Method for directly preparing 2, 5-furandicarboxaldehyde from carbohydrate

Abstract

The invention discloses a preparation method for directly preparing 2, 5-furandicarboxaldehyde from a carbohydrate, and the preparation method comprises the following steps: reacting a mixture I containing the carbohydrate, a catalyst, an organic phase solvent and a water phase solution in an oxygen-containing atmosphere to obtain the 2, 5-furandicarboxaldehyde, the catalyst comprises a component I and a component II; the component I is selected from at least one of aluminum chloride, indium chloride and chromium chloride; and the component II is an organic hydrophobic modified manganese oxide. According to the method, a 5-hydroxymethylfurfural intermediate product generated by reaction is directly oxidized without separation to prepare 2, 5-furandicarboxaldehyde, so that side reactions such as polymerization and the like are reduced; the carbohydrates are dissolved in the water phase and cannot be catalyzed and oxidized by the hydrophobic oxidation catalyst dispersed in the organic phase to generate byproducts, and the method has the advantages of low cost, mild reaction conditions, high product yield and the like.

Description

Technical Field

[0001] The present application relates to a method for directly preparing 2,5-furandicarboxaldehyde from a carbohydrate compound, and belongs to the technical field of organic chemical industry. Background Art

[0002] 2,5-Furandicarboxaldehyde is an important furan platform compound and one of the new energy chemicals that has attracted much attention. 2,5-Furandicarboxaldehyde is an intermediate for synthesizing high-value compounds such as pharmaceutical intermediates, antibacterial agents, adhesives, fluorescent agents, etc. It can also be used to synthesize a variety of new polymer materials such as biomass-based new resins, fluorescent materials, polyols and polyethylene.

[0003] 2,5-Furandicarboxaldehyde is mainly produced by selective oxidation of 5-hydroxymethylfurfural. However, 5-hydroxymethylfurfural is very expensive, which seriously hinders the application of 2,5-Furandicarboxaldehyde. 5-Hydroxymethylfurfural can be produced by catalytic dehydration conversion of glucose, fructose, etc., but 5-Hydroxymethylfurfural is unstable and is prone to side reactions such as polymerization during the separation process, resulting in a very high production cost of 5-Hydroxymethylfurfural.

[0004] CN108675971A reports a method for preparing 2,5-furandicarboxaldehyde from fructose: using fructose as raw material, piperidine nitrogen oxide as catalyst, acid and nitrite as co-catalysts, reacting in the presence of organic solvent and oxygen source, the yield of 2,5-furandicarboxaldehyde can reach more than 90%. However, when glucose is used as raw material in this method, the yield of 2,5-furandicarboxaldehyde is only about 10%. CN112979589A reports a method for preparing 2,5-furandicarboxaldehyde from sucrose or glucose: using cerium dioxide with a particle size of less than 100nm as catalyst and anionic surfactant as dispersant, in solvents such as N,N-dimethylformamide, the yield of 2,5-furandicarboxaldehyde can reach about 80%. However, the reaction conditions of this method are harsh and require a higher reaction pressure of 2 to 5MPa. Summary of the invention

[0005] In order to solve the current problems of high cost of preparing 5-hydroxymethylfurfural and harsh reaction conditions for preparing 2,5-furandicarboxaldehyde from sugar compounds such as glucose and sucrose, the present application provides a method for directly preparing 2,5-furandicarboxaldehyde from sugar compounds. The 5-hydroxymethylfurfural intermediate product generated by the reaction is directly oxidized to produce 2,5-furandicarboxaldehyde without separation, reducing side reactions such as polymerization, and has the advantages of low cost, mild reaction conditions, and high product yield.

[0006] According to one aspect of the present application, a method for directly preparing 2,5-furandicarboxaldehyde from a carbohydrate compound is provided, the preparation method comprising:

[0007] Under an oxygen-containing atmosphere, a mixture I containing a saccharide compound, a catalyst, an organic phase solvent, and an aqueous phase solution is reacted I to obtain the 2,5-furandicarboxaldehyde;

[0008] The catalyst comprises component I and component II;

[0009] The component I is selected from at least one of aluminum chloride, indium chloride and chromium chloride;

[0010] The component II is an organic hydrophobically modified manganese oxide.

[0011] Optionally, the organic hydrophobically modified manganese oxide is a long-chain fatty amine modified manganese oxide.

