Process and apparatus for the preparation of 5,5'-oxybis-methylene-2-furfuraldehyde

Abstract

The application provides a method and device for preparing 5,5'-oxy bis-methylene-2-furfural, and belongs to the technical field of chemical synthesis. The method for preparing 5,5'-oxy bis-methylene-2-furfural comprises the following steps: mixing 5-hydroxymethyl furfural, a catalyst and an organic solvent in a micro-mixer to obtain a mixture; and continuously conveying the mixture into a dynamic tubular reactor to perform a self-etherification reaction, so as to obtain a reaction liquid containing 5,5'-oxy bis-methylene-2-furfural, wherein the inner diameter of the dynamic tubular reactor is 60-80 mm.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, specifically to a method and apparatus for preparing 5,5'-oxybismethylene-2-furfural. Background Technology

[0002] 5,5'-Oxybismethylene-2-furfural has broad application prospects. It can be used not only as a monomer for preparing certain imine polymers with good thermal and electrical conductivity, but also for synthesizing heterocyclic ligands and hepatitis antiviral precursors.

[0003] The following problems exist in the methods for synthesizing 5,5'-oxydimethylene-2-furfural in related technologies: industrially, batch reactors are commonly used for the synthesis of 5,5'-oxydimethylene-2-furfural, which results in long reaction times and low production efficiency; the increase in temperature during the reaction leads to increased pressure, which is not safe enough. Summary of the Invention

[0004] In view of this, the present invention provides a method and apparatus for preparing 5,5'-oxybismethylene-2-furfural.

[0005] According to one aspect of the present invention, a method for preparing 5,5'-oxydimethylene-2-furfural is provided, comprising:

[0006] 5-hydroxymethylfurfural, a catalyst, and an organic solvent are mixed in a micromixer to obtain a mixture;

[0007] The mixture is continuously fed into a dynamic tubular reactor for self-etherification to obtain a reaction solution containing 5,5'-oxydimethylene-2-furfural; wherein the inner diameter of the dynamic tubular reactor is 60~80 mm.

[0008] According to an embodiment of the present invention, the micromixer includes an inlet channel, a first cavity, a plurality of microchannel sections, a second cavity, and an outlet channel connected in sequence. The plurality of microchannel sections are arranged in an array in the direction from the first cavity to the second cavity, and a sub-cavity is provided between two adjacent microchannel sections. The plurality of microchannel sections are used to mix the 5-hydroxymethylfurfural, the catalyst, and the organic solvent under microscale conditions.

[0009] According to an embodiment of the present invention, the microchannel portion includes a plurality of microchannel layers arranged in an array, wherein the microchannel layers are composed of a plurality of V-shaped microchannels arranged in an array.

[0010] According to an embodiment of the present invention, the width of the microchannels in the plurality of microchannel portions decreases sequentially in the direction from the first cavity to the second cavity.

[0011] According to an embodiment of the present invention, the width of the microchannels within the plurality of microchannel portions is 0.5 to 0.8 mm.

[0012] According to an embodiment of the present invention, the height of the microchannels within the plurality of microchannel sections is 0.2 to 0.4 mm.

[0013] According to an embodiment of the present invention, the above-mentioned dynamic tubular reactor includes a reaction cylinder and a rotating shaft, wherein the rotational speed of the rotating shaft is 500~800 r / min.

[0014] According to an embodiment of the present invention, the capacity of the above-mentioned reaction vessel is 50~500 mL.

[0015] According to an embodiment of the present invention, the above-mentioned self-etherification reaction is carried out at 25~165°C, and the stop time in the above-mentioned dynamic tubular reactor is 1~15 min.

[0016] According to an embodiment of the present invention, the method further includes: passing the reaction solution containing 5,5'-oxydimethylene-2-furfural through a dehydration membrane to remove water, thereby obtaining a dehydrated reaction solution; and conveying the dehydrated reaction solution to the micro-mixer through a third liquid phase channel.

[0017] According to an embodiment of the present invention, the mixing of 5-hydroxymethylfurfural, catalyst and organic solvent in a micromixer includes: conveying 5-hydroxymethylfurfural and organic solvent to the micromixer through a first liquid phase channel, or conveying 5-hydroxymethylfurfural, catalyst and organic solvent to the micromixer through the first liquid phase channel; conveying the catalyst and organic solvent to the micromixer through a second liquid phase channel, or not conveying them.

[0018] According to an embodiment of the present invention, the concentration of the above-mentioned 5-hydroxymethylfurfural is 0.5wt% to 15wt%.

