enantiomers by multistage liquid-liquid extraction combines the chiral ionic liquid as an efficient chiral additive, realizes efficient separation of enantiomers, and the multistage liquid-liquid extraction system for separating 2-cyclohexyl mandelic acid enantiomers can be used for a racemate separation process on an industrial scale to obtain a single enantiomer.

Description

Technical Field

[0001] This invention relates to the field of chiral compound separation technology, specifically to a method for multi-stage liquid-liquid extraction to separate 2-cyclohexylmandelic acid enantiomers. Background Technology

[0002] Chiral science and technology are among the forefront and hot topics in contemporary chemical and chemical engineering research. The preparation of single enantiomers is a major fundamental problem urgently needing to be solved in the pharmaceutical and fine chemical industries. Due to the significant demand for pure chiral compounds in the pharmaceutical industry, a large amount of research has been dedicated to developing effective and practical methods. Currently, there are three main categories of methods for obtaining single enantiomeric chiral drugs: chiral source synthesis, asymmetric synthesis, and racemic resolution. Racemic resolution is highly valued due to its simplicity, ease of industrial production, and low cost. Commonly used racemic resolution methods include recrystallization, chromatography, membrane extraction, liquid-liquid extraction, and solid-liquid extraction.

[0003] Chiral liquid-liquid extraction (CLI) has advantages such as wide applicability, continuous operation, ease of industrial production, and relatively low production cost, and has received widespread attention as an ideal alternative technology, achieving many important advances. However, the large-scale industrial application of CLI still requires solving two major challenges: 1) The construction of efficient chiral extraction systems. Using relatively inexpensive extractants such as tartaric acid derivatives, cyclodextrin derivatives, cinchona alkaloid derivatives, and inexpensive chiral metal complexes faces the challenge of low separation factors. Further optimization of existing inexpensive extractants, development of novel efficient chiral extractants, and the adoption of a two-phase recognition extraction mode can lead to more efficient extraction systems; 2) The construction of continuous production processes. Enantiomers are extremely difficult to separate, and single-stage liquid-liquid extraction can only achieve partial enantiomer separation.

[0004] To improve the separation efficiency of enantiomers, this invention proposes a method for resolving 2-cyclohexylmandelic acid enantiomers based on multi-stage liquid-liquid extraction. Summary of the Invention

[0005] To address the insufficient separation efficiency of existing 2-cyclohexylmandelic acid enantiomers, which is difficult to implement on an industrial scale, this invention provides a multi-stage liquid-liquid extraction method for separating 2-cyclohexylmandelic acid enantiomers. This method utilizes a multi-stage liquid-liquid extraction separation approach combined with chiral ionic liquids as highly efficient chiral additives, achieving efficient enantiomer separation. The multi-stage liquid-liquid extraction system for separating 2-cyclohexylmandelic acid enantiomers is designed to be applicable to industrial-scale racemic separation processes to obtain single enantiomers.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] The purpose of this invention is to provide a method for multi-stage liquid-liquid extraction to separate 2-cyclohexylmandelic acid enantiomers, comprising the following steps:

[0008] A chiral ionic liquid was dissolved in a phosphate buffer solution to obtain an aqueous phase 1 containing a chiral extractant; 2-cyclohexylmandelic acid was dissolved in an organic solvent to obtain an organic phase 2; organic phase 2 and aqueous phase 1 were mixed, shaken, allowed to stand, and separated into layers to obtain solution 3;

[0009] The organic phase in solution 3 is mixed with aqueous phase 1, shaken, and allowed to stand to separate to obtain a secondary extract. The organic phase in the secondary extract is then mixed with aqueous phase 1 again, shaken, and allowed to stand to separate to obtain a tertiary extract. The organic phase in the tertiary extract yields the enantiomers of 2-cyclohexylmandelic acid, namely (R)2-cyclohexylmandelic acid and (S)2-cyclohexylmandelic acid.

[0010] Furthermore, the concentration of the chiral ionic liquid in the phosphate buffer solution is 10–35 mmol / L, and the pH of the phosphate buffer solution is 4.5–8.0.

