Method for preparing 2, 5-diformyl furan by catalyzing fructose by using ionic liquid and vanadium complex

Abstract

The invention provides a method for preparing 2, 5-diformyl furan by catalyzing fructose by using an ionic liquid and a vanadium complex, which comprises the following steps: carrying out dehydration reaction by using the fructose as a raw material and the ionic liquid as a reaction solvent and a catalyst to obtain 5-hydroxymethylfurfural, then adding a V / HCP-AQ catalyst, and carrying out oxidation reaction on the 5-hydroxymethylfurfural in an oxygen atmosphere to obtain the 2, 5-diformyl furan. And 3, 5-diformyl furan is obtained. According to the method, the ionic liquid is adopted to replace DMSO to serve as a fructose dehydration and oxidation solvent, ethyl acetate is added into a reaction system for extraction after the reaction is finished, the product 2, 5-diformyl furan can be obtained, and the problem that the product is difficult to separate in the process of preparing the 2, 5-diformyl furan through the fructose one-pot method under a traditional catalytic system is solved.

Description

Technical Field

[0001] This invention relates to the fields of catalyst application and organic synthesis technology, and in particular to a method for preparing 2,5-diformylfuran from fructose using ionic liquids and vanadium complexes. Background Technology

[0002] With the over-consumption of fossil resources and the resulting increasingly severe energy and environmental problems, utilizing renewable biomass resources to produce high-value-added chemicals has become an important direction for the sustainable chemical industry. 2,5-Diformylfuran, as an important biomass-based platform compound, has broad application prospects in adhesives, foam materials, drug synthesis, and novel polymer monomers.

[0003] Currently, the synthesis of 2,5-dicarboxyfuran mainly relies on the oxidation of its precursor, 5-hydroxymethylfurfural. However, 5-hydroxymethylfurfural itself is chemically reactive and easily decomposes or polymerizes under acidic, alkaline, light, and oxygen conditions, resulting in poor stability, difficult separation and purification, and high production costs. Therefore, developing a technology for the efficient one-pot direct preparation of 2,5-dicarboxyfuran from carbohydrates has become a research hotspot in this field.

[0004] Existing research indicates that the one-pot synthesis of 2,5-dicarboxyfuran from carbohydrates (such as fructose and glucose) mainly employs two types of catalytic strategies: (1) Combined catalytic systems: that is, using dehydration catalysts (such as solid acids) and oxidation catalysts (such as V-based, Mn-based, and Ru-based catalysts) stepwise or simultaneously to achieve the dehydration and oxidation of carbohydrates in a single reactor. (2) Bifunctional catalysts: simultaneously constructing acidic sites (responsible for dehydration) and oxidative active sites (responsible for oxidation) on the same catalyst to simplify the reaction process.

[0005] Despite considerable research, existing technologies still face the following prominent challenges: demanding reaction conditions, with most reaction systems requiring the use of environmentally unfriendly solvent DMSO, making product separation from the reaction system difficult; difficulties in catalyst design and recovery, with homogeneous catalysts being hard to recover and prone to metal contamination; heterogeneous catalysts being prone to deactivation due to carbon buildup; and the synergistic mechanism between acidity and oxidation sites in bifunctional catalysts remaining unclear, making it difficult to balance activity and stability. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for preparing 2,5-dicarboxyfuran from fructose using ionic liquids and vanadium complexes. This method addresses the problems of existing 2,5-dicarboxyfuran synthesis methods, such as harsh reaction conditions, the need for environmentally unfriendly solvents, difficulty in product separation, difficulty in catalyst recovery, easy deactivation, easy metal contamination, and difficulty in balancing catalyst activity and stability.

[0007] To achieve the above and other related objectives, the present invention provides a method for preparing 2,5-dicarboxyfuran from fructose using ionic liquids and vanadium complexes as catalysts. The method is characterized by using fructose as a raw material, employing an ionic liquid as a reaction solvent and catalyst to carry out a dehydration reaction to obtain 5-hydroxymethylfurfural, then adding a V / HCP-AQ catalyst, and oxidizing the 5-hydroxymethylfurfural in an oxygen atmosphere to obtain 2,5-dicarboxyfuran.

[0008] Using the catalytic system of this invention, 2,5-diformylfuran can be efficiently synthesized from fructose in a one-pot, two-step process.

[0009] Preferably, the V / HCP-AQ catalyst is prepared by a method comprising the following steps: (1) 2-hydroxy-N-(quinoline-8-yl)benzamide, p-dichlorobenzyl, and anhydrous ferric chloride were dispersed in an organic solvent and reacted in a nitrogen atmosphere; the solid and liquid were separated, the solid was washed and dried to obtain the macromolecular ligand HCP-AQ; (2) Dissolve vanadium oxysulfate and sodium propionate in methanol, add macromolecular ligand HCP-AQ to react, separate solid and liquid, wash the solid, dry, and obtain V / HCP-AQ catalyst.