[0012] Optionally, the preparation method of the long-chain fatty amine-modified manganese oxide comprises:

[0013] (1) adding aqueous ammonia to a mixture II containing an aqueous solution of KMnO4 and an ethanol-water solution of (CH3COO)2Mn until the pH value is 8 to 9, and performing reaction II to obtain manganese oxide;

[0014] (2) reacting a mixture III containing manganese oxide, a long-chain fatty amine and a solvent to obtain a manganese oxide modified with a long-chain fatty amine.

[0015] Optionally, the long-chain fatty amine is selected from at least one of C6 to C12 fatty amines.

[0016] Optionally, the long-chain fatty amine is independently selected from at least one of C6 fatty amine, C7 fatty amine, C8 fatty amine, C9 fatty amine, C10 fatty amine, C11 fatty amine and C12 fatty amine.

[0017] Optionally, the concentration of the KMnO4 aqueous solution is 0.2-0.6 mol / L.

[0018] Optionally, the concentration of the KMnO4 aqueous solution is independently selected from any value among 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L or a range between any two of the above.

[0019] Optionally, the concentration of the (CH3COO)2Mn ethanol-water solution is 0.1-0.3 mol / L.

[0020] Optionally, the concentration of the ethanol-water solution of (CH3COO)2Mn is independently selected from any value among 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L or a range between any two of the above.

[0021] Optionally, the molar ratio of (CH3COO)2Mn in the (CH3COO)2Mn ethanol-water solution to KMnO4 in the KMnO4 aqueous solution is 1:1 to 2:1.

[0022] Optionally, the molar ratio of (CH3COO)2Mn in the ethanol-water solution of (CH3COO)2Mn to KMnO4 in the KMnO4 aqueous solution is independently selected from any value of 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1 or a range between any two of the above.

[0023] Optionally, in the ethanol-water solution of (CH3COO)2Mn, the volume ratio of ethanol to water is 3:1 to 7:1.

[0024] Optionally, in the ethanol-water solution of (CH3COO)2Mn, the volume ratio of ethanol to water is independently selected from any value of 3:1, 4:1, 5:1, 6:1, 7:1 or a range between any two of the above values.

[0025] Optionally, the mass ratio of the manganese oxide to the long-chain fatty amine is 1:1 to 1:2.

[0026] Optionally, the mass ratio of the manganese oxide to the long-chain fatty amine is independently selected from any value of 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, or a range between any two of the above values.

[0027] Optionally, the mass ratio of the manganese oxide to the solvent is 1:4 to 1:8.

[0028] Optionally, the mass ratio of the manganese oxide to the solvent is independently selected from any value of 1:4, 1:5, 1:6, 1:7, 1:8 or a range between any two of the above values.

[0029] Optionally, the solvent is selected from at least one of butanol, tetrahydrofuran, dioxane, cyclohexane and methyl isobutyl ketone.

[0030] Optionally, the temperature of reaction II is 25-50° C., and the time of reaction II is 6-24 h.

[0031] Optionally, the temperature of the reaction II is independently selected from any value of 25°C, 30°C, 35°C, 40°C, 45°C, 50°C or a range between any two of the above values.

[0032] Optionally, the time of the reaction II is independently selected from any value of 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h or a range between any two of the above.

[0033] Optionally, the temperature of the reaction III is 60 to 120° C., and the time of the reaction III is 2 to 6 hours.

[0034] Optionally, the temperature of the reaction III is independently selected from any value of 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or a range between any two of the above values.

[0035] Optionally, the time of the reaction III is independently selected from any value among 2h, 3h, 4h, 5h, 6h or a range between any two of the above.

[0036] Optionally, the carbohydrate compound is selected from at least one of fructose, glucose and sucrose.

[0037] Optionally, the mass of the component I is 1-10% of the mass of the carbohydrate compound.

[0038] Optionally, the mass of component I is independently selected from any value of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the mass of the carbohydrate compound or a range between any two of the above values.

[0039] Optionally, the mass of the component II is 1-10% of the mass of the carbohydrate compound.

[0040] Optionally, the mass of component II is independently selected from any value of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the mass of the carbohydrate compound, or a range between any two of the above values.

[0041] Optionally, the mass percentage concentration of the carbohydrate compound in the mixture I is 10-50%.

[0042] Optionally, the mass percentage concentration of the carbohydrate compound in the mixture I is independently selected from any value of 10%, 20%, 30%, 40%, 50% or a range between any two of the above.

[0043] Optionally, the mass percentage concentration of the sugar compound in the reaction system is 10-50%, wherein the reaction system comprises a two-phase system consisting of the sugar compound, a catalyst, an organic phase solvent and an aqueous phase solution.

