A kind of preparation method of fumaric acid monoester

Abstract

The present invention belongs to the field of biochemical engineering technology, and specifically relates to a method for preparing fumaric acid monoester. Compared with the prior art, in step S1 of the present invention, immobilized lipase is used as a catalyst for transesterification reaction, and maleic acid monoester is synthesized by enzymatic method, which greatly improves the yield of maleic acid monoester, an intermediate product for preparing fumaric acid monoester; on this basis, in step S2 of the present invention, aluminum chloride is also used as a catalyst for isomerization reaction, catalyzing the isomerization of the intermediate product maleic acid monoester, and synthesizing fumaric acid monoester by chemical method. This preparation method is simple and easy to implement; the preparation conditions are mild and environmentally friendly; and the preparation cost is low, the yield is high, and there are no by-products, so no complicated purification process is required.

Description

Technical Field

[0001] The invention belongs to the technical field of biochemical engineering, and particularly relates to a method for preparing fumaric acid monoester. Background Art

[0002] With the improvement of people's living standards and the rapid development of the food industry, food safety issues have attracted widespread attention from the whole society. So far, preservatives in food additives have always been one of the functional ingredients necessary for the development of the industry, which can effectively protect the quality of food, extend its shelf life, and effectively control the growth and decay of microorganisms in food. However, with the long-term use of traditional preservatives, some related safety hazards have begun to emerge frequently.

[0003] At present, the most commonly used traditional preservatives in China are benzoic acid and sorbic acid. Although benzoic acid can play a good preservative role, it has certain toxicity. Excessive intake of benzoic acid can cause harm to the human body and even cause poisoning symptoms. As for sorbic acid, it is expensive and does not have a strong antibacterial effect on some microorganisms. Therefore, research and development of a new type of safe, non-toxic, cheap and easy-to-prepare food preservative has become an important direction for the development of the industry.

[0004] Among the many new preservatives studied, fumarate derivatives have attracted much attention. The α, β-unsaturated carbonyl structure in fumarate derivatives is the functional group for the preservative to exert its antibacterial effect, and fumarate is an antibacterial preservative containing this functional group. In practice, it has been found that dimethyl fumarate has achieved good results in preventing mold in feed, but it is slightly toxic. Fumaric acid monoester compounds have the advantages of dimethyl fumarate, are less toxic, and have less irritation to the skin and mucous membranes, and are expected to become new preservatives.

[0005] There are two traditional methods for producing fumaric acid monoesters: one is to esterify fumaric acid with alcohol under the action of a catalyst to generate fumaric acid monoesters in one step. The disadvantage of this process is that fumaric acid monoesters are easily isomerized to generate fumaric acid diesters, so it is difficult to separate fumaric acid diesters and fumaric acid monoesters in the product, and the subsequent purification process is cumbersome and complicated, and the purity of the fumaric acid monoester product is not high. The second production process uses maleic anhydride as the starting material and acid as a catalyst to react with alcohol to generate maleic acid monoesters; then fumaric acid monoesters are generated under the action of an isomerization catalyst. Although this method does not require separation of products, the yield of fumaric acid monoesters is low. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing fumaric acid monoester with a higher yield, which specifically comprises the following technical scheme:

[0007] A method for preparing fumaric acid monoester comprises the following steps:

[0008] S1, using maleic anhydride and alcohol as reaction substrates and immobilized lipase as catalyst to catalyze transesterification of the reaction substrates in an organic solvent to obtain a reaction solution, and filtering and distilling the reaction solution to obtain maleic acid monoester;

[0009] S2, using aluminum chloride as a catalyst to catalyze the isomerization of the maleic acid monoester obtained in step S1 to obtain fumaric acid monoester.

