Preparation method of 2, 5-furandicarboxylate

Abstract

The invention provides a preparation method of 2, 5-furandicarboxylate, which comprises the following steps: preparing a continuous flow pipeline reactor which comprises a premixing section, a reaction section and a buffer section which are communicated with one another; reaction raw materials at least containing furoic acid, alcohol, dichloromethane and a catalyst are introduced into the premixing section to be mixed and preheated, and a mixed solution is obtained; wherein the catalyst comprises an oxidizing agent and lewis acid containing zinc ions and / or manganese ions; introducing the mixed solution into a reaction section of the continuous flow pipeline reactor for reaction to obtain a reaction product containing 2, 5-furandicarboxylate; and leading out the reaction product containing the 2, 5-furandicarboxylate through the buffer section. The preparation method provided by the invention has the advantages of high product yield, high product purity and capability of realizing continuous preparation.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a method for preparing 2,5-furan dicarboxylate. Background Technology

[0002] 2,5-Furandicarboxylic acid and 2,5-furandicarboxylic esters are important bio-based aromatic monomers, mainly derived from biomass feedstocks. Traditionally, fructose is dehydrated to produce 5-hydroxymethylfurfural (HMF), which is then oxidized to obtain 2,5-furandicarboxylic acid and 2,5-furandicarboxylic esters. However, HMF preparation is difficult and costly, hindering large-scale industrial application. Furthermore, the starting materials for HMF preparation are fructose and glucose, major food ingredients; large-scale industrial production would consume significant amounts of grain. Therefore, preparing 2,5-furandicarboxylic acid and 2,5-furandicarboxylic esters from non-grain biomass resources is an important direction for future development.

[0003] Currently, the main method for preparing 2,5-furandicarboxylic acid from non-grain biomass involves hydrolyzing hemicellulose to obtain furfural, which is then oxidized to obtain furoic acid, followed by a carbonation reaction. For example, furoic acid can be converted to 2,5-furandicarboxylic acid and furan via disproportionation, but this reaction produces isomers, making separation and purification difficult. Another method involves carbonylation of furoic acid to prepare 2,5-furandicarboxylic acid, proceeding through four steps: bromination, esterification, carbonylation, and hydrolysis. However, this synthetic route suffers from long reaction times, numerous byproducts, low yields, and difficulties in separation and purification. Additionally, furoic acid can be directly carboxylated with CO2 via carbonate, but this method requires long reaction times, high temperatures, and difficult product separation and purification, necessitating high CO2 pressure conditions. Furthermore, a bio-enzymatic catalysis method can directly convert furoic acid to 2,5-furandicarboxylic acid under mild conditions, but this reaction has a low conversion rate. Furthermore, the above method can only be used to prepare 2,5-furandicarboxylic acid or 2,5-furandicarboxylic esters through batch reaction in a reactor, and the continuous preparation of 2,5-furandicarboxylic acid or 2,5-furandicarboxylic esters has not yet been achieved. Summary of the Invention

[0004] To solve all or part of the above-mentioned technical problems, the present invention provides the following technical solutions: A first aspect of the present invention provides a continuous preparation method for 2,5-furan dicarboxylate, comprising: Prepare a continuous flow pipeline reactor, which includes a connected premixing section, a reaction section, and a buffer section; A reaction feedstock containing at least furoic acid, alcohol, dichloromethane, and a catalyst is passed into the premixing section for mixing and preheating to obtain a mixed solution; wherein the catalyst includes an oxidant and a Lewis acid containing zinc ions and / or manganese ions; The mixed solution is fed into the reaction section of the continuous flow pipe reactor to carry out the reaction, and a reaction product containing 2,5-furan dicarboxylate is obtained. The reaction product containing 2,5-furan dicarboxylate is exported through the buffer section.

[0005] The preparation method provided by this invention can obtain 2,5-furandicarboxylate in one step. The product yield of this preparation method is high (85%~99% in some embodiments) and high purity (over 98% in some embodiments). Furthermore, the use of a continuous flow pipeline reactor enables continuous preparation, solving the problems of long reaction routes, low overall yield, and inability to continuously prepare 2,5-furandicarboxylate substances in the existing furoic acid method.

[0006] In some embodiments, the temperature of the premixing section is controlled at 30~150°C for preheating.

