A preparation method of alkenyl succinic anhydride

Abstract

The present invention belongs to the technical fields of fine chemical engineering and organic synthesis, and particularly relates to a preparation method of alkenyl succinic anhydride, which comprises the following steps: adding an antioxidant into a mixture of internal octadecene and maleic anhydride, and carrying out a microwave heating reaction to generate alkenyl succinic anhydride; wherein, the antioxidant is a mixture of hydroquinone and 2,6-di-tert-butyl-p-cresol. This preparation method replaces the heating method of traditional kettle reaction with microwave-assisted heating, with more uniform temperature rise and faster rate, which can effectively shorten the reaction time. Meanwhile, the product yield is high, and no toxic and harmful gases are generated during the reaction, which is beneficial to environmental protection and has high production practicability.

Description

Technical Field

[0001] The present invention belongs to the technical fields of fine chemical engineering and organic synthesis, and particularly relates to a method for preparing alkenyl succinic anhydride. Background Art

[0002] With the development of technology, synthetic chemistry plays an increasingly important role in fields such as human health, modern agriculture, new materials, and life sciences. Alkenyl succinic anhydride is a non-volatile amber oily liquid and is an important artificially synthesized organic chemical raw material and an important intermediate for various new materials, playing an important role in fields such as papermaking, surfactants, and water repellents for textiles. At the end of the 20th century, there were three main process routes and methods for industrial production of alkenyl succinic anhydride in the world: synthesis by wax cracking and isomerization to form internal olefins, synthesis by hexene oligomerization to form higher carbon olefins, and synthesis by wax dehydrogenation and separation to form internal olefins. The alkenyl succinic anhydride synthesized from internal olefins as raw materials has high purity, good quality, and a simple synthesis process. However, the traditional synthesis method is mainly carried out in a batch autoclave reaction, with a slow reaction rate and a long reaction time. The overly long reaction time further leads to easy self-polymerization, oxidation, and decomposition of maleic anhydride and olefins, resulting in a large amount of by-products, greatly reducing the yield of alkenyl succinic anhydride, and severely hindering its industrialization process.

[0003] The use of microwave energy has rapidly emerged in the past 20 years and has found new applications in organic and peptide synthesis, polymer chemistry, materials science, nanotechnology, and biochemical processes. In most cases, microwave irradiation has been proven to significantly shorten the reaction time, increase the reaction yield, and improve the purity of the product or the material properties. Microwave-assisted organic synthesis is based on efficient heat transfer achieved by dielectric heating, and dielectric heating mainly depends on the microwave energy absorbed by the solvent or reagent. Compared with traditional heating, the main advantage of dielectric heating is that microwaves directly couple with the dipole or ionic molecules present in the reaction mixture, and energy transfer occurs in less than one nanosecond, resulting in a rapid increase in temperature. In addition, microwave radiation causes volume heating by directly coupling the electromagnetic field with the molecules in the reaction mixture, with minimal or no wall effect. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing alkenyl succinic anhydride, which prepares alkenyl succinic anhydride by a specific microwave-assisted organic synthesis method. Each part of the raw material is heated more uniformly, and the heating rate is faster, which is beneficial to shortening the reaction time and improving the reaction efficiency.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] A method for preparing alkenyl succinic anhydride, comprising the following steps:

[0007] An antioxidant is added to a mixture of internal octadecene and maleic anhydride, and a microwave heating reaction is carried out to produce alkenyl succinic anhydride.

[0008] Among them, the antioxidant is a mixture of hydroquinone and 2,6 - di - tert - butyl - p - cresol.

[0009] The internal octadecene used in the present invention is a straight - chain internal olefin and contains a C=C bond structure at the internal position.

[0010] The boiling point of the reactant maleic anhydride is 202℃. During the traditional heating reaction process, when the reaction temperature is higher than its boiling point, part of the maleic anhydride will evaporate and then condense on the condenser tube, resulting in a reduction in the amount of maleic anhydride actually participating in the reaction and affecting the reaction yield. The microwave - assisted organic synthesis method of the present invention can make the mixture react rapidly by using the local hot - spot effect, avoiding the problem that the reactants are separated and cannot effectively contact due to the evaporation of maleic anhydride caused by slow heating. At the same time, the present invention finds that the local hot - spot effect of microwaves can also reduce the occurrence of side reactions.