[0010] Compared with the prior art, in step S1 of the present invention, immobilized lipase is used as a catalyst for the transesterification reaction, and maleic acid monoester is synthesized by enzymatic method, which greatly improves the yield of maleic acid monoester, an intermediate product, in the preparation of fumaric acid monoester; on this basis, in step S2 of the present invention, aluminum chloride is also used as a catalyst for the isomerization reaction to catalyze the isomerization of the intermediate product maleic acid monoester, and synthesize fumaric acid monoester by chemical method. This preparation method is simple and easy to implement; the preparation conditions are mild and environmentally friendly; and the preparation cost is low, the yield is high, and there are no by-products, so no complicated purification process is required.

[0011] Preferably, the alcohol in step S1 includes one of methanol, ethanol and butanol.

[0012] Preferably, the immobilized lipase comprises one of lipase Novozyme 435, lipase CALA, lipase RML or lipase TLL.

[0013] As further preferred, the immobilized lipase is lipase Novozyme435.

[0014] Preferably, the organic solvent in step S1 includes one of tert-butyl alcohol, n-hexane, cyclohexane, toluene or petroleum ether.

[0015] As further preferred, the organic solvent is n-hexane.

[0016] Preferably, the conditions for the transesterification reaction in step S1 are: temperature 30-60° C., time 2-10 h.

[0017] As further preferred, the conditions for the transesterification reaction in step S1 are: temperature 50° C., time 8 h.

[0018] Preferably, the molar ratio of maleic anhydride to alcohol in step S1 is 1:(1-6).

[0019] As a further preference, the molar ratio of maleic anhydride to alcohol in step S1 is 1:2.

[0020] Preferably, the distillation conditions in step S1 are 2000 Pa and 60°C.

[0021] Preferably, the isomerization conditions in step S2 are: temperature 60-90° C., and time 1-4 h.

[0022] As further preferred, the isomerization conditions in step S2 are: temperature 80° C., and time 3 h.

[0023] Preferably, the preparation method of the fumaric acid monoester further comprises the following steps:

[0024] S3. Recrystallize the fumaric acid monoester obtained in S2 using a methanol aqueous solution to obtain a purified fumaric acid monoester.

[0025] As a further preference, the volume ratio of methanol to water in the methanol aqueous solution is 1:10.

[0026] A fumaric acid monoester prepared by any one of the above preparation methods.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] In step S1 of the present invention, immobilized lipase is used as a catalyst for transesterification reaction, and maleic acid monoester is synthesized by enzymatic method, which greatly improves the yield of maleic acid monoester, an intermediate product, in the preparation of fumaric acid monoester; on this basis, in step S2 of the present invention, aluminum chloride is also used as a catalyst for isomerization reaction to catalyze the isomerization of the intermediate product maleic acid monoester, and synthesize fumaric acid monoester by chemical method. This preparation method is simple and easy to implement; the preparation conditions are mild and environmentally friendly; and the preparation cost is low, the yield is high, and there is no by-product, so no complicated purification process is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to clearly illustrate the embodiments, the drawings of the accompanying drawings are briefly introduced below:

[0030] Figure 1 is the liquid chromatogram of maleic anhydride standard;

[0031] Figure 2 This is the liquid chromatogram of the standard product of monoethyl maleate;

[0032] Figure 3 This is the liquid chromatogram of monoethyl fumarate standard. DETAILED DESCRIPTION

[0033] The present invention will be further described below in the form of specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0034] In the following examples, the liquid chromatograph detection conditions are (Waters 2695 liquid chromatograph): chromatographic column, AQ-C18, 5um, 4.6*250nm (Zhejiang Yuexu Material Technology Co., Ltd.); wavelength, 210nm; mobile phase, 0.01mol / L potassium dihydrogen phosphate: methanol (95:5, V / V); flow rate, 1.000ml / min; column temperature, 26°C; detection time, 10min. The peak time of maleic anhydride is 5.292min, the peak time of monoethyl maleate is 6.202min, and the peak time of monoethyl fumarate is 3.068min.