[0007] In some embodiments, the temperature of the reaction section is controlled to be 50°C to 300°C, preferably 80°C to 250°C, and more preferably 100°C to 200°C.

[0008] In some embodiments, the pressure of the reaction section is controlled to be 0.5 MPa to 5 MPa, preferably 0.5 MPa to 4 MPa, and more preferably 0.8 MPa to 3.0 MPa.

[0009] In some embodiments, the temperature of the buffer section is controlled to be 50~250°C.

[0010] In some embodiments, the reactants are allowed to remain in the premixing section of the continuous flow tubular reactor for 0.01 h to 1 h, preferably 0.1 h to 0.5 h. In some embodiments, the mixed solution is held in the reaction section of the continuous flow tubular reactor for 0.1 h to 15 h, preferably 0.5 h to 10 h; In some embodiments, the reaction product is allowed to remain in the buffer section of the continuous flow pipeline reactor for 0.01h to 5h, preferably 0.1h to 5h.

[0011] In some embodiments, the premixing section includes a first single tube into which at least furoic acid, alcohol, dichloromethane and catalyst are passed for mixing and preheating.

[0012] In some embodiments, the reaction section includes multiple pipes connected in parallel, all of which are connected to the premixing section. After obtaining the mixed solution in the premixing section, the mixed solution directly enters the multiple pipes of the reaction section for reaction. The reaction section can perform a delayed, heat-preserving reaction while ensuring high mass and heat transfer efficiency of the materials. The multiple parallel pipes in the reaction section can increase production capacity while reducing backmixing and channeling that may occur in long or wide pipes, thus helping to maintain excellent mass, heat, and reaction performance.

[0013] In some embodiments, the buffer section includes a second single tube through which the reaction product is discharged. The buffer section lowers the temperature of the mother liquor below the solvent boiling point before the discharge port, preventing significant solvent evaporation caused by the system pressure being reduced to atmospheric pressure during the discharge process.

[0014] In some embodiments, the pipes in the premixing section, reaction section, and buffer section are all pipes with a large length-to-diameter ratio (e.g., a length-to-diameter ratio of 50 to 5000). The advantage of this configuration is that the larger specific surface area is conducive to achieving efficient heat exchange and mass transfer, and improving reaction safety.

[0015] In some embodiments, a turbulence-inducing structure is provided in the pipes of the reaction section. This turbulence-inducing structure can be, for example, a baffle type, a channel-cutting type, or an internal component type, which can enhance radial mixing, reduce axial backmixing, improve the mass transfer coefficient, and enhance heat transfer.

[0016] In some embodiments, the alcohol is a small molecule alcohol with 1 to 5 carbon atoms. The alcohol may include, for example, one or more combinations of methanol, ethanol, propanol, butanol, and n-pentanol, preferably one or more combinations of methanol, ethanol, and propanol.

[0017] In some embodiments, the molar ratio of alcohol to furoic acid is 0.01 to 50:1, preferably 5 to 30:1, and more preferably 10 to 20:1. The molar ratio of alcohol to furoic acid can be adjusted within the above range according to the actual needs of the preparation process, for example, 10:1, 12:1, 14:1, 16:1, 18:1, or any range between two such values.

[0018] In some embodiments, the molar ratio of dichloromethane to furoic acid is 1.2 to 3.0:1, preferably 1.6 to 2.4:1.

[0019] In some embodiments, the Lewis acid may include, for example, one or more combinations of zinc chloride, zinc bromide, zinc iodide, diethylzinc, zinc acetylacetonate, manganese chloride, manganese bromide, manganese iodide, manganese isooctanoate, manganese acetate, and manganese acetylacetonate.

[0020] In some embodiments, the oxidant includes one or more combinations of sodium hypochlorite, potassium permanganate, hydrogen peroxide, and potassium dichromate.

[0021] Lewis acid catalysts catalyze the C-alkylation of furoic acid by introducing a C atom at the 5-position of the furan ring, while the oxidant oxidizes it to a carboxyl group.

[0022] Furthermore, the molar ratio of Lewis acid to furoic acid is 0.001 to 0.5:1, preferably 0.005 to 0.3:1.

