Method for preparing 2, 5-furandicarboxylic acid from fructose

Abstract

The invention provides a method for preparing 2, 5-furandicarboxylic acid from fructose, and relates to the technical field of organic synthesis. The invention relates to a method for preparing 2, 5-furandicarboxylic acid from fructose, which comprises the following steps: adding a reaction solvent, fructose and inorganic acid into a reaction container, heating to 80-150 DEG C, and reacting for 0.5-3 hours; and after the reaction is finished, continuing to add brominated salt, piperidine nitrogen oxide and halogenated isocyanuric acid, and carrying out oxidation reaction at 15-70 DEG C for 0.5-5 hours to obtain the 2, 5-furandicarboxylic acid. According to the method, a one-pot two-step method is adopted, FDCA is directly obtained after fructose is subjected to a dehydration reaction and an oxidation reaction, halogenated isocyanuric acid is adopted as an oxidizing agent, piperidine nitrogen oxide is adopted as a catalyst, bromide is adopted as a co-catalyst, the oxidation efficiency is high, the effect is good, and FDCA is high in yield and good in purity.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis and relates to a method for preparing 2,5-furandicarboxylic acid from fructose. Background Art

[0002] Due to the increasing shortage of traditional petrochemical resources and environmental pollution problems, people have gradually turned their attention to biomass materials. Among them, 2,5-furandicarboxylic acid (FDCA), as one of the important intermediate compound derivatives, can be polymerized with ethylene glycol to produce polyethylene 2,5-furandicarboxylate (PEF). Due to its wide biomass source and good air barrier properties, it is expected to become the most potential substitute for petroleum-based polyethylene terephthalate (PET), and therefore has broad market prospects.

[0003] At present, the method of preparing 2,5-furandicarboxylic acid from biomass mostly adopts the furfural method, which is to dehydrate fructose to generate 5-hydroxymethylfurfural (5-Hydroxymethylfurfural, HMF), and then oxidize it to obtain 2,5-furandicarboxylic acid. In this process, due to the difficulty in separating and extracting HMF, the production cost remains high. Therefore, it is of great significance to study how to realize the reaction process from fructose to FDCA in a one-pot two-step method with low cost, simplicity and high efficiency.

[0004] Document 1 discloses a method for obtaining the product 2,5-furandicarboxaldehyde by using fructose as a raw material, piperidine nitrogen oxide as a catalyst, acid and nitrite as co-catalysts in the presence of an organic solvent and an oxygen source. However, in this method, hydrochloric acid, hydrobromic acid, and hydroiodic acid are suitable for use as acids to achieve a higher yield, and what is obtained is 2,5-furandicarboxaldehyde, not 2,5-furandicarboxylic acid.

[0005] Document 1: CN108675971A. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method for preparing 2,5-furandicarboxylic acid from fructose.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing 2,5-furandicarboxylic acid from fructose comprises: adding a reaction solvent, fructose and an inorganic acid into a reaction container, heating to 80-150° C. and reacting for 0.5-3 hours; after the reaction is completed, continuing to add a bromide salt, piperidine nitrogen oxide and a halogenated isocyanuric acid, and performing an oxidation reaction at 15-70° C. for 0.5-5 hours to obtain the 2,5-furandicarboxylic acid.

[0009] Preferably, the reaction solvent consists of water and an organic solvent in a weight ratio of 1:(1-100).

[0010] More preferably, the solubility of the organic solvent in water at 20° C. is not less than 5 g / 100 ml.

[0011] Preferably, the inorganic acid is selected from one or a combination of two or more of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.

[0012] Preferably, the weight ratio of the reaction solvent, the fructose and the inorganic acid is (10-100):1:(0.001-0.1).

[0013] Preferably, the bromide salt is selected from one or a combination of two or more of sodium bromide, potassium bromide, lithium bromide, calcium bromide, copper bromide, zinc bromide, nickel bromide and magnesium bromide.

[0014] Preferably, the piperidine N-oxide is selected from 2,2,6,6-tetramethylpiperidine N-oxide and its derivatives.