[0035] Example 1

[0036] In 4 groups of 10mL centrifuge tubes, 0.3g maleic anhydride and 0.38mL ethanol reaction substrates were dissolved in 3.6mL n-hexane organic solvent, 0.01g immobilized lipase Novozyme 435 was added, the centrifuge tubes were sealed, and the reaction was carried out at a constant temperature of 200r / min at different temperatures (30℃, 40℃, 50℃, 60℃) for 8h, and then samples were taken for liquid chromatography analysis. The conversion rate of the transesterification reaction was calculated and plotted, and Table 1 is as follows:

[0037] Table 1. Enzyme catalysis results at different reaction temperatures

[0038] temperature Reaction conversion rate (%) 30℃ 89.0％ 40℃ 92.4％ 50℃ 96.5％ 60℃ 91.2％

[0039] By observing Table 1, it can be found that at 30-60°C, the immobilized lipase Novozyme 435 can achieve a good catalytic effect on the reaction substrate, and the conversion rate of maleic anhydride reaches more than 89%. In particular, when the immobilized lipase Novozyme 435 catalyzes the reaction substrate for transesterification at 50°C, the reaction conversion rate is as high as 96.5%. It can be seen that the use of the enzyme catalysis method in step S1 of the present invention can effectively increase the yield of the intermediate product maleic acid monoester, thereby indirectly increasing the yield of fumaric acid monoester.

[0040] Example 2

[0041] In 5 groups of 10mL centrifuge tubes, different organic solvents (80% v / w, n-hexane, cyclohexane, toluene, petroleum ether, tert-butanol) were taken as reaction media, and reaction substrates containing 0.3g maleic anhydride and 0.38mL ethanol, as well as 0.01g immobilized lipase Novozyme 435 were added. The centrifuge tubes were sealed and reacted at an oscillation speed of 200r / min and a constant temperature of 50°C for 8h, and then samples were taken for liquid chromatography analysis. At the same time, the conversion rate of the transesterification reaction was calculated and plotted, and Table 2 is as follows:

[0042] Table 2. Enzymatic conversion results of different organic solvents

[0043] Organic solvents Reaction conversion rate (%) n-Hexane 96.8％ Cyclohexane 84.5％ Toluene 92.6％ Petroleum ether 86.0％ Tert-Butanol 77.0％

[0044] By observing Table 2, it can be found that the selection of organic solvent for transesterification reaction will directly affect the yield of intermediate product maleic acid monoester. The best organic solvent is n-hexane, at which the reaction conversion rate is as high as 96.8%. When tert-butyl alcohol is selected as organic solvent, the reaction conversion rate is only 77%.

[0045] Example 3

[0046] In 4 groups of 10 mL centrifuge tubes, 0.3 g of maleic anhydride and 0.38 mL of ethanol were dissolved in 3.6 mL of n-hexane organic solvent, and 0.01 g of different immobilized lipases (lipase Novozyme 435, lipase CALA, lipase RML, lipase TLL) were used as catalysts. The centrifuge tubes were sealed and reacted at an oscillation speed of 200 r / min and a constant temperature of 50°C for 8 hours, and then samples were taken for liquid chromatography analysis. At the same time, the conversion rate of the transesterification reaction was calculated and plotted, and Table 3 is as follows:

[0047] Table 3. Enzymatic conversion results of different lipases

[0048] Immobilized lipase Manufacturer Reaction conversion rate (%) Lipase Novozyme435 Novozymes 96.8％ Lipase CALA Qingdao Blue Biotechnology 93.5％ Lipase RML Qingdao Blue Biotechnology 84.2％ Lipase TLL Qingdao Blue Biotechnology 89.0％

[0049] By observing Table 3, it can be concluded that in the process of preparing maleic acid monoester by enzyme-catalyzed transesterification reaction, the selection of immobilized lipase type will have a certain influence on the reaction conversion rate. Among them, when lipase Novozyme435 is selected, the reaction conversion rate is the highest, reaching 96.8%, and when lipase RML is selected, the reaction conversion rate is the lowest, reaching 84.2%. Therefore, the immobilized lipase in step S1 of the present invention is preferably lipase Novozyme435.

