Preparation method of D-panthenol

Abstract

The invention relates to a preparation method of D-panthenol. The preparation method comprises the following steps: (1) carrying out mixed reaction on DL-pantoic acid lactone and D-pantoic acid lactone hydrolase, extracting, and separating a water phase to obtain D-pantoic acid; (2) mixing the D-pantoic acid with a compound enzyme auxiliary agent for reaction to obtain D-pantoic acid lactone; (3) mixing the D-pantoic acid lactone with beta aminopropanol for reaction to obtain D-panthenol crude product slurry; (4) purifying the D-panthenol crude product slurry to obtain D-panthenol; the compound enzyme auxiliary agent comprises esterase, carbonyl reductase, alcohol dehydrogenase and alcohol nitrile enzyme. According to the method disclosed by the invention, the esterase, the carbonyl reductase, the alcohol dehydrogenase and the alcohol nitrile enzyme act synergistically to catalyze an esterification reaction in D-pantoic acid molecules and promote the D-pantoic acid molecules to form a lactone structure, so that side reactions are reduced, the efficiency of the esterification reaction of the D-pantoic acid is improved, and finally, the yield and the purity of the D-panthenol are improved.

Description

Technical Field

[0001] The invention belongs to the field of chemical and pharmaceutical production, and in particular relates to a method for preparing D-panthenol. Background Art

[0002] D-Panthenol, also known as provitamin B5, has a variety of skin care benefits, including strong barrier, deep moisturizing, efficient soothing, etc. It can penetrate deep into the skin to provide nourishment and protection for the skin. It has the effects of strong moisturizing, promoting repair, anti-inflammatory soothing, and antioxidant protection. It is a penetrating moisturizer and skin protectant.

[0003] D-panthenol can not only generate hydrogen bonds with water molecules to maintain the normal moisture content of the stratum corneum, but also be converted into pantothenic acid through contact with the human body, and then synthesize coenzyme A, promote human metabolism, protect the mucous membranes on the surface of the skin and the luster of hair, prevent the occurrence of hair loss, and achieve long-lasting moisturizing while also having the effect of preventing hair loss and promoting hair growth. Therefore, D-panthenol, as a moisturizer and repair agent, is particularly suitable for the pharmaceutical and cosmetic industries, such as oral liquids, eye drops, compound VB injections, shampoos, mousses, moisturizers, etc.

[0004] CN101851171A discloses a method for preparing D-panthenol, which directly uses D-pantolactone and 3-aminopropanol to react in one pot to prepare D-panthenol. Since there are a lot of solids in the reaction system and the viscosity of the product D-panthenol is very high, the method has the problems of long reaction time and incomplete conversion. At the same time, the product is not further purified after the solvent-free process reaction, which puts forward extremely high requirements on the reaction conversion rate and the quality of the raw materials, and the reaction cost is high but the purity is low.

[0005] Therefore, developing a method for preparing D-panthenol with high yield and high purity has become a technical problem that needs to be solved urgently. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for preparing D-panthenol.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing D-panthenol, characterized in that the preparation method comprises the following steps:

[0009] (1) mixing DL-pantoic acid lactone and D-pantoic acid lactone hydrolase for reaction, extracting, and separating the aqueous phase to obtain D-pantoic acid;

[0010] (2) mixing D-pantoic acid with a composite enzyme auxiliary agent to react to obtain D-pantoic acid lactone;

[0011] (3) mixing D-pantolactone and β-aminopropanol to react to obtain a crude D-pantothenol slurry;

[0012] (4) purifying the crude D-panthenol slurry to obtain D-panthenol;

[0013] The composite enzyme auxiliary comprises esterase, carbonyl reductase, alcohol dehydrogenase and alcohol nitrile enzyme.

