阅读说明：本技术 一种维生素c棕榈酸酯的制备方法 (Preparation method of vitamin C palmitate ) 是由 伏传久 王珂 乔树兵 陈斌 朱东来 于 2020-11-27 设计创作，主要内容包括：本发明提供了一种维生素C棕榈酸酯的制备方法。所述制备方法包括如下步骤：将维生素C、棕榈酸、脂肪酶和分子筛与有机溶剂混合,在保护气氛下,先在第一温度下进行酯化反应,然后在第二温度下进行酯化反应,生成维生素C棕榈酸酯；所述第一温度和第二温度的范围为40-65℃,且所述第一温度低于所述第二温度。与现有的生物法合成维生素C棕榈酸酯相比,本发明提供的方法采用两段法进行酯化反应,既减少了维生素C的破坏,又保证了酯化反应充分进行,从而提高了维生素C棕榈酸酯的摩尔收率。(The invention provides a preparation method of vitamin C palmitate. The preparation method comprises the following steps: mixing vitamin C, palmitic acid, lipase, a molecular sieve and an organic solvent, performing esterification reaction at a first temperature under a protective atmosphere, and performing esterification reaction at a second temperature to generate vitamin C palmitate; the first temperature and the second temperature range from 40 ℃ to 65 ℃, and the first temperature is lower than the second temperature. Compared with the prior method for synthesizing the vitamin C palmitate by a biological method, the method provided by the invention adopts a two-stage method for esterification reaction, so that the damage of the vitamin C is reduced, the full esterification reaction is ensured, and the molar yield of the vitamin C palmitate is improved.)

1. The preparation method of the vitamin C palmitate is characterized by comprising the following steps:

mixing vitamin C, palmitic acid, lipase, a molecular sieve and an organic solvent, performing esterification reaction at a first temperature under a protective atmosphere, and performing esterification reaction at a second temperature to generate vitamin C palmitate;

the first temperature and the second temperature range from 40 ℃ to 65 ℃, and the first temperature is lower than the second temperature.

2. The preparation method according to claim 1, wherein the molar ratio of the vitamin C to the palmitic acid is 1: 6-8;

and/or the mass volume ratio of the vitamin C to the organic solvent is 0.02-0.1 g/mL.

3. The process according to claim 1 or 2, wherein the lipase is selected from one or a combination of two of Rhizopus lipase, Aspergillus lipase, Mucor lipase, Candida lipase and pancreatic lipase, preferably Aspergillus lipase and/or Mucor lipase;

and/or, the lipase is immobilized lipase;

and/or the mass ratio of the lipase to the vitamin C is 1: 1-10;

and/or the mass volume ratio of the lipase to the organic solvent is 10-15 g/L.

4. The method according to any one of claims 1 to 3, wherein the mass-to-volume ratio of the molecular sieve to the organic solvent is 10 to 50 g/L.

5. The production method according to any one of claims 1 to 4, wherein the organic solvent is selected from one or a combination of at least two of isopropyl alcohol, n-butanol, n-pentanol, t-butanol, and 2-methyl-2-octanol, preferably 2-methyl-2-octanol.

6. The method according to any one of claims 1 to 5, wherein the gas in the protective atmosphere is nitrogen.

7. The method according to any one of claims 1 to 6, wherein the first temperature is 40 to 45 ℃;

and/or the reaction time at the first temperature is 30-70 h.

8. The method of any one of claims 1 to 7, wherein the second temperature is 60 to 65 ℃;

and/or the reaction time at the second temperature is 30-120 h;

and/or the total time of the esterification reaction is 100-150 h.

9. The production method according to any one of claims 1 to 8, characterized in that the production method further comprises a purification operation;

preferably, the purification method comprises the following steps: filtering the reaction solution after the reaction is finished, removing lipase and molecular sieve, drying the filtrate to remove the solvent, and obtaining a first mixture containing vitamin C palmitate, palmitic acid and vitamin C;

extracting palmitic acid in the first mixture by using n-hexane, and carrying out solid-liquid separation to obtain a second mixture containing vitamin C and vitamin C palmitate;

extracting vitamin C in the second mixture by pure water, carrying out solid-liquid separation, and drying a filter cake to obtain the vitamin C palmitate.