[0044] Optionally, the mass ratio of the organic phase solvent to the aqueous phase solution is 1:2 to 2:1.

[0045] Optionally, the organic phase solvent and the aqueous phase solution constitute a two-phase system.

[0046] Optionally, the organic phase solvent is selected from at least one of butanol, tetrahydrofuran, dioxane, cyclohexane and methyl isobutyl ketone.

[0047] Optionally, the aqueous phase solution is an aqueous solution of alkali metal halide.

[0048] Optionally, the alkali metal halide in the aqueous solution of alkali metal halide is selected from at least one of sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide and potassium iodide.

[0049] Optionally, the oxygen-containing atmosphere is selected from air atmosphere and / or oxygen atmosphere.

[0050] Optionally, the temperature of the reaction I is 60-100° C., and the time of the reaction I is 1-4 hours.

[0051] Optionally, the temperature of the reaction I is independently selected from any value of 60°C, 70°C, 80°C, 90°C, 100°C or a range between any two of the above values.

[0052] Optionally, the reaction time I is independently selected from any value among 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, or a range between any two of the above.

[0053] Optionally, the pressure of the reaction I is 0.1-0.3 MPa.

[0054] Optionally, the pressure of the reaction I is independently selected from any value among 0.1MPa, 0.15MPa, 0.2MPa, 0.25MPa, 0.3MPa or a range between any two of the above values.

[0055] According to the present application, the catalyst is extremely important. When there is no catalyst or the catalyst activity is low, the conversion rate of the sugar compound is very low. Only when the catalyst activity and selectivity are high can a high conversion rate of the sugar compound and a high selectivity of 2,5-furandicarboxaldehyde be obtained.

[0056] According to the present application, component I in the catalyst has multiple functions of catalyzing the hydrolysis of sucrose into glucose and fructose, the isomerization of glucose into fructose, and the dehydration of fructose into 5-hydroxymethylfurfural.

[0057] According to the present application, the role of the two-phase system consisting of an organic phase solvent and an aqueous phase solution is that: component I in the catalyst is dissolved in the aqueous phase, catalyzing the conversion of sugar compounds into 5-hydroxymethylfurfural, and the generated 5-hydroxymethylfurfural will not accumulate to cause side reactions such as polymerization, but will be immediately extracted into the organic phase and catalyzed and oxidized by the organic hydrophobic catalyst (component II in the catalyst) dispersed in the organic phase to be converted into 2,5-furandicarboxaldehyde; on the other hand, the sugar compound is dissolved in the aqueous phase and will not be catalyzed and oxidized by the organic hydrophobic catalyst (component II in the catalyst) dispersed in the organic phase to produce by-products, thereby improving the selectivity of 2,5-furandicarboxaldehyde.

[0058] The beneficial effects of this application include:

[0059] The present application provides a method for directly preparing 2,5-furandicarboxaldehyde from a carbohydrate compound. The 5-hydroxymethylfurfural intermediate product generated by the reaction is directly oxidized to obtain 2,5-furandicarboxaldehyde without separation, thereby reducing side reactions such as polymerization. The carbohydrate compound is dissolved in an aqueous phase and will not be catalyzed and oxidized by a hydrophobic oxidation catalyst dispersed in an organic phase to produce by-products. The method has the advantages of low cost, mild reaction conditions, and high product yield. DETAILED DESCRIPTION

[0060] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0061] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0062] Unless otherwise specified, conventional methods were used for testing.

[0063] The conversion rate and yield in the examples of this application are calculated as follows:

[0064]

[0065]

[0066] The present application adopts Waters 2695 liquid chromatography analysis to determine the conversion rate of sugar compounds and the yield of 2,5-furandicarboxaldehyde.

[0067] Example 1

[0068] 100mL of 0.4mol / L KMnO4 aqueous solution was added dropwise to 300mL of 0.2mol / L (CH3COO)2Mn ethanol-water solution (ethanol / water volume ratio of 5 / 1), and aqueous ammonia was added dropwise to the resulting solution until the pH was 8, and the solution was stirred at 25°C for 6h, filtered, and the resulting solid was washed with distilled water and dried at 80°C for 12h to obtain 8.7g of manganese oxide, which was mixed with 8.7g of n-hexylamine and 52.1g of dioxane, heated and stirred at 100°C for 4h, then cooled to room temperature, filtered, and the resulting solid was washed with ethanol and allowed to stand at room temperature for 12h to obtain 16.8g of n-hexylamine-modified manganese oxide catalyst I.