[0010] The preparation route of the V / HCP-AQ catalyst is shown below: .

[0011] More preferably, the V / HCP-AQ catalyst is prepared by a method comprising the following steps: (1) 2-hydroxy-N-(quinoline-8-yl)benzamide, p-dichlorobenzyl, anhydrous ferric chloride and organic solvent were added to a reaction flask and reacted at a certain temperature under a nitrogen atmosphere. After the reaction was completed, the solid was collected by filtration and washed with a large amount of methanol until the washing liquid was colorless. Then the solid was dried under vacuum to obtain the macromolecular ligand HCP-AQ. (2) Vanadium oxysulfate and sodium propionate were dissolved in methanol, and the macromolecular ligand HCP-AQ was added to the above solution and reacted at a certain temperature. After the reaction was completed, the solid was collected by filtration, and the solid was washed with methanol until the washing liquid was colorless. The solid was then dried under vacuum to obtain the V / HCP-AQ catalyst.

[0012] Preferably, in step (1), the molar ratio of 2-hydroxy-N-(quinoline-8-yl)benzamide to p-dichlorobenzyl and anhydrous ferric chloride is 1:(1~3):(2~5), more preferably 1:(1.15~1.6):(2.5~4).

[0013] Preferably, in step (1), the organic solvent is selected from one or more of toluene, methanol, ethyl acetate, ethanol and dichloroethane, more preferably dichloroethane.

[0014] Preferably, the reaction temperature is 50~120℃, more preferably 80~100℃; the reaction time is 10~30h, more preferably 18~24h.

[0015] Preferably, in step (2), the mass ratio of the macromolecular ligand HCP-AQ to vanadium oxysulfate and sodium propionate is 1:(1~3):(1~3); more preferably, it is 1:(1~1.5):(1~1.5).

[0016] Preferably, the reaction temperature is 40~100℃, more preferably 50~80℃, and the reaction time is 10~30h, more preferably 15~25h.

[0017] Preferably, the ionic liquid is selected from one of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hydrogen sulfate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium bromide, and 1-butyl-3-methylimidazolium chloride; more preferably, it is 1-butyl-3-methylimidazolium bromide or 1-butyl-3-methylimidazolium chloride.

[0018] Preferably, the mass ratio of fructose to ionic liquid is 1:(2~7), more preferably 1:(3~5).

[0019] Preferably, the dehydration reaction temperature is 100~140℃; the dehydration reaction time is 10min~1h.

[0020] Preferably, the mass ratio of catalyst V / HCP-AQ to fructose is 1:(2~9), more preferably 1:(2~5).

[0021] Preferably, the oxidation reaction temperature is 100~140℃ and the reaction time is 10~20h, more preferably 12~18h.

[0022] As described above, the present invention has the following beneficial effects: (1) In this invention, ionic liquid is used instead of DMSO as the solvent for fructose dehydration and oxidation. After the reaction is completed, ethyl acetate is added to the reaction system for extraction to obtain the product 2,5-dicarboxyfuran, which solves the problem of difficult separation of products in the one-pot preparation of 2,5-dicarboxyfuran from fructose under the traditional catalytic system. (2) After separating the product 2,5-dicarboxyfuran, acetonitrile is added to the mixture of ionic liquid and catalyst, and the catalyst can be separated by filtration. The ionic liquid can be obtained by desolvation of the filtrate under reduced pressure, thus realizing the recovery of ionic liquid and catalyst. (3) The catalytic system of the present invention is mainly composed of V / HCP-AQ catalyst and ionic liquid. The catalytic system has excellent catalytic effect and can be recycled. Attached Figure Description

[0023] Figure 1 The image shows the infrared spectrum of the V / HCP-AQ catalyst prepared according to this invention.

[0024] Figure 2 The image shows the XRD pattern of the V / HCP-AQ catalyst prepared in this invention.

[0025] Figure 3 The image shows the XPS spectrum of the V / HCP-AQ catalyst prepared in this invention.

[0026] Figure 4 The N2 adsorption-desorption isotherm spectrum of the V / HCP-AQ catalyst prepared in this invention is shown.

