A method for selectively oxidizing 5-hydroxymethylfurfural to 2,5-dicarbonylfuran without TEMPO

Abstract

The application discloses a method for preparing 2,5-diformylfuran by selectively oxidizing 5-hydroxymethylfurfural without TEMPO, which comprises the following steps: taking 5-hydroxymethylfurfural as raw material, taking a chlorine-containing metal salt as a main active component of a catalyst, taking dichlorodiphenylmethane as a halogenating agent, halogenating 5-hydroxymethylfurfural into 5-chloromethylfurfural, taking dimethyl sulfoxide as a solvent and an oxidizing agent, and oxidizing to obtain the 2,5-diformylfuran under normal pressure and at 80-180 DEG C for a certain time, wherein the chlorine-containing metal salt is one of anhydrous cupric chloride, zinc chloride, ferric chloride, niobium chloride and aluminum chloride; the amount of the chlorine-containing metal salt is 0.01-0.1 mmol; the dimethyl sulfoxide is used as the solvent, the catalyst used is cheap and easy to obtain, the reaction is carried out at 100 DEG C for 24 h, the yield of 2,5-diformylfuran can reach 94.25% at most, the reaction condition is mild, the requirement for equipment is low, and the method is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of organic compound preparation, and in particular relates to a method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO. Background Technology

[0002] Currently, 2,5-dicarboxyfuran is prepared using 5-hydroxymethylfurfural as a raw material, mainly by oxidation with oxidants such as manganese dioxide, chromium trioxide, and sodium hypochlorite. However, this preparation method causes serious environmental pollution, has a long reaction time, requires large amounts of oxidants and reaction solvents, and has a very low product yield. Many non-precious metals also use TEMPO for highly selective oxidation of 5-hydroxymethylfurfural to prepare 2,5-dicarboxyfuran, but the product is difficult to process, causing separation difficulties, and can form impurities with other substances, making purification difficult.

[0003] To address the above problems, this invention proposes a method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO.

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention. Summary of the Invention

[0005] In view of the above-mentioned technical deficiencies, the present invention is proposed.

[0006] Therefore, one of the objectives of this invention is to overcome the shortcomings of the prior art and provide a method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO, characterized in that it includes: using 5-hydroxymethylfurfural as raw material, a chlorinated metal salt as the main active component of the catalyst, and dichlorodiphenylmethane as a halogenating agent to halogenate 5-hydroxymethylfurfural to 5-chloromethylfurfural; using dimethyl sulfoxide as a solvent and oxidant; reacting at 80-180°C for a certain time under normal pressure to obtain the 2,5-dicarboxyfuran; wherein the chlorinated metal salt is one of anhydrous copper chloride, zinc chloride, ferric chloride, niobium chloride, aluminum chloride, etc.; and the amount of the chlorinated metal salt used is 0.01-0.1 mmol.

[0008] As a preferred embodiment of the method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO according to the present invention, wherein the chlorine-containing metal salt is anhydrous copper chloride.

[0009] In a preferred embodiment of the method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO according to the present invention, the amount of the chlorine-containing metal salt is 0.03 mmol.

[0010] In a preferred embodiment of the method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO as described in this invention, the halogenating agent is dichlorodiphenylmethane.

[0011] In a preferred embodiment of the method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO according to the present invention, the amount of dichlorodiphenylmethane used is 1-2 mmol.

[0012] In a preferred embodiment of the method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO according to the present invention, the amount of dichlorodiphenylmethane used is 1.04 mmol.

[0013] As a preferred embodiment of the TEMPO-free selective oxidation of 5-hydroxymethylfurfural to prepare 2,5-dicarboxyfuran according to the present invention, wherein: the dimethyl sulfoxide is used as both a solvent and an oxidant, and the concentration of 5-hydroxymethylfurfural is 0.2 mol / L.

[0014] As a preferred embodiment of the method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO according to the present invention, wherein the reaction is carried out at 80-180°C for a certain period of time under normal pressure, wherein the reaction time is 18-48 h.