[0019] According to embodiments of the present invention, the catalyst is one or more of p-toluenesulfonic acid, sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, phosphomolybdic acid, ferric chloride, and ferric sulfate.

[0020] According to an embodiment of the present invention, the concentration of the catalyst is 0.05wt% to 1wt%.

[0021] According to embodiments of the present invention, the organic solvent is one or more selected from dimethyl carbonate, toluene, acetone, acetonitrile, and dichloromethane.

[0022] The present invention also provides an apparatus for preparing 5,5'-oxydimethylene-2-furfural, comprising: a micromixer adapted to continuously receive 5-hydroxymethylfurfural, a catalyst, and an organic solvent, and mix them to obtain a mixture; and a dynamic tubular reactor located downstream of the micromixer, adapted to continuously receive the mixture from the micromixer and subject the mixture to a self-etherification reaction to obtain a reaction solution containing 5,5'-oxydimethylene-2-furfural, wherein the inner diameter of the dynamic tubular reactor is 60-80 mm.

[0023] According to embodiments of the present invention, the present invention enhances the mixing effect through a micro-mixer, and enables the reaction to reach temperature and mass equilibrium in a short time through the flow system in the dynamic tubular reactor, thereby obtaining reaction products more quickly, shortening the reaction time, improving production efficiency, and reducing the occurrence of side reactions. Furthermore, the continuous flow preparation process and the relatively small reaction volume of the dynamic tubular reactor of the present invention avoid the pressure increase caused by heating in a closed reaction vessel during the reaction process, making the reaction process of the present invention safer.

[0024] The apparatus for preparing 5,5'-oxydimethylene-2-furfural provided by this invention is relatively simple and easy to build, and is more convenient and safer than reaction vessels; moreover, micromixers and dynamic tubular reactors are usually designed in a modular manner, which can be quickly adjusted and scaled up according to production needs, thereby improving the flexibility and scalability of production. Attached Figure Description

[0025] Figure 1 The flowchart illustrating the method for preparing 5,5'-oxybismethylene-2-furfural provided in the embodiments of the present invention is shown in the figure.

[0026] Figure 2 A schematic cross-sectional view of a micromixer provided in an embodiment of the present invention is shown.

[0027] Figure 3 A schematic cross-sectional view of the reaction vessel of the dynamic tubular reactor provided in an embodiment of the present invention is shown.

[0028] Figure 4 A schematic diagram of the rotation axis of the dynamic tubular reactor provided in an embodiment of the present invention is shown.

[0029] Figure 5 The diagram schematically illustrates an apparatus for preparing 5,5'-oxybismethylene-2-furfural according to an embodiment of the present invention.

[0030] Figure 6 The 1H NMR spectrum of crude 5,5'-oxydimethylene-2-furfural provided in Example 1 of this invention;

[0031] Figure 7 The 1H NMR spectrum of pure 5,5'-oxybis(methylene-2-furfural) provided in Example 1 of this invention;

[0032] The meanings of the reference numerals in the above figures are as follows:

[0033] 1-First liquid phase channel;

[0034] 2-Second liquid phase channel;

[0035] 3-First plunger pump;

[0036] 4-Second plunger pump;

[0037] 5- Micro mixer;

[0038] 51 - Entrance passage;

[0039] 52-First cavity;

[0040] 53 - Multiple microchannel sections;

[0041] 531 - First Microchannel Section;

[0042] 532-Second Microchannel Section

[0043] 54 - Second cavity;

[0044] 55 - Export Channel;

[0045] 56-Sub cavity;

[0046] 6-Dynamic tubular reactor;

[0047] 61-Reaction cylinder;

[0048] 62 - Rotation axis;

[0049] 7-Water removal membrane;

[0050] 8-Quenching device;

[0051] 9-Back pressure valve;

[0052] 10-Analytical equipment. Detailed Implementation

[0053] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0054] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0055] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0056] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0057] This invention provides a method for preparing 5,5'-oxydimethylene-2-furfural based on a dynamic tubular reactor. Unless otherwise specified, the experimental methods described in the following examples are conventional methods; and the reagents and materials mentioned are commercially available unless otherwise specified.

