Method for preparing 2, 5-diformyl furan from cellulose through one-step method

Abstract

The invention discloses a method for preparing 2, 5-diformyl furan from cellulose by a one-step method, which is characterized by comprising the following steps of: dissolving cellulose serving as a raw material, bromine salt or aluminum salt serving as a main active ingredient of a catalyst, oxygen and DMSO (dimethyl sulfoxide) serving as oxidants and a solvent system consisting of DMSO / TEAC (tetraethylammonium chloride), and reacting at normal pressure to obtain 2, 5-diformyl furan. The preparation method comprises the following steps of: reacting bromine salt or aluminum salt for a certain time at the temperature of between 80 and 180 DEG C, and converting cellulose into 2, 5-diformyl furan through cascade reaction by adopting a one-step method, and the bromine salt or the aluminum salt is one of aluminum bromide, iron bromide, copper bromide, aluminum chloride, aluminum nitrate nonahydrate and the like; the dosage of the bromine salt or the aluminum salt is 0.01 to 0.50 mmol; according to the present invention, the solvent system composed of dimethyl sulfoxide (DMSO) / tetraethylammonium chloride (TEAC) is adopted, the used catalyst is cheap and easily available, the reaction is performed at 140 DEG C for 20 h, the yield of the 2, 5-diformyl furan can achieve 66.3%, the reaction condition is mild, the requirement on the equipment is low, and the method is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of organic compound preparation, and particularly relates to a one-step method for preparing 2,5-diformylfuran from cellulose. Background Art

[0002] The efficient utilization of biomass resources is particularly important in today's increasingly severe global energy and environmental challenges. Efficient utilization of biomass resources is one of the key pathways to sustainable development. Cellulose, as a major component of biomass, is not only widely available, found in virtually every part of plants, including stems, leaves, and bark, but is also renewable and biodegradable, making it an ideal sustainable resource. These advantages give cellulose broad application prospects in a variety of fields, including energy, materials, and chemicals.

[0003] 2,5-Diformylfuran (DFF) is an important bio-based platform compound. Its molecular structure contains two formyl groups and a furan ring, and it exhibits excellent chemical activity and reactivity. It can be used as a monomer to synthesize biodegradable polyesters (such as PEF), replacing petroleum-based PET for packaging and fiber applications. It can also serve as a pharmaceutical intermediate in the synthesis of antimicrobial agents and anticancer drug precursors. It can also be used as a functional material to prepare fluorescent materials, adsorbents, or crosslinkers. Furthermore, it can promote the utilization of renewable resources and reduce carbon emissions in green chemistry. The application of DFF aligns with the needs of sustainable development and has significant potential in the chemical, pharmaceutical, and materials sectors. However, the high commercial price of DFF and the high cost of preparing DFF from HMF hinder its large-scale production and application.

[0004] In view of the above problems, the present invention proposes a one-step method for preparing 2,5-diformylfuran from cellulose inexpensively and environmentally friendly manner. Summary of the Invention

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, one of the objects of the present invention is to overcome the deficiencies of the prior art and provide a one-step method for preparing 2,5-diformylfuran from cellulose.

[0008] To solve the above technical problems, the present invention provides the following technical solution: A method for preparing 2,5-diformylfuran from cellulose in one step, which is characterized in that: including, using cellulose as a raw material, a solvent system composed of dimethyl sulfoxide (DMSO) / tetraethylammonium chloride (TEAC) to dissolve cellulose, using a bromide salt or an aluminum salt as the main active ingredient of the catalyst, and converting cellulose into 2,5-diformylfuran through a series of cascade reactions by a one-step method. The reaction process is as follows: Cellulose is first degraded into 5-hydroxymethylfurfural, which is converted into 5-bromomethylfurfural under the action of hydrobromic acid, and then using DMSO as an oxidant, 5-bromomethylfurfural undergoes Kornblum oxidation reaction to obtain the said 2,5-diformylfuran, or using oxygen as an oxidant to oxidize 5-hydroxymethylfurfural to obtain the said 2,5-diformylfuran. Under atmospheric pressure conditions, the reaction is carried out at 80-180°C for a certain period of time to obtain the said 2,5-diformylfuran. Among them, the said bromide salt or aluminum salt is one of aluminum bromide, iron bromide, copper bromide, aluminum chloride, aluminum nitrate nonahydrate, etc.; the dosage of the said bromide salt or aluminum salt is 0.01-0.50 mmol.