[0069] Example 2

[0070] 100mL of 0.6mol / L KMnO4 aqueous solution was added dropwise to 200mL of 0.3mol / L (CH3COO)2Mn ethanol-water solution (ethanol / water volume ratio is 3 / 1), and aqueous ammonia was added dropwise to the resulting solution until the pH was 9, and the mixture was stirred at 50°C for 24h, filtered, and the resulting solid was washed with distilled water and dried at 100°C for 6h to obtain 10.9g of manganese oxide, which was mixed with 21.8g of n-octylamine and 87.3g of methyl isobutyl ketone, heated and stirred at 120°C for 2h, then cooled to room temperature, filtered, and the resulting solid was washed with ethanol and allowed to stand at room temperature for 6h to obtain 20.6g of n-octylamine-modified manganese oxide catalyst II.

[0071] Example 3

[0072] 100mL of 0.2mol / L KMnO4 aqueous solution was added dropwise to 400mL of 0.1mol / L (CH3COO)2Mn ethanol-water solution (ethanol / water volume ratio of 7 / 1), and aqueous ammonia was added dropwise to the resulting solution until the pH was 8, and the mixture was stirred at 40°C for 12h, filtered, and the resulting solid was washed with distilled water and dried at 60°C for 24h to obtain 5.0g of manganese oxide, which was mixed with 10.0g of n-heptylamine and 20.0g of cyclohexane, heated and stirred at 60°C for 6h, then cooled to room temperature, filtered, and the resulting solid was washed with ethanol and allowed to stand at room temperature for 24h to obtain 10.9g of n-heptylamine-modified manganese oxide catalyst III.

[0073] Embodiment 4-5

[0074] Examples 4 to 5 are similar to Example 1, except that different long-chain fatty amines are used. Other preparation conditions are the same as those of Example 1.

[0075] The difference between Example 4 and Example 1 is that 8.7 g of n-decylamine is used instead of n-hexylamine to obtain 17.0 g of manganese oxide catalyst IV modified with n-decylamine.

[0076] The difference between Example 5 and Example 1 is that 8.7 g of dodecylamine is used instead of n-hexylamine to obtain 17.2 g of dodecylamine-modified manganese oxide catalyst V.

[0077] Example 6

[0078] 10g of glucose, 1g of chromium chloride, 1g of manganese oxide catalyst I modified by n-hexylamine, 12g of cyclohexane, and 12g of 20% sodium bromide aqueous solution were mixed, stirred, heated to 80°C, charged with oxygen to a pressure of 0.2MPa, and reacted for 2h. Liquid chromatography analysis showed that the glucose conversion rate was 100% and the 2,5-furandicarboxaldehyde yield was 88%.

[0079] Example 7

[0080] 10g of fructose, 0.1g of aluminum chloride, 0.1g of n-octylamine-modified manganese oxide catalyst II, 20g of tetrahydrofuran, and 20g of 25% sodium chloride aqueous solution were mixed, stirred, heated to 60°C, charged with oxygen to a pressure of 0.1MPa, and reacted for 4h. Liquid chromatography analysis showed that the fructose conversion rate was 100% and the 2,5-furandicarboxaldehyde yield was 96%.

[0081] Example 8

[0082] 10g sucrose, 0.2g indium chloride, 0.2g n-heptylamine-modified manganese oxide catalyst III, 45g butanol, and 45g 15% sodium iodide aqueous solution were mixed, stirred, heated to 100°C, charged with oxygen to a pressure of 0.3MPa, and reacted for 1h. Liquid chromatography analysis showed that the sucrose conversion rate was 100% and the 2,5-furandicarboxaldehyde yield was 92%.

[0083] Example 9

[0084] 10g of glucose, 0.3g of chromium chloride, 0.5g of manganese oxide catalyst IV modified by n-decylamine, 20g of dioxane, and 20g of 25% potassium bromide aqueous solution were mixed, stirred, heated to 90°C, charged with oxygen to a pressure of 0.2MPa, and reacted for 3h. Liquid chromatography analysis showed that the glucose conversion rate was 100% and the 2,5-furandicarboxaldehyde yield was 86%.