[0015] More preferably, the derivative is the 2,2,6,6-tetramethylpiperidine nitrogen oxide substituted at the 4-position.

[0016] Preferably, the halogenated isocyanuric acid is selected from one or a combination of two or more of bromoisocyanuric acid, dichloroisocyanuric acid, trichloroisocyanuric acid, chloroisocyanuric acid and chlorobromoisocyanuric acid.

[0017] Preferably, the weight ratio of the fructose, the bromide salt, the piperidine nitrogen oxide and the halogenated isocyanuric acid is 1:(0.01-1):(0.001-0.1):(0.5-10).

[0018] The beneficial effects of the present invention are:

[0019] (1) The present invention adopts a "one-pot two-step method" to directly prepare FDCA from a fructose raw material in the same reaction vessel through two steps of heating dehydration and oxidation. Fructose is first converted into HMF by heating dehydration, and then piperidine nitrogen oxide is added as a catalyst, halogenated isocyanuric acid is added as an oxidant, and bromide salt is added as a co-catalyst. The reaction process is mild, the conversion rate of fructose is high, the post-reaction treatment is simple, and a high-purity FDCA product can be obtained.

[0020] (2) The present invention uses bromide salt as a co-catalyst for halogenated isocyanuric acid, which can significantly improve the efficiency of converting the raw material HMF into FDCA through oxidation reaction, thereby increasing the conversion rate of HMF and the yield of FDCA. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0022] In order to realize the "one-pot method" to directly prepare FDCA from fructose and obtain FDCA with high yield and purity, the present invention provides a method for preparing 2,5-furandicarboxylic acid from fructose, comprising: adding a reaction solvent, fructose and an inorganic acid into a reaction container, heating to 80-150° C. and reacting for 0.5-3 h; after the reaction is completed, continuing to add a bromide salt, piperidine nitrogen oxide and a halogenated isocyanuric acid, and performing an oxidation reaction at 15-70° C. for 0.5-5 h to obtain 2,5-furandicarboxylic acid.

[0023] The present invention adopts a "one-pot two-step method" to directly prepare FDCA from fructose. Fructose is first dehydrated to generate 5-hydroxymethylfurfural HMF, and then raw materials such as an oxidant, a catalyst, and a co-catalyst are added to a reaction container for oxidation reaction, so that FDCA with high yield and high purity can be obtained, and the reaction process is mild and the post-treatment is simple.

[0024] In a preferred embodiment of the present invention, the reaction solvent is composed of water and an organic solvent in a weight ratio of 1: (1-100). The reaction solvent is composed of water and an organic solvent, which can dissolve fructose well and is conducive to the dehydration reaction of fructose by inorganic acid. For example, the weight ratio of water and the organic solvent can be any value or any value between 1: 1, 1: 5, 1: 10, 1: 15, 1: 20, 1: 25, 1: 30, 1: 35, 1: 40, 1: 45, 1: 50, 1: 60, 1: 70, 1: 80, 1: 90, 1: 100, etc., without particular limitation. More preferably, the reaction solvent is composed of water and an organic solvent in a weight ratio of 1: (5-100).

[0025] In a more preferred embodiment of the present invention, the solubility of the organic solvent in water at 20°C is not less than 5g / 100ml. The organic solvent has a certain solubility in water, and the organic solvent can form a reaction solvent with water. For example, the organic solvent can be methyl isobutyl ketone, ethyl acetate, acetonitrile, acetone, DMSO, DMF, DMAc, methyl ethyl ketone, 1,4-dioxane, methyl pyrrolidone, etc.

[0026] In a preferred embodiment of the present invention, the inorganic acid is selected from one or a combination of two or more of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid. The inorganic acid is used to dehydrate fructose, and the conversion rate of the reaction is high, and fructose can be relatively fully converted into HMF. In the present invention, the concentration of the inorganic acid is not particularly limited, and can be 0.5-5 mol / L, or, for example, the hydrochloric acid can be concentrated hydrochloric acid. In addition, the dehydration uses an inorganic acid, and the inorganic acid contributes to the decomposition of the halogenated isocyanuric acid in the subsequent oxidation reaction of HMF to FDCA, and continuously and stably releases hypohalous acid, which has a stable and continuous oxidation effect on the oxidation reaction process.