[0014] In the present invention, D-pantoic acid lactone hydrolase specifically decomposes D-pantoic acid lactone in DL-pantoic acid lactone to generate D-pantoic acid, D-pantoic acid undergoes esterification reaction under the action of composite enzyme auxiliary agent to obtain D-pantoic acid lactone, and D-pantoic acid lactone reacts with β-aminopropanol to generate D-panthenol. Among them, esterase, carbonyl reductase, alcohol dehydrogenase and alcohol nitrilase act synergistically to catalyze the esterification reaction in D-pantoic acid molecule, promote it to form lactone structure, reduce the occurrence of side reactions, improve the efficiency of D-pantoic acid esterification reaction, and finally improve the yield and purity of D-panthenol.

[0015] Preferably, the composite enzyme auxiliary agent comprises, by weight, 1 part of esterase, 2-5 parts of carbonyl reductase, 0.5-2 parts of alcohol dehydrogenase and 1-3 parts of alcohol nitrile enzyme.

[0016] Among them, the specific point values ​​in 2 to 5 parts can be selected from 2 parts, 3 parts, 4 parts, 5 parts, etc., the specific point values ​​in 0.5 to 2 parts can be selected from 0.5 parts, 1 parts, 1.5 parts, 2 parts, etc., and the specific point values ​​in 1 to 3 parts can be selected from 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, etc.

[0017] The specific weight proportions of esterase, carbonyl reductase, alcohol dehydrogenase and alcohol nitrile enzyme in the composite enzyme auxiliary agent can further optimize the synergistic relationship of esterase, carbonyl reductase, alcohol dehydrogenase and alcohol nitrile enzyme, and further improve the yield and purity of D-panthenol.

[0018] Preferably, the mass ratio of D-pantoic acid to the complex enzyme auxiliary agent in step (2) is 1:(0.05-0.1). The specific point value in 0.05-0.1 can be selected from 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc.

[0019] Preferably, the mixing in step (2) also includes mixing with CaCl2, corn starch and hydroquinone.

[0020] During the esterification reaction of D-pantoic acid, the addition of CaCl2 can solve the inactivation and aggregation problems of the composite enzyme additives and maintain the reaction activity of the enzyme. At the same time, the combination of corn starch and hydroquinone can further improve the stability of the esterification reaction of D-pantoic acid through synergistic effect.

[0021] Preferably, the reaction temperature in step (2) is 40-60° C., and the reaction time is 4-20 h.

[0022] Among them, the specific point values ​​in 40-60°C can be selected from 40°C, 45°C, 50°C, 55°C, 60°C, etc., and the specific point values ​​in 4-20h can be selected from 4h, 8h, 12h, 16h, 20h, etc.

[0023] Preferably, the purification in step (4) comprises the following steps:

[0024] (I) filtering the crude D-panthenol slurry, and purifying the filtrate obtained by ion exchange resin;

[0025] (II) subjecting the crude D-panthenol purified by ion exchange resin to activated carbon adsorption treatment;

[0026] (III) ultrafiltration of the mixed liquid after the activated carbon adsorption treatment;

[0027] (IV) subjecting the filtrate after ultrafiltration to secondary treatment with activated carbon;

[0028] (V) cooling the mixed solution after the secondary treatment with activated carbon and crystallizing it to obtain D-panthenol.

[0029] In the present invention, the crude D-panthenol slurry is first purified by ion exchange resin to remove hydroquinone, and then ultrafiltration is performed, so as to better improve the purity of the prepared D-panthenol.

[0030] Furthermore, after ion exchange resin purification and ultrafiltration, an activated carbon adsorption treatment is performed respectively to further remove impurities in the solution, thereby obtaining a D-panthenol product with higher purity.

[0031] Preferably, the ion exchange resin in step (I) comprises a sulfonic acid group-modified styrene divinyl benzene copolymer.

[0032] Preferably, the eluent used in the ion exchange resin purification is water.

[0033] Preferably, the particle size of the activated carbon in step (II) is 4 to 6 mm.

[0034] Among them, the specific point values ​​in the range of 4 to 6 mm may be selected as 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, etc.

[0035] Preferably, the time for the activated carbon adsorption treatment in step (II) is 30 to 50 minutes.