[0023] Furthermore, the molar ratio of the oxidant to furoic acid is 1.0~3.0:1, preferably 1.0~2.2:1.

[0024] In some embodiments, the continuous preparation method of the 2,5-furandicarboxylate does not require the addition of any solvent.

[0025] A second aspect of the present invention provides a method for preparing 2,5-furan dicarboxylate, comprising: reacting a mixed reaction system containing furfuric acid, an alcohol, dichloromethane, and a catalyst, wherein the catalyst comprises an oxidant and a Lewis acid containing zinc ions and / or manganese ions. Using the catalyst, high product yield and purity can be obtained.

[0026] In some embodiments, the Lewis acid includes one or more combinations of zinc chloride, zinc bromide, zinc iodide, diethylzinc, zinc acetylacetonate, manganese chloride, manganese bromide, manganese iodide, manganese isooctanoate, manganese acetate, and manganese acetylacetonate.

[0027] In some embodiments, the oxidant includes one or more combinations of sodium hypochlorite, potassium permanganate, hydrogen peroxide, and potassium dichromate.

[0028] In some preferred embodiments, the Lewis acid includes diethylzinc and manganese iodide, and the oxidant includes potassium permanganate and hydrogen peroxide. This combination can further improve the yield, for example, to 99%.

[0029] In some embodiments, the molar ratio of Lewis acid to furoic acid is 0.001 to 0.5:1, preferably 0.005 to 0.3:1.

[0030] In some embodiments, the molar ratio of the oxidant to furoic acid is 1.0~3.0:1, preferably 1.0~2.2:1.

[0031] In some embodiments, the reaction temperature is 50°C to 300°C, preferably 80°C to 250°C, and more preferably 100°C to 200°C.

[0032] In some embodiments, the reaction pressure is 0.5 MPa to 5 MPa, preferably 0.5 MPa to 4 MPa, and more preferably 0.8 MPa to 3.0 MPa.

[0033] In some embodiments, the reaction time is 0.1 h to 15 h.

[0034] In some embodiments, the alcohol is a small molecule alcohol with 1 to 5 carbon atoms. The alcohol may include, for example, one or more combinations of methanol, ethanol, propanol, butanol, and n-pentanol.

[0035] In some embodiments, the molar ratio of alcohol to furoic acid is 2~50:1, preferably 5~30:1, and more preferably 10~20:1.

[0036] In some embodiments, the molar ratio of dichloromethane to furoic acid is 1.2 to 3.0:1, preferably 1.6 to 2.4:1.

[0037] In some embodiments, the preparation method specifically includes: mixing furoic acid, alcohol, dichloromethane and catalyst and preheating at a temperature of 30°C to 150°C to obtain a mixed solution, and then reacting the mixed solution.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects: the preparation method provided by the present invention uses an oxidant and a Lewis acid containing zinc ions and / or manganese ions as the oxidant, resulting in high total product yield and high purity, and the reaction is simple, efficient and short; and it can be used in conjunction with a continuous flow pipeline reactor to achieve continuous preparation of 2,5-furandicarboxylate. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the continuous flow pipeline reactor used in Embodiment 1 of the present invention. Detailed Implementation

[0041] The invention will be more fully understood through the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as intended to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0042] In addition, unless otherwise specified, all raw materials used in the following embodiments can be purchased from the market or other sources, and all production and testing equipment used are known in the art, as are the testing methods used.

[0043] In the following specific embodiments, the 1H-NMR spectrum was measured using a Bruker 600AVANCE III spectrometer at 600 MHz, with deuterated dimethyl sulfoxide (DMSO) as the spectroscopy wavelength. d .

[0044] Product analysis was performed using an Agilent 7890B-5977A liquid chromatography-mass spectrometry system.

[0045] Reagents for which density, concentration, or other parameters are not specified in the examples are all commercially available pure reagents.

[0046] Example 1 This embodiment provides a continuous flow pipeline reactor and a method for the continuous preparation of 2,5-furan dicarboxylate using the continuous flow pipeline reactor.

