Process for preparing 11-bromo-undecylenic acid through microwave-assisted synthesis

Abstract

The invention discloses a microwave-assisted synthesis process of 11-bromo-undecylenic acid, which comprises the following specific steps: mixing undecylenic acid and a non-polar solvent, adding an initiator, stirring and mixing, conveying the obtained mixed solution of preliminary reaction into a microwave reaction kettle, adjusting the microwave power, controlling a certain temperature, adding a catalyst, and reacting for 2-4 hours; and carrying out anti-Markov addition on the mixed solution and hydrogen bromide gas in a microwave reaction device to generate a bromo-undecanoic acid solution, feeding the prepared addition solution into a crystallization kettle, carrying out freezing crystallization, and filtering a crystallized product to obtain the 11-bromo-undecylenic acid. According to the microwave reaction kettle, through hydrogen bromide aeration and mechanical stirring, the gas-liquid mass transfer area is increased, and the mass transfer efficiency is improved; the 11-bromo-undecanoic acid is synthesized under the assistance of microwaves, so that stirring on a molecular level can be realized, the reaction time is greatly shortened, and the yield of a target product is effectively improved; meanwhile, the non-polar solvent with weak microwave absorption capacity is adopted, so that the heat effect generated by microwaves is effectively avoided, and the yield of the target product is higher.

Description

Technical Field

[0001] The invention relates to a synthesis process for synthesizing 11-bromodencanoic acid by rapid reaction of undecylenic acid and hydrogen bromide through microwave assistance. Background Art

[0002] The chemical name of nylon 11 (PA11) is polyamide 11, and its structure is H[NH(CH2) 10 CO] n OH, as a nylon material with low water absorption and excellent low-temperature impact performance, PA11 plays an irreplaceable and important role in automobile oil pipelines, electronic appliances, municipal gas pipelines, offshore oil field development, etc. The development of PA11 in China is restricted by the preparation technology of polymerization monomers, so the synthesis of 11-bromodencanoic acid is of great significance.

[0003] In the prior art, undecylenic acid and hydrogen bromide undergo an anti-Markovnikov addition reaction to prepare bromodencanoic acid, usually using benzoyl peroxide or azobisisobutyronitrile as an initiator, and taking toluene as a reaction solvent, dissolving undecylenic acid and the initiator in toluene, and introducing HBr gas. After the reaction is completed, the mixture is aged, washed with deionized water until neutral, frozen and crystallized, filtered, and air-dried to obtain 11-bromodencanoic acid. Chinese patent CN202211136892.9 discloses a method for preparing 11-bromodencanoic acid from undecylenic acid, solvent, composite initiator and hydrogen bromide as raw materials, using tower and kettle series reactors, with a maximum yield of 96.04%; Chinese patent CN201410045612.2 prepares undecylenic acid, toluene and benzene into raw material liquid in proportion, uses benzoyl peroxide or diethylbutyl azo as initiator, and reacts with hydrogen bromide in a double kettle reactor to generate 11-bromodencanoic acid solution, and the required time is 80 minutes. The methods of the prior art all have the disadvantages of small gas-liquid contact mass transfer interface, slow reaction speed and high operating cost. Summary of the invention

[0004] In view of the technical problems existing in the prior art, the object of the present invention is to provide an efficient and simple microwave-assisted process for preparing 11-bromodencanoic acid. The solvent used in the present invention is a non-polar solvent with weak microwave absorption ability, which can avoid the thermal effect generated by microwaves, and the reactants undecylenic acid and hydrogen bromide have certain polarity, and under the action of the microwave field, stirring at the molecular level can be achieved. Therefore, the method of the present invention has the advantages of fast reaction speed and high yield of the target product;

[0005] The technical solution adopted by the present invention is as follows:

[0006] A process for microwave-assisted synthesis of 11-bromodencenoic acid comprises the following steps:

[0007] 1) undecylenic acid and a non-polar solvent are mixed, an initiator is added, and the mixture is stirred and mixed in a batching kettle to obtain a mixed solution for a preliminary reaction;