[0058] In related technologies, the synthesis of 5,5'-oxydimethylene-2-furfural using a batch reactor involves a long reaction time, typically 1-24 hours, resulting in low production efficiency. Furthermore, the increased temperature during the reaction leads to higher pressure, posing safety risks. In developing this invention, it was discovered that a dynamic tubular reactor, through its continuous flow production, can improve production efficiency, yield, and product consistency. Moreover, the dynamic tubular reactor allows for precise control of key parameters such as temperature, pressure, and flow rate, optimizing reaction efficiency. It also offers better safety and stability, along with efficient heat exchange performance, while its modular design enhances production flexibility and scalability. However, with increased production efficiency, issues such as incomplete reaction or low yield may arise.

[0059] In the process of realizing this invention, it was discovered that the above-mentioned problems of incomplete reaction or low yield may be caused by uneven mixing of reaction raw materials. Micro mixers can enhance the mixing effect of reaction raw materials. Using micro mixers in conjunction with dynamic tubular reactors can shorten reaction time and improve production efficiency while ensuring product yield.

[0060] Figure 1 The reaction flow diagram for preparing 5,5'-oxybismethylene-2-furfural is shown in the embodiment of the present invention.

[0061] According to some embodiments of the present invention, the present invention provides a method for 5,5'-oxybis(methylene-2-furfural), referring to... Figure 1 As shown, it includes steps S110 to S120.

[0062] In step S110, 5-hydroxymethylfurfural, the catalyst, and the organic solvent are mixed in a micromixer to obtain a mixture;

[0063] In step S120, the mixture is continuously fed into a dynamic tubular reactor for a self-etherification reaction to obtain a reaction solution containing 5,5'-oxydimethylene-2-furfural; wherein the inner diameter of the dynamic tubular reactor is 60~80 mm.

[0064] According to embodiments of the present invention, the present invention enhances the mixing effect through a micro-mixer, and enables the reaction to reach temperature and mass equilibrium in a short time through the flow system of a dynamic tubular reactor, thereby obtaining reaction products more quickly, shortening the reaction time, improving production efficiency, and reducing the occurrence of side reactions. Furthermore, the continuous flow preparation process and the relatively small reaction volume of the dynamic tubular reactor of the present invention avoid the pressure increase caused by heating in a closed reaction vessel during the reaction process, making the reaction process of the present invention safer.

[0065] According to an embodiment of the present invention, the reaction process for preparing 5,5'-oxybismethylene-2-furfural is as follows:

[0066]

[0067] According to embodiments of the present invention, the concentration of 5-hydroxymethylfurfural is 0.5 wt% to 15 wt%, preferably 0.5 to 7.0 wt%. Specifically, the concentration of 5-hydroxymethylfurfural can be 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, 7.0 wt%, 7.5 wt%, 8.0 wt%, 9.0 wt%, 10.0 wt%, 11.0 wt%, 13.0 wt%, or 15.0 wt%, preferably 6.0 wt%. During the experiments related to the present invention, it was found that a suitable concentration of 5-hydroxymethylfurfural can achieve both high production efficiency and product yield.

[0068] According to embodiments of the present invention, the catalyst is one or more selected from p-toluenesulfonic acid, sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, phosphomolybdic acid, ferric chloride, and ferric sulfate, preferably p-toluenesulfonic acid. The concentration of the catalyst is 0.05~1wt%, preferably 0.12~0.24wt%. Specifically, the concentration of the catalyst is 0.05wt%, 0.10wt%, 0.12wt%, 0.16wt%, 0.24wt%, 0.30wt%, 0.40wt%, 0.50wt%, 0.70wt%, or 1.00wt%.

[0069] According to embodiments of the present invention, the organic solvent is one or more of dimethyl carbonate, toluene, acetone, acetonitrile, and dichloromethane, preferably acetonitrile.

[0070] According to embodiments of the present invention, the self-etherification reaction is carried out at 25~165°C, preferably 25~90°C. Specifically, the temperature of the self-etherification reaction can be 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, or 165°C.

[0071] According to embodiments of the present invention, the dwell time in the dynamic tubular reactor is 1 to 15 minutes, preferably 1.5 to 10 minutes. Specifically, the dwell time in the dynamic tubular reactor 6 is 1 minute, 1.5 minutes, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, or 15 minutes. Appropriate reaction temperature and time can balance production efficiency and yield.

[0072] According to embodiments of the present invention, water generated in the incompletely reacted solution can be removed using a dehydration membrane, and the dehydrated reaction solution can be recycled. The obtained reaction solution can be qualitatively and / or quantitatively analyzed by one or more analytical devices, such as liquid chromatography, proton nuclear magnetic resonance spectroscopy, and carbon spectroscopy. If the qualitative and / or quantitative analyses do not meet the product requirements, the reaction solution containing 5,5'-oxydimethylene-2-furfural can be dehydrated using a dehydration membrane to obtain a dehydrated reaction solution; the dehydrated reaction solution is then transported to a micromixer through a third liquid phase channel.