[0009] As a preferred scheme of the method for preparing 2,5-diformylfuran from cellulose according to the present invention, among them: the said bromide salt or aluminum salt is aluminum bromide.

[0010] As a preferred scheme of the method for preparing 2,5-diformylfuran from cellulose according to the present invention, among them: the dosage of the said aluminum bromide is 0.10 mmol.

[0011] As a preferred scheme of the method for preparing 2,5-diformylfuran from cellulose according to the present invention, among them: the solvent system composed of dimethyl sulfoxide (DMSO) / tetraethylammonium chloride (TEAC), among which, the dosage of cellulose is 16.2 mg.

[0012] As a preferred scheme of the method for preparing 2,5-diformylfuran from cellulose according to the present invention, among them: under the said atmospheric pressure conditions, the reaction is carried out at 80-180°C for a certain period of time, among which, the reaction time is 16-48 h.

[0013] As a preferred scheme of the method for preparing 2,5-diformylfuran from cellulose according to the present invention, among them: under the said atmospheric pressure conditions, the reaction is carried out at 80-180°C for a certain period of time, which means reacting at 140°C for 20 h.

[0014] As a preferred scheme of the method for preparing 2,5-diformylfuran from cellulose according to the present invention, among them: the said detection of the product includes, after the reaction is completed, taking 20 μL of the reaction solution and adding 1 mL of acetonitrile, and detecting the yield by high performance liquid chromatography.

[0015] The beneficial technical effects of the present invention:

[0016] The present invention uses aluminum bromide as the main active component of the catalyst, cellulose as the raw material, and a solvent system composed of dimethyl sulfoxide (DMSO) / tetraethylammonium chloride (TEAC) to dissolve cellulose. Using DMSO and oxygen as oxidants, under this system, at normal pressure, the reaction is carried out at 140 °C for 20 h, and the highest yield of 2,5-diformylfuran can reach 66.3%. The reaction conditions are mild, the requirements for equipment are low, the catalytic system is cheap and easily available, no toxic solvents are used, it is green and environmentally friendly, and the product yield and selectivity are high. Brief Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0018] Figure 1 It is the HPLC (high performance liquid chromatography) spectrum of 2,5-diformylfuran prepared in Example 1 of the present invention. Detailed Embodiments

[0019] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail in conjunction with the embodiments of the specification.

[0020] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0021] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" that appears in different places in this specification does not all refer to the same embodiment, nor is it a separate or selectively exclusive embodiment from other embodiments.

[0022] Example 1

[0023] Add 16.2 mg of cellulose to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreat at 80 °C for 15 min, add 26.67 mg of AlBr3 and 182 μL of water, then connect an oxygen balloon, and stir at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The high performance liquid chromatography detection results of the reaction mixture are as Figure 1As shown, from Figure 1 it can be seen that the product 2,5-diformylfuran was successfully obtained in this implementation. Among them, the conditions for HPLC detection are as follows: an RP-C18 column (250×4.6 mm) was used, and the mobile phase was acetonitrile and 0.1% aqueous acid (acetic acid) solution (Vacetonitrile:Vacid water = 65:35). The detection results showed that the peak time of HMF was about 5.5 min, and the peak time of DFF was about 6.2 - 6.3 min. The reaction mixture was measured by high-performance liquid chromatography, and the yield of 2,5-diformylfuran at a reaction temperature of 140 °C was 66.3%.

[0024] Example 2

[0025] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 29.57 mg of FeBr3 and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high-performance liquid chromatography, and the yield of 2,5-diformylfuran was 13.6%.

[0026] Example 3

[0027] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 40.4 mg of CuBr2 and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high-performance liquid chromatography, and the yield of 2,5-diformylfuran was 14.1%.

[0028] Example 4

[0029] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 13.33 mg of AlCl3 and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high-performance liquid chromatography, and the yield of 2,5-diformylfuran was 11.3%.

[0030] Example 5

[0031] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 37.5 mg of Al(NO3)3·9H2O and 182 μL of water were added, and then an oxygen balloon was connected. The mixture was stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The yield of 2,5-diformylfuran in the reaction mixture was measured by high performance liquid chromatography to be 7.2%.

[0032] The raw materials prepared in Examples 1-5 and the yields of 2,5-diformylfuran are shown in Table 1.

