Preparation method of 5-hydroxymethyl furoic acid

Abstract

The invention provides a preparation method of 5-hydroxymethyl furoic acid, and relates to the technical field of furoic acid synthesis. According to the preparation method of the 5-hydroxymethyl furoic acid, the 5-hydroxymethyl furfural is used as a reaction substrate, the organic nitrogen oxide is used as a catalyst, the bromide is used as an auxiliary agent, the chlorite is used as an oxidizing agent, the 5-hydroxymethyl furoic acid is obtained through the oxidation reaction under the acidic medium, and the preparation method has the advantages of being mild in reaction condition, short in reaction time, high in product yield, high in purity and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of furoic acid synthesis and relates to a method for preparing 5-hydroxymethylfurfural acid. Background Art

[0002] Developing and utilizing biomass resources to prepare polymer materials, bulk chemicals, etc. for replacing petroleum resources is of great significance. 5-Hydroxymethylfurfural (HMF) is one of the important biomass-based platform compounds and can be further converted to prepare various high-value-added compounds, such as 5-hydroxymethylfurfural acid (HMFCA), 2,5-diformylfuran (DFF), 2,5-furandicarboxylic acid (FDCA), etc. Among them, HMFCA can not only be used as a polymerization reaction monomer for degradable polymer materials but also as an intermediate for medicines and pesticides, having important application values.

[0003] The prior art CN113968834A discloses mixing 5-hydroxymethylfurfural, an oxidation catalyst, and a solvent and reacting in the presence of an oxygen source to obtain HMFCA. The oxidation catalyst is a dicarboximide compound, and the oxygen source is oxygen or air. This method needs to carry out the reaction under high pressure, and the reaction time is relatively long, and there is no report on the purity and yield of HMFCA after purification. The prior arts CN112778248A and CN112778250A respectively disclose methods for preparing 5-hydroxymethylfurfural acid. Under air and / or oxygen conditions, a carrier loaded with an active component is used as the catalyst. In this method, the carrier needs to be pretreated with a basic nitrogen-containing compound, and an expensive noble metal needs to be used as the active component.

[0004] The applicant believes that the methods of the above prior arts still need to be further improved. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a method for preparing 5-hydroxymethylfurfural acid.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing 5-hydroxymethylfurfural acid, using 5-hydroxymethylfurfural as a reaction substrate, an organic nitrogen oxide as a catalyst, a bromide salt as an auxiliary agent, and a chlorite as an oxidant, and carrying out an oxidation reaction in an acidic medium to obtain.

[0008] Preferably, the molar ratio of the 5-hydroxymethylfurfural to the organic nitrogen oxide is 1:0.001 - 0.1.

[0009] Preferably, the organic nitrogen oxide is selected from one or a combination of two or more of 2,2,6,6-tetramethylpiperidine-n-oxide, 4-hydroxy-2,2,6,6-tetramethylpiperidine-n-oxide, 4-acetamido-2,2,6,6-tetramethylpiperidine-n-oxide, 4-amino-2,2,6,6-tetramethylpiperidine-n-oxide, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine-n-oxide, and N-methylmorpholine-n-oxide.

[0010] Preferably, the weight ratio of the 5-hydroxymethylfurfural to the bromide salt is 1:0.01-1.

[0011] Preferably, the bromide salt is selected from one or a combination of two or more of sodium bromide, potassium bromide, calcium bromide, magnesium bromide, aluminum bromide, and lithium bromide.

[0012] Preferably, the weight ratio of the 5-hydroxymethylfurfural to the chlorite is 1:0.5-3;

[0013] The chlorite is selected from one or a combination of two or more of sodium chlorite, potassium chlorite, magnesium chlorite, barium chlorite, and calcium chlorite.

[0014] Preferably, the acidic medium comprises water and an alcohol solvent, and the pH of the acidic medium is not higher than 5.

[0015] More preferably, the weight ratio of the 5-hydroxymethylfurfural to the water is 1:10-50;

[0016] The weight ratio of the 5-hydroxymethylfurfural to the alcohol solvent is 1:1-150.

[0017] Preferably, the reaction temperature of the oxidation reaction is 5-40 °C, and the reaction time is 0.5-3 h.