[0050] Example 4

[0051] In three groups of 10 mL centrifuge tubes, 0.3 g of maleic anhydride and 0.38 mL of different alcohols (methanol, ethanol, butanol) were dissolved in 3.6 mL of n-hexane organic solvent, 0.01 g of lipase Novozyme 435 was used as a catalyst, the centrifuge tubes were sealed, and the reaction was carried out at an oscillation speed of 200 r / min and a constant temperature of 50°C, and then samples were taken for liquid chromatography analysis. At the same time, the conversion rate of the transesterification reaction was calculated and plotted, and Table 4 is as follows:

[0052] Table 4. Enzymatic conversion results of different short-chain alcohols

[0053] alcohol Time (h) Conversion rate (%) Methanol 6.5h 98.8％ Ethanol 8h 97.5％ Butanol 10h 97.0％

[0054] By observing Table 4, it can be concluded that lipase Novozyme 435 can catalyze methanol, ethanol and butanol to produce maleic acid monoesters, and the conversion rate is extremely high, reaching more than 95%.

[0055] Example 5

[0056] In three groups of 10 mL centrifuge tubes, maleic anhydride and ethanol in different molar ratios (see the table below) were dissolved in 3.6 mL of n-hexane organic solvent, 0.01 g of lipase Novozyme 435 was used as a catalyst, the centrifuge tubes were sealed, and the reaction was carried out at an oscillation speed of 200 r / min and a constant temperature of 50°C for 8 hours, and then samples were taken for liquid chromatography analysis. At the same time, the conversion rate of the transesterification reaction was calculated and plotted, and Table 5 is as follows:

[0057] Table 5. Enzyme conversion results at different molar ratios

[0058] Molar Ratio Conversion rate (%) 1∶6 90％ 1∶2 96％ 1∶1 85％

[0059] By observing Table 5, it can be concluded that when the molar ratio of maleic anhydride to ethanol is 1:2, the reaction conversion rate is the highest.

[0060] Example 6

[0061] In 4 groups of 10 mL centrifuge tubes, 0.3 g of maleic anhydride and 0.38 mL of ethanol were dissolved in 3.6 mL of n-hexane organic solvent, 0.01 g of lipase Novozyme 435 was used as a catalyst, the centrifuge tubes were sealed, and the reaction was carried out for different times (2 h, 4 h, 8 h, 10 h) at an oscillation speed of 200 r / min and a constant temperature of 50 ° C, and then samples were taken for liquid chromatography analysis. At the same time, the conversion rate of the transesterification reaction was calculated and plotted, and Table 6 is as follows:

[0062] Table 6. Enzyme conversion results at different reaction times

[0063] Reaction time Conversion rate (%) 2h 64.5％ 4h 76.6％ 8h 96.5％ 10h 96.6％

[0064] By observing Table 6, it can be concluded that in the step of preparing maleic acid monoester by enzyme catalysis, as the reaction time continues to increase, the conversion rate is higher. However, when the reaction time is 8h and the reaction time is 10h, the difference in conversion rate is only 0.1%. Therefore, based on the reaction efficiency, the optimal reaction time for the transesterification reaction in step S1 is 8h.

[0065] Example 7

[0066] In 4 groups of 10 mL centrifuge tubes, 10 g of monomethyl maleate obtained in Example 4 (methanol as a reaction substrate) and 0.25 g of aluminum chloride were added, and heated at different temperatures (60° C., 70° C., 80° C., 90° C.) for 3 h to synthesize monomethyl fumarate. Samples were taken for liquid chromatography analysis, and the conversion rate was calculated and plotted. Table 7 is as follows:

[0067] Table 7. Effect of reaction temperature on conversion of monomethyl fumarate

[0068] temperature Conversion rate (%) 60℃ 78.5％ 70℃ 88.4％ 80℃ 99.2％ 90℃ 95.6％

[0069] By observing Table 7, it can be concluded that the change of the isomerization reaction temperature will have a greater impact on the conversion rate. Specifically, when the isomerization temperature reaches 60°C, the conversion rate only reaches 78.5%. Then, as the temperature continues to increase, the conversion rate continues to increase until the conversion rate of the reaction reaches 99.2% at 80°C. Thereafter, when the temperature is increased, the conversion rate shows a decreasing trend. It can be seen that the optimal temperature for the isomerization reaction in step S2 of the present invention is 80°C.