[0036] Among them, the specific point values ​​in 30 to 50 minutes can be selected as 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, etc.

[0037] Preferably, the ultrafiltration membrane molecular weight cutoff in step (III) is 8000 to 12000 Da.

[0038] Among them, the specific point values ​​in 8000-12000Da can be selected from 8000Da, 9000Da, 10000Da, 11000Da, 12000Da, etc.

[0039] Preferably, the particle size of the activated carbon in step (IV) is 1 to 3 mm.

[0040] Among them, the specific point values ​​in 1 to 3 mm can be selected from 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc.

[0041] Preferably, the time for the secondary treatment of activated carbon in step (IV) is 20 to 40 minutes.

[0042] Among them, the specific point values ​​in 20 to 40 minutes can be selected as 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.

[0043] Preferably, the temperature of the cooling crystallization in step (V) is 5 to 15° C., and the number of cooling crystallization is 3 to 6 times.

[0044] Among them, the specific point values ​​in 5-15°C can be selected from 5°C, 7°C, 9°C, 11°C, 13°C, 15°C, etc.; the specific point values ​​in 3-6 times can be selected from 3 times, 4 times, 5 times, 6 times, etc.

[0045] In the present invention, the number of cooling crystallization is controlled within 3 to 6 times, which not only ensures the production efficiency but also improves the product yield.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention uses D-pantoic acid lactone hydrolase to specifically split D-pantoic acid lactone in DL-pantoic acid lactone to generate D-pantoic acid, and D-pantoic acid undergoes esterification reaction under the action of a composite enzyme auxiliary agent to obtain D-pantoic acid lactone, and D-pantoic acid lactone reacts with β-aminopropanol to generate D-panthenol. In the preparation method of D-panthenol provided by the present invention, esterase, carbonyl reductase, alcohol dehydrogenase and alcohol nitrile enzyme work synergistically to catalyze the esterification reaction within the D-pantoic acid molecule, promote it to form a lactone structure, reduce the occurrence of side reactions, improve the efficiency of the D-pantoic acid esterification reaction, and ultimately improve the yield and purity of D-panthenol.

[0048] Furthermore, by controlling the content of esterase 1 part, carbonyl reductase 2-5 parts, alcohol dehydrogenase 0.5-2 parts, and alcohol nitrilase 1-3 parts in the composite enzyme auxiliary, the synergistic effect of each enzyme preparation can be further optimized, and the final yield and purity of D-panthenol can be improved. At the same time, during the esterification reaction of D-pantoic acid, corn starch and hydroquinone are compounded, and the synergistic effect of the two can improve the stability of the esterification reaction, and ultimately affect the purity and yield of D-panthenol.

[0049] Furthermore, in the process of purifying the crude D-panthenol slurry, the crude D-panthenol slurry is first purified by ion exchange resin to remove hydroquinone, and then ultrafiltration is performed, which can better improve the purity of the prepared D-panthenol. In addition, after ion exchange resin purification and ultrafiltration, activated carbon adsorption treatment is performed once respectively, which can further remove impurities in the solution, thereby obtaining a D-panthenol product with higher purity. DETAILED DESCRIPTION

[0050] In order to further explain the technical means and effects adopted by the present invention, the technical solution of the present invention is further described below in conjunction with the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments.

[0051] The sources of the raw materials in the following examples are shown in Table 1:

[0052] Table 1

[0053] raw material factory Brand D-pantolactone hydrolase Wuhan Shuou Technology D-pantolactone hydrolase Esterase Hunan Jushuo Esterase Carbonyl reductase Enri Libai Carbonyl reductase Alcohol dehydrogenase Shaanxi Aibonyi Alcohol dehydrogenase Alcohol nitrilase Shangke Biotechnology ES-HNL-101

[0054] Example 1

[0055] This embodiment provides a method for preparing D-panthenol, comprising the following steps:

[0056] (1) 100 g of DL-pantoic acid lactone and 1 g of D-pantoic acid lactone hydrolase were mixed in water, reacted at 50° C. for 10 h, and the obtained hydrolyzate was extracted and separated using dichloromethane (the volume ratio of dichloromethane to the hydrolyzate was 1:10), and the aqueous phase was collected to obtain D-pantoic acid.