[0008] 2) conveying the mixed liquid in the batching kettle to a microwave reactor, and simultaneously blowing hydrogen bromide gas into the mixed liquid in the microwave reactor, wherein the microwave reactor is provided with a coil heat exchange device for adjusting the reaction temperature, adjusting the mixed liquid in the microwave reactor to the reaction temperature, turning on the microwave, and allowing the undecylenic acid and the hydrogen bromide gas to undergo an anti-Markovnikov addition reaction under the action of microwave radiation to generate a solution containing 11-bromodencanoic acid;

[0009] 3) The reaction solution obtained in step 2) is transported from the discharge port of the microwave reactor to a crystallization kettle for freezing and crystallization, and the crystallized product is transported from the discharge port of the crystallization kettle to a filtering device through a delivery pump for filtration to obtain a 11-bromodencenoic acid product.

[0010] Furthermore, the non-polar solvent in step 1) is a mixture of one or more of n-hexane, cyclohexane, methylcyclohexane, petroleum ether, cyclohexanone, and n-heptane, and the mass ratio of undecylenic acid to the non-polar solvent is 1:3-7, preferably 1:4-5.

[0011] Furthermore, in step 1), the initiator is a mixture of one or more of benzoyl peroxide, dodecyl peroxide, di-tert-butyl peroxide, and ditoluoyl peroxide, and the total amount thereof is 0.5-5% of the mass of undecylenic acid, preferably 0.8-1.2%.

[0012] Furthermore, during the reaction in step 2), the molar ratio of undecylenic acid to hydrogen bromide is controlled at 1:1-5, preferably 1:1.5-2.

[0013] Furthermore, in step 2), the microwave power is set to 100-5000 W, preferably 2000-5000 W, the microwave is controlled by a pulse switch, and the running time and the stopping time in one cycle of microwave radiation are 5-60 s respectively, preferably 10-30 s.

[0014] Furthermore, in step 2), the reaction temperature in the microwave reactor is 10-40° C., preferably 10-20° C., and the residence time of the mixed solution in the microwave reactor is 10-60 min, preferably 20-40 min.

[0015] Furthermore, in step 3), the crystallization kettle is equipped with an agitator and a heat exchange coil, the speed of the agitator of the crystallization kettle is set to 10 to 100 r / min, the crystallization temperature is -10 to -20°C, the time is 2 to 6 hours, and the gauge pressure is -30 to -50 KPa.

[0016] Furthermore, the crystallized product is transported from the discharge port of the crystallization kettle to a filtration device through a delivery pump for filtration, the filtration pressure is 0.1 to 0.5 MPa, and the temperature is -10 to -20°C; the filtrate is transported to the batching kettle for reuse.

[0017] Furthermore, an aeration device is provided at the bottom of the microwave reactor, and the aeration device is a tubular, plate or disc aerator, and hydrogen bromide gas is introduced into the bottom of the microwave reactor through the aeration device.

[0018] Furthermore, one or more magnetrons are evenly arranged around the side wall of the microwave reactor, and the magnetrons are connected to a microwave generator, and the microwave generator is controlled by a microwave pulse control system.

[0019] Furthermore, the microwave reaction kettle is equipped with a stirrer, and the stirring speed is 20-100 r / min, preferably 40-60 r / min.

[0020] By adopting the above technology, compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. The present invention increases the gas-liquid mass transfer area and improves the mass transfer efficiency through an aerator and mechanical stirring.

[0022] 2. The present invention adopts microwave-assisted synthesis of 11-bromodencanoic acid, which can achieve stirring at the molecular level, greatly shorten the reaction time, and effectively improve the yield of the target product.

[0023] 3. The present invention adopts a non-polar solvent with weak microwave absorption ability, which effectively avoids the thermal effect caused by microwaves, is conducive to the anti-Markovnikov addition reaction, and makes the yield of the target product higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the process flow of microwave-assisted synthesis of 11-bromodencanoic acid;

[0025] Figure 2 It is a schematic diagram of the structure of the device of the present invention;