[0011] The antioxidant of the present invention plays a key role in improving the product yield. The main reason is that the side reactions caused by oxidation are significantly reduced. It is found in the experiment that when a mixed antioxidant composed of hydroquinone and 2,6 - di - tert - butyl - p - cresol is used, the improvement degree of the product yield far exceeds the best effects of their individual use.

[0012] Preferably, in terms of the amount of substance, the usage ratio of the internal octadecene to maleic anhydride is 1:1 to 2:1.

[0013] Preferably, in terms of the mass of maleic anhydride, the dosage of the antioxidant is 0.1 - 1.0 wt%, more preferably 0.3 - 0.8 wt%.

[0014] Preferably, a wave - absorbing agent is further added to the mixture. The wave - absorbing agent is selected from at least one of silicon carbide, carbon nanotubes, carbon black, activated carbon and graphene, and more preferably silicon carbide. The present invention uses silicon carbide, carbon nanotubes, carbon black and graphene as wave - absorbing agents, which have excellent wave - absorbing effects and improve the efficiency of converting microwave energy into heat energy. Further preferably, silicon carbide is used as the wave - absorbing agent, which has the highest wave - absorbing effect and low cost at the same time.

[0015] Preferably, in terms of mass, the usage ratio of the wave - absorbing agent to maleic anhydride is 1:1 to 5:1.

[0016] Preferably, the microwave heating reaction is carried out under anaerobic conditions and at a pressure of 100 - 300 kPa (gauge pressure).

[0017] Preferably, the reaction solution is stirred while the microwave heating reaction is carried out, and the stirring speed is 50 - 300 r / min.

[0018] Preferably, the irradiation time of the microwave heating reaction is 2 to 10 h (preferably 7 to 10 h), the microwave power is 300 to 800 W, and the reaction temperature is 180 to 300 °C.

[0019] Preferably, the microwave heating reaction is an intermittent reaction.

[0020] Preferably, after the microwave heating reaction, the following steps are further included:

[0021] Vinyl succinic anhydride is separated from the product by vacuum distillation.

[0022] More preferably, the vacuum distillation specifically includes the following steps:

[0023] S1. Place the product after the microwave heating reaction in a vacuum distillation device, raise the temperature to 130 to 150 °C for distillation until no product is distilled out;

[0024] S2. Continue to heat the product remaining in S1 to 230 to 280 °C for distillation to distill out vinyl succinic anhydride.

[0025] Further preferably, the distillation processes in S1 and S2 are carried out under vacuum, and the absolute pressure is 0.1 to 0.2 kPa.

[0026] Further preferably, the distillation processes in S1 and S2 are carried out with stirring, and the stirring speed is 100 to 200 r / min.

[0027] The beneficial effects of the present invention are at least as follows:

[0028] The present invention provides a preparation method of vinyl succinic anhydride with a simple preparation process and higher efficiency. The microwave-assisted heating method is used to replace the heating method of the traditional kettle reaction. Microwaves can directly couple with the dipole or ionic molecules existing in the reaction mixture, with faster energy transfer, more uniform heating, and faster heating rate, which can effectively shorten the reaction time. The preparation time of vinyl succinic anhydride is shortened to 2 to 10 h, and a large amount of vinyl succinic anhydride can be prepared in 3 to 10 h without adding microwave absorbents. At the same time, the product yield of this preparation method is high, and the reaction does not produce toxic and harmful gases, which is beneficial to environmental protection and has high production practicability. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1 It is a comparison of the infrared spectra of the alkenyl succinic anhydride prepared in Example 1 and the standard sample.

[0031] Figure 2 It is the simulated 1H NMR spectrum of maleic anhydride.

[0032] Figure 3 It is the simulated 1H NMR spectrum of internal octadecene.

[0033] Figure 4 It is the simulated 1H NMR spectrum of alkenyl succinic anhydride.