[0047] Figure 1 This is a schematic diagram of the continuous flow pipeline reactor provided in this embodiment, as shown below. Figure 1 As shown, it includes a premixing section, a reaction section, and a buffer section connected in series. The premixing section includes a first single pipe, which is used for mixing and preheating the reaction raw materials. The reaction section includes multiple pipes arranged in parallel, all of which are connected to the premixing section and are equipped with flow turbulence mechanisms. The reaction section is used to carry out a delayed heat preservation reaction while ensuring that the reaction raw materials maintain a high mass and heat transfer efficiency. The buffer section includes a second single pipe, which is used for collecting and discharging the reaction product.

[0048] In this embodiment, the premixing section, reaction section, and buffer section all use pipes with a large length-to-diameter ratio, specifically 2000. Pipes with a large length-to-diameter ratio have a large specific surface area, which is beneficial for achieving efficient heat and mass transfer and improving reaction safety. However, the specific length-to-diameter ratio of the pipes in different embodiments can be flexibly selected according to actual conditions. Setting multiple parallel pipes in the reaction section can increase production capacity while reducing backmixing and channeling that may occur in long or thick pipes, which is beneficial for maintaining excellent mass transfer, heat transfer, and reaction performance. In this embodiment, three pipes are specifically set, but in other embodiments, the number of reaction section pipes can be flexibly selected as needed.

[0049] The method for continuous preparation of 2,5-furandicarboxylate using the above-mentioned continuous flow tubular reactor specifically includes the following steps: 11.2 g of furoic acid was dissolved in 32 g of methanol, and 10.2 g of dichloromethane, 0.06815 g of zinc chloride, and 44 g of potassium dichromate were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow tubular reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous mixed solution. This mixed solution was then passed into the reaction section of the continuous flow tubular reactor for reaction, where the temperature was set at 100 °C, the pressure at 2.4 MPa, and the residence time was 8 h. After the reaction was completed, the reaction product containing dimethyl 2,5-furandicarboxylate was passed into a buffer section, where the temperature was set at 60 °C and the residence time was 5 min. The resulting reaction product was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0050] The yield of dimethyl 2,5-furandicarboxylate obtained in this example was 85%, and the purity measured by HPLC was 98.1%.

[0051] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0052] Example 2 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 38.4 g of methanol, and 11.9 g of dichloromethane, 0.2252 g of zinc bromide, and 23 g of hydrogen peroxide solution (30%) were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow tubular reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous solution. This solution was then passed into the reaction section of the continuous flow tubular reactor for reaction, where the temperature was set at 160 °C, the pressure at 2.6 MPa, and the residence time was 6 h. After the reaction was completed, the temperature in the buffer section was set at 60 °C and the residence time was 5 min. The resulting product was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0053] The yield of dimethyl 2,5-furandicarboxylate obtained in this example was 88%, and the purity determined by HPLC was 99%.

[0054] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0055] Example 3 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 44.8 g of methanol, and 13.6 g of dichloromethane, 1.5961 g of zinc iodide, and 17.7 g of sodium hypochlorite solution (5% available chlorine content) were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow pipe reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous mixed solution. This mixed solution was then passed into the reaction section of the continuous flow pipe reactor for reaction, where the temperature was set at 180 °C, the pressure at 2.8 MPa, and the residence time was 4 h. After the reaction was completed, the reaction product containing dimethyl 2,5-furandicarboxylate was passed into the buffer section, where the temperature was set at 60 °C and the residence time was 5 min. The resulting reaction product was collected, the solid was evaporated, and recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0056] The yield of dimethyl 5-furandicarboxylate obtained in this example was 86.5%, and the purity measured by HPLC was 98.3%.

[0057] through 1 H-NMR (600MHz, DMSO-) dThe results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0058] Example 4 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 51.2 g of methanol, and 15.3 g of dichloromethane, 1.235 g of diethylzinc, and 25 g of potassium permanganate were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow tubular reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous solution. This solution was then passed into the reaction section of the continuous flow tubular reactor for reaction, where the temperature was set at 200 °C, the pressure at 3.0 MPa, and the residence time was 2 h. After the reaction was completed, the reaction product containing dimethyl 2,5-furandicarboxylate was passed into a buffer section, where the temperature was set at 60 °C and the residence time was 5 min. The resulting reaction product was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0059] The yield of dimethyl 2,5-furandicarboxylate prepared in this example was 95%, and the purity determined by HPLC was 99.6%.