10. The production method according to any one of claims 1 to 9, characterized by comprising the steps of:

adding vitamin C, palmitic acid, lipase and a molecular sieve into 2-methyl-2-octanol, wherein the mass-volume ratio of the vitamin C to an organic solvent is 0.02-0.1 g/mL, the mass ratio of the lipase to the vitamin C is 1: 1-10, the molar ratio of the vitamin C to the palmitic acid is 1: 6-8, the addition amount of the lipase is 10-15 g/L, and the addition amount of the molecular sieve is 10-50 g/L;

under the protection of nitrogen, firstly reacting for 30-70h at 40-45 ℃, then reacting for 30-120h at 60-65 ℃, and controlling the total reaction time to be 100-150h to generate the vitamin C palmitate;

filtering the reaction solution after the reaction is finished, removing lipase and molecular sieve, and removing the solvent from the filtrate through vacuum drying to obtain a first mixture containing vitamin C palmitate, palmitic acid and vitamin C;

extracting palmitic acid in the first mixture by using n-hexane, performing centrifugal separation, and repeating the extraction and the centrifugal separation for 3-4 times to obtain a second mixture containing vitamin C and vitamin C palmitate;

and extracting vitamin C in the second mixture by using pure water, then washing for 2-3 times by adding water, carrying out centrifugal separation, and drying a filter cake to obtain the vitamin C palmitate.

Technical Field

The invention belongs to the technical field of biochemical engineering, and particularly relates to a preparation method of vitamin C palmitate.

Background

The vitamin C palmitate (chemical name of palmitoyl-O-6-L-ascorbic acid ester) belongs to vitamin C fatty acid esters, and the structural formula of the vitamin C palmitate is as follows:

the molecular formula is as follows: c₂₂H₃₈O₇Molecular weight: 414.54.

the vitamin C palmitate not only keeps the anti-oxidation property of the vitamin C, but also has considerable solubility in animal oil and vegetable oil, and is widely applied to the fields of food, cosmetics, medicine, health and the like.

The synthesis of fat-soluble vitamin C is a difficult and complex problem in the synthesis industry. At present, the synthesis methods of vitamin C palmitate are mainly chemical synthesis methods and enzyme catalysis synthesis methods.

The chemical synthesis method of the vitamin C palmitate mainly comprises a sulfuric acid method, a hydrofluoric acid method and the like. Wherein, the sulfuric acid method takes vitamin C and palmitic acid as raw materials, and sulfuric acid as a catalyst and a solvent to synthesize the vitamin C palmitate. The chemical method has complex process, produces more byproduct impurities, has certain technical difficulty in the aspect of extraction, separation and purification technology, and increases the environmental protection treatment pressure. The catalytic specificity of the biological enzyme is utilized to reduce the byproducts and improve the product quality, which is a hot technique in recent years. The method for researching and developing the vitamin C palmitate by direct biological enzyme reaction reduces the reagents and procedures required by purification, and realizes the requirements of simple separation and purification solvent, low toxicity, recoverability, low separation and purification cost and high product purity, which are the main problems to be solved by the products.

CN 102127571A discloses a production method for synthesizing L-ascorbyl palmitate by non-aqueous phase enzymatic synthesis, which takes L-ascorbic acid and palmitic acid as raw materials and immobilized lipase as a catalyst to react for 20-50h at 50 ℃ for one-step synthesis of L-ascorbyl palmitate. CN111607625A discloses a method for producing ascorbyl palmitate by an enzyme method, which takes L-ascorbic acid and methyl palmitate as raw materials and immobilized lipase as a catalyst to react for 1h at 50 ℃ to synthesize L-ascorbyl palmitate by one step.