[0027] In a preferred embodiment of the present invention, the weight ratio of the reaction solvent, fructose and the inorganic acid is (10-100):1:(0.001-0.1). For example, the weight ratio of the reaction solvent, fructose and the inorganic acid can be 10:1:0.001, 10:1:0.005, 10:1:0.01, 10:1:0.03, 10:1:0.06, 10:1:0.1, 30:1:0.001, 30:1:0.005, 30:1:0.01, 30:1:0.05, 30:1:0.1, 50:1:0 :1:0.001, 50:1:0.005, 50:1:0.01, 50:1:0.05, 50:1:0.1, 100:1:0.001, 100:1:0.005, 100:1:0.01, 100:1:0.03, 100:1:0.05, 100:1:0.1, etc., or any value therebetween, without particular limitation. More preferably, the weight ratio of the reaction solvent to fructose may be 10-80:1, for example, the weight ratio may be 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 60:1, 70:1, 80:1, etc., or any value therebetween, without particular limitation. More preferably, the weight ratio of fructose to inorganic acid can be 1:0.005-0.08. For example, it can be any value among 1:0.005, 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04, 1:0.045, 1:0.05, 1:0.055, 1:0.06, 1:0.065, 1:0.07, 1:0.075, 1:0.08, etc. or any value in between, without particular limitation.

[0028] Halogenated isocyanuric acid is an oxidant with good oxidizability. It decomposes into isocyanuric acid and hypohalous acid in water and provides stable and lasting oxidation. For chloroisocyanuric acid, if bromide ions are present in water, bromide ions can react with hypochlorous acid to generate hypobromous acid with higher oxidizability. In the present invention, bromide salts are used as co-catalysts to improve the oxidizing properties of halogenated isocyanuric acid, especially chloroisocyanuric acid, and improve the oxidation effect on HMF, and the conversion rate of HMF to FDCA is higher. In a preferred embodiment of the present invention, the bromide salt is selected from one or a combination of two or more of sodium bromide, potassium bromide, lithium bromide, calcium bromide, copper bromide, zinc bromide, nickel bromide and magnesium bromide. Considering the cost dimension, the bromide salt is more preferably sodium bromide.

[0029] In a preferred embodiment of the present invention, the piperidine nitrogen oxide is selected from 2,2,6,6-tetramethylpiperidine nitrogen oxide and its derivatives. 2,2,6,6-tetramethylpiperidine nitrogen oxide TEMPO is a common piperidine nitrogen oxide, which plays a good catalytic and oxidative role.

[0030] In a more preferred embodiment of the present invention, the derivative is a 4-substituted 2,2,6,6-tetramethylpiperidine nitrogen oxide. For example, the 2,2,6,6-tetramethylpiperidine nitrogen oxide derivative can be 4-hydroxy-2,2,6,6-tetramethylpiperidine nitrogen oxide, 4-amino-2,2,6,6-tetramethylpiperidine nitrogen oxide, 4-methoxy-2,2,6,6-tetramethylpiperidine nitrogen oxide, 4-nitrile-2,2,6,6-tetramethylpiperidine nitrogen oxide, 4-acetamido-2,2,6,6-tetramethylpiperidine nitrogen oxide, 4-formyl-2,2,6,6-tetramethylpiperidine nitrogen oxide, etc.

[0031] The present invention uses halogenated isocyanuric acid as the main oxidant, which can be decomposed into isocyanuric acid and hypohalous acid under acidic conditions, has good oxidizability and can provide continuous and stable oxidizability, and the decomposition product is soluble in an organic solvent, which is conducive to the purification and separation of the product FDCA, and the post-processing after the reaction is simpler. In a preferred embodiment of the present invention, the halogenated isocyanuric acid is selected from one or a combination of two or more of bromoisocyanuric acid, dichloroisocyanuric acid, trichloroisocyanuric acid, chloroisocyanuric acid and chlorobromoisocyanuric acid. In the prior art, HMF is oxidized to FDCA, and sodium hypochlorite, hydrogen peroxide, etc. are generally used as oxidants. It is necessary to react under alkaline conditions, and the reaction needs to be adjusted to precipitate FDCA after the reaction. Such an operation will produce high-salt wastewater, which is not conducive to the post-processing operation after the reaction and the purification of the product. If sodium hypochlorite, hydrogen peroxide, etc. are used as oxidants, and under acidic conditions, the oxidation performance will be poor, which is not conducive to the oxidation of HMF and conversion into FDCA.