[0034] Figure 5 It is the NMR spectrum of the alkenyl succinic anhydride prepared in Example 1. Detailed implementation manners

[0035] The present invention will be described below by way of the best embodiments. It should be understood by those skilled in the art that the embodiments are only used to illustrate the present invention rather than to limit the scope of the present invention.

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention. For those not specified in the embodiments, the techniques or conditions described in the literature in the art or according to the product specifications are followed.

[0037] Example 1

[0038] A method for preparing alkenyl succinic anhydride specifically includes the following steps:

[0039] (1) Mix 65.16 g of internal octadecene and 21.50 g of maleic anhydride thoroughly and put them into a microwave reactor, then add 0.01 g of hydroquinone and 0.01 g of 2,6 - di - tert - butyl - p - cresol, and stir well at room temperature.

[0040] (2) Add 21.50 g of silicon carbide to step (1), and purge the air by introducing nitrogen for 5 - 10 min.

[0041] (3) Seal the microwave reactor, and the initial pressure of the system is 200 kPa.

[0042] (4) Heat to 220 °C under microwave irradiation (microwave power of 800 W) for reaction. Keep stirring during the reaction, with a stirring speed of 200 r / min, and continue the reaction for 10 h to produce alkenyl succinic anhydride.

[0043] (5) Place the product after the reaction in a vacuum distillation apparatus, and carry out vacuum distillation at 140 °C, a pressure of 0.1 kPa (absolute pressure), and a rotation speed of 150 r / min to remove the residual reactants.

[0044] (6) Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is alkenyl succinic anhydride.

[0045] Figure 1 It is a comparison of the infrared spectra of the alkenyl succinic anhydride prepared in Example 1 and the standard sample.

[0046] Figure 2 It is the simulated 1H NMR spectrum of maleic anhydride; Figure 3 It is the simulated 1H NMR spectrum of internal octadecene; Figure 4 It is the simulated 1H NMR spectrum of alkenyl succinic anhydride. Figure 5 It is the 1H NMR spectrum of the alkenyl succinic anhydride prepared in Example 1.

[0047] Through the above characterization and comparison, it can be corroborated that alkenyl succinic anhydride was successfully prepared in Example 1.

[0048] Example 2

[0049] A method for preparing alkenyl succinic anhydride specifically includes the following steps:

[0050] (1) Thoroughly mix 65.16 g of internal octadecene and 21.50 g of maleic anhydride and place them in a microwave reactor, then add 0.01 g of hydroquinone and 0.01 g of 2,6-di-tert-butyl-p-cresol, and stir thoroughly at room temperature.

[0051] (2) Add 21.50 g of carbon nanotubes to step (1), and introduce nitrogen for 5 - 10 min to evacuate the air.

[0052] (3) Seal the microwave reactor, and the initial pressure of the system is 200 kPa.

[0053] (4) Heat to 220 °C under microwave irradiation (800 W microwave power) for reaction, keep stirring during the reaction, the stirring speed is 200 r / min, and continue the reaction for 10 h to produce alkenyl succinic anhydride.

[0054] (5) Place the product after the reaction in a vacuum distillation apparatus, and carry out vacuum distillation at 140 °C, a pressure of 0.1 kPa, and a rotation speed of 150 r / min to remove the residual reactants.

[0055] (6) Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is alkenyl succinic anhydride.

[0056] Example 3

[0057] A method for preparing alkenyl succinic anhydride, specifically comprising the following steps:

[0058] (1) Thoroughly mix 65.16 g of internal octadecene and 21.50 g of maleic anhydride and place them in a microwave reactor. Then add 0.01 g of hydroquinone and 0.01 g of 2,6 - di - tert - butyl - p - cresol, and stir well at room temperature.

[0059] (2) Add 21.50 g of carbon black to step (1), and introduce nitrogen for 5 - 10 min to evacuate the air.

[0060] (3) Seal the microwave reactor, and the initial pressure of the system is 200 kPa.

[0061] (4) Heat to 220 °C under microwave irradiation (800 W microwave power) for reaction. Keep stirring during the reaction, with a stirring speed of 200 r / min, and continue the reaction for 10 h to produce alkenyl succinic anhydride.