[0060] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0061] Example 5 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 57.6 g of methanol, and 17.0 g of dichloromethane, 13.181 g of zinc acetylacetonate, and 28.3 g of hydrogen peroxide solution (30%) were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow pipe reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous mixed solution. This mixed solution was then passed into the reaction section of the continuous flow pipe reactor for reaction, where the temperature was set at 180 °C, the pressure at 2.8 MPa, and the residence time was 4 h. After the reaction was completed, the reaction product containing dimethyl 2,5-furandicarboxylate was passed into the buffer section, where the temperature was set at 60 °C and the residence time was 5 min. The resulting reaction product was collected, the solid was evaporated, and recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0062] The yield of dimethyl 2,5-furandicarboxylate obtained in this example was 92%, and the purity determined by HPLC was 99.3%.

[0063] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0064] Example 6 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 64 g of methanol, and 18.7 g of dichloromethane, 0.06292 g of manganese chloride, and 17.7 g of sodium hypochlorite solution (with an effective chlorine content of 5%) were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow tubular reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous mixed solution. This mixed solution was then passed into the reaction section of the continuous flow tubular reactor for reaction, where the temperature was set at 180 °C, the pressure at 2.8 MPa, and the residence time at 4 h. The temperature in the buffer section was 60 °C and the residence time at 5 min. The resulting product was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0065] The yield of dimethyl 2,5-furandicarboxylate obtained in this example was 88.3%, and the purity determined by HPLC was 99.2%.

[0066] through 1 H-NMR (600MHz, DMSO-) dThe results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0067] Example 7 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 38.4 g of methanol, and 20.4 g of dichloromethane, 0.06815 g of manganese bromide, and 35 g of hydrogen peroxide solution (30%) were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow pipe reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous solution. This solution was then passed into the reaction section of the continuous flow pipe reactor for reaction, where the temperature was 180 °C, the pressure was 2.8 MPa, and the residence time was 4 h. After the reaction was completed, the reaction product containing dimethyl 2,5-furandicarboxylate was passed into a buffer section, where the temperature was set at 60 °C and the residence time was 5 min. The resulting reaction product was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0068] The yield of dimethyl 2,5-furandicarboxylate obtained in this example was 88.5%, and the purity determined by HPLC was 98.2%.

[0069] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0070] Example 8 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 44.8 g of methanol, and 22.1 g of dichloromethane, 1.5437 g of manganese iodide, and 23 g of hydrogen peroxide solution (30%) were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow pipe reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous mixed solution. This mixed solution was then passed into the reaction section of the continuous flow pipe reactor for reaction, where the temperature was set at 200 °C, the pressure at 3.0 MPa, and the residence time was 2 h. After the reaction was completed, the reaction product containing dimethyl 2,5-furandicarboxylate was introduced into a buffer section, where the temperature was set at 60 °C and the residence time was 5 min. The resulting reaction product was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0071] The yield of dimethyl 2,5-furandicarboxylate obtained in this example was 93.1%, and the purity determined by HPLC was 98.5%.

[0072] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0073] Example 9 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 51.2 g of methanol, and 23.8 g of dichloromethane, 3.4135 g of manganese isooctanoate, and 19.1 g of sodium hypochlorite solution (with an available chlorine content of 5%) were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow tubular reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous mixed solution. This mixed solution was then passed into the reaction section of the continuous flow tubular reactor for reaction, where the temperature was set at 160 °C, the pressure at 2.6 MPa, and the residence time at 6 h. After the reaction was completed, the reaction product containing dimethyl 2,5-furandicarboxylate was passed into the buffer section, where the temperature was set at 60 °C and the residence time at 5 min. The resulting reaction product was collected, the solid was evaporated, and recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0074] The yield of dimethyl 2,5-furandicarboxylate obtained in this example was 87.6%, and the purity determined by HPLC was 99.1%.