[0033] Table 1 Effects of different catalyst types and oxygen on the yield of DFF

[0034]

[0035] * The reaction raw material was MCC (16.2 mg), and the solvent was DMSO (3 mL) / TEAC (1.25 g)

[0036] * The reaction temperature was 140 °C and the reaction time was 20 h

[0037] As can be seen from Table 1, the table shows the effects of different catalysts on the yield of DFF. In contrast, the target compound with the highest yield can be obtained when AlBr3 is used as the catalyst, and AlBr3 is a better catalyst. All experiments were carried out under the condition of connecting an oxygen balloon, indicating that the oxygen environment has little effect on these catalysts.

[0038] Example 6

[0039] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected. The mixture was stirred at 140 °C for 18 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The yield of 2,5-diformylfuran at the reaction temperature of 140 °C was measured by high performance liquid chromatography to be 49%.

[0040] Example 7

[0041] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected. The mixture was stirred at 140 °C for 22 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The yield of 2,5-diformylfuran at the reaction temperature of 140 °C was measured by high performance liquid chromatography to be 60.7%.

[0042] Example 8

[0043] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr₃ and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 24 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 59.8%.

[0044] The raw materials prepared in Examples 6-8 and the yields of 2,5-diformylfuran are shown in Table 2.

[0045] Table 2 Effect of reaction time on the yield of DFF

[0046]

[0047] *The reaction raw material is MCC (16.2 mg), and the solvent is DMSO (3 mL) / TEAC (1.25 g)

[0048] *The reaction temperature is 140 °C

[0049] As can be seen from Table 2, when other conditions are the same, when reacting at 140 °C for 20 h, DFF obtains the highest yield, and increasing or decreasing the reaction time will reduce the yield of DFF.

[0050] Example 9

[0051] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (0.5 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr₃ and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 48.3%.

[0052] Example 10

[0053] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.0 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr₃ and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 60.5%.

[0054] Example 11

[0055] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.5 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 58.6%.

[0056] The raw materials prepared in Examples 9-11 and the yields of 2,5-diformylfuran are shown in Table 3.

[0057] Table 3 Effect of different TEAC dosages on the yield of DFF

[0058] Example TEAC (g) DFF Yield (%) 1 1.25 66.3 9 0.50 48.3 10 1.00 60.5 11 1.50 58.6

[0059] * The reaction raw material is MCC (16.2 mg), and the solvent is DMSO (3 mL) / TEAC

[0060] * The reaction temperature is 140 °C and the reaction time is 20 h

[0061] As can be seen from Table 3, when other conditions are the same, different dosages of tetraethylammonium chloride have an impact on the yield of DFF. When the dosage of TEAC in the DMSO / TEAC combination is 1.25 g, the yield of DFF is the highest. It shows that the dosage of tetraethylammonium chloride has a significant impact on the yield of DFF, and there is an optimal dosage range.

[0062] Example 12

[0063] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 18.67 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 40.6%.

[0064] Example 13

[0065] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 24 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 51%.

[0066] Example 14

[0067] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 29.34 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 55.1%.

[0068] The raw materials prepared in Examples 12-14 and the yields of 2,5-diformylfuran are shown in Table 4.

[0069] Table 4 Effects of different amounts of AlBr3 on the yield of DFF

[0070] Example <![CDATA[AlBr3(mmol)]]> DFF Yield (%) 1 0.1 66.3 12 0.07 40.6 13 0.09 51 14 0.11 55.1

[0071] *The reaction raw material is MCC (16.2 mg), and the solvent is DMSO (3 mL) / TEAC (1.25 g)

[0072] *The reaction temperature is 140 °C and the reaction time is 20 h

[0073] It can be seen from Table 4 that when other conditions are the same, different amounts of AlBr3 catalyst have a certain effect on the yield of DFF. When the amount of AlBr3 is 0.1 mmol, the yield of DFF is the highest, reaching 66.3%. Generally speaking, the amount of AlBr3 has a significant effect on the yield of DFF, and there is an optimal dosage range.

[0074] Example 15

[0075] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected. The mixture was stirred at 130 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The yield of 2,5-diformylfuran in the reaction mixture was measured by high performance liquid chromatography to be 57.9% at the reaction temperature of 130 °C.

[0076] Example 16

[0077] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected. The mixture was stirred at 150 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The yield of 2,5-diformylfuran in the reaction mixture was measured by high performance liquid chromatography to be 51.9% at the reaction temperature of 150 °C.