[0011] Further, the chiral ionic liquid is 1-butyl-3-methylimidazolium-L-glutamate, 1-butyl-3-methylimidazolium-L-phenylalanine, 1-butyl-3-methylimidazolium-L-serine, tetraethylammonium-L-glutamate, or 1-butyl-2 or 3-dimethylimidazolium (trifluoromethanesulfonyl)imide.

[0012] Furthermore, the concentration of 2-cyclohexylmandelic acid in organic solvents is 1.0–4.0 mmol / L.

[0013] Furthermore, the organic solvent is n-octanol, chloroform, ethyl acetate, n-pentane, or cyclohexanone.

[0014] Furthermore, during the process of obtaining solution 3, organic phase 2 and aqueous phase 1 are mixed in equal volumes.

[0015] Furthermore, the temperature for each mixing of the mechanical phase and the aqueous phase is 25–45°C, the reaction time is 4 hours, and the mixture is allowed to stand for 1 hour to separate into layers.

[0016] Furthermore, in the secondary and tertiary extracts, the organic phase and aqueous phase 1 are mixed in equal volumes.

[0017] Furthermore, the enantiomeric excess percentage of 2-cyclohexylmandelic acid was 40.6%, and the separation factor was 3.77.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention adopts a multi-stage liquid-liquid extraction separation method, combined with chiral ionic liquid as a highly efficient chiral additive, to achieve efficient separation of enantiomers. The multi-stage liquid-liquid extraction system used to separate 2-cyclohexylmandelic acid enantiomers can be used in industrial-scale racemic separation processes to obtain single enantiomers.

[0020] (2) The present invention has a high separation factor, excellent enantiomeric excess, and good chiral extraction effect; it is low in cost, mild in conditions, simple in operation, and easy to realize industrial production; it has a wide range of applications, can be operated continuously, and has relatively low production cost; it does not involve solids and gases, and no by-products or toxic substances are generated.

[0021] (3) Sales of chiral drugs with a single enantiomer have reached US$800 billion, while the market share of chiral drugs in my country exceeds US$100 billion. Due to the low cost of raw materials and high added value of this product, its social and economic benefits are enormous. Attached Figure Description

[0022] Figure 1 Examples 11-16 of this invention illustrate the effects of different concentrations of chiral ionic liquids [Bmim][L-Phe] on partition coefficients and separation factors.

[0023] Figure 2 Examples 17-22 of this invention illustrate the effect of different concentrations of 2-cyclohexylmandelic acid enantiomers on partition coefficients and separation factors.

[0024] Figure 3 Examples 23-28 of this invention illustrate the effect of pH values ​​of different phosphate buffer solutions on partition coefficients and separation factors.

[0025] Figure 4 Examples 29-33 of this invention illustrate the effect of different temperatures on the partition coefficient and separation factor.

[0026] Figure 5 This is a multistage liquid-liquid chiral extraction chromatogram of the enantiomeric form of 2-cyclohexylmandelic acid in Example 34 of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0029] This invention provides a method for multi-stage liquid-liquid extraction to separate 2-cyclohexylmandelic acid enantiomers, comprising the following steps:

[0030] A chiral ionic liquid was dissolved in a phosphate buffer solution to obtain an aqueous phase 1 containing a chiral extractant; 2-cyclohexylmandelic acid was dissolved in an organic solvent to obtain an organic phase 2; organic phase 2 and aqueous phase 1 were mixed, shaken, allowed to stand, and separated into layers to obtain solution 3;

[0031] The organic phase in solution 3 is mixed with aqueous phase 1, shaken, and allowed to stand to separate to obtain a secondary extract. The organic phase in the secondary extract is then mixed with aqueous phase 1 again, shaken, and allowed to stand to separate to obtain a tertiary extract. The organic phase in the tertiary extract yields the enantiomers of 2-cyclohexylmandelic acid, namely (R)2-cyclohexylmandelic acid and (S)2-cyclohexylmandelic acid.