[0073] According to embodiments of the present invention, the reaction solution containing 5,5'-oxydimethylene-2-furfural can also be separated and purified to prepare purified 5,5'-oxydimethylene-2-furfural. Specifically, the purification steps can be as follows: the hot reactants are filtered while hot, and the resulting filtrate is rotary evaporated to obtain crude 5,5'-oxydimethylene-2-furfural. The crude 5,5'-oxydimethylene-2-furfural is recrystallized from methanol:water = 1:1 (volume ratio) to obtain pure 5,5'-oxydimethylene-2-furfural.

[0074] The method for preparing 5,5'-oxydimethylene-2-furfural provided by the present invention can be as follows: After the reactor is connected, water, ethanol and organic solvent are first pumped in to clean the reaction system, then the reaction substrate solution is pumped in and mixed in a micro mixer, and then purified after reacting in a dynamic tubular reactor at a certain temperature for a certain time.

[0075] The present invention also provides an apparatus for preparing 5,5'-oxybismethylene-2-furfural, comprising:

[0076] A micromixer suitable for continuously receiving 5-hydroxymethylfurfural, a catalyst, and an organic solvent, and mixing them to obtain a mixture;

[0077] A dynamic tubular reactor, located downstream of a micromixer, is suitable for continuously receiving mixtures from the micromixer and subjecting the mixtures to a self-etherification reaction to obtain a reaction solution containing 5,5'-oxydimethylene-2-furfural. The inner diameter of the dynamic tubular reactor is 60-80 mm.

[0078] The apparatus for preparing 5,5'-oxydimethylene-2-furfural provided by this invention is relatively simple and easy to build, and is more convenient and safer than reaction vessels; moreover, micromixers and dynamic tubular reactors are usually designed in a modular manner, which can be quickly adjusted and scaled up according to production needs, thereby improving the flexibility and scalability of production.

[0079] The present invention does not limit the shape of the micromixer; for example, it can be a cylindrical shape, a conical shape, etc., specifically, it can be a cylindrical, square, or rectangular cylinder. To promote fluid mixing, the micromixer can adopt a spiral structure, a baffle structure, or other geometric structures that can promote fluid turbulence and mixing.

[0080] One preferred solution is as follows: Figure 2 As shown, the micromixer may include an inlet channel 51, a first chamber 52, multiple microchannel sections 53, a second chamber 54, and an outlet channel 55 connected in sequence. The multiple microchannel sections 53 are arranged in an array from the first chamber 52 to the second chamber 54, and a sub-chamber 56 is provided between adjacent microchannel sections. The multiple microchannel sections 53 are used to mix 5-hydroxymethylfurfural, a catalyst, and an organic solvent under microscale conditions, which can be micrometer or centimeter scale conditions. The sub-chamber 56 is used to mix the 5-hydroxymethylfurfural, catalyst, and organic solvent flowing out of each microchannel within the microchannel section. The first chamber 52, the second chamber 54, and the sub-chamber 56 are used to contain 5-hydroxymethylfurfural, the catalyst, and the organic solvent, and to mix them.

[0081] According to an embodiment of the present invention, the microchannel section 53 includes a plurality of microchannel layers arranged in an array, each microchannel layer being composed of a plurality of V-shaped microchannels arranged in an array. Specifically, each microchannel section 53 may include a plurality of microchannel layers arranged in parallel along a direction perpendicular to the first cavity 52 to the second cavity 54. Each microchannel layer may be composed of a plurality of V-shaped microchannels arranged in an array. The top inlet of the V-shaped microchannel is connected to the first cavity 52 or a sub-cavity 56, and the bottom outlet of the V-shaped microchannel is connected to the sub-cavity 56 or the second cavity 54. The top inlets of the plurality of V-shaped microchannels may be connected to improve the mixing effect. The sub-cavity 56 located between two adjacent microchannel sections can mix 5-hydroxymethylfurfural, catalyst, and organic solvent between different microchannel layers within the microchannel section, thereby improving the mixing effect.

[0082] According to an embodiment of the present invention, the widths of the microchannels within the plurality of microchannel portions 53 may be equal.

[0083] More preferably, the width of the microchannels in the plurality of microchannel sections 53 decreases sequentially in the direction from the first cavity 52 to the second cavity 54.