[0018] Preferably, after the oxidation reaction, it further includes: purification;

[0019] Preferably, the operation of the purification is:

[0020] Removing the alcohol solvent to obtain an aqueous phase;

[0021] Extracting the aqueous phase with an extraction organic solvent to obtain an extract; the extraction organic solvent is insoluble or hardly soluble in water;

[0022] Removing the extraction organic solvent from the extract to obtain the 5-hydroxymethylfuroic acid.

[0023] The beneficial effects of the present invention are as follows: The present invention uses bromide salts as additives, chlorite salts as oxidants, and organic nitrogen oxides as catalysts. HMFCA is obtained through an oxidation reaction with HMF as the reaction substrate. The reaction conditions are relatively mild, the reaction time is short, the post-treatment is relatively simple, and the product yield and purity are relatively high. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the HPLC chromatogram of HMFCA obtained in Example 1 and commercially available HMFCA;

[0025] Among them, the upper figure a is the HPLC chromatogram of HMFCA obtained in Example 1, and the lower figure b is the HPLC chromatogram of commercially available HMFCA. DETAILED DESCRIPTION OF THE INVENTION

[0026] The technical solutions of the present invention will be further described and illustrated through specific embodiments below.

[0027] In order to obtain milder reaction conditions and avoid using noble metal catalysts, the present invention provides a method for preparing 5-hydroxymethylfurfural acid. Using 5-hydroxymethylfurfural as the reaction substrate, organic nitrogen oxides as the catalyst, bromide salts as the additive, and chlorite salts as the oxidant, an oxidation reaction is carried out in an acidic medium to obtain it.

[0028] The aldehyde group and hydroxymethyl group in the structure of 5-hydroxymethylfurfural (HMF) have reducibility, and the reducibility of the aldehyde group is stronger than that of the hydroxymethyl group. Therefore, different oxidation products will be obtained under different oxidation conditions. For example, the aldehyde group is oxidized to a carboxyl group and the hydroxymethyl group is not oxidized, both the aldehyde group and the hydroxymethyl group are oxidized to carboxyl groups, the hydroxymethyl group is oxidized to an aldehyde group, etc. Therefore, the oxidation reaction conditions have an important influence on the oxidation reaction of HMF and the oxidation products. The present invention uses organic nitrogen oxides as the catalyst, bromide salts as the additive, and chlorite salts as the oxidant. In an acidic medium, HMF is oxidized to HMFCA. The reaction conditions are mild, the reaction time is short, and the yield of HMFCA is high.

[0029] In some embodiments, the molar ratio of 5-hydroxymethylfurfural to organic nitrogen oxides is 1:0.001 - 0.1. For example, the molar ratio can be any value among 1:0.001, 1:0.003, 1:0.005, 1:0.008, 1:0.01, 1:0.02, 1:0.03, 1:0.05, 1:0.06, 1:0.08, 1:0.09, 1:0.1, etc., without special limitation. Further, the molar ratio of 5-hydroxymethylfurfural to organic nitrogen oxides can be 1:0.005 - 0.06.

[0030] In some embodiments, the organic nitrogen oxide is selected from one or a combination of two or more of 2,2,6,6-tetramethylpiperidine-N-oxide (TMEPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxide, 4-acetamido-2,2,6,6-tetramethylpiperidine-N-oxide, 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine-N-oxide, and N-methylmorpholine-N-oxide (NMO). Further, the organic nitrogen oxide is selected from TEMPO or NMO. In the present invention, the organic nitrogen oxide, as a catalyst, can improve the oxidation performance of chlorite, with more sufficient oxidation and higher selectivity.

[0031] In some embodiments, the weight ratio of 5-hydroxymethylfurfural to the bromide salt is 1:0.01 - 1. For example, the weight ratio can be any value among 1:0.01, 1:0.03, 1:0.05, 1:0.06, 1:0.08, 1:0.1, 1:0.15, 1:0.3, 1:0.5, 1:0.6, 1:0.7, 1:0.75, 1:0.8, 1:0.9, 1:1, etc., without any particular limitation. Further, the weight ratio of 5-hydroxymethylfurfural to the bromide salt can be 1:0.05 - 0.5.

[0032] In some embodiments, the bromide salt is selected from one or a combination of two or more of sodium bromide, potassium bromide, calcium bromide, magnesium bromide, aluminum bromide, and lithium bromide. Further, considering raw material cost and availability, the bromide salt can be selected from sodium bromide. In the present invention, the bromide salt, as an auxiliary for the oxidation reaction, can accelerate the oxidation reaction, improve the efficiency of the oxidation reaction, with more sufficient oxidation and higher selectivity.