However, the existing biological method for synthesizing vitamin C palmitate adopts a one-step method for esterification reaction, so that the damage of vitamin C is inevitable, the yield of vitamin C palmitate is easily low, and the improvement is needed.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a preparation method of vitamin C palmitate. Compared with the prior art, the preparation method provided by the invention adopts a two-stage method for esterification reaction, so that the molar yield of the vitamin C palmitate is improved.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a preparation method of vitamin C palmitate, which comprises the following steps:

mixing vitamin C, palmitic acid, lipase, a molecular sieve and an organic solvent, performing esterification reaction at a first temperature under a protective atmosphere, and performing esterification reaction at a second temperature to generate vitamin C palmitate;

the first temperature and the second temperature are in the range of 40-65 ℃ (for example, 40 ℃, 42 ℃, 45 ℃, 48 ℃, 50 ℃, 52 ℃, 55 ℃, 58 ℃, 60 ℃, 62 ℃ or 65 ℃ and the like can be adopted), and the first temperature is lower than the second temperature.

Compared with the prior art of synthesizing the vitamin C palmitate by a biological method, the method adopts a two-stage method for esterification reaction, adopts lower temperature in the early stage, can avoid the damage of the vitamin C, can further promote the esterification reaction by increasing the esterification reaction temperature in the later stage, is beneficial to reducing the oxidative damage of the vitamin C by performing the whole esterification reaction under the protective atmosphere, and thus improves the molar yield of the vitamin C palmitate.

In one embodiment of the invention, the molar ratio of the vitamin C to the palmitic acid is 1: 6-8; for example, 1:6, 1:6.2, 1:6.5, 1:6.8, 1:7, 1:7.2, 1:7.5, 1:7.8, or 1:8, etc. may be used.

In one embodiment of the present invention, the mass-to-volume ratio of the vitamin C to the organic solvent is 0.02 to 0.1 g/mL; for example, it may be 0.02g/mL, 0.03g/mL, 0.04g/mL, 0.05g/mL, 0.06g/mL, 0.07g/mL, 0.08g/mL, 0.09g/mL, or 0.1g/mL, etc.

If the addition amount of the vitamin C in the reaction liquid is too much, the vitamin C is not completely dissolved, so that the yield is reduced; if the amount of vitamin C added to the reaction mixture is too small, the reaction raw materials are insufficient, and the yield is also lowered.

In one embodiment of the present invention, the lipase is selected from one or a combination of two of rhizopus lipase, aspergillus lipase, mucor lipase, candida lipase and pancrelipase, preferably aspergillus lipase and/or mucor lipase.

In one embodiment of the present invention, the lipase is an immobilized lipase.

In the immobilized lipase, the lipase is immobilized on a carrier by a physical or chemical method. The immobilized lipase is adopted, on one hand, the efficiency of enzyme catalytic reaction is improved, on the other hand, most of lipase is convenient to recover, and the recovered lipase still has certain activity after being used for several times, so that part of cost can be saved.

In one embodiment of the present invention, the mass ratio of the lipase to the vitamin C is 1:1 to 10; for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10, etc. If the addition amount of the lipase is too large, the cost is increased; too little lipase addition will result in incomplete esterification.

In one embodiment of the present invention, the mass-to-volume ratio of the lipase to the organic solvent is 10 to 15 g/L; for example, it may be 10g/L, 10.5g/L, 11g/L, 11.5g/L, 12g/L, 12.5g/L, 13g/L, 13.5g/L, 14g/L, 14.5g/L, or 15 g/L.

In one embodiment of the invention, the mass-to-volume ratio of the molecular sieve to the organic solvent is 10 to 50 g/L; for example, 10g/L, 12g/L, 15g/L, 18g/L, 20g/L, 25g/L, 30g/L, 35g/L, 40g/L, 45g/L, or 50g/L, etc. may be mentioned.

In the present invention, the molecular sieve mainly functions to remove water produced by the reaction and promote the forward progress of the esterification reaction, and the amount thereof to be added is preferably kept within the above range. If the addition amount of the molecular sieve is too much, the molecular sieve can absorb the bound water of the lipase, reduce the catalytic activity of the lipase and cause the yield of the vitamin C palmitate to be reduced; if the amount of the molecular sieve added is too small, the amount of water increases, and the excessive amount of water also changes the active structure of the enzyme to reduce the activity of the enzyme.