[0084] For example, the microchannel section 53 includes a first microchannel section 531 and a second microchannel section 532, wherein the first microchannel section 531 is close to the first cavity 52, and the second microchannel section 532 is close to the second cavity 54. The width of the microchannel in the first microchannel section 531 can be equal to the width of the microchannel in the second microchannel section 532. The width of the microchannel in the first microchannel section 531 can also be greater than the width of the microchannel in the second microchannel section 532. In this case, the micromixer has a better mixing effect.

[0085] According to an embodiment of the present invention, the width of the microchannels within the plurality of microchannel portions 53 is 0.5 to 0.8 mm. Specifically, the width of the microchannels within the plurality of microchannel portions 53 can be 0.5 mm, 0.6 mm, 0.7 mm, or 0.8 mm, preferably 0.6 mm.

[0086] According to an embodiment of the present invention, the height of the microchannels within the plurality of microchannel portions 53 is 0.2 to 0.4 mm. Specifically, the height of the microchannels within the plurality of microchannel portions 53 can be 0.2 mm, 0.3 mm, or 0.4 mm, preferably 0.3 mm.

[0087] According to an embodiment of the present invention, the plurality of microchannel portions 53 may further include other microchannel portions located between the first microchannel portion 531 and the second microchannel portion 532. The width of the microchannels in the other microchannel portions may be 0.5~0.8 mm, and the height may be 0.2~0.4 mm. In the direction from the first cavity 52 to the second cavity 54, the width of each microchannel portion may be designed in a hierarchical manner from large to small to obtain a better mixing effect.

[0088] According to embodiments of the present invention, such as Figure 3 and Figure 4 As shown, the dynamic tubular reactor may include a reaction vessel 61 and a rotating shaft 62, the rotating shaft 62 rotating at a speed of 500~800 r / min. Specifically, the rotating shaft 62 can rotate at 500 r / min, 600 r / min, 700 r / min, or 800 r / min. The reaction vessel 61 has a capacity of 50~500 mL. Specifically, the reaction vessel 61 can have a capacity of 50 mL, 100 mL, 150 mL, 200 mL, 300 mL, 400 mL, or 500 mL. The rotation of the rotating shaft causes the material flow to exhibit plug flow characteristics, effectively reducing backmixing and improving the selectivity and conversion rate of the reaction.

[0089] According to an embodiment of the present invention, fins of different shapes can be distributed on the rotating shaft 62 according to the reaction requirements to enhance the mixing effect. The outer diameter of the dynamic tubular reactor 6 can be equipped with a large-area contact circulating heating and insulation system to quickly and accurately adjust the temperature of the reaction system, thereby improving production efficiency and consistency, which is conducive to large-scale industrial application.

[0090] Figure 5 A schematic diagram of an apparatus for 5,5'-oxybismethylene-2-furfural provided in an embodiment of the present invention is shown.

[0091] like Figure 5 As shown, the apparatus for preparing 5,5'-oxybismethylene-2-furfural may include: a first liquid phase channel 1, a second liquid phase channel 2, a first plunger pump 3, a second plunger pump 4, a micromixer 5, a dynamic tubular reactor 6, a dehydration membrane 7, a quenching device 8, a back pressure valve 9, and an analytical device 10.

[0092] According to an embodiment of the present invention, a first plunger pump 3 may be provided on the first liquid phase channel 1 to pump 5-hydroxymethylfurfural and an organic solvent, or 5-hydroxymethylfurfural, a catalyst, and an organic solvent, into the micromixer 5. A second plunger pump 4 may be provided on the second liquid phase channel 2 to pump the catalyst and organic solvent into the micromixer 5, or no delivery may be performed.

[0093] According to an embodiment of the present invention, 5-hydroxymethylfurfural, a catalyst, and an organic solvent can be transported to a micro-mixer 5 through a first liquid phase channel 1, so that 5-hydroxymethylfurfural, a catalyst, and an organic solvent are mixed in the micro-mixer 5 to obtain a mixture.

[0094] In the process of realizing this invention, it was discovered that when 5-hydroxymethylfurfural, the catalyst, and the organic solvent are transported through the first liquid phase channel 1, the catalyst (e.g., ferric sulfate) may not be completely dissolved, which can easily cause the catalyst to deposit in the first liquid phase channel 1, affecting the smooth progress of subsequent mixing and reaction. Heating can be considered to promote the dissolution of the catalyst, but this may bring new problems: the self-etherification reaction may occur prematurely in the first liquid phase channel 1.