[0075] through 1H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0076] Example 10 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 57.6 g of methanol, and 25.5 g of dichloromethane, 0.1266 g of manganese acetylacetone, and 47.7 g of potassium dichromate were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow tubular reactor. The temperature of the premixing section was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous mixed solution. This mixed solution was then passed into the reaction section of the continuous flow tubular reactor for reaction. The reaction section temperature was 140 °C, the pressure was 2.5 MPa, and the residence time was 5 h. After the reaction was completed, the reaction product containing dimethyl 2,5-furandicarboxylate was passed into the buffer section. The temperature of the buffer section was 60 °C and the residence time was 5 min. The resulting reaction product was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0077] The yield of dimethyl 2,5-furandicarboxylate obtained in this example was 86.2%, and the purity determined by HPLC was 99.3%.

[0078] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0079] Example 11 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 46 g of ethanol, and 17.0 g of dichloromethane, 0.1363 g of zinc chloride, and 24.6 g of sodium hypochlorite solution (with an effective chlorine content of 5%) were added. The mixture was pumped into a continuous flow tubular reactor. The premixing section was heated to 60 °C and the residence time was 1 min to mix and preheat the solution, resulting in a homogeneous solution. This solution was then passed into the reaction section of the continuous flow tubular reactor for reaction. The reaction section was heated to 180 °C and the residence time was 4 h, with a pressure of 2.8 MPa. The buffer section was heated to 60 °C and the residence time was 5 min. The product solution was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain diethyl 2,5-furandicarboxylate with a yield of 85.7% and a purity of 98.3% as determined by HPLC.

[0080] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 212.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0081] Example 12 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 60 g of propanol, and 17.0 g of dichloromethane, 0.1363 g of zinc chloride, and 31.9 g of hydrogen peroxide solution (30%) were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow pipe reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous mixed solution. This mixed solution was then passed into the reaction section of the continuous flow pipe reactor for reaction, where the temperature was set at 180 °C, the pressure at 2.8 MPa, and the residence time was 4 h. After the reaction was completed, the reaction product containing dipropyl 2,5-furandicarboxylate was passed into the buffer section, where the temperature was set at 60 °C and the residence time was 5 min. The resulting reaction product was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain dipropyl 2,5-furandicarboxylate.

[0082] The yield of dipropyl 2,5-furandicarboxylate prepared in this example was 86.3%, and the purity determined by HPLC was 98.4%.

[0083] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 240.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0084] Example 13 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 74 g of butanol, and 17.0 g of dichloromethane, 0.1363 g of zinc chloride, and 21 g of sodium hypochlorite solution (with an available chlorine content of 5%) were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow tubular reactor, where the temperature was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous mixed solution. This mixed solution was then passed into the reaction section of the continuous flow tubular reactor for reaction, where the temperature was set at 180 °C, the pressure at 2.8 MPa, and the residence time at 4 h. The temperature in the buffer section was 60 °C and the residence time at 5 min. The resulting product was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain dibutyl 2,5-furandicarboxylate.

[0085] The yield of dibutyl 2,5-furandicarboxylate prepared in this example was 85.2%, and the purity determined by HPLC was 99.3%.

[0086] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 268.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0087] Example 14 This embodiment provides a continuous preparation method for 2,5-furan dicarboxylate, using the same continuous flow pipeline reactor as in Example 1, and specifically includes the following steps: 11.2 g of furoic acid was dissolved in 88 g of n-pentanol, and 17.0 g of dichloromethane, 0.1363 g of zinc chloride, and 50 g of potassium dichromate were added to form a mixture. This mixture was pumped into the premixing section of a continuous flow tubular reactor. The temperature of the premixing section was set at 60 °C and the residence time was 1 min to mix and preheat, obtaining a homogeneous mixed solution. This mixed solution was then passed into the reaction section of the continuous flow tubular reactor for reaction. The reaction section temperature was 180 °C, the pressure was 2.8 MPa, and the residence time was 4 h. After the reaction was completed, the reaction product containing dipentyl 2,5-furandicarboxylate was passed into the buffer section. The temperature of the buffer section was 60 °C and the residence time was 5 min. The resulting reaction product was collected, the solid was evaporated, and the solid was recrystallized from ethyl acetate to obtain dipentyl 2,5-furandicarboxylate.

[0088] The yield of dipentyl 2,5-furandicarboxylate prepared in this example was 85.6%, and the purity determined by HPLC was 99.1%.