[0027] Figure 5 This is a pore size distribution spectrum of the V / HCP-AQ catalyst prepared in this invention. Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0030] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0031] In the following embodiments of the present invention, the preparation method of the V / HCP-AQ catalyst includes the following steps: (1) 1.32 g of 2-hydroxy-N-(quinoline-8-yl)benzamide (5 mmol), 1.05 g of p-dichlorobenzyl (6 mmol), 2.445 g of anhydrous ferric chloride (15 mmol) and 40 mL of dichloroethane were added to a reaction flask and reacted at 90 °C for 20 h under a nitrogen atmosphere. After the reaction was completed, the solid was collected by filtration and washed with a large amount of methanol until the washing liquid was colorless. Then the solid was dried under vacuum at 80 °C to obtain the macromolecular ligand HCP-AQ; (2) 1.63 g of vanadium oxysulfate (10 mmol) and 1.44 g of sodium propionate (15 mmol) were dissolved in 50 mL of methanol. 1.2 g of the macromolecular ligand HCP-AQ was added to the above solution, and the mixture was stirred at 70 °C for 24 h. After the reaction was completed, the solid was collected by filtration and washed with a large amount of methanol until the washing liquid was colorless. The solid was then dried under vacuum at 80 °C to obtain the macromolecular ligand HCP-AQ. After the reaction was completed, the solid was collected by filtration and washed with methanol until the filtrate was colorless. The solid was then dried under vacuum at 80 °C to obtain the V / HCP-AQ catalyst.

[0032] The characterization results of the V / HCP-AQ catalyst prepared in the embodiments of this application are as follows: Figures 1-5 As shown: from Figure 1 It can be seen that V=O (972 cm⁻¹) appears in the infrared spectrum. -1 The characteristic peaks at 2900 cm⁻¹ confirmed the successful incorporation of vanadium into V / HCP-AQ. Furthermore, the characteristic peaks at 2900 cm⁻¹ further confirmed the successful incorporation of vanadium. -1 (Methylene C–H stretching vibration), 1650 cm -1 (Amide I, C=O stretching vibration), 1531 cm -1 (Amide II, N–H bending vibration) and 1317 cm-1 The characteristic peaks appearing at (amide III, C–N stretching / N–H deformation vibrations) also indicate the formation of the catalyst's organic framework HCP-AQ.

[0033] from Figure 2 It can be seen that the XRD patterns of HCP-AQ and V / HCP-AQ show two broad diffraction peaks at 16.3° and 22.3°, indicating that HCPs are amorphous. Simultaneously, the two spectral lines exhibit highly consistent overall characteristics, with only slight differences in local intensity, indicating that the introduction of vanadium species did not alter the amorphous network structure of the catalyst support, thus confirming the high dispersion of vanadium on the catalyst surface.

[0034] from Figure 3 It can be seen that the XPS full spectrum confirms the presence of C, N, O, and V elements in the V / HCP-AQ catalyst. High-resolution spectrum fitting results indicate that V 2p 3 / 2 The peaks at 517.0 eV and 515.8 eV in the spectrum are assigned to V, respectively. 5+ and V 4+ The peaks at 531.6 eV and 533.0 eV in the O 1s spectrum can be identified as the amide carbonyl group (C=O) and the CO bond, respectively; the peaks at 399.2 eV and 400.3 eV in the N 1s spectrum correspond to pyridine nitrogen and amide nitrogen, respectively. This indicates that vanadium exists in multiple valence states in the catalyst, which is consistent with the HCP-AQ structure revealed in the infrared spectrum.

[0035] from Figure 4 It can be seen that the N2 adsorption-desorption isotherms of the V / HCP-AQ catalyst exhibit complex characteristics: in the low-pressure region, it shows a type III isotherm, indicating that the interaction between the material surface and nitrogen molecules is weak and the microporous structure is underdeveloped; in the high-pressure region, it turns into a type II isotherm, accompanied by a type H3 hysteresis loop, which confirms the existence of slit-like mesopores formed by the accumulation of plate-like particles in the material.

[0036] from Figure 5 It can be seen that the pore size of the V / HCP-AQ catalyst is concentrated at 13 nm and is accompanied by a large number of macropores. Example 1

[0037] 90 mg of fructose (0.5 mmol) and 300 mg of 1-butyl-3-methylimidazolium bromide ionic liquid (1.4 mmol) were added to a sealed tube. The tube was placed in an oil bath at 120 °C and stirred for 20 min under air atmosphere. 30 mg of V / HCP-AQ catalyst was added to the above reaction system, the tube was sealed with a rubber stopper, the air inside the sealed tube was replaced with oxygen three times, an oxygen bulb was inserted, and the reaction was carried out at 120 °C for 14 h. After the reaction was completed, the reaction solution was cooled, and ethyl acetate was added for extraction to obtain an ethyl acetate layer containing the product 2,5-dicarboxyfuran. Gas chromatography with internal standard analysis showed that the yield of 2,5-dicarboxyfuran was 65%. Acetonitrile was added to the mixture of ionic liquid and catalyst, and the mixture was filtered to obtain the catalyst. The filtrate was desolvated under reduced pressure to obtain the ionic liquid, thus achieving the recovery of the ionic liquid and catalyst. Example 2