[0095] To address the aforementioned issues, 5-hydroxymethylfurfural and the organic solvent can be transported to the micromixer 5 through the first liquid phase channel 1; the catalyst and the organic solvent can be transported to the micromixer 5 through the second liquid phase channel 2; then, the 5-hydroxymethylfurfural, catalyst, and organic solvent are mixed within the micromixer 5 to obtain a mixture. By transporting 5-hydroxymethylfurfural and the catalyst separately, the second liquid phase channel 2 can be heated individually, promoting the dissolution of the catalyst and ensuring its smooth transport to the micromixer 5 for mixing, while simultaneously preventing premature self-etherification.

[0096] Therefore, the micro mixer 5 can be a two-way, three-way, or four-way mixer, located downstream of the first liquid phase channel 1 and / or the second liquid phase channel 2, and upstream of the dynamic tubular reactor 6.

[0097] When the micromixer 5 is suitable for continuously receiving 5-hydroxymethylfurfural, catalyst and organic solvent from the first liquid phase channel 1 to mix and obtain a mixture, the micromixer 5 can be a two-way mixer.

[0098] When suitable for continuously receiving 5-hydroxymethylfurfural and organic solvent from the first liquid phase channel 1 and catalyst and organic solvent from the second liquid phase channel 2, the micromixer 5 can be a three-way mixer. Specifically, the micromixer 5 may include: two inlet channels: one inlet channel connected to the first liquid phase channel 1 for receiving 5-hydroxymethylfurfural and organic solvent; and one inlet channel connected to the second liquid phase channel 2 for receiving catalyst and organic solvent; and one outlet channel 55 connected to the dynamic tubular reactor 6 for discharging the mixture.

[0099] This application does not limit the shape and size of the inlet channel 51 and the outlet channel 55. For example, the inlet channel 51 and the outlet channel 55 of the micro mixer 5 can both be circular channels with an outer diameter of 3.0 mm and an inner diameter of 2.0 mm.

[0100] According to an embodiment of the present invention, a dewatering membrane 7, a quenching device 8, a back pressure valve 9, and an analytical device 10 may also be provided downstream of the dynamic tubular reactor 6.

[0101] The dehydration membrane 7 removes water generated in the reaction solution, allowing the dehydrated reaction solution to be recycled for further reaction. Specifically, the dehydrated reaction solution can be transported to the micro-mixer 5 through the third liquid phase channel; in this case, the micro-mixer 5 can be a four-way micro-mixer.

[0102] Quenching device 8 is suitable for ensuring rapid and uniform cooling of fluid in the system. For example, it can be a coil structure, plate heat exchanger or other heat exchange structure that can effectively reduce the temperature of the fluid.

[0103] Back pressure valve 9 is suitable for regulating the pressure and flow rate of fluids to ensure stable flow and reaction of fluids in the system. For example, it can be a spring-loaded structure, a piston structure, or other mechanical structure that can precisely control the pressure and flow rate of fluids.

[0104] The analytical device 10 is suitable for qualitative and / or quantitative analysis of compounds. The analytical device 10 can also be located before the dehydration membrane, suitable for analyzing the reaction liquid output from the dynamic tubular reactor 6; or it can be located after the dehydration membrane, suitable for analyzing the reaction liquid after dehydration.

[0105] The present invention will be further illustrated by the following embodiments. In the detailed description below, numerous specific details are set forth for ease of explanation to provide a comprehensive explanation of the embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict.

[0106] Example 1

[0107] This embodiment provides a method for preparing 5,5'-oxybis(methylene-2-furfural), comprising the following steps:

[0108] After the reaction apparatus was connected and cleaned, the back pressure valve was fixed at 2 MPa. An acetonitrile solution of 8 wt% 5-hydroxymethylfurfural (HMF) and an acetonitrile solution of 0.96 wt% p-toluenesulfonic acid catalyst were pumped in at a flow rate of 24.25 mL / min and mixed in a micromixer, resulting in a mixture of 6 wt% 5-hydroxymethylfurfural and 0.24 wt% p-toluenesulfonic acid catalyst. The mixture was then passed into a 97 mL dynamic tubular reactor at 80°C for 2 minutes to obtain the reaction solution, which was then qualitatively and quantitatively analyzed. The reaction mixture was subsequently purified by: filtering the hot reactants while hot, and then rotary evaporating the filtrate to obtain crude 5,5'-oxydimethylene-2-furfural. Crude 5,5'-oxydimethylene-2-furfural was recrystallized from methanol:water (1:1, volume ratio) to obtain pure 5,5'-oxydimethylene-2-furfural, with a molar yield of 95.63%. Qualitative and quantitative analysis was performed using gas chromatography. Finally, the crude, purified, and pure 5,5'-oxydimethylene-2-furfural samples were analyzed by 1H NMR spectroscopy. Figure 6 , Figure 7 As shown.