[0032] This invention employs a multi-stage liquid-liquid extraction separation method, combining chiral ionic liquids as highly efficient chiral additives to achieve efficient enantiomer separation. The process involves dissolving the chiral ionic liquid in phosphate buffer solutions of different pH values ​​to obtain an aqueous phase containing the chiral extractant; dissolving the 2-cyclohexylmandelic acid enantiomers in an organic solvent to obtain an organic phase containing the enantiomers; mixing equal volumes of the aqueous phase containing the chiral extractant and the organic phase containing the 2-cyclohexylmandelic acid enantiomers, shaking, allowing to stand, and separating the layers; the two enantiomers of 2-cyclohexylmandelic acid are enriched to varying degrees in the organic and aqueous phases based on their different recognition abilities and steric effects, resulting in a primary extraction solution; subsequently, the organic phase after standing and separating is subjected to multi-stage extraction, and the enantiomer content in the extracted organic phase is determined. This multi-stage liquid-liquid extraction system for separating 2-cyclohexylmandelic acid enantiomers utilizes a strategy applicable to industrial-scale racemic separation processes to obtain single enantiomers.

[0033] In some preferred embodiments, the concentration of the chiral ionic liquid in the phosphate buffer solution is 10–35 mmol / L, and the pH of the phosphate buffer solution is 4.5–8.0. The purpose of the chiral ionic liquid is to provide a microenvironment for chiral recognition and reaction, and the purpose of the phosphate buffer solution is to provide different pH values ​​for the extraction solution. The effect of increasing or decreasing the concentration of the chiral ionic liquid on the experiment is demonstrated in the examples. Increasing the concentration will improve the extraction efficiency, and reaching the optimal concentration will result in the best extraction effect. Further increasing the concentration will decrease the extraction efficiency. As a preferred technical solution of the present invention, the concentration of the chiral ionic liquid can be any specific value between 10 and 35 mmol / L, such as 10 mmol / L, 15 mmol / L, 20 mmol / L, 25 mmol / L, 30 mmol / L, or 35 mmol / L, etc.; the pH of the phosphate buffer solution can be any specific value between 4.5 and 8.0, such as 4.5, 5.0, 6.8, 7.0, 7.4, or 8.0, etc.

[0034] In some preferred embodiments, the chiral ionic liquid is 1-butyl-3-methylimidazolium-L-glutamate ([Bmim][L-Glu]), 1-butyl-3-methylimidazolium-L-phenylalanine ([Bmim][L-Phe]), 1-butyl-3-methylimidazolium-L-serine ([Bmim][L-Ser]), tetraethylammonium-L-glutamate, or 1-butyl-2 or 3-dimethylimidazolium (trifluoromethanesulfonyl)imide ([Bmim][Tf2N]).

[0035] In some preferred embodiments, the concentration of 2-cyclohexylmandelic acid in the organic solvent is 1.0–4.0 mmol / L. As a preferred technical solution of the present invention, the concentration of 2-cyclohexylmandelic acid can be any specific value between 1.0 and 4.0 mmol / L, such as 1.0 mmol / L, 1.5 mmol / L, 2.0 mmol / L, 2.5 mmol / L, 3.0 mmol / L, or 4.0 mmol / L. Increasing the concentration of 2-cyclohexylmandelic acid improves the extraction efficiency, reaching the optimal concentration for the best extraction effect; further increases in concentration decrease the extraction efficiency.

[0036] In some preferred embodiments, the organic solvent is n-octanol, chloroform, ethyl acetate, n-pentane, or cyclohexanone.

[0037] In some preferred embodiments, during the process of obtaining solution 3, the organic phase 2 and the aqueous phase are mixed in equal volumes. Equal volume mixing, as a preferred technical solution of the present invention, ensures consistent external conditions and guarantees equal adsorption of the two phases.