[0057] (2) The D-pantoic acid obtained in step (1) (containing 50 g of D-pantoic acid), 3.5 g of a composite enzyme auxiliary (1 part of esterase, 3 parts of carbonyl reductase, 1 part of alcohol dehydrogenase, 2 parts of alcohol nitrile enzyme), 5 g of corn starch, 2 g of hydroquinone and 50 g of a 20% by mass CaCl2 aqueous solution were mixed, stirred, and reacted at 50°C for 10 h to obtain D-pantoic acid lactone.

[0058] (3) mixing the D-pantolactone obtained in step (2), 20 g of β-aminopropanol and 50 g of anhydrous methanol, stirring, reacting at 50° C. for 18 h, and concentrating under reduced pressure until the anhydrous methanol is evaporated, discharging the material to obtain a crude D-pantolactone slurry;

[0059] (4) Filter the crude D-panthenol slurry, and purify the filtrate with a cation exchange resin, wherein the cation exchange resin is a styrene divinylbenzene copolymer modified with a sulfonic acid group, and the eluent used for purification is water. 10 g of activated carbon with a particle size of 5 mm is added to the mixed solution obtained after the ion exchange resin purification, and the activated carbon is removed by filtration after adsorption for 40 minutes.

[0060] (5) The filtrate obtained after filtering and removing the activated carbon in step (4) was ultrafiltered using an ultrafiltration membrane with a membrane cutoff molecular weight of 10,000 Da, and 10 g of activated carbon with a particle size of 2 mm was added to the filtrate after ultrafiltration. After adsorption for 30 minutes, the activated carbon was filtered out.

[0061] (6) The filtrate obtained after the secondary treatment with activated carbon in step (5) was evaporated and concentrated to 50%, and the mixture was cooled and crystallized at 10° C. The cooling and crystallization operation was repeated 5 times to obtain D-panthenol.

[0062] Example 2

[0063] This embodiment provides a method for preparing D-panthenol, comprising the following steps:

[0064] (1) 100 g of DL-pantoic acid lactone and 1.2 g of D-pantoic acid lactone hydrolase were mixed in water, reacted at 55° C. for 15 h, and the obtained hydrolyzate was extracted and separated using 1,2-dichloromethane (the volume ratio of 1,2-dichloromethane to the hydrolyzate was 1:10), and the aqueous phase was collected to obtain D-pantoic acid.

[0065] (2) The D-pantoic acid obtained in step (1) (containing 50 g of D-pantoic acid), 5 g of a composite enzyme auxiliary (1 part of esterase, 2 parts of carbonyl reductase, 2 parts of alcohol dehydrogenase, 1 part of alcohol nitrile enzyme), 4.5 g of corn starch, 2.5 g of hydroquinone and 50 g of a 20% by mass CaCl2 aqueous solution were mixed, stirred, and reacted at 45°C for 15 h to obtain D-pantoic acid lactone.

[0066] (3) mixing the D-pantolactone obtained in step (2), 15 g of β-aminopropanol and 40 g of anhydrous methanol, stirring, reacting at 50° C. for 15 h, concentrating under reduced pressure until the anhydrous methanol is evaporated, and discharging to obtain a crude D-pantolactone slurry;

[0067] (4) The crude D-panthenol slurry was filtered, and the filtrate was purified by cation exchange resin, wherein the cation exchange resin was sulfonic acid group-modified styrene divinylbenzene copolymer, and the eluent used for purification was water. 10 g of activated carbon with a particle size of 5.5 mm was added to the mixed solution obtained after the ion exchange resin purification, and the activated carbon was removed by filtration after adsorption for 35 minutes.