In an embodiment of the present invention, the organic solvent is selected from one or a combination of at least two of isopropyl alcohol, n-butanol, n-pentanol, t-butanol, and 2-methyl-2-octanol. Preferably 2-methyl-2-octanol

In one embodiment of the present invention, the gas in the protective atmosphere is nitrogen.

In one embodiment of the invention, the first temperature is 40-45 ℃; for example, the temperature may be 40 ℃, 40.5 ℃, 41 ℃, 41.5 ℃, 42 ℃, 42.5 ℃, 43 ℃, 43.5 ℃, 44 ℃, 44.5 ℃ or 45 ℃.

In one embodiment of the invention, the reaction time at the first temperature is 30 to 70 hours; for example, 30h, 32h, 35h, 38h, 40h, 42h, 45h, 48h, 50h, 52h, 55h, 58h, 60h, 62h, 65h, 68h, 70h, or the like may be used.

In one embodiment of the invention, the second temperature is 60-65 ℃; for example, the temperature may be 60 ℃, 60.5 ℃, 61 ℃, 61.5 ℃, 62 ℃, 62.5 ℃, 63 ℃, 63.5 ℃, 64 ℃, 64.5 ℃ or 65 ℃.

In one embodiment of the invention, the reaction time at the second temperature is 30 to 120 h; for example, 30h, 35h, 40h, 45h, 50h, 55h, 60h, 65h, 70h, 80h, 90h, 100h, 110h, 120h, or the like may be used.

In one embodiment of the present invention, the total time of the esterification reaction is 100-150 h; for example, the number of the channels may be 100h, 105h, 110h, 115h, 120h, 125h, 130h, 135h, 140h, 145h, 150h, or the like.

In the present invention, by controlling the temperature and time of the two-stage esterification reaction within the above ranges, it is possible to further reduce the destruction of vitamin C and promote the esterification reaction to proceed sufficiently, thereby further improving the yield of vitamin C palmitate.

In one embodiment of the present invention, the preparation method further comprises a purification operation.

Preferably, the purification method comprises the following steps: filtering the reaction solution after the reaction is finished, removing lipase and molecular sieve, drying the filtrate to remove the solvent, and obtaining a first mixture containing vitamin C palmitate, palmitic acid and vitamin C;

extracting palmitic acid in the first mixture by using n-hexane, and carrying out solid-liquid separation to obtain a second mixture containing vitamin C and vitamin C palmitate;

extracting vitamin C in the second mixture by pure water, carrying out solid-liquid separation, and drying a filter cake to obtain the vitamin C palmitate.

The direct washing for removing the vitamin C can avoid the use of organic solvents, reduce the post-treatment steps and can be well separated from the vitamin C palmitate.

In the purification step, the lipase and the molecular sieve obtained by filtering can be reused after being washed and dried. The filtrate obtained after the first mixture is extracted by the normal hexane can be concentrated and dried to respectively recover the normal hexane and the palmitic acid, and the vitamin C aqueous solution can be concentrated, cooled and crystallized to be recovered.

In one embodiment of the present invention, the preparation method comprises the steps of:

adding vitamin C, palmitic acid, lipase and a molecular sieve into 2-methyl-2-octanol, wherein the mass-volume ratio of the vitamin C to an organic solvent is 0.02-0.1 g/mL, the mass ratio of the lipase to the vitamin C is 1: 1-10, the molar ratio of the vitamin C to the palmitic acid is 1: 6-8, the addition amount of the lipase is 10-15 g/L, and the addition amount of the molecular sieve is 10-50 g/L;

under the protection of nitrogen, firstly reacting for 30-70h at 40-45 ℃, then reacting for 30-120h at 60-65 ℃, and controlling the total reaction time to be 100-150h to generate the vitamin C palmitate;

filtering the reaction solution after the reaction is finished, removing lipase and molecular sieve, and removing the solvent from the filtrate through vacuum drying to obtain a first mixture containing vitamin C palmitate, palmitic acid and vitamin C;

extracting palmitic acid in the first mixture by using n-hexane, performing centrifugal separation, and repeating the extraction and the centrifugal separation for 3-4 times to obtain a second mixture containing vitamin C and vitamin C palmitate;

and extracting vitamin C in the second mixture by using pure water, then washing for 2-3 times by adding water, carrying out centrifugal separation, and drying a filter cake to obtain the vitamin C palmitate.