[0085] Example 10

[0086] 10g of glucose, 0.5g of aluminum chloride, 0.3g of dodecylamine-modified manganese oxide catalyst V, 25g of methyl isobutyl ketone, and 25g of 25% potassium iodide aqueous solution were mixed, stirred, heated to 70°C, charged with oxygen to a pressure of 0.2MPa, and reacted for 2h. Liquid chromatography analysis showed that the glucose conversion rate was 100% and the 2,5-furandicarboxaldehyde yield was 89%.

[0087] Comparative Example 1

[0088] The difference between Comparative Example 1 and Example 6 is that no chromium chloride catalyst is used, and other reaction conditions are the same as those of Example 6. Liquid chromatography analysis shows that the glucose conversion rate is 18% and the 2,5-furandicarboxaldehyde yield is 14%.

[0089] Comparative Example 2

[0090] The difference between Comparative Example 2 and Example 6 is that the manganese oxide catalyst I modified with n-hexylamine is not used, and other reaction conditions are the same as those in Example 6. Liquid chromatography analysis shows that the glucose conversion rate is 100% and the 2,5-furandicarboxaldehyde yield is 1%.

[0091] Comparative Example 3

[0092] The difference between Comparative Example 3 and Example 6 is that 24 g of cyclohexane is used as solvent, sodium bromide aqueous solution is not used, and other reaction conditions are the same as those of Example 6. Liquid chromatography analysis shows that the glucose conversion rate is 100% and the 2,5-furandicarboxaldehyde yield is 26%.

[0093] Comparative Example 4

[0094] The difference between Comparative Example 4 and Example 6 is that 24 g of 20% sodium bromide aqueous solution is used as solvent, cyclohexane is not used, and other reaction conditions are the same as those of Example 6. Liquid chromatography analysis shows that the glucose conversion rate is 100% and the 2,5-furandicarboxaldehyde yield is 29%.

[0095] Comparative Example 5

[0096] The difference between Comparative Example 5 and Example 6 is that 1 g of manganese oxide prepared by the method of Example 1 is used as a catalyst instead of 1 g of n-hexylamine-modified manganese oxide catalyst I, and other reaction conditions are the same as those in Example 6. Liquid chromatography analysis shows that the glucose conversion rate is 100% and the 2,5-furandicarboxaldehyde yield is 28%.

[0097] The results of Examples 1-10 show that, under an oxygen-containing atmosphere, a mixture of a two-phase system consisting of a sugar compound, a catalyst, an organic solvent and an aqueous phase is reacted to obtain 2,5-furandicarboxaldehyde; wherein the oxygen-containing atmosphere is an air atmosphere and / or an oxygen atmosphere; the catalyst comprises component I and component II; wherein component I is selected from at least one of aluminum chloride, indium chloride and chromium chloride, and component II is an organic hydrophobically modified manganese oxide, the conversion rate of the sugar compound can reach 100%, and the yield of 2,5-furandicarboxaldehyde can reach up to more than 95%.

[0098] The results of Comparative Example 1 show that when the chromium chloride catalyst is not used, the conversion rate of glucose is very low. This is because chromium chloride plays an important role in the isomerization of glucose into fructose.

[0099] The results of Comparative Example 2 show that glucose can be completely converted using only chromium chloride catalyst without using n-hexylamine-modified manganese oxide catalyst I, but the yield of 2,5-furandicarboxaldehyde is very low. This is because n-hexylamine-modified manganese oxide catalyst I plays an important role in the oxidation conversion of 5-hydroxymethylfurfural into 2,5-furandicarboxaldehyde.

[0100] The results of Comparative Examples 3 and 4 show that when only cyclohexane or sodium bromide aqueous solution is used instead of the two-phase system consisting of cyclohexane and sodium bromide aqueous solution, the yield of 2,5-furandicarboxaldehyde is very low, indicating that the two-phase system consisting of organic solvent and aqueous phase plays an important role in the reaction process.

[0101] The results of Comparative Example 5 show that the yield of 2,5-furandicarboxaldehyde is very low when manganese oxide that has not been modified with long-chain fatty amines is used as a catalyst. It is speculated that this is because the unmodified manganese oxide is mainly distributed in the aqueous phase and has poor contact with 5-hydroxymethylfurfural that is mainly distributed in the organic phase, resulting in poor catalysis of the oxidation of 5-hydroxymethylfurfural into 2,5-furandicarboxaldehyde.