[0089] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 296.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0090] Example 15 Example 15 is essentially the same as Example 1, except that Example 15 uses a reaction vessel instead of a continuous flow tubular reactor. The preparation method of Example 15 specifically includes: 11.2 g of furoic acid was dissolved in 32 g of methanol, and then 10.2 g of dichloromethane, 0.06815 g of zinc chloride, and 44 g of potassium dichromate were added and mixed thoroughly to form a mixed reaction system, which was then added to a reaction vessel. The mixed reaction system was reacted at 100 °C and 2.4 MPa for 8 h to obtain a reaction product containing dimethyl 2,5-furandicarboxylate. The reaction product was evaporated to precipitate a solid, which was then recrystallized from ethyl acetate to obtain dimethyl 2,5-furandicarboxylate.

[0091] The yield of Example 15 was 69%, and the purity measured by HPLC was 93.5%.

[0092] Comparing Examples 1 and 15, it was found that the continuous flow tubular reactor, with its physical structure (such as large specific surface area), overcomes the bottleneck of the traditional batch reactor in the transfer process (mass transfer and heat transfer). While increasing the reaction rate, it significantly reduces by-products, improves product purity, and achieves improved reaction selectivity.

[0093] Comparative Example 1 Comparative Example 1 is essentially the same as Example 1, except that the catalyst used in Comparative Example 1 is 0.1345 g of copper chloride and 44 g of potassium dichromate. The rest of the procedures are the same as in Example 1 and will not be repeated here.

[0094] In Comparative Example 1, the yield of dimethyl 2,5-furandicarboxylate was 76.5%, and the purity determined by HPLC was 96.2%.

[0095] through 1 H-NMR (600MHz, DMSO-) d The results showed that the furan ring had CH, 2H, δ(7.39); CH3, 6H, δ(3.81), and the molecular weight was 184.1 as determined by liquid chromatography-mass spectrometry (LC-MS).

[0096] The rest is the same as in Example 1, and will not be described again here.

[0097] The raw materials used in the above embodiments and comparative examples, the reaction products obtained, and their yields and purities are summarized in Table 1: Table 1

[0098] Comparing Example 1 with Comparative Example 1, it was found that compared with using copper salt as Lewis acid catalyst, using Lewis acid catalyst containing zinc ions and / or manganese ions resulted in higher yield and product purity, and the obtained product could be directly used as a polymerization monomer for subsequent reactions.

[0099] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained high product yields and purity in all cases.

[0100] In summary, this invention uses furoic acid as a raw material, an oxidant, and inexpensive Lewis acids containing zinc and / or manganese as catalysts to prepare high-purity 2,5-furan dicarboxylate in high yield through a continuous reaction. The method provided by this invention is simple, efficient, has a short process flow, and produces few byproducts. In some embodiments, the total product yield can reach 85%-99%, and it can be used for continuous industrial production. The obtained product has high purity, meeting the requirements for use as a raw material for high-performance polyesters, epoxy resins, polyamides, polyurethanes, and other polymers, as well as as a chemical raw material and pharmaceutical intermediate. Furthermore, since furoic acid can be obtained from non-grain biomass sources, it can reduce the current dependence of bio-based polymer materials on food resources and promote the sustainable development of the bio-based polymer materials industry.

[0101] All aspects, embodiments, features, and examples of this invention should be considered illustrative and used to explain and illustrate the invention, but not to limit the invention. The scope of the invention is defined only by the claims.