[0032] In a preferred embodiment of the present invention, the weight ratio of fructose, bromide salt, piperidine nitrogen oxide and halogenated isocyanuric acid is 1:(0.01-1):(0.001-0.1):(0.5-10). For example, the weight ratio of fructose, bromide salt, piperidine nitrogen oxide and halogenated isocyanuric acid can be any value among 1:0.01:0.001:1, 1:0.1:0.001:1, 1:0.5:0.001:1, 1:1:0.001:1, 1:0.1:0.01:1, 1:0.1:0.03:1, 1:0.1:0.06:1, 1:0.1:0.1:1, 1:0.1:0.05:1, 1:0.1:0.05:3, 1:0.1:0.05:5, 1:0.1:0.05:8, 1:0.1:0.05:10 etc. or any value in between, without any particular limitation. More preferably, the weight ratio of fructose to bromide salt can be 1:0.03-0.8. For example, the weight ratio can be any value among 1:0.03, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:0.65, 1:0.7, 1:0.75, 1:0.8, etc. or any value in between, without any particular limitation. More preferably, the weight ratio of fructose to piperidine N oxide can be 1:0.005-0.08. For example, the weight ratio can be any value among 1:0.005, 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04, 1:0.045, 1:0.05, 1:0.055, 1:0.06, 1:0.065, 1:0.07, 1:0.075, 1:0.08, etc. or any value in between, without particular limitation. For example, the weight ratio of fructose to halogenated isocyanuric acid can be 1:1-10. For example, the weight ratio can be any value among 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:10, etc. or any value in between, without any particular limitation.

[0033] The technical solution of the present invention is further described and illustrated according to various embodiments below. Unless otherwise specified, the parts described in the following embodiments are parts by weight.

[0034] Example 1

[0035] Take 18g of fructose, 50ml of water and 300ml of methyl isobutyl ketone and add them to a high-pressure reactor. After stirring and dissolving, add 0.3g of concentrated hydrochloric acid, seal the reactor, heat to 120℃ for reaction for 1h, quickly cool to room temperature after the reaction, continue to add 0.18g of TEMPO, 1.08g of sodium bromide and 23.4g of trichloroisocyanuric acid to the reactor, heat to 50℃ and stir for reaction for 1h, quickly cool to room temperature after the reaction to obtain the reaction product, centrifuge at 3000rpm for 30min, collect the solid, wash the solid with 100ml of water 3 times, and obtain a white FDCA solid after vacuum freeze-drying.

[0036] The purity of FDCA measured by HPLC was 98.0%; based on the weight of FDCA solid, the molar yield was calculated to be 83.2%.

[0037] Example 2

[0038] The difference between this embodiment and embodiment 1 is that the concentrated hydrochloric acid in embodiment 1 is adjusted to an equal weight of a sulfuric acid solution with a concentration of 5 mol / L. The remaining steps remain unchanged.

[0039] The purity of FDCA measured by HPLC was 98.1%; based on the weight of FDCA solid, the molar yield was calculated to be 81.5%.

[0040] Example 3

[0041] The difference between this embodiment and embodiment 1 is that 23.4 g of trichloroisocyanuric acid in embodiment 1 is adjusted to 54 g. The other steps remain unchanged.

[0042] The purity of FDCA measured by HPLC was 97.7%; based on the weight of FDCA solid, the molar yield was calculated to be 84.1%.

[0043] Example 4

[0044] The difference between this embodiment and embodiment 1 is that the amount of sodium bromide in embodiment 1 is adjusted from 1.08 g to 1.8 g. The remaining steps remain unchanged.