[0026] Attached Figure 2 The markings include: 1- batching kettle; 2- microwave reaction kettle; 3- crystallization kettle; 4- filter; 5- delivery pump. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0028] The structure diagram of the reaction device used in this reaction example is as follows Figure 2As shown, it includes a batching kettle 1, a microwave reactor 2, a crystallization kettle 3 and a filter 4. The batching kettle 1 is provided with a feed port and a discharge port, the discharge port is connected to the feed port of the microwave reactor 2, and the mixed solution is delivered to the microwave reactor 2 through a delivery pump 5. The microwave reactor 2 is provided with a feed port at the top, an air inlet at the bottom of the microwave reactor 2, and an aeration device at the bottom of the microwave reactor. The aeration device can be a tubular, plate or disc aerator, and hydrogen bromide gas is introduced into the bottom of the microwave reactor through the aeration device. After the gas enters, anti-Markovnikov addition occurs with the undecylenic acid raw material. The outlet of the microwave reactor 2 is connected to the delivery pump 5, and the material is delivered to the crystallization kettle 3 by the delivery pump 5 for freezing crystallization; the crystallized product is delivered from the discharge port of the crystallization kettle 3 to the filter device 4 through the delivery pump 5 for filtration.

[0029] The microwave reactor 2 is provided with a microwave generator, and the microwave power is selected to be 100-5000W. The microwave reactor 2 is provided with a coil heat exchange device to control the reaction temperature. The reaction temperature of the mixed solution in the microwave reactor 2 is 20-40°C. The microwave reactor 2 is provided with a stirring device, and the stirring speed is 20-100r / min.

[0030] The microwave energy synthesis of 11-bromodecaneic acid in the above device comprises the following steps:

[0031] Step S1, first set the reaction time of the microwave reactor 2 to 10-60min, the reaction temperature to 20-40°C, the microwave power to 100-5000W, and the stirring speed to 20-100r / min.

[0032] Step S2, weighing undecylenic acid, solvent and benzoyl peroxide, feeding them into the batching kettle 1 from the feed port, stirring to form a reaction solution, and feeding them into the kettle from the feed port of the microwave reactor 2, wherein the mass ratio of n-hexane, petroleum ether and cyclohexane in the solvent is 5:3:2.

[0033] Step S3, feeding hydrogen bromide gas into the microwave reactor 2 from the gas inlet at the bottom of the microwave reactor 2, wherein the molar ratio of undecylenic acid to hydrogen bromide is 1:1.5.

[0034] Step S4, starting the set microwave reactor 2, performing anti-Markovnikov addition in the microwave reactor 2, and maintaining the reaction time for 10-60 minutes.

[0035] Step S5, feeding the addition liquid into the crystallization kettle 3 from the discharge port of the microwave reactor 2, maintaining the rotation speed of the crystallization kettle agitator at 10 to 100 r / min, the crystallization temperature at -10 to -20°C, the time at 2 to 6 hours, and the gauge pressure at -30 to -50 KPa for freeze crystallization.

[0036] Step S6, the crystallized product is transported from the discharge port of the crystallization kettle 3 to the filtering device 4 through the delivery pump 5 for filtration, and the filtrate is sent to the batching kettle 1 to serve as a solvent again, and the filtered substance is 11-bromodecane acid.

[0037] The above-mentioned preparation device and preparation method are described below in conjunction with specific examples.

[0038] Embodiment 1:

[0039] Step S1, first set the reaction time of the microwave reactor 2 to 30 min, the reaction temperature to 40° C., select the microwave power to 5000 W, and the stirring speed to 60 r / min.

[0040] Step S2, weighing 100 kg of undecylenic acid, 400 kg of a mixed solvent and 1 kg of benzoyl peroxide, feeding them into a batching kettle 1 from a feed port, stirring to form a reaction solution, and feeding them into a microwave reactor 2 from a feed port, wherein the mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

[0041] Step S3, feeding hydrogen bromide gas into the microwave reactor 2 from the gas inlet at the bottom of the microwave reactor 2, wherein the molar ratio of undecylenic acid to hydrogen bromide is 1:1.5.

[0042] Step S4, start the set microwave reactor 2, perform anti-Markovnikov addition in the microwave reactor 2, the microwave is controlled by a pulse switch, the running time and the stopping time in one cycle of microwave radiation are 20 seconds each, and the reaction time is 30 minutes.