[0038] In some preferred embodiments, the temperature for each mixing of the organic and aqueous phases is 25–45°C, the reaction time is 4 hours, and the mixture is allowed to stand for 1 hour to separate into layers. As a preferred technical solution of the present invention, the mixing temperature can be any specific value between 25 and 45°C, such as 25°C, 30°C, 35°C, 40°C, or 45°C.

[0039] In some preferred embodiments, during the multi-stage extraction process, the organic phase and aqueous phase 1 are mixed in equal volumes.

[0040] In some preferred embodiments, the enantiomeric excess percentage of 2-cyclohexylmandelic acid is 40.6%, and the separation factor is 3.77.

[0041] Chiral liquid-liquid extraction (CLI) has advantages such as wide applicability, continuous operation, ease of industrial production, and relatively low production cost, and has received widespread attention as an ideal alternative technology, achieving many important advances. To improve enantiomer separation efficiency, this invention employs a multi-stage CLI method, combined with chiral ionic liquids as highly efficient chiral additives, to achieve efficient enantiomer separation. We have successfully developed a multi-stage CLI system for separating the enantiomers of 2-cyclohexylmandelic acid. The designed strategy can be used in industrial-scale racemic separation processes to obtain single enantiomers. This invention features a high separation factor, excellent enantiomer excess, and good chiral extraction effect; it is low-cost, operates under mild conditions, is simple to operate, and is easy to industrialize; it has a wide applicability, can be operated continuously, and has relatively low production costs; it does not involve solids or gases, and produces no byproducts or toxic substances.

[0042] The following description, in conjunction with specific embodiments, provides further details.

[0043] Example 1

[0044] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0045] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0046] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0047] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0048] Example 2

[0049] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0050] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0051] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of chloroform to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0052] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0053] Example 3

[0054] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0055] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0056] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of ethyl acetate to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0057] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0058] Example 4

[0059] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0060] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0061] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-pentane to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0062] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0063] Example 5

[0064] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0065] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0066] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of cyclohexanone to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0067] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25°C and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography (HPLC) to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In HPLC, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0068] Examples 1-5 illustrate the effects of different organic solvents on the partition coefficient and separation factor, as shown in Table 1. Table 1 shows that the dissolution of the 2-cyclohexylmandelic acid enantiomers in different solvents affects the selection of enantiomers by the chiral extractant. Furthermore, when octanol is used as the solvent, 1-butyl-3-methylimidazolium-L-phenylalanine salt exhibits the best extraction effect on the 2-cyclohexylmandelic acid enantiomers.

[0069] Table 1. Effects of different organic solvents on partition coefficient and separation factor

[0070]

[0071]

[0072] Example 6

[0073] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0074] S1. Dissolve 0.2541 g of 1-butyl-3-methylimidazolium-L-glutamate in 20 mL of phosphate buffer solution with a pH of 7.4 to obtain an aqueous phase with a concentration of 30 mmol / L.

[0075] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0076] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0077] Example 7

[0078] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0079] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with a pH of 7.4 to obtain an aqueous phase with a concentration of 30 mmol / L.

[0080] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0081] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0082] Example 8

[0083] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0084] S1. Dissolve 0.1459 g of 1-butyl-3-methylimidazolium-L-serine salt in 20 mL of phosphate buffer solution with a pH of 7.4 to obtain an aqueous phase with a concentration of 30 mmol / L.

[0085] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0086] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0087] Example 9

[0088] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0089] S1. Dissolve 0.2433 g of tetraethylammonium-L-glutamate in 20 mL of phosphate buffer solution with a pH of 7.4 to obtain an aqueous phase with a concentration of 30 mmol / L.

[0090] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0091] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0092] Example 10

[0093] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0094] S1, 0.2600 g of 1-butyl-2,3-dimethylimidazolium (trifluoromethylsulfonyl)imide was dissolved in 20 mL of phosphate buffer solution with a pH of 7.4 to obtain an aqueous phase with a concentration of 30 mmol / L;

[0095] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0096] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0097] Examples 5-10 illustrate the effects of different chiral extractants on the partition coefficient and separation factor, as shown in Table 2. Table 2 shows that different chiral ionic liquids exhibit varying selectivity for the enantiomeric form of 2-cyclohexylmandelic acid when used as chiral extractants, with 1-butyl-3-methylimidazolium-L-phenylalanine salt showing the best extraction effect.