[0070] Example 8

[0071] In 4 groups of 10 mL centrifuge tubes, 10 g of monomethyl maleate obtained in Example 4 (methanol as a reaction substrate) and 0.25 g of aluminum chloride were added, and heated at 80° C. for different isomerization times (1 h, 2 h, 3 h, 4 h) to synthesize monomethyl fumarate. Samples were taken for liquid chromatography analysis, and the conversion rate was calculated and plotted. Table 8 is as follows:

[0072] Table 8. Effect of reaction time on conversion of monomethyl fumarate

[0073] Reaction time (h) Conversion rate (%) 1h 68.6％ 2h 86.2％ 3h 99.4％ 4h 99.5％

[0074] By observing Table 8, it can be concluded that as the reaction time increases, the conversion rate increases. However, when the reaction time is 3 h and the reaction time is 4 h, the difference in conversion rate is only 0.1%. Therefore, based on the reaction efficiency, the optimal reaction time for isomerization in step S2 is 3 h.

[0075] Example 9

[0076] In three groups of 10 mL centrifuge tubes, 10 g of the maleic acid monoester obtained in Example 4 (methanol as a reaction substrate) and 0.25 g of aluminum chloride were added, and the mixture was heated at 80 ° C for 3 h for isomerization to synthesize fumaric acid monoester, and samples were taken for liquid chromatography analysis. After the reaction was complete, the mixture was cooled to room temperature to obtain a crude fumaric acid monoester. Recrystallization was performed using a 1:10 methanol aqueous solution to obtain a purified fumaric acid monoester. The conversion rate and product yield of the reaction are shown in Table 9.

[0077] Table 9. Conversion rate and product yield

[0078]

[0079] By observing the above table, it can be seen that the yield of the fumaric acid monoester prepared by the preparation method of the present invention is extremely high, which can effectively solve the technical problems of low conversion rate and yield in the prior art.

Claims

1. A method for preparing a fumaric acid monoester, characterized in that: The following steps are involved: S1. Using maleic anhydride and alcohol as reaction substrates and immobilized lipase as catalyst, catalyzing the transesterification reaction of the reaction substrates in an organic solvent to obtain a reaction solution, and filtering and distilling the reaction solution to obtain maleic acid monoester; the alcohol includes one of methanol, ethanol, and butanol; the immobilized lipase includes one of lipase Novozyme435, lipase CALA, lipase RML, or lipase TLL; the organic solvent includes one of tert-butyl alcohol, n-hexane, cyclohexane, toluene, or petroleum ether; S2, using aluminum chloride as a catalyst to catalyze the isomerization of the maleic acid monoester obtained in step S1 to obtain fumaric acid monoester.

2. The method for preparing a fumaric acid monoester according to claim 1, characterized in that: In step S1, the transesterification reaction The appropriate conditions are: temperature 30-60℃, time 2-10h.

3. The method for preparing a fumaric acid monoester according to claim 1, characterized in that: In step S1, maleic anhydride The molar ratio of ethanol to alcohol is 1:(1-6).

4. A method for synthesizing fumaric acid monoester according to claim 1, characterized in that: Distillation conditions in step S1 2000Pa, 60℃.

5. The method for preparing a fumaric acid monoester according to claim 1, characterized in that: In step S2, the isomerization The conditions are: temperature 60-90°C, time 1-4h.

6. The method for preparing a fumaric acid monoester according to claim 1, characterized in that: The following steps are also included: S3. Recrystallize the fumaric acid monoester obtained in S2 using a methanol aqueous solution to obtain a purified fumaric acid monoester.

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