Compared with the prior art, the invention has the following beneficial effects:

compared with the prior art of synthesizing the vitamin C palmitate by a biological method, the method adopts a two-stage method for esterification reaction, adopts lower temperature in the early stage, can avoid the damage of the vitamin C, can further promote the esterification reaction by increasing the esterification reaction temperature in the later stage, is beneficial to reducing the oxidative damage of the vitamin C by performing the whole esterification reaction under the protective atmosphere, thereby improving the yield of the vitamin C palmitate, and the molar yield of the vitamin C palmitate reaches 83-87%.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the specific embodiments are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

In the embodiment of the invention, part of raw materials are as follows:

immobilized lipase: the manufacturer: dong Henghua Dai Biotechnology, Inc., type: aspergillus lipase and Mucor lipase;

molecular sieve: the manufacturer: anhui Tianpu gram environmental protection adsorption material, model: 4A spherical 4 x 8 mesh.

Example 1

The embodiment provides a preparation method of vitamin C palmitate, which comprises the following steps:

adding vitamin C (17.6g, 0.1mol), palmitic acid (153.6g, 0.6mol), Aspergillus immobilized lipase (3.52g, calculated as lipase) and molecular sieve (15.8g) to 2-methyl-2-octanol (352 mL);

reacting for 50h at 40 ℃ under the protection of nitrogen, then reacting for 50h at 65 ℃, and carrying out enzyme catalysis to synthesize the vitamin C palmitate;

after the reaction is finished, the reaction solution is filtered by a filter membrane with the aperture of 0.15mm, the immobilized lipase and the molecular sieve are removed, and the immobilized lipase and the molecular sieve are reused after being washed and dried; vacuum drying the filtrate to remove the solvent 2-methyl-2-octanol to obtain a first mixture comprising vitamin C palmitate, palmitic acid and vitamin C;

extracting palmitic acid in the first mixture by using 30mL of n-hexane at normal temperature, performing centrifugal separation, repeating the extraction and the centrifugal separation for 4 times to obtain a second mixture containing vitamin C and vitamin C palmitate, and concentrating and drying extraction solvents of the n-hexane and a solute of the palmitic acid for respective recovery and reuse;

extracting vitamin C in the second mixture with 50mL of pure water, washing with 25mL of water for 2 times, centrifuging, drying the filter cake to obtain vitamin C palmitate, wherein the purity is 98.7% by liquid chromatography, and the molar yield (calculated by vitamin C) of the vitamin C palmitate is 86.1%.

Example 2

The embodiment provides a preparation method of vitamin C palmitate, which comprises the following steps:

adding vitamin C (17.6g, 0.1mol), palmitic acid (179.2g, 0.7mol), Mucor immobilized lipase (4.41g, calculated as lipase) and molecular sieve (10.1g) to isopropanol (440 mL);

under the protection of nitrogen, firstly reacting for 30h at 45 ℃, then reacting for 70h at 60 ℃, and synthesizing the vitamin C palmitate under enzyme catalysis;

after the reaction is finished, the reaction solution is filtered by a filter membrane with the aperture of 0.15mm, the immobilized lipase and the molecular sieve are removed, and the immobilized lipase and the molecular sieve are reused after being washed and dried; vacuum drying the filtrate to remove the solvent isopropanol to obtain a first mixture comprising vitamin C palmitate, palmitic acid and vitamin C;

extracting palmitic acid in the first mixture by using 25mL of n-hexane at normal temperature, performing centrifugal separation, repeating the extraction and the centrifugal separation for 4 times to obtain a second mixture containing vitamin C and vitamin C palmitate, and concentrating and drying extraction solvents of the n-hexane and a solute of the palmitic acid for respective recovery and reuse;

extracting vitamin C in the second mixture by using 50mL of pure water, then washing the mixture for 2 times by using 25mL of water, carrying out centrifugal separation, drying a filter cake to obtain vitamin C palmitate, wherein the purity of the vitamin C palmitate is 99.1% by liquid chromatography detection, and the molar yield (calculated by vitamin C) of the vitamin C palmitate is 84.9%.