[0098] Table 2. Effects of different chiral extractants on partition coefficient and separation factor.

[0099] Example 5 Octyl alcohol-phosphate buffer / [Bmim][L-Phe] 2.47 1.83 1.35 Example 6 Octyl alcohol-phosphate buffer / [Bmim][L-Glu] 1.45 1.64 1.09 Example 7 Octyl alcohol-phosphate buffer / [Bmin][L-Ser] 1.00 1.23 1.23 Example 8 Octyl alcohol-phosphate buffer / [TEA][L-Glu] 0.43 0.40 1.06 Example 9 Octyl alcohol-phosphate buffer / [Bmim][Tf2N] 0.82 0.85 0.96 Example 10 octanol-phosphate buffer 0.63 0.66 0.97

[0100] Example 11

[0101] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0102] S1. Dissolve 0.0607 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 10 mmol / L chiral extractant.

[0103] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0104] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0105] Example 12

[0106] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0107] S1. Dissolve 0.0910 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 15 mmol / L chiral extractant.

[0108] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0109] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0110] Example 13

[0111] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0112] S1. Dissolve 0.1213 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 20 mmol / L chiral extractant.

[0113] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0114] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0115] Example 14

[0116] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0117] S1. Dissolve 0.1517 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing a chiral extractant with a concentration of 25 mmol / L.

[0118] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0119] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0120] Example 15

[0121] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0122] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with a pH of 7.4 to obtain an aqueous phase containing a chiral extractant with a concentration of 30 mmol / L.

[0123] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0124] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0125] Example 16

[0126] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0127] S1. Dissolve 0.2123 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 35 mmol / L chiral extractant.

[0128] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0129] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0130] Examples 11-16 illustrate the effects of different concentrations of chiral ionic liquids on the partition coefficient and separation factor, as shown in Table 3. Table 3 shows that different concentrations of chiral ionic liquids affect the partition coefficient and separation factor after extraction. The optimal extraction effect is achieved when the concentration of the chiral ionic liquid 1-butyl-3-methylimidazolium-L-phenylalanine salt ([Bmim][L-Phe]) is 30 mmol / L.

[0131] Table 3. Effects of different concentrations of chiral ionic liquids on partition coefficient and separation factor.

[0132] Example 11 10 0.98 0.93 1.05 Example 12 15 1.05 0.93 1.12 Example 13 20 1.09 0.96 1.13 Example 14 25 1.13 0.99 1.14 Example 15 30 2.47 1.83 1.35 Example 16 35 1.36 1.11 1.22

[0133] Figure 1 Examples 11-16 of this invention illustrate the effect of different concentrations of chiral ionic liquid [Bmim][L-Phe] on the partition coefficient and separation factor. Different concentrations of the chiral ionic liquid affect the partition coefficient and separation factor after extraction; the extraction effect is optimal when the concentration of the chiral ionic liquid [Bmim][L-Phe] is 30 mmol / L.

[0134] Example 17

[0135] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0136] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0137] S2. Dissolve 0.0047 g of 2-cyclohexylmandelic acid enantiomers in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomers with a concentration of 1.0 mmol / L.

[0138] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0139] Example 18

[0140] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0141] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0142] S2. Dissolve 0.0070 g of 2-cyclohexylmandelic acid enantiomers in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomers with a concentration of 1.5 mmol / L.

[0143] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25°C and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography (HPLC) to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In HPLC, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0144] Example 19

[0145] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0146] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0147] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomers in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomers with a concentration of 2.0 mmol / L.

[0148] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0149] Example 20

[0150] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0151] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0152] S2. Dissolve 0.0117 g of 2-cyclohexylmandelic acid enantiomers in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomers with a concentration of 2.5 mmol / L.