[0102] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A method for the continuous production of 2,5-furan dicarboxylate, characterized in that, The application relates to a method for preparing 2,5-furandicarboxylic acid ester. The method comprises the following steps: a continuous flow pipe reactor is prepared, which comprises a premixing section, a reaction section and a buffer section; reaction raw materials containing at least furfuryl acid, alcohol, dichloromethane and a catalyst are introduced into the premixing section to mix and preheat, so as to obtain a mixed solution; wherein the catalyst comprises an oxidant and a Lewis acid containing zinc ions and / or manganese ions; the mixed solution is introduced into the reaction section of the continuous flow pipe reactor to react, so as to obtain a reaction product containing 2,5-furandicarboxylic acid ester; 2. The continuous manufacturing process of claim 1, wherein, the reaction product containing 2,5-furandicarboxylic acid ester is led out through the buffer section. The temperature of the premixing section is controlled to be 30 DEG C to 150 DEG C to preheat; and / or, the temperature of the reaction section is controlled to be 50 DEG C to 300 DEG C and the pressure is controlled to be 0.5 MPa to 5 MPa to react, preferably, the temperature of the reaction section is controlled to be 80 DEG C to 250 DEG C and the pressure is controlled to be 0.5 MPa to 4 MPa; and / or, the reaction raw materials are allowed to stay in the premixing section of the continuous flow pipe reactor for 0.01 h to 1 h; and / or, the mixed solution is allowed to stay in the reaction section of the continuous flow pipe reactor for 0.1 h to 15 h; 3. The continuous manufacturing process of claim 1, wherein: and / or, the reaction product is allowed to stay in the buffer section of the continuous flow pipe reactor for 0.01 h to 5 h. The premixing section comprises a first single pipe, and at least furfuryl acid, alcohol, dichloromethane and a catalyst are introduced into the first single pipe to mix and preheat; and / or, the reaction section comprises a plurality of pipes arranged in parallel, and the plurality of pipes are communicated with the premixing section; after the mixed solution is obtained in the premixing section, the mixed solution is directly introduced into the plurality of pipes of the reaction section to react; 4. The continuous manufacturing process of claim 3, wherein: and / or, the buffer section comprises a second single pipe, and the reaction product is led out through the second single pipe.

5. The continuous manufacturing process of claim 1, wherein: A turbulence structure is arranged in the pipe of the reaction section. The alcohol is a small molecule alcohol with carbon atom number C1 to C5, preferably a combination of one or more of methanol, ethanol, propanol, butanol and n-pentanol; and / or, the molar ratio of the alcohol to furfuryl acid is 0.01 to 50:1, preferably 5 to 30:1, and more preferably 10 to 20:1; 6. The continuous manufacturing process of claim 5, wherein: and / or, the molar ratio of dichloromethane to furfuryl acid is 1.2 to 3.0:

1. The molar ratio of the Lewis acid to furfuryl acid is 0.001 to 0.5:1; and / or, the molar ratio of the oxidant to furfuryl acid is 1.0 to 3.0:1; and / or, the Lewis acid comprises a combination of one or more of zinc chloride, zinc bromide, zinc iodide, diethyl zinc, zinc acetylacetone, manganese chloride, manganese bromide, manganese iodide, manganese iso-octoate, manganese acetate and manganese acetylacetone; 7. A method for producing 2,5-furan dicarboxylate, characterized by, and / or, the oxidant comprises a combination of one or more of sodium hypochlorite, potassium permanganate, hydrogen peroxide and potassium dichromate. The application also relates to a method for preparing 2,5-furandicarboxylic acid ester.

8. The method of claim 7, wherein: The method comprises the following steps: a mixed reaction system containing furfuryl acid, alcohol, dichloromethane and a catalyst is allowed to react, wherein the catalyst comprises an oxidant and a Lewis acid containing zinc ions and / or manganese ions. The temperature of the reaction is 50 DEG C to 300 DEG C and the pressure is 0.5 MPa to 5 MPa. And / or, the reaction time is 0.1h~15h; And / or, the alcohol is a small molecule alcohol with carbon number C1~C5, preferably including a combination of one or more of methanol, ethanol, propanol, butanol, n-pentanol; And / or, the molar ratio of alcohol to furoic acid is 2~50:1; And / or, the molar ratio of dichloromethane to furoic acid is 1.2~3.0:

1.

9. The method of claim 8, wherein: The molar ratio of the Lewis acid to furoic acid is 0.001~0.5:1; And / or, the molar ratio of the oxidizing agent to furoic acid is 1.0~3.0:1; And / or, the Lewis acid includes a combination of one or more of zinc chloride, zinc bromide, zinc iodide, diethyl zinc, zinc acetylacetone, manganese chloride, manganese bromide, manganese iodide, manganese iso-octoate, manganese acetate, manganese acetylacetone; And / or, the oxidizing agent includes a combination of one or more of sodium hypochlorite, potassium permanganate, hydrogen peroxide, potassium dichromate.

10. The method of claim 7, wherein, Specifically includes: At least mix the furoic acid, alcohol, dichloromethane and catalyst and preheat under temperature conditions of 30℃~150℃ to obtain a mixed solution, and then make the mixed solution react.

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