[0068] (5) The filtrate obtained after filtering and removing the activated carbon in step (4) was ultrafiltered using an ultrafiltration membrane with a membrane cutoff molecular weight of 12000Da, and 10g of activated carbon with a particle size of 3mm was added to the filtrate after ultrafiltration. After adsorption for 20min, the activated carbon was filtered out.

[0069] (6) The filtrate obtained after the secondary treatment with activated carbon in step (5) was evaporated and concentrated to 50%, and the mixture was cooled and crystallized at 7° C. The cooling and crystallization operation was repeated 6 times to obtain D-panthenol.

[0070] Example 3

[0071] This embodiment provides a method for preparing D-panthenol, comprising the following steps:

[0072] (1) 100 g of DL-pantoic acid lactone and 0.8 g of D-pantoic acid lactone hydrolase were mixed in water and reacted at 45° C. for 12 h. The obtained hydrolyzate was extracted and separated using ethyl acetate (the volume ratio of ethyl acetate to the hydrolyzate was 1:10), and the aqueous phase was collected to obtain D-pantoic acid.

[0073] (2) The D-pantoic acid obtained in step (1) (containing 50 g of D-pantoic acid), 2.5 g of a composite enzyme auxiliary (1 part of esterase, 5 parts of carbonyl reductase, 0.5 parts of alcohol dehydrogenase, 3 parts of alcohol nitrile enzyme), 5.5 g of corn starch, 1.5 g of hydroquinone and 50 g of a 20% by mass CaCl2 aqueous solution were mixed, stirred, and reacted at 65°C for 8 h to obtain D-pantoic acid lactone.

[0074] (3) mixing the D-pantoic acid lactone obtained in step (2), 25 g of β-aminopropanol and 55 g of anhydrous methanol, stirring, reacting at 50° C. for 20 h, concentrating under reduced pressure until the anhydrous methanol is evaporated, and discharging to obtain a crude D-pantothenol slurry;

[0075] (4) The crude D-panthenol slurry is filtered, and the filtrate is purified by a cation exchange resin, wherein the cation exchange resin is a styrene divinylbenzene copolymer modified with a sulfonic acid group, and the eluent used for purification is water. 10 g of activated carbon with a particle size of 4.5 mm is added to the mixed solution obtained after the ion exchange resin purification, and the activated carbon is removed by filtration after adsorption for 50 minutes.

[0076] (5) The filtrate obtained after filtering and removing the activated carbon in step (4) was ultrafiltered using an ultrafiltration membrane with a membrane cutoff molecular weight of 8000Da, and 10g of activated carbon with a particle size of 1.5mm was added to the filtrate after ultrafiltration. After adsorption for 35min, the activated carbon was filtered out.

[0077] (6) The filtrate obtained after the secondary treatment with activated carbon in step (5) was evaporated and concentrated to 50%, and the mixture was cooled and crystallized at 12° C. The cooling and crystallization operation was repeated three times to obtain D-panthenol.

[0078] Example 4

[0079] This embodiment provides a method for preparing D-panthenol, which differs from Embodiment 1 only in that 3.5 g of composite enzyme auxiliary (1 part esterase, 3 parts carbonyl reductase, 1 part alcohol dehydrogenase, 2 parts alcohol nitrile enzyme) in step (1) is replaced with 3.5 g of composite enzyme auxiliary (1 part esterase, 1 part carbonyl reductase, 3 parts alcohol dehydrogenase, 4 parts alcohol nitrile enzyme).

[0080] Example 5

[0081] This embodiment provides a method for preparing D-panthenol, which differs from Embodiment 1 only in that 3.5 g of composite enzyme auxiliary (1 part esterase, 3 parts carbonyl reductase, 1 part alcohol dehydrogenase, 2 parts alcohol nitrile enzyme) in step (1) is replaced with 3.5 g of composite enzyme auxiliary (1 part esterase, 6 parts carbonyl reductase, 0.2 parts alcohol dehydrogenase, 0.8 parts alcohol nitrile enzyme).