[0062] (5) Place the reaction product in a vacuum distillation device, and carry out vacuum distillation at 140 °C, 0.1 kPa pressure, and 150 r / min rotation speed to remove the residual reactants.

[0063] (6) Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is alkenyl succinic anhydride.

[0064] Example 4

[0065] A method for preparing alkenyl succinic anhydride, specifically comprising the following steps:

[0066] (1) Thoroughly mix 65.16 g of internal octadecene and 21.50 g of maleic anhydride and place them in a microwave reactor. Then add 0.01 g of hydroquinone and 0.01 g of 2,6 - di - tert - butyl - p - cresol, and stir well at room temperature.

[0067] (2) Add 21.50 g of graphene to step (1), and introduce nitrogen for 5 - 10 min to evacuate the air.

[0068] (3) Seal the microwave reactor, and the initial pressure of the system is 200 kPa.

[0069] (4) Heat to 220 °C under microwave irradiation (800 W microwave power) for reaction. Keep stirring during the reaction, with a stirring speed of 200 r / min, and continue the reaction for 10 h to produce alkenyl succinic anhydride.

[0070] (5) Place the reaction product in a vacuum distillation device, and carry out vacuum distillation at 140 °C, 0.1 kPa pressure, and 150 r / min rotation speed to remove the residual reactants.

[0071] (6)Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is alkenyl succinic anhydride.

[0072] Example 5

[0073] A method for preparing alkenyl succinic anhydride specifically includes the following steps:

[0074] (1) Thoroughly mix 65.16 g of internal octadecene and 21.50 g of maleic anhydride and place them in a microwave reactor. Then add 0.01 g of hydroquinone and 0.01 g of 2,6 - di - tert - butyl - p - cresol, and stir well at room temperature.

[0075] (2) Add 21.50 g of silicon carbide to step (1), and introduce nitrogen for 5 - 10 minutes to evacuate the air.

[0076] (3) Seal the microwave reactor, and the initial pressure of the system is 200 kPa.

[0077] (4) Heat to 220 °C for reaction under microwave irradiation (microwave power of 800 W), keep stirring during the reaction, the stirring speed is 200 r / min, and continue the reaction for 5 h to produce alkenyl succinic anhydride.

[0078] (5) Place the reaction product in a vacuum distillation device, and conduct vacuum distillation at 140 °C, a pressure of 0.1 kPa, and a rotation speed of 150 r / min to remove the residual reactants.

[0079] (6)Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is alkenyl succinic anhydride.

[0080] Example 6

[0081] A method for preparing alkenyl succinic anhydride specifically includes the following steps:

[0082] (1) Thoroughly mix 65.16 g of internal octadecene and 21.50 g of maleic anhydride and place them in a microwave reactor. Then add 0.01 g of hydroquinone and 0.01 g of 2,6 - di - tert - butyl - p - cresol, and stir well at room temperature.

[0083] (2) Add 43.00 g of silicon carbide to step (1), and introduce nitrogen for 5 - 10 minutes to evacuate the air.

[0084] (3) Seal the microwave reactor, and the initial pressure of the system is 200 kPa.

[0085] (4) Heat to 220 °C for reaction under microwave irradiation (microwave power of 800 W), keep stirring during the reaction, the stirring speed is 200 r / min, and continue the reaction for 10 h to produce alkenyl succinic anhydride.

[0086] (5) Place the product after the reaction in a vacuum distillation apparatus, and carry out vacuum distillation at 140 °C, 0.1 kPa pressure, and 150 r / min rotation speed to remove the residual reactants.

[0087] (6) Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is the alkenyl succinic anhydride.

[0088] Example 7

[0089] A method for preparing alkenyl succinic anhydride specifically includes the following steps:

[0090] (1) Thoroughly mix 65.16 g of internal octadecene and 21.50 g of maleic anhydride in a three-necked flask, then add 0.01 g of hydroquinone and 0.01 g of 2,6-di-tert-butyl-p-cresol, and stir thoroughly at room temperature.

[0091] (2) Add 21.50 g of silicon carbide to step (1), and continuously introduce nitrogen.