[0033] In some embodiments, the weight ratio of 5-hydroxymethylfurfural to the chlorite is 1:0.5 - 3. For example, the weight ratio can be any value among 1:0.5, 1:0.6, 1:0.8, 1:0.9, 1:1, 1:1.2, 1:1.3, 1:1.5, 1:1.7, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.5, 1:2.7, 1:2.8, 1:3, etc., without any particular limitation. Further, the weight ratio of 5-hydroxymethylfurfural to the chlorite can be 1:0.5 - 1.5.

[0034] The present invention uses chlorite as an oxidant with moderate oxidation ability. Under the catalysis of organic nitrogen oxides and with bromide salts as an auxiliary agent, the aldehyde group in HMF can be oxidized to a carboxyl group, but the hydroxymethyl group is not oxidized or less oxidized. Therefore, HMFCA can be directly obtained from HMF through oxidation. The chlorite is selected from one or a combination of two or more of sodium chlorite, potassium chlorite, magnesium chlorite, barium chlorite, and calcium chlorite. Further, considering raw material costs and availability, the chlorite can be selected from sodium chlorite.

[0035] In some embodiments, the acidic medium comprises water and an alcohol solvent, and the pH of the acidic medium is not higher than 5. In the oxidation reaction of the present invention, the reaction solvent can be a combination of water and an alcohol solvent. The pH of the reaction solvent is not higher than 5, such as pH 2, 2.5, 3, 3.5, 4, 4.5, 5, etc., which can further improve the oxidation ability of sodium chlorite and result in a higher conversion rate of HMF to HMFCA. For the acid used in the acidic medium, it can be an organic acid or an inorganic acid, such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid, propionic acid, etc., without particular limitation. For the alcohol solvent, it can be ethanol, methanol, isopropanol, butanol, ethylene glycol, propanol, etc., without particular limitation.

[0036] In some embodiments, the weight ratio of 5-hydroxymethylfurfural to water is 1:10 - 50. For example, the weight ratio can be any value among 1:10, 1:12, 1:15, 1:18, 1:20, 1:25, 1:27, 1:30, 1:32, 1:33, 1:35, 1:37, 1:40, 1:42, 1:43, 1:45, 1:47, 1:50, etc., without particular limitation;

[0037] The weight ratio of 5-hydroxymethylfurfural to the alcohol solvent is 1:1 - 150. For example, the weight ratio can be any value among 1:1, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, 1:110, 1:120, 1:130, 1:140, 1:150, etc., without particular limitation. Further, the weight ratio of 5-hydroxymethylfurfural to the alcohol solvent can be 1:18 - 100.

[0038] There is no particular limitation on the specific operation of the preparation method of the present invention. For example, all raw materials can be stirred and mixed evenly and then directly reacted, or HMF, organic nitrogen oxides, bromide salts, alcohol solvents, part of the water, and acid can be mixed evenly, and then a mixture of chlorite and the remaining water is gradually added and reacted.

[0039] In some embodiments, the reaction temperature of the oxidation reaction is 5 - 40 °C, and the reaction time is 0.5 - 3 h. The conditions of the oxidation reaction of the present invention are relatively mild, and it can be carried out at room temperature or at a temperature around room temperature, and the reaction time is short.

[0040] In some embodiments, after the oxidation reaction, it further includes: purification;

[0041] The operation of purification is as follows:

[0042] Remove the alcohol solvent to obtain an aqueous phase; methods such as vacuum distillation or rotary evaporation can be used to remove the alcohol solvent, which is well known to those skilled in the art;

[0043] Extract the aqueous phase with an extraction organic solvent to obtain an extract; the extraction organic solvent is insoluble or hardly soluble in water; the extraction organic solvent being insoluble or hardly soluble in water means that the solubility of the extraction organic solvent in pure water at 25 °C does not exceed 10 g / 100 g of water, such as ethyl acetate, butyl acetate, dichloromethane, chloroform, 1,1 - dichloroethane, etc.

[0044] Remove the extraction organic solvent in the extract by distillation and other means to obtain 5 - hydroxymethylfurfural.

[0045] The technical solutions of the present invention will be further described and illustrated according to the following examples. Unless otherwise specified, the parts mentioned in the following examples are parts by weight.