Example 3

The embodiment provides a preparation method of vitamin C palmitate, which comprises the following steps:

adding vitamin C (17.6g, 0.1mol), palmitic acid (204.8g, 0.8mol), Aspergillus lipase and Mucor lipase mixed immobilized lipase (mass ratio is 1:1, total mass is 5.28g calculated by lipase) and molecular sieve (10.5g) into tert-butyl alcohol (352 mL);

under the protection of nitrogen, firstly reacting for 70h at 42 ℃, then reacting for 80h at 63 ℃, and synthesizing the vitamin C palmitate under enzyme catalysis;

after the reaction is finished, the reaction solution is filtered by a filter membrane with the aperture of 0.15mm, the immobilized lipase and the molecular sieve are removed, and the immobilized lipase and the molecular sieve are reused after being washed and dried; vacuum drying the filtrate to remove the solvent tert-butanol to obtain a first mixture comprising vitamin C palmitate, palmitic acid and vitamin C;

extracting palmitic acid in the first mixture by using 35mL of n-hexane at normal temperature, performing centrifugal separation, repeating the extraction and the centrifugal separation for 4 times to obtain a second mixture containing vitamin C and vitamin C palmitate, and concentrating and drying extraction solvents of the n-hexane and a solute of the palmitic acid for respective recovery and reuse;

extracting vitamin C in the second mixture with 50mL of pure water, washing with 25mL of water for 2 times, centrifuging, drying the filter cake to obtain vitamin C palmitate, wherein the purity is 98.5% by liquid chromatography, and the molar yield (calculated by vitamin C) of the vitamin C palmitate is 84.5%.

Example 4

The embodiment provides a preparation method of vitamin C palmitate, which comprises the following steps:

adding vitamin C (17.6g, 0.1mol), palmitic acid (153.6g, 0.6mol), Aspergillus immobilized lipase (1.76g, calculated as lipase) and molecular sieve (3.52g) to 2-methyl-2-octanol (176 mL);

reacting for 50h at 40 ℃ under the protection of nitrogen, then reacting for 50h at 65 ℃, and carrying out enzyme catalysis to synthesize the vitamin C palmitate;

after the reaction is finished, the reaction solution is filtered by a filter membrane with the aperture of 0.15mm, the immobilized lipase and the molecular sieve are removed, and the immobilized lipase and the molecular sieve are reused after being washed and dried; vacuum drying the filtrate to remove the solvent 2-methyl-2-octanol to obtain a first mixture comprising vitamin C palmitate, palmitic acid and vitamin C;

extracting palmitic acid in the first mixture by using 30mL of n-hexane at normal temperature, performing centrifugal separation, repeating the extraction and the centrifugal separation for 4 times to obtain a second mixture containing vitamin C and vitamin C palmitate, and concentrating and drying extraction solvents of the n-hexane and a solute of the palmitic acid for respective recovery and reuse;

extracting vitamin C in the second mixture with 50mL of pure water, washing with 25mL of water for 2 times, centrifuging, drying the filter cake to obtain vitamin C palmitate, wherein the purity is 98.5% by liquid chromatography, and the molar yield (calculated by vitamin C) of the vitamin C palmitate is 85.1%.