[0109] The apparatus for preparing 5,5'-oxybismethylene-2-furfural is as follows: Figures 2-5 As shown, it includes: a first liquid phase channel 1, a second liquid phase channel 2, a first plunger pump 3, a second plunger pump 4, a micromixer 5, a dynamic tubular reactor 6, a dehydration membrane 7, a quenching device 8, a back pressure valve 9, and an analytical device 10. 5-hydroxymethylfurfural, the catalyst, and the organic solvent are transported to the micromixer 5 through the first liquid phase channel 1.

[0110] The microchannels in the micromixer 5 have a width of 0.6 mm and a height of 0.3 mm. The rotating shaft in the dynamic tubular reactor 6 rotates at a speed of 700 r / min; the reaction cylinder has a width of 600 mm, an outer diameter of 160 mm, and an inner diameter of 70 mm.

[0111] Examples 2 to 22:

[0112] The preparation processes of Examples 2 to 22 were the same as those of Example 1, except that the reaction parameters were changed according to Table 1 below, including: In Examples 2 to 22, the concentration of the substrate 5-hydroxymethylfurfural (HMF) was adjusted to 0.5wt%, 2wt%, 7.5wt%, and 9wt%, respectively; in Example 6, p-toluenesulfonic acid was replaced with sulfuric acid; in Examples 7 to 9, the concentration of p-toluenesulfonic acid was adjusted to 0.05wt%, 0.12wt%, and 0.16wt%, respectively; in Examples 10 to 13, the temperature was adjusted to 60℃, 70℃, 90℃, and 100℃, respectively; and in Examples 14 to 18, the residence time was adjusted to 1 min, 5 min, 8 min, and 10 min, respectively. min, 15 min; In Example 19, the organic solvent was changed to acetone; In Examples 20 to 22, the catalysts were changed to phosphomolybdic acid, ferric chloride and ferric sulfate, respectively. 5-hydroxymethylfurfural and organic solvent were transported to micromixer 5 through the first liquid phase channel 1, and catalyst and organic solvent were transported to micromixer 5 through the second liquid phase channel 2. The reaction parameters and product yields are shown in Table 1 below.

[0113] Table 1

[0114]

[0115] A comparison between Examples 1 to 22 shows that the yield of 5,5'-oxydimethylene-2-furfural prepared in Example 10 was 99.9%, the highest yield. In other words, the best yield of 5,5'-oxydimethylene-2-furfural was achieved when the concentration of the substrate 5-hydroxymethylfurfural was 6 wt%, the organic acid was p-toluenesulfonic acid with a concentration of 0.24 wt%, the solvent was acetonitrile, the self-etherification reaction temperature was 60°C, and the reaction time was 2 min.

[0116] Comparative Example 1

[0117] The preparation of 5,5'-oxybis(methylene-2-furfural) by dehydration of 5-hydroxymethylfurfural in a reaction flask includes the following steps:

[0118] In a 250 mL three-necked flask equipped with a Dean-Stark apparatus, 3.0030 g of 5-hydroxymethylfurfural, 50.16 g of acetone, and 0.1332 g of p-toluenesulfonic acid catalyst were added sequentially. The reaction was carried out at 60 °C for 1 h, 2 h, 3 h, 4 h, 5 h, and 6 h. Samples were taken and analyzed by gas chromatography. The molar yields of 5,5'-oxydimethylene-2-furfural were 67.34%, 68.27%, 70.49%, 72.31%, 71.23%, and 73.26%, respectively.

[0119] Comparative Example 2

[0120] The preparation process of Comparative Example 2 was the same as that of Example 1, except that the micromixer 5 was adjusted to a three-way pipe, and the molar yield of 5,5'-oxybismethylene-2-furfural was 87.53%.

[0121] A comparison between Example 1 and Comparative Example 1 shows that the method for preparing 5,5'-oxydimethylene-2-furfural using a micromixer and a dynamic tubular reactor, compared to a batch reactor, shortens the reaction time and achieves a higher product yield; furthermore, it avoids the safety issues associated with a reaction vessel. A comparison between Example 1 and Comparative Example 2 shows that the combined use of a micromixer and a dynamic tubular reactor can improve the yield of 5,5'-oxydimethylene-2-furfural.