[0015] As a preferred embodiment of the method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO according to the present invention, wherein: the reaction at 80-180°C for a certain time under normal pressure conditions refers to the reaction at 100°C for 24 hours.

[0016] As a preferred embodiment of the method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO according to the present invention, the detection product includes: after the reaction is completed, taking 20 μl of liquid, adding 1 ml of acetonitrile, and detecting the product by liquid chromatography.

[0017] Beneficial technical effects of the present invention:

[0018] This invention uses a chlorine-containing metal salt as the main active component of the catalyst, dichlorodiphenylmethane as the halogenating agent, to halogenate 5-hydroxymethylfurfural to 5-chloromethylfurfural. Dimethyl sulfoxide is used as both the solvent and the oxidant. Under this system, at atmospheric pressure and 100°C for 24 hours, the yield of 2,5-dicarboxyfuran can reach up to 94.25%. The reaction conditions are mild, the equipment requirements are low, the catalytic system is inexpensive and readily available, no toxic solvents are used, making it environmentally friendly, and the product yield and selectivity are high.

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Attached Figure Description

[0020] in:

[0021] Figure 1 The HPLC (high performance liquid chromatography) chromatogram of 2,5-dicarboxyfuran prepared in Example 1 of this invention is shown.

[0022] Figure 2 The figure shows the temperature and time conditions under which 2,5-diformylfuran was prepared in Example 9 of this invention. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0026] Example 1

[0027] Anhydrous CuCl2, 126 mg of 5-hydroxymethylfurfural, and 0.2 mL of dichlorodiphenylmethane were added to 5 mL of dimethyl sulfoxide. The mixture was stirred at 100 °C for 24 h under normal pressure to obtain a reaction mixture containing the target product, 2,5-diformylfuran. The yield of 2,5-diformylfuran was determined to be 94.25% by HPLC.

[0028] The HPLC detection results of the reaction mixture are as follows Figure 2 As shown, from Figure 2 It can be seen that the product 2,5-dicarboxyfuran was successfully obtained in this embodiment, and the yield of 2,5-dicarboxyfuran in this example is 94.25%. The HPLC detection conditions were as follows: a C18 reversed-phase column (250 × 4.6 mm) was used, and the mobile phase was acetonitrile and 0.1% acid solution (acetic acid) (V acetonitrile:V acid solution = 65:35). The detection results showed that the peak time of HMF was approximately 5.4-5.5 min, and the peak time of DFF was approximately 6.2 min.

[0029] Example 2

[0030] CuCl2, 126 mg of 5-hydroxymethylfurfural, and 0.2 mL of dichlorodiphenylmethane were added to 5 mL of dimethyl sulfoxide. The mixture was stirred at 100 °C for 24 h under normal pressure to obtain a reaction mixture containing the target product, 2,5-dicarboxyfuran. The yield of 2,5-dicarboxyfuran was determined by HPLC.

[0031] Example 3

[0032] NbCl5, 126 mg of 5-hydroxymethylfurfural, and 0.2 mL of dichlorodiphenylmethane were added to 5 mL of dimethyl sulfoxide. The mixture was stirred at 100 °C for 24 h under normal pressure to obtain a reaction mixture containing the target product, 2,5-dicarboxyfuran. The yield of 2,5-dicarboxyfuran was determined by HPLC.

[0033] Example 4

[0034] ZnCl2, 126 mg of 5-hydroxymethylfurfural, and 0.2 mL of dichlorodiphenylmethane were added to 5 mL of dimethyl sulfoxide. The mixture was stirred at 100 °C for 24 h under normal pressure to obtain a reaction mixture containing the target product, 2,5-dicarboxyfuran. The yield of 2,5-dicarboxyfuran was determined by HPLC.