[0078] Example 17

[0079] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected. The mixture was stirred at 160 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The yield of 2,5-diformylfuran in the reaction mixture was measured by high performance liquid chromatography to be 40.6% at the reaction temperature of 160 °C.

[0080] The raw material preparation and the yield of 2,5-diformylfuran in Examples 15 - 17 are shown in Table 5.

[0081] Table 5 Effect of reaction temperature on the yield of DFF

[0082]

[0083] * The reaction raw material is MCC (16.2 mg), and the solvent is DMSO (3 mL) / TEAC (1.25 g)

[0084] * The reaction time is 20 h

[0085] As can be seen from Table 5, when other conditions are the same, the highest yield of DFF is obtained by reacting at 140 °C for 20 h. Increasing or decreasing the reaction temperature will reduce the yield of DFF.

[0086] Example 18

[0087] 16.2 mg of cellulose was added to the solvent system composed of DMSO (2 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 52%.

[0088] Example 19

[0089] 16.2 mg of cellulose was added to the solvent system composed of DMSO (4 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 51.7%.

[0090] Example 20

[0091] 16.2 mg of cellulose was added to the solvent system composed of DMSO (5 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then an oxygen balloon was connected, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 41.3%.

[0092] The raw materials prepared in Examples 18 to 20 and the yields of 2,5-diformylfuran are shown in Table 6.

[0093] Table 6 Effect of Solvent Dosage on the Yield of DFF

[0094]

[0095] * The reaction raw material is MCC (16.2 mg), and the solvent is DMSO / TEAC (1.25 g)

[0096] * The reaction temperature is 140 °C and the reaction time is 20 h

[0097] As can be seen from Table 6, when other conditions are the same, when the dosage of DMSO in the DMSO / TEAC combination is 3 ml, higher yield of DFF can be obtained. Increasing or decreasing the dosage of DMSO in the mixed solvent of DMSO / TEAC will reduce the yield of DFF.

[0098] Example 21

[0099] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then air was introduced, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 50.5%.

[0100] Example 22

[0101] 16.2 mg of cellulose was added to the solvent system composed of DMSO (3 ml) / TEAC (1.25 g), pretreated at 80 °C for 15 min, 26.67 mg of AlBr3 and 182 μL of water were added, and then a nitrogen balloon (without oxygen) was added, and stirred at 140 °C for 20 h to obtain a reaction mixture containing the target product 2,5-diformylfuran. The reaction mixture was measured by high performance liquid chromatography, and the yield of 2,5-diformylfuran at the reaction temperature of 140 °C was 44.1%.

[0102] The raw materials prepared and the yields of 2,5-diformylfuran in Examples 21 to 23 are shown in Table 7.

[0103] Table 7 Effect of oxygen on the yield of DFF

[0104] Example Oxygen State DFF Yield (%) 1 With Oxygen Balloon 66.3 21 Without Oxygen Balloon but Containing Air 50.5 22 Nitrogen Balloon (Without Oxygen) 44.1

[0105] * The reaction raw material is MCC (16.2 mg), and the solvent is DMSO (3 ml) / TEAC (1.25 g)

[0106] * The reaction temperature is 14 °C, and the reaction time is 20 h

[0107] As can be seen from Table 7, under the condition that other conditions are the same, when an oxygen balloon is introduced into the reaction system, the higher the oxygen concentration, the greater the improvement in the yield of DFF.

[0108] The present invention uses aluminum bromide as the main active ingredient of the catalyst, cellulose as the raw material, oxygen and DMSO as the oxidants, dissolves cellulose in a solvent system composed of dimethyl sulfoxide (DMSO) / tetraethylammonium chloride (TEAC), and through a series of cascade reactions, first degrades it into 5-hydroxymethylfurfural, which is then converted into 5-bromomethylfurfural under the action of hydrobromic acid. The 5-bromomethylfurfural undergoes Kornblum oxidation reaction to obtain the said 2,5-diformylfuran. At the same time, oxygen also oxidizes 5-hydroxymethylfurfural to obtain the said 2,5-diformylfuran. Under this system, at normal pressure, reacting at 140 °C for 20 h, the yield of 2,5-diformylfuran can reach up to 66.3%. The reaction conditions are mild, the requirements for equipment are low, the catalytic system is cheap and easily available, it is green and environmentally friendly, and the product yield and selectivity are high.