[0153] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25°C and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography (HPLC) to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In HPLC, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0154] Example 21

[0155] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0156] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0157] S2. Dissolve 0.0139 g of 2-cyclohexylmandelic acid enantiomers in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomers with a concentration of 3.0 mmol / L.

[0158] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25°C and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography (HPLC) to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In HPLC, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0159] Example 22

[0160] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0161] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0162] S2. Dissolve 0.0187 g of 2-cyclohexylmandelic acid enantiomers in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomers with a concentration of 4.0 mmol / L.

[0163] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0164] Examples 17-22 illustrate the effects of different concentrations of 2-cyclohexylmandelic acid enantiomers on the partition coefficient and separation factor, as shown in Table 4. Table 4 shows that different concentrations of 2-cyclohexylmandelic acid enantiomers affect the partition coefficient and separation factor after extraction. The extraction effect is optimal when the concentration of 2-cyclohexylmandelic acid enantiomers is 2 mmol / L.

[0165] Table 4. Effects of different concentrations of 2-cyclohexylmandelic acid enantiomeric properties on partition coefficient and separation factor.

[0166] Example 17 1.0 1.85 1.82 1.02 Example 18 1.5 1.95 1.59 1.23 Example 19 2.0 2.47 1.83 1.35 Example 20 2.5 4.28 3.52 1.22 Example 21 3.0 3.03 2.62 1.16 Example 22 4.0 1.32 1.18 1.12

[0167] Figure 2 The effects of different concentrations of 2-cyclohexylmandelic acid enantiomeric fractions on partition coefficients and separation factors are illustrated in Examples 17-22 of this invention. Figure 2 As shown, different enantiomeric concentrations of 2-cyclohexylmandelic acid affect the partition coefficient and separation factor after extraction. The extraction effect is optimal when the enantiomeric concentration of 2-cyclohexylmandelic acid is 2 mmol / L.

[0168] Example 23

[0169] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0170] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 4.5 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0171] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0172] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0173] Example 24

[0174] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0175] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with a pH of 5.0 to obtain an aqueous phase containing a chiral extractant with a concentration of 30 mmol / L.

[0176] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0177] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0178] Example 25

[0179] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0180] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 6.8 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0181] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0182] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0183] Example 26

[0184] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0185] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with a pH of 7.0 to obtain an aqueous phase containing a chiral extractant with a concentration of 30 mmol / L.

[0186] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0187] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0188] Example 27

[0189] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0190] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0191] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0192] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0193] Example 28

[0194] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0195] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with a pH of 8.0 to obtain an aqueous phase containing a chiral extractant with a concentration of 30 mmol / L.

[0196] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0197] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25℃ and shake for 4 h, let stand for 1 h to separate the layers, and use high performance liquid chromatography to determine (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase. In the high performance liquid chromatography, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A Chiral NQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0198] Examples 23-28 illustrate the effects of different pH values ​​of phosphate buffer solutions on the partition coefficient and separation factor, as shown in Table 5. Table 5 shows that the pH of the solution affects the partition coefficient and separation factor of the extraction, with the optimal extraction effect observed at a pH of 7.4.

[0199] Table 5. Effects of pH on partition coefficient and separation factor of different phosphate buffer solutions.

[0200] Example 23 4.5 2.45 2.36 1.04 Example 24 5.0 2.00 1.89 1.06 Example 25 6.8 2.12 1.84 1.15 Example 26 7.0 2.52 2.04 1.24 Example 27 7.4 2.47 1.83 1.35 Example 28 8.0 1.81 1.57 1.18

[0201] Figure 3Examples 23-28 of this invention illustrate the effect of pH values ​​of different phosphate buffer solutions on the partition coefficient and separation factor. Figure 3 As shown, the pH of the solution affects the partition coefficient and separation factor of the extraction, and the extraction effect is optimal when the pH value is 7.4.