[0035] Example 5

[0036] AlCl3·6H2O, 126 mg of 5-hydroxymethylfurfural, and 0.2 mL of dichlorodiphenylmethane were added to 5 mL of dimethyl sulfoxide. The mixture was stirred at 100 °C for 24 h under normal pressure to obtain a reaction mixture containing the target product, 2,5-dicarboxyfuran. The yield of 2,5-dicarboxyfuran was determined by HPLC.

[0037] Example 6

[0038] Anhydrous AlCl3, 126 mg of 5-hydroxymethylfurfural, and 0.2 mL of dichlorodiphenylmethane were added to 5 mL of dimethyl sulfoxide. The mixture was stirred at 100 °C for 24 h under normal pressure to obtain a reaction mixture containing the target product, 2,5-dicarboxyfuran. The yield of 2,5-dicarboxyfuran was determined by HPLC.

[0039] Example 7

[0040] Anhydrous FeCl3, 126 mg of 5-hydroxymethylfurfural, and 0.2 mL of dichlorodiphenylmethane were added to 5 mL of dimethyl sulfoxide. The mixture was stirred at 100 °C for 24 h under normal pressure to obtain a reaction mixture containing the target product, 2,5-dicarboxyfuran. The yield of 2,5-dicarboxyfuran was determined by HPLC.

[0041] The preparation of raw materials and the yield of 2,5-diformylfuran in Examples 1-7 are shown in Table 1.

[0042] Table 1 Effects of different catalysts and dosages on HMF conversion and DFF yield

[0043]

[0044]

[0045] *The amount of HMF used was 1 mmol, the amount of dimethyl sulfoxide was 5 ml, the amount of dichlorodiphenylmethane was 0.2 ml, the reaction time was 24 h, and the reaction temperature was 100 °C.

[0046] As shown in Table 1, different chlorine-containing metal salt catalysts can all yield the target compound. Among them, anhydrous CuCl2 and CuCl2 as catalysts can yield higher HMF conversion and higher yield of the target compound. The highest yield of DFF is obtained when the catalyst dosage is 0.03 mmol. Increasing or decreasing the catalyst dosage will decrease the yield. Anhydrous CuCl2 is the better catalyst.

[0047] Example 8

[0048] Under the experimental conditions of Example 1, 4.04 mg of anhydrous CuCl2, 126 mg of 5-hydroxymethylfurfural, and 0.2 ml of dichlorodiphenylmethane were added to anhydrous or aqueous dimethyl sulfoxide. The mixture was stirred at 100 °C for 24 h under normal pressure to obtain a reaction mixture containing the target product 2,5-diformylfuran. The yield of 2,5-diformylfuran was determined by HPLC. The experimental conditions and results are shown in Table 2.

[0049] Table 2 Effect of solvent type and dosage on DFF yield

[0050]

[0051] *The amount of HMF used is 1 mmol, and the amount of catalyst is 0.03 mmol.

[0052] *Reaction temperature: 100℃; Reaction time: 24 hours

[0053] As shown in Table 2, when the solvent is anhydrous dimethyl sulfoxide or dimethyl sulfoxide, the yield of DFF shows an increasing trend and the yield is the highest when the amount used is 5 ml. However, dimethyl sulfoxide is more effective than anhydrous dimethyl sulfoxide. As shown in Table 2, the concentration of the solution and whether the solvent contains water will affect the yield.

[0054] Example 9

[0055] Under the experimental conditions of Example 8, 4.04 mg of anhydrous CuCl2, 126 mg of 5-hydroxymethylfurfural, and dichlorodiphenylmethane were added to 5 ml of dimethyl sulfoxide. The mixture was heated and stirred for a certain time under normal pressure to obtain a reaction mixture containing the target product, 2,5-diformylfuran. The yield of 2,5-diformylfuran was determined by HPLC. The experimental conditions and results are shown in Table 3 and... Figure 1 .

[0056] Table 3 Effects of temperature and dichlorodiphenylmethane dosage on DFF yield

[0057]

[0058] *The dosage of HMF is 1 mmol, the dosage of catalyst is 0.03 mmol, and the dosage of dimethyl sulfoxide is 5 ml.