[0109] The inventors found that using aluminum bromide as the main active ingredient of the catalyst, aluminum bromide has high catalytic activity, probably because aluminum bromide has strong Lewis acidity, and the HBr generated in the system replaces the hydroxyl group of 5-hydroxymethylfurfural to be converted into 5-bromomethylfurfural. Then, using DMSO as the oxidant, the 5-bromomethylfurfural undergoes Kornblum oxidation reaction, thereby promoting the formation of 2,5-diformylfuran. At the same time, the oxygen in the system also oxidizes 5-hydroxymethylfurfural to obtain 2,5-diformylfuran.

[0110] The present invention uses a solvent system composed of dimethyl sulfoxide (DMSO) / tetraethylammonium chloride (TEAC) to dissolve cellulose, reacts at 140 °C for 20 h, and the yield of 2,5-diformylfuran can reach up to 66.3%. Thus, it can be seen that the solvent system composed of dimethyl sulfoxide (DMSO) / tetraethylammonium chloride (TEAC) can significantly improve the catalytic effect, and the reaction time is short, the reaction conditions are mild, the requirements for equipment are low, and it is suitable for industrial production.

[0111] In summary, the present invention uses cellulose as the raw material, a solvent system composed of dimethyl sulfoxide (DMSO) / tetraethylammonium chloride (TEAC) to dissolve cellulose, aluminum bromide as the main active ingredient of the catalyst, oxygen and DMSO as the oxidants, and uses a one-step method to convert cellulose into 2,5-diformylfuran through a series of cascade reactions. At normal pressure, reacting at 140 °C for 20 h, after oxidation, the said 2,5-diformylfuran is obtained. The oxidation efficiency is high, the product yield and selectivity are high, the catalyst is cheap and easily available, and it has good industrial application prospects.

[0112] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for preparing 2,5-diformylfuran by a one-step process using microcrystalline cellulose (MCC), characterized in that: Comprising, Using cellulose as raw material, a solvent system composed of dimethyl sulfoxide (DMSO) / tetraethylammonium chloride (TEAC) is used to dissolve cellulose. With bromide salt or aluminum salt as the main active ingredient of the catalyst, cellulose is converted into 2,5-diformylfuran through a series of cascade reactions by a one-step method. The reaction process is as follows: Cellulose is first degraded into 5-hydroxymethylfurfural, which is then converted into 5-bromomethylfurfural under the action of hydrobromic acid. Then, using DMSO as the oxidant, 5-bromomethylfurfural undergoes Kornblum oxidation reaction to obtain the said 2,5-diformylfuran, or using oxygen as the oxidant, 5-hydroxymethylfurfural is oxidized to obtain the said 2,5-diformylfuran. Under atmospheric pressure conditions, the reaction is carried out at 80-180°C for a certain time to obtain the said 2,5-diformylfuran, wherein, The said bromide salt or aluminum salt is one of aluminum bromide, iron bromide, copper bromide, aluminum chloride, aluminum nitrate nonahydrate, etc.; The dosage of the said bromide salt or aluminum salt is 0.01-0.50 mmol.

2. The method for preparing 2,5-diformylfuran from cellulose according to claim 1, characterized in that: The said bromide salt or aluminum salt is aluminum bromide.

3. The method for preparing 2,5-diformylfuran from cellulose according to claim 1 or 2, characterized in that: For the said aluminum bromide, its dosage is 0.10 mmol.

4. The method for preparing 2,5-diformylfuran from cellulose according to claim 1, wherein: For the solvent system composed of dimethyl sulfoxide (DMSO) / tetraethylammonium chloride (TEAC), wherein the dosage of cellulose is 16.2 mg.

5. The method for preparing 2,5-diformylfuran from cellulose according to claim 1, characterized in that: Under the said atmospheric pressure conditions, the reaction is carried out at 80-180°C for a certain time, wherein the reaction time is 16-48 h.

6. The method for preparing 2,5-diformylfuran from cellulose according to claim 1 or 8, characterized in that: Under the said atmospheric pressure conditions, the reaction is carried out at 80-180°C for a certain time, which means the reaction is carried out at 140°C for 20 h.

7. The method for preparing 2,5-diformylfuran from cellulose according to claim 1, wherein: For the said detection of the product, comprising, after the reaction is completed, 20 μL of the reaction solution is taken and added to 1 mL of acetonitrile, and the yield is detected by high performance liquid chromatography (HPLC).

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