[0045] The purity of FDCA measured by HPLC was 97.8%; based on the weight of FDCA solid, the molar yield was calculated to be 80.1%.

[0046] Example 5

[0047] The difference between this embodiment and embodiment 1 is that the methyl isobutyl ketone in embodiment 1 is adjusted to an equal weight of ethyl acetate. The remaining steps remain unchanged.

[0048] The purity of FDCA measured by HPLC was 98.5%; based on the weight of FDCA solid, the molar yield was calculated to be 80.7%.

[0049] Example 6

[0050] The difference between this embodiment and embodiment 1 is that the amount of methyl isobutyl ketone in embodiment 1 is adjusted from 300 ml to 500 ml. The other steps remain unchanged.

[0051] The purity of FDCA measured by HPLC was 98.3%; based on the weight of FDCA solid, the molar yield was calculated to be 81.4%.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Example 1 is that the concentrated hydrochloric acid in Example 1 is adjusted to an equal weight of FeCl3. The other steps remain unchanged.

[0054] The purity of FDCA was measured by HPLC to be 98.1%; based on the weight of FDCA solid, the molar yield was calculated to be 50.7%.

[0055] Comparative Example 2

[0056] The difference between this comparative example and Example 1 is that sodium bromide is not added in Example 1. The remaining steps remain unchanged.

[0057] The purity of FDCA was measured by HPLC to be 98.3%; based on the weight of FDCA solid, the molar yield was calculated to be 64.9%.

[0058] Comparative Example 3

[0059] The difference between this comparative example and Example 1 is that the trichloroisocyanuric acid in Example 1 is adjusted to an equal weight of hypochlorous acid. The other steps remain unchanged.

[0060] The purity of FDCA was measured by HPLC to be 75.1%; based on the weight of FDCA solid, the molar yield was calculated to be 67.4%.

[0061] Comparative Example 4

[0062] The difference between this comparative example and Example 1 is that the trichloroisocyanuric acid in Example 1 is adjusted to an equal weight of hydrogen peroxide. The other steps remain unchanged.

[0063] The purity of FDCA measured by HPLC was 80.1%; based on the weight of FDCA solid, the molar yield was calculated to be 71.3%.

[0064] Comparative Example 5

[0065] The difference between this comparative example and Example 1 is that TEMPO is not added in Example 1. The other steps remain unchanged.

[0066] The purity of FDCA measured by HPLC was 84.5%; based on the weight of FDCA solid, the molar yield was calculated to be 60.6%.

[0067] Comparative Example 6

[0068] The difference between this comparative example and Example 1 is that TEMPO in Example 1 is replaced by an equal weight of hydrogen peroxide. The other steps remain unchanged.

[0069] The purity of FDCA was measured by HPLC to be 85.1%; based on the weight of FDCA solid, the molar yield was calculated to be 75.6%.

[0070] Example 7

[0071] Take 18g of fructose, 50ml of water and 400ml of acetone and add them to a high-pressure reactor. After stirring and dissolving, add 1g of concentrated hydrochloric acid, seal the reactor, heat to 120℃ for reaction for 1h, quickly cool to room temperature after the reaction, continue to add 0.18g of TEMPO, 1.8g of sodium bromide and 36g of chlorobromoisocyanuric acid to the reactor, heat to 30℃ and stir for reaction for 4h, quickly cool to room temperature after the reaction to obtain the reaction product, centrifuge at 3000rpm for 30min, collect the solid, wash the solid with 100ml of water 3 times, and obtain a white FDCA solid after vacuum freeze-drying.

[0072] The purity of FDCA measured by HPLC was 98.0%; based on the weight of FDCA solid, the molar yield was calculated to be 82.8%.

[0073] Example 8

[0074] The difference between this example and Example 7 is that the amount of TEMPO in Example 7 is adjusted from 0.18 g to 0.54 g. The other steps remain unchanged.

[0075] The purity of FDCA measured by HPLC was 98.5%; based on the weight of FDCA solid, the molar yield was calculated to be 83.7%.