[0202] Example 29

[0203] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0204] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0205] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0206] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, and shake them separately in a constant temperature shaker at 25 °C for 4 h. Let them stand for 1 h to separate the layers. Use high performance liquid chromatography (HPLC) to determine the levorotatory 2-cyclohexylmandelic acid and dextrorotatory 2-cyclohexylmandelic acid in the organic phase. In HPLC, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A ChiralNQ(2)-RH column (3 μm, 2.1 × 100 mm), the flow rate is 0.25 mL / min, and the wavelength is 270 nm.

[0207] Example 30

[0208] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0209] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0210] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0211] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, shake them separately in a constant temperature shaker at 30 °C for 4 h, let them stand for 1 h to separate the layers, and use high performance liquid chromatography (HPLC) to determine the levorotatory 2-cyclohexylmandelic acid and dextrorotatory 2-cyclohexylmandelic acid in the organic phase. In HPLC, the mobile phase was 0.1% formic acid water-acetonitrile, the chromatographic column was A Chiral NQ(2)-RH column (3 μm, 2.1 × 100 mm), the flow rate was 0.25 mL / min, and the wavelength was 270 nm.

[0212] Example 31

[0213] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0214] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0215] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0216] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, shake them separately in a constant temperature shaker at 35℃ for 4 h, let them stand for 1 h to separate the layers, and use high performance liquid chromatography (HPLC) to determine the levorotatory 2-cyclohexylmandelic acid and dextrorotatory 2-cyclohexylmandelic acid in the organic phase. In HPLC, the mobile phase was 0.1% formic acid water-acetonitrile, the chromatographic column was A ChiralNQ(2)-RH column (3μm, 2.1×100mm), the flow rate was 0.25 mL / min, and the wavelength was 270 nm.

[0217] Example 32

[0218] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0219] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0220] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0221] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, and shake them separately in a constant temperature shaker at 40℃ for 4 h. Let them stand for 1 h to separate the layers. Use high performance liquid chromatography (HPLC) to determine the levorotatory 2-cyclohexylmandelic acid and dextrorotatory 2-cyclohexylmandelic acid in the organic phase. In HPLC, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A ChiralNQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25 mL / min, and the wavelength is 270 nm.

[0222] Example 33

[0223] A method for resolving enantiomers of 2-cyclohexylmandelic acid includes the following steps:

[0224] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0225] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0226] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, and shake them separately in a constant temperature shaker at 45℃ for 4 h. Let them stand for 1 h to separate the layers. Use high performance liquid chromatography (HPLC) to determine the levorotatory 2-cyclohexylmandelic acid and dextrorotatory 2-cyclohexylmandelic acid in the organic phase. In HPLC, the mobile phase is 0.1% formic acid water-acetonitrile, the chromatographic column is A ChiralNQ(2)-RH column (3μm, 2.1×100mm), the flow rate is 0.25mL / min, and the wavelength is 270nm.

[0227] Examples 29-33 illustrate the effects of different extraction temperatures on the partition coefficient and separation factor, as shown in Table 6. Table 6 shows that the extraction temperature affects both the partition coefficient and separation factor, with the optimal extraction effect observed at 25°C.

[0228] Table 6. Effects of different extraction temperatures on partition coefficient and separation factor.

[0229] Example 29 25 2.47 1.83 1.35 Example 30 30 1.96 1.60 1.23 Example 31 35 1.44 1.23 1.17 Example 32 40 1.28 1.13 1.13 Example 33 45 1.02 0.93 1.10

[0230] Figure 4 Examples 29-33 of this invention illustrate the effect of different temperatures on the partition coefficient and separation factor; for example... Figure 4 As mentioned above, the extraction temperature affects the distribution coefficient and separation factor of the extraction, and the extraction effect is best when the temperature is 25℃.

[0231] Example 34

[0232] A method for resolving 2-cyclohexylmandelic acid enantiomers by multi-stage liquid-liquid extraction includes the following steps:

[0233] S1. Dissolve 0.1820 g of 1-butyl-3-methylimidazolium-L-phenylalanine salt in 20 mL of phosphate buffer solution with pH 7.4 to obtain an aqueous phase containing 30 mmol / L chiral extractant.