[0046] Example 1

[0047] Take 1.261 g of HMF (10 mmol), 0.0156 g of TEMPO (0.1 mmol), 0.103 g of sodium bromide (1 mmol), 0.02 g of acetic acid, 5 ml of water and 50 ml of methanol (39.7 g) and add them to a flask and mix well. Slowly dropwise add an oxidant solution prepared from 0.9 g of sodium chlorite and 20 ml of water into the flask within 30 min. While dropping the oxidant solution, stir the reaction solution in the flask. After dropping, the pH of the reaction solution is 4.0, and continue to stir and react at room temperature (20 °C) for 60 min. Rotate - evaporate the reaction solution to remove methanol, extract the aqueous phase twice with 20 ml of ethyl acetate and then separate the layers. Rotate - evaporate the ethyl acetate extract to remove ethyl acetate to obtain a pale - yellow solid HMFCA. The molar yield of HMFCA is measured to be 87.2%. The purity of HMFCA is measured to be 98.2% by HPLC.

[0048] The HPLC (High - Performance Liquid Chromatography) chromatogram results of the product HMFCA and commercially available HMFCA are as shown in the appendix Figure 1 as follows. Among them, the upper figure a is the HPLC chromatogram of the product HMFCA in this example, and the lower figure b is the HPLC chromatogram of commercially available HMFCA. Figure 1It can be seen that the product obtained in this embodiment is HMFCA.

[0049] The above HPLC test method is as follows: Dissolve the sample to be tested in ultrapure water, sonicate it for 5 min using an ultrasonic cleaner, then shake it for 1 min, and sonicate it for another 5 min to completely dissolve the sample in water. Then, make up the volume to a mother liquor with a concentration of 1 g / L using a volumetric flask. Next, take 1 g of the mother liquor and dilute it 10 times with ultrapure water to obtain the test solution. The test solution is filtered through a 0.2 μm filter paper before testing. The HPLC instrument model is Waters 2695, the mobile phase is a 5 mmol / L sulfuric acid aqueous solution, the test wavelength is 260 nm, the injection volume is 10 μL, and the test temperature is 25°C.

[0050] Examples 2 - 7

[0051] Examples 2 - 7 are based on Example 1 with adjusted reaction conditions. The adjusted reaction conditions and results are shown in Table 1 below.

[0052] Table 1

[0053]

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that in Example 1, sodium chlorite is replaced with an equal weight of sodium hypochlorite (using a 12 wt% sodium hypochlorite aqueous solution, calculated based on the actual weight of sodium hypochlorite, and the amount of water is deducted accordingly). The remaining steps remain unchanged. The molar yield of the obtained HMFCA is 45.7%, and the purity is 60.4%.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that in Example 1, sodium chlorite is replaced with an equal weight of hydrogen peroxide (30 wt% concentration). The remaining steps remain unchanged. The molar yield of the obtained HMFCA is 41.8%, and the purity is 55.2%.

[0058] Comparative Example 3

[0059] The difference between this comparative example and Example 1 is that in Example 1, sodium bromide is replaced with an equal weight of sodium nitrate. The remaining steps remain unchanged. The molar yield of the obtained HMFCA is 20.3%, and the purity is 85.1%.

[0060] Comparative Example 4

[0061] The difference between this comparative example and Example 1 is that in Example 1, acetic acid is not added. The remaining steps remain unchanged. The molar yield of the obtained HMFCA is 35.5%, and the purity is 74.2%.

[0062] Example 8

[0063] 1.261 g of HMF (10 mmol), 0.0312 g of TEMPO (0.2 mmol), 0.206 g of sodium bromide, 0.03 g of acetic acid, 8 ml of water and 80 ml of methanol were added to a flask and mixed evenly. An oxidant solution prepared from 0.7 g of sodium chlorite and 10 ml of water was slowly added dropwise to the flask within 30 min. While adding the oxidant solution, the reaction solution in the flask was stirred. After the addition, the pH of the reaction solution was 3.5, and the reaction was continued to stir at room temperature (20 °C) for 2 h. The reaction solution was rotary evaporated to remove methanol. The aqueous phase was extracted twice with 30 ml of ethyl acetate and then separated. The ethyl acetate extract was rotary evaporated to remove ethyl acetate to obtain a pale yellow solid HMFCA. The molar yield of HMFCA was measured to be 89.1%. The purity of HMFCA was measured to be 98.5% by HPLC.