[0092] (3) Heat to 220 °C under microwave irradiation (800 W microwave power) for atmospheric pressure reaction. Keep stirring during the reaction, with a stirring speed of 200 r / min, and continuously react for 10 h to produce alkenyl succinic anhydride.

[0093] (4) Place the product after the reaction in a vacuum distillation apparatus, and carry out vacuum distillation at 140 °C, 0.1 kPa pressure, and 150 r / min rotation speed to remove the residual reactants.

[0094] (5) Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is the alkenyl succinic anhydride.

[0095] Example 8

[0096] A method for preparing alkenyl succinic anhydride specifically includes the following steps:

[0097] (1) Measure 65.16 g of internal octadecene, 21.50 g of maleic anhydride, 0.01 g of hydroquinone and 0.01 g of 2,6-di-tert-butyl-p-cresol, mix them thoroughly, and slowly heat to 50 °C until all the solids are dissolved after stirring evenly.

[0098] (2) Add 21.50 g of silicon carbide to a flow reactor, and uniformly and continuously introduce the dissolved solution into the flow reactor, and introduce nitrogen to evacuate the air.

[0099] (3) Heat the flow reactor to 220 °C under microwave irradiation (800 W microwave power) for reaction, with the system pressure of 200 kPa, and continuously react for 10 h to produce alkenyl succinic anhydride.

[0100] (5) Place the product after the reaction in a vacuum distillation apparatus, and carry out vacuum distillation at 140 °C, 0.1 kPa pressure, and 150 r / min rotation speed to remove the residual reactants.

[0101] (6) Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is alkenyl succinic anhydride.

[0102] Comparative Example 1

[0103] A method for preparing alkenyl succinic anhydride specifically includes the following steps:

[0104] (1) Thoroughly mix 65.16 g of internal octadecene and 21.50 g of maleic anhydride and place them in a kettle reactor, then add 0.01 g of hydroquinone and 0.01 g of 2,6 - di - tert - butyl - p - cresol, and stir thoroughly at room temperature.

[0105] (2) Pass nitrogen for 5 - 10 min to evacuate the air.

[0106] (3) Seal the kettle reactor, and the system pressure is 200 kPa.

[0107] (4) Heat to 220 °C for reaction under the heating of an electric heating tube, keep stirring during the reaction, the stirring speed is 200 r / min, and continue the reaction for 10 h to produce alkenyl succinic anhydride.

[0108] (5) Place the product after the reaction in a vacuum distillation apparatus, and carry out vacuum distillation at 140 °C, 0.1 kPa pressure, and 150 r / min rotation speed to remove the residual reactants.

[0109] (6) Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is alkenyl succinic anhydride.

[0110] Comparative Example 2

[0111] A method for preparing alkenyl succinic anhydride specifically includes the following steps:

[0112] (1) Thoroughly mix 65.16 g of internal octadecene and 21.50 g of maleic anhydride and place them in a microwave reactor, then add 0.02 g of hydroquinone, and stir thoroughly at room temperature.

[0113] (2) Add 21.50 g of silicon carbide to step (1), and pass nitrogen for 5 - 10 min to evacuate the air.

[0114] (3) Seal the microwave reactor, and the initial system pressure is 200 kPa.

[0115] (4) Heat to 220 °C for reaction under microwave irradiation (800 W microwave power), the stirring speed is 200 r / min, and continue the reaction for 10 h to produce alkenyl succinic anhydride.

[0116] (5) Place the product after the reaction in a vacuum distillation apparatus, and carry out vacuum distillation at 140 °C, a pressure of 0.1 kPa, and a rotation speed of 150 r / min to remove the residual reactants.

[0117] (6) Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is the alkenyl succinic anhydride.

[0118] Comparative Example 3

[0119] A method for preparing alkenyl succinic anhydride specifically includes the following steps:

[0120] (1) Thoroughly mix 65.16 g of internal octadecene and 21.50 g of maleic anhydride and put them into a microwave reactor, then add 0.02 g of 2,6 - di - tert - butyl - p - cresol, and stir thoroughly at room temperature.