[0082] Example 6

[0083] This embodiment provides a method for preparing D-panthenol, which differs from Embodiment 1 only in that 5 g corn starch and 2 g hydroquinone in step (2) are replaced with 7 g corn starch.

[0084] Example 7

[0085] This embodiment provides a method for preparing D-panthenol, which differs from Embodiment 1 only in that 5 g corn starch and 2 g hydroquinone in step (2) are replaced with 7 g hydroquinone.

[0086] Example 8

[0087] This embodiment provides a method for preparing D-panthenol, which differs from Embodiment 1 only in that the processing sequence of ion exchange resin purification and ultrafiltration treatment is changed, namely:

[0088] After obtaining the crude D-panthenol slurry in step (3), the crude D-panthenol slurry is filtered, and the filtered crude D-panthenol slurry is ultrafiltered using an ultrafiltration membrane with a membrane molecular weight cutoff of 10000 Da, and 10 g of activated carbon with a particle size of 5 mm is added to the filtrate after ultrafiltration, and the activated carbon is removed by filtration after adsorption for 40 minutes;

[0089] The filtrate obtained after filtering and removing the activated carbon was purified by ion exchange resin, and 10 g of activated carbon with a particle size of 2 mm was added to the mixed solution obtained after the ion exchange resin purification, and the activated carbon was removed by filtering after adsorption for 30 minutes;

[0090] The filtrate obtained after the secondary treatment of the activated carbon is treated in the manner of step (6) in Example 1 to obtain D-panthenol.

[0091] Example 9

[0092] This embodiment provides a method for preparing D-panthenol, which differs from Embodiment 1 only in that the activated carbon treatment in step (4) is removed, that is, the mixed solution obtained after the ion exchange resin purification in step (4) is directly subjected to the ultrafiltration treatment in step (5).

[0093] Example 10

[0094] This embodiment provides a method for preparing D-panthenol, which differs from Embodiment 1 only in that the activated carbon treatment in step (5) is removed, that is, the filtrate obtained after the ultrafiltration treatment in step (5) is directly subjected to the evaporation concentration treatment in step (6).

[0095] Comparative Example 1

[0096] This comparative example provides a method for preparing D-panthenol, which differs from Example 1 only in that 3.5 g of the composite enzyme auxiliary (1 part of esterase, 3 parts of carbonyl reductase, 1 part of alcohol dehydrogenase, and 2 parts of alcohol nitrilase) in step (1) is replaced with 3.5 g of the composite enzyme auxiliary (3 parts of carbonyl reductase, 1 part of alcohol dehydrogenase, and 2 parts of alcohol nitrilase).

[0097] Comparative Example 2

[0098] This comparative example provides a method for preparing D-panthenol, which differs from Example 1 only in that 3.5 g of the composite enzyme auxiliary (1 part of esterase, 3 parts of carbonyl reductase, 1 part of alcohol dehydrogenase, and 2 parts of alcohol nitrilase) in step (1) is replaced with 3.5 g of the composite enzyme auxiliary (1 part of esterase, 1 part of alcohol dehydrogenase, and 2 parts of alcohol nitrilase).

[0099] Comparative Example 3

[0100] This comparative example provides a method for preparing D-panthenol, which differs from Example 1 only in that 3.5 g of the composite enzyme auxiliary (1 part esterase, 3 parts carbonyl reductase, 1 part alcohol dehydrogenase, 2 parts alcohol nitrile enzyme) in step (1) is replaced by 3.5 g of the composite enzyme auxiliary (1 part esterase, 3 parts carbonyl reductase, 2 parts alcohol nitrile enzyme).

[0101] Comparative Example 4

[0102] This comparative example provides a method for preparing D-panthenol, which differs from Example 1 only in that 3.5 g of the composite enzyme auxiliary (1 part of esterase, 3 parts of carbonyl reductase, 1 part of alcohol dehydrogenase, 2 parts of alcohol nitrile enzyme) in step (1) is replaced by 3.5 g of the composite enzyme auxiliary (1 part of esterase, 3 parts of carbonyl reductase, 1 part of alcohol dehydrogenase).