[0122] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art to the technical methods within the spirit and principles of the present invention are still included within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing 5,5'-oxydimethylene-2-furfural, comprising: 5-hydroxymethylfurfural, a catalyst, and an organic solvent are mixed in a micromixer to obtain a mixture; The mixture is continuously fed into a dynamic tubular reactor for self-etherification reaction to obtain a reaction solution containing 5,5'-oxydimethylene-2-furfural, wherein the inner diameter of the dynamic tubular reactor is 60-80 mm. The stop time in the dynamic tubular reactor is 2-4 minutes. The self-etherification reaction is carried out at 60~90℃; The concentration of 5-hydroxymethylfurfural is 0.5wt%~7.5wt%; The concentration of the catalyst is 0.05 wt% to 1 wt%. The catalyst is one or more of p-toluenesulfonic acid, sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, phosphomolybdic acid, ferric chloride, and ferric sulfate. The dynamic tubular reactor includes a reaction cylinder and a rotating shaft, on which fins are distributed; The micromixer includes an inlet channel, a first cavity, a plurality of microchannel sections, a second cavity, and an outlet channel connected in sequence. The plurality of microchannel sections are arranged in an array in the direction from the first cavity to the second cavity, and a sub-cavity is provided between two adjacent microchannel sections. The plurality of microchannel sections are used to mix the 5-hydroxymethylfurfural, the catalyst, and the organic solvent under microscale conditions. The width of the microchannels within the plurality of microchannel sections decreases sequentially from the first cavity to the second cavity; The microchannel section includes multiple microchannel layers arranged in an array, and each microchannel layer is composed of multiple sets of V-shaped microchannels arranged in an array.

2. The method according to claim 1, wherein, The width of the microchannels within the plurality of microchannel sections is 0.5~0.8mm; The height of the microchannels within the plurality of microchannel sections is 0.2~0.4 mm.

3. The method according to claim 1 or 2, wherein, The rotational speed of the rotating shaft is 500~800 r / min; The capacity of the reaction vessel is 50~500 mL.

4. The method according to claim 1 or 2, further comprising: The reaction solution containing 5,5'-oxydimethylene-2-furfural was dehydrated by passing it through a dehydration membrane to obtain a dehydrated reaction solution. The dehydrated reaction solution is transported to the micromixer through the third liquid phase channel.

5. The method according to claim 1 or 2, wherein, The mixing of 5-hydroxymethylfurfural, the catalyst, and the organic solvent within the micromixer includes: 5-hydroxymethylfurfural and organic solvent are transported to the micromixer through a first liquid phase channel, and the catalyst and organic solvent are transported to the micromixer through a second liquid phase channel, or 5-hydroxymethylfurfural, catalyst and organic solvent are transported to the micromixer through the first liquid phase channel.

6. The method according to claim 1 or 2, wherein, The organic solvent is one or more of dimethyl carbonate, toluene, acetone, acetonitrile, and dichloromethane.

7. An apparatus for preparing 5,5'-oxybis(methylene-2-furfural), comprising: A micromixer suitable for continuously receiving 5-hydroxymethylfurfural, a catalyst, and an organic solvent, and mixing them to obtain a mixture; A dynamic tubular reactor, located downstream of the micromixer, is adapted to continuously receive the mixture from the micromixer and subject the mixture to a self-etherification reaction to obtain a reaction solution containing 5,5'-oxydimethylene-2-furfural, wherein the inner diameter of the dynamic tubular reactor is 60-80 mm. The stop time in the dynamic tubular reactor is 2-4 minutes. The self-etherification reaction is carried out at 60~90℃; The dynamic tubular reactor includes a reaction cylinder and a rotating shaft, on which fins are distributed; The micromixer includes an inlet channel, a first cavity, a plurality of microchannel sections, a second cavity, and an outlet channel connected in sequence. The plurality of microchannel sections are arranged in an array in the direction from the first cavity to the second cavity, and a sub-cavity is provided between two adjacent microchannel sections. The plurality of microchannel sections are used to mix the 5-hydroxymethylfurfural, the catalyst, and the organic solvent under microscale conditions. The width of the microchannels within the plurality of microchannel sections decreases sequentially from the first cavity to the second cavity; The microchannel section includes multiple microchannel layers arranged in an array, and each microchannel layer is composed of multiple sets of V-shaped microchannels arranged in an array.

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