[0102] In summary, the present application reacts a mixture of a two-phase system consisting of a saccharide compound, a catalyst, an organic solvent and an aqueous phase under an oxygen-containing atmosphere to obtain 2,5-furandicarboxaldehyde; wherein the oxygen-containing atmosphere is an air atmosphere and / or an oxygen atmosphere; the catalyst comprises component I and component II; wherein component I is selected from at least one of aluminum chloride, indium chloride and chromium chloride, and component II is an organic hydrophobically modified manganese oxide. The 5-hydroxymethylfurfural intermediate product generated by the reaction of the method is directly oxidized to obtain 2,5-furandicarboxaldehyde without separation, thereby reducing side reactions such as polymerization; the saccharide compound is dissolved in the aqueous phase and will not be catalyzed and oxidized by the hydrophobic oxidation catalyst dispersed in the organic phase to produce by-products, which has the advantages of low cost, mild reaction conditions and high product yield.

[0103] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for directly preparing 2,5-furandicarboxaldehyde from a carbohydrate compound, characterized in that: The preparation method comprises: Under an oxygen-containing atmosphere, a mixture I containing a saccharide compound, a catalyst, an organic phase solvent, and an aqueous phase solution is reacted I to obtain the 2,5-furandicarboxaldehyde; The catalyst comprises component I and component II; The component I is selected from at least one of aluminum chloride, indium chloride and chromium chloride; The component II is an organic hydrophobically modified manganese oxide.

2. The preparation method according to claim 1, characterized in that: The organic hydrophobically modified manganese oxide is a manganese oxide modified by a long-chain fatty amine.

3. The preparation method according to claim 2, characterized in that: The preparation method of the long-chain fatty amine-modified manganese oxide comprises: (1) adding aqueous ammonia to a mixture II containing an aqueous solution of KMnO4 and an ethanol-water solution of (CH3COO)2Mn until the pH value is 8 to 9, and performing reaction II to obtain manganese oxide; (2) reacting a mixture III containing manganese oxide, a long-chain fatty amine and a solvent to obtain a manganese oxide modified with a long-chain fatty amine.

4. The preparation method according to claim 2 or 3, characterized in that: The long-chain fatty amine is selected from at least one of C6 to C12 fatty amines; Preferably, the concentration of the KMnO4 aqueous solution is 0.2-0.6 mol / L; Preferably, the concentration of the (CH3COO)2Mn ethanol-water solution is 0.1-0.3 mol / L.

5. The preparation method according to claim 3, characterized in that: The molar ratio of (CH3COO)2Mn in the (CH3COO)2Mn ethanol-water solution to KMnO4 in the KMnO4 aqueous solution is 1:1 to 2:1; Preferably, in the ethanol-water solution of (CH3COO)2Mn, the volume ratio of ethanol to water is 3:1 to 7:1; Preferably, the mass ratio of the manganese oxide to the long-chain fatty amine is 1:1 to 1:2; Preferably, the mass ratio of the manganese oxide to the solvent is 1:4 to 1:8; Preferably, the solvent is selected from at least one of butanol, tetrahydrofuran, dioxane, cyclohexane and methyl isobutyl ketone.

6. The preparation method according to claim 3, characterized in that: The temperature of the reaction II is 25 to 50° C., and the time of the reaction II is 6 to 24 hours; Preferably, the temperature of the reaction III is 60-120° C., and the time of the reaction III is 2-6 hours.

7. The preparation method according to claim 1, characterized in that: The sugar compound is selected from at least one of fructose, glucose and sucrose; Preferably, the mass of component I is 1 to 10% of the mass of the carbohydrate compound; Preferably, the mass of component II is 1 to 10% of the mass of the carbohydrate compound; Preferably, the mass percentage concentration of the carbohydrate compound in the mixture I is 10 to 50%; Preferably, the mass ratio of the organic phase solvent to the aqueous phase solution is 1:2 to 2:

1.

8. The preparation method according to claim 1, characterized in that: The organic phase solvent and the aqueous phase solution constitute a two-phase system; Preferably, the organic phase solvent is selected from at least one of butanol, tetrahydrofuran, dioxane, cyclohexane, and methyl isobutyl ketone; Preferably, the aqueous phase solution is an aqueous solution of an alkali metal halide; Preferably, the alkali metal halide in the aqueous solution of alkali metal halide is selected from at least one of sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide and potassium iodide.

9. The preparation method according to claim 1, characterized in that: The oxygen-containing atmosphere is selected from an air atmosphere and / or an oxygen atmosphere.

10. The preparation method according to claim 1, characterized in that: The temperature of the reaction I is 60-100° C., and the time of the reaction I is 1-4 hours; Preferably, the pressure of the reaction I is 0.1-0.3 MPa.

Images