[0121] (2) Add 21.50 g of silicon carbide to step (1), and introduce nitrogen for 5 - 10 min to evacuate the air.

[0122] (3) Seal the microwave reactor, and the initial pressure of the system is 200 kPa.

[0123] (4) Heat to 220 °C under microwave irradiation (microwave power of 800 W) for reaction, with a stirring speed of 200 r / min, and continue the reaction for 10 h to produce alkenyl succinic anhydride.

[0124] (5) Place the product after the reaction in a vacuum distillation apparatus, and carry out vacuum distillation at 140 °C, a pressure of 0.1 kPa, and a rotation speed of 150 r / min to remove the residual reactants.

[0125] (6) Continue to raise the temperature to 250 °C for vacuum distillation, and collect the distillate, which is the alkenyl succinic anhydride.

[0126] Implementation effect

[0127] In order to more clearly understand the yields of alkenyl succinic anhydride in the above Examples 1 - 8 and Comparative Example 1, Table 1 gives the results obtained under different conditions. Among them, the calculation formula for the product yield is: Yield = (Actual production amount of the target product) / (Theoretical production amount of the target product) * 100%.

[0128] Table 1 Yields of different alkenyl succinic anhydrides

[0129] Name Product Yield / % Example 1 96 Example 2 88 Example 3 90 Example 4 93 Example 5 81 Example 6 95 Example 7 32 Example 8 68 Comparative Example 1 61 Comparative Example 2 72 Comparative Example 3 84

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing alkenyl succinic anhydride, comprising the following steps: Adding an antioxidant to a mixture of isooctadecene and maleic anhydride, and carrying out a microwave heating reaction to generate alkenyl succinic anhydride; Wherein, the antioxidant is a mixture of hydroquinone and 2,6 - di - tert - butyl - p - cresol; based on the mass of maleic anhydride, the dosage of the antioxidant is 0.1 - 1.0 wt%; a wave - absorbing agent is also added to the mixture, and the wave - absorbing agent is selected from at least one of silicon carbide, carbon nanotubes, carbon black, activated carbon, and graphene; By mass, the microwave heating reaction is carried out under anaerobic conditions and at 200 - 300 kPa; the irradiation time of the microwave heating reaction is 2 - 10 h, the microwave power is 300 - 800 W, and the reaction temperature is 180 - 300 °C.

2. The preparation method of an alkenyl succinic anhydride according to claim 1, characterized in that, By the amount of substance, the dosage ratio of isooctadecene to maleic anhydride is 1:1 - 2:

1.

3. A method for preparing alkenyl succinic anhydride according to claim 1, characterized in that, Based on the mass of maleic anhydride, the dosage of the antioxidant is 0.3 - 0.8 wt%.

4. A method for preparing an alkenyl succinic anhydride according to any one of claims 1-3, characterized in that, The wave - absorbing agent is silicon carbide.

5. A method for preparing an alkenyl succinic anhydride according to any one of claims 1-3, characterized in that, By mass, the dosage ratio of the wave - absorbing agent to maleic anhydride is 1:1 - 5:

1.

6. A method for preparing an alkenyl succinic anhydride according to any one of claims 1-3, characterized in that, During the microwave heating reaction, the reaction solution is stirred, and the stirring speed is 50 - 300 r / min.

7. A method for preparing an alkenyl succinic anhydride according to any one of claims 1 to 3, characterized in that, After the microwave heating reaction, the following steps are further included: Separating alkenyl succinic anhydride from the product by vacuum distillation.

8. The preparation method of an alkenyl succinic anhydride according to claim 7, characterized in that, The vacuum distillation specifically includes the following steps: S1. Placing the product after the microwave heating reaction in a vacuum distillation device, raising the temperature to 130 - 150 °C for distillation until no product is distilled out; S2. Continuing to heat the product remaining in S1 to 230 - 280 °C for distillation to distill out alkenyl succinic anhydride; The distillation processes in S1 and S2 are carried out under vacuum, and the absolute pressure is 0.1 - 0.2 kPa; And / or, the distillation processes in S1 and S2 are carried out with stirring, and the stirring speed is 100 - 200 r / min.

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