[0064] Example 9

[0065] The difference between this example and Example 8 is that in Example 8, TEMPO was adjusted from 0.2 mmol to 0.5 mmol, and sodium bromide was adjusted from 0.206 g to 0.07 g. The remaining steps remained unchanged. The molar yield of the obtained HMFCA was 84.7%, and the purity was 96.8%.

[0066] Example 10

[0067] The difference between this example and Example 8 is that in Example 8, TEMPO was adjusted from 0.2 mmol to 0.05 mmol, sodium bromide was adjusted from 0.206 g to 0.07 g, and the reaction time was adjusted from 2 h to 3 h. The remaining steps remained unchanged. The molar yield of the obtained HMFCA was 83.2%, and the purity was 97.1%.

[0068] Example 11

[0069] The difference between this example and Example 8 is that in Example 8, sodium bromide was adjusted from 0.206 g to 0.15 g, sodium chlorite was adjusted from 0.7 g to 1.2 g, and the reaction time was adjusted from 2 h to 1.5 h. The remaining steps remained unchanged. The molar yield of the obtained HMFCA was 88.5%, and the purity was 98.0%.

[0070] As described above, the basic principles, main features and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments are only preferred embodiments of the present invention, and the scope of implementation of the present invention cannot be limited thereby. That is, equivalent changes and modifications made according to the scope of the present invention patent and the content of the specification should still fall within the scope covered by the present invention. The scope of protection required by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing 5-hydroxymethyl furoic acid, characterized in that, The product is obtained by oxidation reaction in an acidic medium with 5-hydroxymethylfurfural as a reaction substrate, organic nitrogen oxides as catalysts, bromide salts as auxiliary agents and chlorite as an oxidant.

2. The preparation method of 5-hydroxymethyl furoic acid according to claim 1, characterized in that The molar ratio of the 5-hydroxymethylfurfural to the organic nitrogen oxide is 1:0.001-0.

1.

3. The preparation method of 5-hydroxymethyl furoic acid according to claim 1 or 2, characterized in that, The organic nitrogen oxide is selected from one or a combination of two or more of 2,2,6,6-tetramethylpiperidine nitrogen oxide, 4-hydroxy-2,2,6,6-tetramethylpiperidine nitrogen oxide, 4-acetylamino-2,2,6,6-tetramethylpiperidine nitrogen oxide, 4-amino-2,2,6,6-tetramethylpiperidine nitrogen oxide, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine nitrogen oxide and N-methylmorpholine nitrogen oxide.

4. The preparation method of 5-hydroxymethyl furoic acid according to claim 1, characterized in that, The weight ratio of the 5-hydroxymethylfurfural to the bromide salt is 1:0.01-1.

5. The method for preparing 5-hydroxymethyl furoic acid according to claim 1 or 4, characterized in that, The bromide salt is selected from one or a combination of two or more of sodium bromide, potassium bromide, calcium bromide, magnesium bromide, aluminum bromide and lithium bromide.

6. The method for preparing 5-hydroxymethyl furoic acid according to claim 1, wherein The weight ratio of the 5-hydroxymethylfurfural to the chlorite is 1:0.5-3; The chlorite is selected from one or a combination of two or more of sodium chlorite, potassium chlorite, magnesium chlorite, barium chlorite and calcium chlorite.

7. The method for preparing 5-hydroxymethyl furoic acid according to claim 1, wherein The acidic medium comprises water and an alcohol solvent, and the pH of the acidic medium is not higher than 5.

8. The method for preparing 5-hydroxymethyl furoic acid according to claim 7, wherein The weight ratio of the 5-hydroxymethylfurfural to the water is 1:10-50; The weight ratio of the 5-hydroxymethylfurfural to the alcohol solvent is 1:1-150.

9. The method for preparing 5-hydroxymethyl furoic acid according to claim 1, wherein The reaction temperature of the oxidation reaction is 5-40° C., and the reaction time is 0.5-3 h.

10. The method for preparing 5-hydroxymethyl furoic acid according to claim 1, characterized in that: The oxidation reaction further includes: purification; Preferably, the purification operation is: removing the alcohol solvent to obtain an aqueous phase; Extracting the aqueous phase with an extraction organic solvent to obtain an extract; the extraction organic solvent is insoluble or poorly soluble in water; The extraction organic solvent in the extract is removed to obtain the 5-hydroxymethyl furoic acid.

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