[0103] Test Example 1

[0104] Purity and yield testing

[0105] The D-panthenol prepared in the examples and comparative examples was analyzed by high performance liquid chromatography, and the mass of D-panthenol in the sample was obtained based on the peak area and the standard curve of D-panthenol with known concentration, and the yield and the purity of the prepared D-panthenol were calculated respectively:

[0106] The calculation formula of the yield is: Y = the mass of D-panthenol in the sample / the theoretical mass of D-panthenol × 100%, wherein the theoretical mass of D-panthenol is 50g / 148×205=69.26g;

[0107] The purity of the prepared D-panthenol is calculated as follows: P = mass of D-panthenol in the sample / total mass of the sample×100%.

[0108] The yields of the methods of various examples and comparative examples and the purity of the prepared D-panthenol are shown in Table 2.

[0109] Test Example 2

[0110] Optical purity test

[0111] The specific rotation of the D-panthenol samples prepared in the examples and comparative examples was tested using a polarimeter, and the optical purity of the D-panthenol samples was calculated based on the specific rotation of the D-panthenol samples and pure D-panthenol:

[0112] The calculation formula of optical purity is: E = specific rotation of prepared D-panthenol / specific rotation of pure D-panthenol×100%.

[0113] The results of the optical purity of D-panthenol prepared in various examples and comparative examples are shown in Table 2.

[0114] Test Example 3

[0115] Product color test

[0116] 5 g of D-panthenol prepared in each example and comparative example was dissolved in 25 ml of water and placed in a colorimetric tube. The color was observed visually under natural light. The results are shown in Table 2.

[0117] Table 2

[0118] sample Yield purity Optical purity color Example 1 95.3％ 97.7％ 99.95％ Colorless and transparent Example 2 94.1％ 96.5％ 99.7％ Colorless and transparent Example 3 93.5％ 95.9％ 99.1％ Colorless and transparent Example 4 92.5％ 94.1％ 97.9％ Colorless and transparent Example 5 92.2％ 94.6％ 97％ Colorless and transparent Example 6 91.5％ 93.9％ 96.3％ Colorless and transparent Example 7 91.3％ 93.3％ 95.8％ Colorless and transparent Example 8 91.1％ 92.8％ 94.3％ Colorless and transparent Example 9 90.5％ 92.5％ 93.6％ Light yellow Example 10 90.1％ 91.9％ 93.1％ Light yellow Comparative Example 1 73.3％ 69％ 90％ Light yellow Comparative Example 2 72.9％ 64.3％ 82％ Light yellow Comparative Example 3 72.1％ 64.5％ 80％ Light yellow Comparative Example 4 71.2％ 68.6％ 77％ Light yellow

[0119] It can be seen from the test data in Table 2 that the yield of D-panthenol in the preparation method of D-panthenol of the present invention is as high as 95.3%, the purity of the prepared product D-panthenol is as high as 97.7%, and the optical purity is as high as 99.95%.

[0120] From the comparison between Example 1 and Comparative Examples 1 to 4, it can be seen that when any one of esterase, carbonyl reductase, alcohol dehydrogenase or alcohol nitrile enzyme is removed from the composite enzyme auxiliary agent, the esterification reaction degree of D-pantoic acid will be affected, and ultimately the yield and purity of D-panthenol will be greatly reduced.

[0121] From the comparison between Example 1 and Examples 4-5, it can be seen that in the preparation method of the present invention, by controlling 1 part of esterase, 2-5 parts of carbonyl reductase, 0.5-2 parts of alcohol dehydrogenase, and 1-3 parts of alcohol nitrilase in the composite enzyme auxiliary agent, the synergistic relationship of each enzyme preparation can be further optimized, and the final yield and purity of D-panthenol can be improved. From the comparison between Example 1 and Examples 6-7, it can be seen that during the esterification reaction of D-pantoic acid, corn starch and hydroquinone are compounded, and the synergistic effect of the two can improve the stability of the esterification reaction, and ultimately affect the purity and yield of D-panthenol.