[0059] *Reaction time is 24 hours

[0060] *The dosage of HMF is 1 mmol, the dosage of catalyst is 0.03 mmol, the dosage of dimethyl sulfoxide is 5 ml, and the dosage of dichlorodiphenylmethane is 0.2 ml.

[0061] As shown in Table 3, when other conditions are constant, the reaction temperature is 100℃, and both increasing and decreasing the temperature will decrease the yield. When other conditions are constant, the amount of dichlorodiphenylmethane added is 0.2 ml, and both increasing and decreasing the amount of dichlorodiphenylmethane will decrease the yield. When the amount added is 0 ml, the reaction yield is almost zero. When other conditions are constant, the reaction time is 24 h, and both longer and shorter reaction times will decrease the yield.

[0062] This experiment uses a chlorine-containing metal salt as the main active component of the catalyst, dichlorodiphenylmethane as the halogenating agent, and dimethyl sulfoxide as the solvent and oxidant. Under this system, at atmospheric pressure and 100℃ for 24 hours, the yield of 2,5-dicarboxyfuran can reach up to 94.25%. The reaction conditions are mild, the equipment requirements are low, the catalytic system is inexpensive and readily available, no toxic solvents are used, making it environmentally friendly, and the product yield is high, the selectivity is high, and the product separation operation is simple.

[0063] The inventors discovered that when using one of the following as the main active components of a catalyst—anhydrous copper chloride, zinc chloride, ferric chloride, niobium chloride, or aluminum chloride—at a dosage of 0.03 mmol, the yield of 2,5-dicarboxyfuran and the conversion rate of 5-hydroxymethylfurfural were both low when using NbCl5, ZnCl2, AlCl3·6H2O, anhydrous AlCl3, or anhydrous FeCl3 as catalysts. However, when using anhydrous CuCl2 as a catalyst, the yield of 2,5-dicarboxyfuran was 94.25%, and the yield of 2,5-dicarboxyfuran was 84.52%, with the conversion rate of 5-hydroxymethylfurfural reaching 100% in both cases.

[0064] Through preliminary exploratory experiments, the inventors discovered that using anhydrous dimethyl sulfoxide as a solvent, after a reaction time of 24 hours, the conversion rate of 5-hydroxymethylfurfural was 100%, and the yield of 2,5-dicarboxyfuran was 89.64%; using dimethyl sulfoxide as a solvent, after a reaction time of 24 hours, the conversion rate of 5-hydroxymethylfurfural was 100%, and the yield of 2,5-dicarboxyfuran was 94.25%. Therefore, it is evident that using dimethyl sulfoxide as a solvent in this invention significantly improves the catalytic effect, provides mild reaction conditions, has low equipment requirements, and is suitable for industrial production.

[0065] In summary, this invention uses 5-hydroxymethylfurfural as a raw material, a chlorinated metal salt as the main active component of the catalyst, and dichlorodiphenylmethane as a halogenating agent to halogenate 5-hydroxymethylfurfural to 5-chloromethylfurfural. Dimethyl sulfoxide is used as both a solvent and an oxidizing agent. Under normal pressure and at 80–180°C for a certain time, the reaction yields 2,5-dicarboxyfuran after oxidation. The invention exhibits high oxidation efficiency, high product yield, high selectivity, and uses an inexpensive and readily available catalyst. Furthermore, the product is easily separated and purified, demonstrating promising prospects for industrial application.

[0066] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing 2,5-dicarboxyfuran by selective oxidation of 5-hydroxymethylfurfural without TEMPO, characterized in that, 0.03 mmol of CuCl2, 126 mg of 5-hydroxymethylfurfural, and 0.2 ml of dichlorodiphenylmethane were added to 5 ml of dimethyl sulfoxide. The mixture was stirred at 100 °C for 24 h under normal pressure to obtain a reaction mixture containing the target product 2,5-dicarboxyfuran.

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