[0043] Step S5, feeding the reaction liquid obtained in step S4 into the crystallization kettle 3 from the discharge port of the microwave reactor 2, maintaining the rotation speed of the crystallization kettle agitator at 50r / min, the crystallization temperature at -15°C, the time at 4h, and the gauge pressure at -40KPa for freeze crystallization.

[0044] Step S6, the crystallized product is transported from the discharge port of the crystallization kettle 3 to the filtering device 4 through the delivery pump 5 for filtration, and the filtrate is sent to the microwave reaction kettle 2 to serve as a solvent again, and the filtered substance is 11-bromodecane acid.

[0045] Embodiment 2:

[0046] Step S1, first set the reaction time of the microwave reactor 2 to 30 min, the reaction temperature to 30° C., select the microwave power to 5000 W, and the stirring speed to 60 r / min.

[0047] Step S2, weighing 100 kg of undecylenic acid, 400 kg of a mixed solvent and 1 kg of benzoyl peroxide, feeding them into a batching kettle 1 from a feed port, stirring to form a reaction solution, and feeding them into a microwave reactor 2 from a feed port, wherein the mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

[0048] Step S3, feeding hydrogen bromide gas into the microwave reactor 2 from the gas inlet at the bottom of the microwave reactor 2, wherein the molar ratio of undecylenic acid to hydrogen bromide is 1:1.5.

[0049] Step S4, start the set microwave reactor 2, perform anti-Markovnikov addition in the microwave reactor 2, the microwave is controlled by a pulse switch, the running time and the stopping time in one cycle of microwave radiation are 20 seconds each, and the reaction time is 30 minutes.

[0050] Step S5, feeding the reaction liquid obtained in step S4 into the crystallization kettle 3 from the discharge port of the microwave reactor 2, maintaining the rotation speed of the crystallization kettle agitator at 50r / min, the crystallization temperature at -15°C, the time at 4h, and the gauge pressure at -40KPa for freeze crystallization.

[0051] Step S6, the crystallized product is transported from the discharge port of the crystallization kettle 3 to the filtering device 4 through the delivery pump 5 for filtration, and the filtrate is sent to the microwave reaction kettle 2 to serve as a solvent again, and the filtered substance is 11-bromodecane acid.

[0052] Embodiment 3:

[0053] Step S1, first set the reaction time of the microwave reactor 2 to 30 min, the reaction temperature to 20° C., select the microwave power to 5000 W, and the stirring speed to 60 r / min.

[0054] Step S2, weighing 100 kg of undecylenic acid, 400 kg of a mixed solvent and 1 kg of benzoyl peroxide, feeding them into a batching kettle 1 from a feed port, stirring to form a reaction solution, and feeding them into a microwave reactor 2 from a feed port, wherein the mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

[0055] Step S3, feeding hydrogen bromide gas into the microwave reactor 2 from the gas inlet at the bottom of the microwave reactor 2, wherein the molar ratio of undecylenic acid to hydrogen bromide is 1:1.5.

[0056] Step S4, start the set microwave reactor 2, perform anti-Markovnikov addition in the microwave reactor 2, the microwave is controlled by a pulse switch, the running time and the stopping time in one cycle of microwave radiation are 20 seconds each, and the reaction time is 30 minutes.

[0057] Step S5, feeding the reaction liquid obtained in step S4 into the crystallization kettle 3 from the discharge port of the microwave reactor 2, maintaining the rotation speed of the crystallization kettle agitator at 50r / min, the crystallization temperature at -15°C, the time at 4h, and the gauge pressure at -40KPa for freeze crystallization.

[0058] Step S6, the crystallized product is transported from the discharge port of the crystallization kettle 3 to the filtering device 4 through the delivery pump 5 for filtration, and the filtrate is sent to the microwave reaction kettle 2 to serve as a solvent again, and the filtered substance is 11-bromodecane acid.

[0059] Embodiment 4:

[0060] Step S1, first set the reaction time of the microwave reactor 2 to 30 min, the reaction temperature to 10° C., select the microwave power to 5000 W, and the stirring speed to 60 r / min.