[0234] S2. Dissolve 0.0092 g of 2-cyclohexylmandelic acid enantiomer in 20 mL of n-octanol to obtain an organic phase of 2-cyclohexylmandelic acid enantiomer with a concentration of 2.0 mmol / L.

[0235] S3. Mix 2 mL of the aqueous phase from S1 and 2 mL of the organic phase from S2, place them in a constant temperature shaker at 25°C and shake for 4 h, let stand for 1 h to separate the layers, and obtain a single-stage extraction solution.

[0236] S4. Mix 2 mL each of the organic phase from the S3 single-stage extraction solution and the aqueous phase from S1, and shake in a constant temperature shaker at 25℃ for 4 hours. Let stand for 1 hour to separate the layers, obtaining a secondary extract. Mix 2 mL each of the organic phase from the secondary extract and the aqueous phase from S1, and shake in a constant temperature shaker at 25℃ for 4 hours. Let stand for 1 hour to separate the layers, obtaining a tertiary extract. Use high performance liquid chromatography (HPLC) to determine the (S)2-cyclohexylmandelic acid and (R)2-cyclohexylmandelic acid in the organic phase of the tertiary extract.

[0237] Figure 5 This is a multi-stage liquid-liquid chiral extraction chromatogram of the enantiomeric form of 2-cyclohexylmandelic acid from Example 34 of the present invention; as shown... Figure 5 As shown, multi-stage extraction can improve extraction efficiency, enabling enantioselectivity to reach a maximum of 40.6%.

[0238] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0239] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for multi-stage liquid-liquid extraction to separate 2-cyclohexylmandelic acid enantiomers, characterized in that, Includes the following steps: A chiral ionic liquid was dissolved in a phosphate buffer solution to obtain an aqueous phase 1 containing a chiral extractant; 2-cyclohexylmandelic acid was dissolved in an organic solvent to obtain an organic phase 2; organic phase 2 and aqueous phase 1 were mixed, shaken, allowed to stand, and separated into layers to obtain solution 3; The organic phase in solution 3 was mixed with aqueous phase 1, shaken, and allowed to stand to separate, yielding a secondary extract. The organic phase in the secondary extract was then mixed with aqueous phase 1 again, shaken, and allowed to stand to separate, yielding a tertiary extract. The organic phase in the tertiary extract yielded the enantiomer of 2-cyclohexylmandelic acid, which is (…). R 2-Cyclohexylmandelic acid and ( S 2-Cyclohexylmandelic acid; The chiral ionic liquid is 1-butyl-3-methylimidazolium- L -Phenylalanine salt; The organic solvent is n-octanol; The concentration of the chiral ionic liquid in the phosphate buffer solution is 35 mmol / L, and the pH of the phosphate buffer solution is 7.

4. The concentration of 2-cyclohexylmandelic acid in organic solvents is 2.0 mmol / L; The organic phase and aqueous phase are mixed at a temperature of 25°C each time.

2. The method for multi-stage liquid-liquid extraction resolution of 2-cyclohexylmandelic acid enantiomers according to claim 1, characterized in that, In the process of obtaining solution 3, organic phase 2 and aqueous phase 1 are mixed in equal volumes.

3. The method for multi-stage liquid-liquid extraction resolution of 2-cyclohexylmandelic acid enantiomers according to claim 1, characterized in that, The reaction time for each mixing of the organic phase and the aqueous phase is 4 hours, followed by 1 hour of standing and separation.

4. The method for multi-stage liquid-liquid extraction resolution of 2-cyclohexylmandelic acid enantiomers according to claim 1, characterized in that, In the secondary and tertiary extracts, the organic phase and aqueous phase 1 are mixed in equal volumes.

5. The method for multi-stage liquid-liquid extraction resolution of 2-cyclohexylmandelic acid enantiomers according to claim 1, characterized in that, The enantiomeric excess percentage of 2-cyclohexylmandelic acid was 40.6%, and the separation factor was 3.77.

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