[0076] Example 9

[0077] The difference between this example and Example 7 is that the amount of TEMPO in Example 7 is adjusted from 0.18 g to 0.9 g. The other steps remain unchanged.

[0078] The purity of FDCA measured by HPLC was 97.7%; based on the weight of FDCA solid, the molar yield was calculated to be 84.1%.

[0079] Example 10

[0080] The difference between this embodiment and embodiment 8 is that the amount of chlorobromoisocyanuric acid in embodiment 8 is adjusted from 36 g to 108 g. The remaining steps remain unchanged.

[0081] The purity of FDCA was measured by HPLC to be 97.5%; based on the weight of FDCA solid, the molar yield was calculated to be 85.1%.

[0082] Embodiment 11

[0083] The difference between this embodiment and embodiment 7 is that the amount of sodium bromide in embodiment 7 is adjusted from 1.8 g to 5.4 g. The remaining steps remain unchanged.

[0084] The purity of FDCA measured by HPLC was 98.2%; based on the weight of FDCA solid, the molar yield was calculated to be 83.5%.

[0085] From the experiments and results of the above embodiments and comparative examples, it can be seen that the "one-pot two-step method" of the present invention can directly prepare FDCA from fructose, the conversion rate of fructose is high, and the yield of FDCA is high and the purity is good.

[0086] As described above, the basic principles, main features and advantages of the present invention are shown and described. Those skilled in the art should understand that the present invention is not limited by the above embodiments, which are only preferred embodiments of the present invention and cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the scope of the present invention and the content of the specification should still be within the scope of the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing 2,5-furandicarboxylic acid from fructose, characterized in that: include: Add a reaction solvent, fructose and an inorganic acid into a reaction container, raise the temperature to 80-150° C. and react for 0.5-3 hours; after the reaction is completed, continue to add bromide salt, piperidine nitrogen oxide and halogenated isocyanuric acid, and carry out oxidation reaction at 15-70° C. for 0.5-5 hours to obtain the 2,5-furandicarboxylic acid.

2. The method for preparing 2,5-furandicarboxylic acid from fructose according to claim 1, characterized in that: The reaction solvent consists of water and an organic solvent in a weight ratio of 1:(1-100).

3. The method for preparing 2,5-furandicarboxylic acid from fructose according to claim 2, characterized in that: The solubility of the organic solvent in water at 20° C. is not less than 5 g / 100 ml.

4. The method for preparing 2,5-furandicarboxylic acid from fructose according to claim 1, characterized in that: The inorganic acid is selected from one or a combination of two or more of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.

5. The method for preparing 2,5-furandicarboxylic acid from fructose according to claim 1, characterized in that: The weight ratio of the reaction solvent, the fructose and the inorganic acid is (10-100):1:(0.001-0.1).

6. The method for preparing 2,5-furandicarboxylic acid from fructose according to claim 1, characterized in that: The bromide salt is selected from one or a combination of two or more of sodium bromide, potassium bromide, lithium bromide, calcium bromide, copper bromide, zinc bromide, nickel bromide and magnesium bromide.

7. The method for preparing 2,5-furandicarboxylic acid from fructose according to claim 1, characterized in that: The piperidine nitrogen oxide is selected from 2,2,6,6-tetramethylpiperidine nitrogen oxide and its derivatives.

8. The method for preparing 2,5-furandicarboxylic acid from fructose according to claim 7, characterized in that: The derivative is the 2,2,6,6-tetramethylpiperidine nitrogen oxide substituted at the 4-position.

9. The method for preparing 2,5-furandicarboxylic acid from fructose according to claim 1, characterized in that: The halogenated isocyanuric acid is selected from one or a combination of two or more of bromoisocyanuric acid, dichloroisocyanuric acid, trichloroisocyanuric acid, chloroisocyanuric acid and chlorobromoisocyanuric acid.

10. The method for preparing 2,5-furandicarboxylic acid from fructose according to claim 1, characterized in that: The weight ratio of the fructose, the bromide salt, the piperidine nitrogen oxide and the halogenated isocyanuric acid is 1:(0.01-1):(0.001-0.1):(0.5-10).