[0038] The difference between Example 2 and Example 1 is that the amount of V / HCP-AQ catalyst used is different, specifically 10 mg, and the gas phase yield of the product 2,5-dicarboxyfuran is 25%. Example 3

[0039] The difference between Example 3 and Example 1 is that the amount of V / HCP-AQ catalyst used is different, specifically 40 mg, and the gas phase yield of the product 2,5-dicarboxyfuran is 66%. Example 4

[0040] The difference between Example 4 and Example 1 is that the dehydration reaction and oxidation reaction temperatures are different, both being 100°C, and the gas phase yield of the product 2,5-dicarboxyfuran is 35%. Example 5

[0041] The difference between Example 5 and Example 1 is that the dehydration reaction and oxidation reaction temperatures are different, both being 140°C, and the gas phase yield of the product 2,5-dicarboxyfuran is 62%. Example 6

[0042] The V / HCP-AQ catalyst from Example 1 was repeatedly used in the reaction to prepare 2,5-dicarboxyfuran from fructose, following the same method as in Example 1. The catalyst was recovered five times, and the reaction results are shown in Table 1. Table 1. Recovered V / HCP-AQ catalyst for the fructose-to-2,5-dicarboxyfuran reaction

[0043] As shown in Table 1, in the recovery experiment, the yield of 2,5-dicarboxyfuran gradually decreased from 61% in the first cycle to 49% in the fifth cycle. The V / HCP-AQ catalyst still maintained about 75% of its initial activity after five cycles, which proves the basic stability and reusability of the catalyst.

[0044] Example 7 The ionic liquid from Example 1 was repeatedly used in the reaction to prepare 2,5-dicarboxyfuran from fructose, following the same method as in Example 1. The liquid was recovered five times, and the reaction results are shown in Table 2. Table 2. Reaction of recycled ionic liquids for the preparation of 2,5-dicarboxyfuran from fructose

[0045] As shown in Table 2, in the recovery experiment, the yield of 2,5-dicarboxyfuran gradually decreased from 60% in the first cycle to 49% in the fifth cycle. The ionic liquid still maintained about 75% of its initial activity after five cycles, which proves the basic stability and reusability of the ionic liquid.

[0046] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing 2,5-diformylfuran from fructose using ionic liquids and vanadium complexes as catalysts, characterized in that, Using fructose as a raw material and ionic liquid as a reaction solvent and catalyst, a dehydration reaction was carried out to obtain 5-hydroxymethylfurfural. Then, V / HCP-AQ catalyst was added, and 5-hydroxymethylfurfural under an oxygen atmosphere underwent an oxidation reaction to obtain 2,5-dicarboxyfuran.

2. The method according to claim 1, characterized in that: The V / HCP-AQ catalyst was prepared by a method comprising the following steps: (1) 2-hydroxy-N-(quinoline-8-yl)benzamide, p-dichlorobenzyl, and anhydrous ferric chloride were dispersed in an organic solvent and reacted in a nitrogen atmosphere; the solid and liquid were separated, the solid was washed and dried to obtain the macromolecular ligand HCP-AQ; (2) Dissolve vanadium oxysulfate and sodium propionate in methanol, add macromolecular ligand HCP-AQ to react, separate solid and liquid, wash the solid, dry, and obtain V / HCP-AQ catalyst.

3. The method according to claim 2, characterized in that: In step (1), the molar ratio of 2-hydroxy-N-(quinoline-8-yl)benzamide to p-dichlorobenzyl and anhydrous ferric chloride is 1:(1~3):(2~5).

4. The method according to claim 2, characterized in that: In step (1), the organic solvent is selected from one or more of toluene, methanol, ethyl acetate, ethanol and dichloroethane; the reaction temperature is 50~120℃ and the reaction time is 10~30h.

5. The method according to claim 2, characterized in that: In step (2), the mass ratio of the macromolecular ligand HCP-AQ to vanadium oxysulfate and sodium propionate is 1:(1~3):(1~3); the reaction temperature is 40~100℃ and the reaction time is 10~30h.

6. The method according to claim 1, characterized in that: The ionic liquid is selected from one of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hydrogen sulfate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium bromide, and 1-butyl-3-methylimidazolium chloride.

7. The method according to claim 1, characterized in that: The mass ratio of fructose to ionic liquid is 1:(2~7).

8. The method according to claim 1, characterized in that: The dehydration reaction temperature is 100~140℃; the dehydration reaction time is 10min~1h.

9. The method according to claim 1, characterized in that: The mass ratio of catalyst V / HCP-AQ to fructose is 1:(2~9).

10. The method according to claim 1, characterized in that: The oxidation reaction temperature is 100~140℃, and the reaction time is 10~20h.

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