Example 5

The embodiment provides a preparation method of vitamin C palmitate, which comprises the following steps:

adding vitamin C (17.6g, 0.1mol), palmitic acid (153.6g, 0.6mol), Aspergillus immobilized lipase (13.2g, calculated as lipase) and molecular sieve (8.8g) to 2-methyl-2-octanol (880 mL);

reacting for 50h at 40 ℃ under the protection of nitrogen, then reacting for 50h at 65 ℃, and carrying out enzyme catalysis to synthesize the vitamin C palmitate;

after the reaction is finished, the reaction solution is filtered by a filter membrane with the aperture of 0.15mm, the immobilized lipase and the molecular sieve are removed, and the immobilized lipase and the molecular sieve are reused after being washed and dried; vacuum drying the filtrate to remove the solvent 2-methyl-2-octanol to obtain a first mixture comprising vitamin C palmitate, palmitic acid and vitamin C;

extracting palmitic acid in the first mixture by using 30mL of n-hexane at normal temperature, performing centrifugal separation, repeating the extraction and the centrifugal separation for 4 times to obtain a second mixture containing vitamin C and vitamin C palmitate, and concentrating and drying extraction solvents of the n-hexane and a solute of the palmitic acid for respective recovery and reuse;

extracting vitamin C in the second mixture with 50mL of pure water, washing with 25mL of water for 2 times, centrifuging, drying the filter cake to obtain vitamin C palmitate, wherein the purity is 98.3% by liquid chromatography, and the molar yield (calculated by vitamin C) of the vitamin C palmitate is 85.1%.

Example 6

This example provides a method for preparing vitamin C palmitate, which is different from example 1 in that the esterification reaction conditions are as follows: the reaction was carried out at 50 ℃ for 50h and then at 55 ℃ for 50 h. The purity of the obtained vitamin C palmitate product is 99.1 percent and the molar yield of the vitamin C palmitate product (calculated by vitamin C) is 83.2 percent through liquid chromatography detection.

Example 7

This example provides a method for preparing vitamin C palmitate, which is different from example 1 in that the esterification reaction conditions are as follows: the reaction was carried out at 40 ℃ for 20h and then at 65 ℃ for 80 h. The purity of the obtained vitamin C palmitate product is 98.6 percent and the molar yield of the vitamin C palmitate product (calculated by vitamin C) is 83.5 percent through liquid chromatography detection.

Example 8

This example provides a method for preparing vitamin C palmitate, which is different from example 1 in that the esterification reaction conditions are as follows: the reaction was carried out at 40 ℃ for 80h and then at 65 ℃ for 20 h. The purity of the obtained vitamin C palmitate product is 99.3 percent and the molar yield of the vitamin C palmitate product (calculated by vitamin C) is 84.1 percent through liquid chromatography detection.

Comparative example 1

Provided is a method for preparing vitamin C palmitate, which is different from the method in example 1 in that the esterification reaction conditions are as follows: the reaction was carried out at 65 ℃ for 100 h. The purity of the obtained vitamin C palmitate product is 97.2 percent and the molar yield of the vitamin C palmitate product (calculated by vitamin C) is 81.1 percent through liquid chromatography detection.

Comparative example 2

Provided is a method for preparing vitamin C palmitate, which is different from the method in example 1 in that the esterification reaction conditions are as follows: the reaction was carried out at 40 ℃ for 100 h. The purity of the obtained vitamin C palmitate product is 99.6 percent and the molar yield of the vitamin C palmitate product (calculated by vitamin C) is 81.6 percent through liquid chromatography detection.

As can be seen from the above example 1 and comparative examples 1-2, the invention adopts the two-stage method to carry out the esterification reaction, thereby not only reducing the damage of the vitamin C, but also ensuring the full progress of the esterification reaction, and simultaneously, the whole reaction process is carried out under the protective atmosphere, reducing the oxidative damage of the vitamin C, and further obviously improving the molar yield of the vitamin C palmitate.

Wherein, compared with the example 1, the temperature of the first step esterification reaction is higher, and the temperature of the second step esterification reaction is lower in the example 6; the first esterification reaction time in example 7 was short, and the second esterification reaction time was long; the first esterification reaction time of example 8 was longer, and the second esterification reaction time was shorter; therefore, the molar yield of the vitamin C palmitate is reduced.

Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.