[0122] From the comparison between Example 1 and Examples 8 to 10, it can be seen that in the purification process of D-panthenol, the crude D-panthenol slurry is first purified by ion exchange resin and then ultrafiltration, which can better improve the purity of the prepared D-panthenol; in addition, after ion exchange resin purification and ultrafiltration, activated carbon adsorption treatment is performed once respectively, which can further remove impurities in the solution, and ultimately affect the optical purity and color state of the product D-panthenol.

[0123] The applicant declares that the present invention illustrates the technical solution of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0124] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0125] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for preparing D-panthenol, characterized in that: The preparation method comprises the following steps: (1) mixing DL-pantoic acid lactone and D-pantoic acid lactone hydrolase for reaction, extracting, and separating the aqueous phase to obtain D-pantoic acid; (2) mixing D-pantoic acid with a composite enzyme auxiliary agent to react to obtain D-pantoic acid lactone; (3) mixing D-pantolactone and β-aminopropanol to react to obtain a crude D-pantothenol slurry; (4) purifying the crude D-panthenol slurry to obtain D-panthenol; The composite enzyme auxiliary comprises esterase, carbonyl reductase, alcohol dehydrogenase and alcohol nitrile enzyme.

2. The method for preparing D-panthenol according to claim 1, characterized in that: In terms of weight, the composite enzyme auxiliary agent comprises 1 part of esterase, 2-5 parts of carbonyl reductase, 0.5-2 parts of alcohol dehydrogenase and 1-3 parts of alcohol nitrile enzyme.

3. The method for preparing D-panthenol according to claim 1 or 2, characterized in that: The mass ratio of D-pantoic acid to the complex enzyme auxiliary agent in step (2) is 1:(0.05-0.1).

4. The method for preparing D-panthenol according to any one of claims 1 to 3, characterized in that: The mixing in step (2) also includes mixing with CaCl2, corn starch and hydroquinone.

5. The method for preparing D-panthenol according to any one of claims 1 to 4, characterized in that: The reaction temperature in step (2) is 40 to 60° C., and the reaction time is 4 to 20 hours.

6. The method for preparing D-panthenol according to any one of claims 1 to 5, characterized in that: The purification in step (4) comprises the following steps: (I) filtering the crude D-panthenol slurry, and purifying the filtrate obtained by ion exchange resin; (II) subjecting the crude D-panthenol purified by ion exchange resin to activated carbon adsorption treatment; (III) ultrafiltration of the mixed liquid after the activated carbon adsorption treatment; (IV) subjecting the filtrate after ultrafiltration to secondary treatment with activated carbon; (V) cooling the mixed solution after the secondary treatment with activated carbon and crystallizing it to obtain D-panthenol.

7. The method for preparing D-panthenol according to claim 6, characterized in that: The ion exchange resin in step (I) comprises a sulfonic acid group-modified styrene divinyl benzene copolymer; Preferably, the eluent used in the ion exchange resin purification is water; Preferably, the particle size of the activated carbon in step (II) is 4 to 6 mm; Preferably, the time for the activated carbon adsorption treatment in step (II) is 30 to 50 minutes.

8. The method for preparing D-panthenol according to claim 6 or 7, characterized in that: The ultrafiltration membrane cut-off molecular weight in step (III) is 8000 to 12000 Da.

9. The method for preparing D-panthenol according to any one of claims 6 to 8, characterized in that: The particle size of the activated carbon in step (IV) is 1 to 3 mm; Preferably, the time for the secondary treatment of activated carbon in step (IV) is 20 to 40 minutes.

10. The method for preparing D-panthenol according to any one of claims 5 to 9, characterized in that: The temperature of the cooling crystallization in step (V) is 5 to 15° C., and the number of cooling crystallization is 3 to 6 times.