[0061] Step S2, weighing 100 kg of undecylenic acid, 400 kg of a mixed solvent and 1 kg of benzoyl peroxide, feeding them into a batching kettle 1 from a feed port, stirring to form a reaction solution, and feeding them into a microwave reactor 2 from a feed port, wherein the mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

[0062] Step S3, feeding hydrogen bromide gas into the microwave reactor 2 from the gas inlet at the bottom of the microwave reactor 2, wherein the molar ratio of undecylenic acid to hydrogen bromide is 1:1.5.

[0063] Step S4, start the set microwave reactor 2, perform anti-Markovnikov addition in the microwave reactor 2, the microwave is controlled by a pulse switch, the running time and the stopping time in one cycle of microwave radiation are 20 seconds each, and the reaction time is 30 minutes.

[0064] Step S5, feeding the reaction liquid obtained in step S4 into the crystallization kettle 3 from the discharge port of the microwave reactor 2, maintaining the rotation speed of the crystallization kettle agitator at 50r / min, the crystallization temperature at -15°C, the time at 4h, and the gauge pressure at -40KPa for freeze crystallization.

[0065] Step S6, the crystallized product is transported from the discharge port of the crystallization kettle 3 to the filtering device 4 through the delivery pump 5 for filtration, and the filtrate is sent to the microwave reaction kettle 2 to serve as a solvent again, and the filtered substance is 11-bromodecane acid.

[0066] Embodiment 5:

[0067] Step S1, first set the reaction time of the microwave reactor 2 to 30 min, the reaction temperature to 40° C., select the microwave power to 5000 W, and the stirring speed to 20 r / min.

[0068] Step S2, weighing 100 kg of undecylenic acid, 400 kg of a mixed solvent and 1 kg of benzoyl peroxide, feeding them into a batching kettle 1 from a feed port, stirring to form a reaction solution, and feeding them into a microwave reactor 2 from a feed port, wherein the mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

[0069] Step S3, feeding hydrogen bromide gas into the microwave reactor 2 from the gas inlet at the bottom of the microwave reactor 2, wherein the molar ratio of undecylenic acid to hydrogen bromide is 1:1.5.

[0070] Step S4, start the set microwave reactor 2, perform anti-Markovnikov addition in the microwave reactor 2, the microwave is controlled by a pulse switch, the running time and the stopping time in one cycle of microwave radiation are 20 seconds each, and the reaction time is 30 minutes.

[0071] Step S5, feeding the reaction liquid obtained in step S4 into the crystallization kettle 3 from the discharge port of the microwave reactor 2, maintaining the rotation speed of the crystallization kettle agitator at 50r / min, the crystallization temperature at -15°C, the time at 4h, and the gauge pressure at -40KPa for freeze crystallization.

[0072] Step S6, the crystallized product is transported from the discharge port of the crystallization kettle 3 to the filtering device 4 through the delivery pump 5 for filtration, and the filtrate is sent to the microwave reaction kettle 2 to serve as a solvent again, and the filtered substance is 11-bromodecane acid.

[0073] Embodiment 6:

[0074] Step S1, first set the reaction time of the microwave reactor 2 to 30 min, the reaction temperature to 30° C., select the microwave power to 5000 W, and the stirring speed to 20 r / min.

[0075] Step S2, weighing 100 kg of undecylenic acid, 400 kg of a mixed solvent and 1 kg of benzoyl peroxide, feeding them into a batching kettle 1 from a feed port, stirring to form a reaction solution, and feeding them into a microwave reactor 2 from a feed port, wherein the mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

[0076] Step S3, feeding hydrogen bromide gas into the microwave reactor 2 from the gas inlet at the bottom of the microwave reactor 2, wherein the molar ratio of undecylenic acid to hydrogen bromide is 1:1.5.

[0077] Step S4, start the set microwave reactor 2, perform anti-Markovnikov addition in the microwave reactor 2, the microwave is controlled by a pulse switch, the running time and the stopping time in one cycle of microwave radiation are 20 seconds each, and the reaction time is 30 minutes.

[0078] Step S5, feeding the reaction liquid obtained in step S4 into the crystallization kettle 3 from the discharge port of the microwave reactor 2, maintaining the rotation speed of the crystallization kettle agitator at 50r / min, the crystallization temperature at -15°C, the time at 4h, and the gauge pressure at -40KPa for freeze crystallization.

[0079] Step S6, the crystallized product is transported from the discharge port of the crystallization kettle 3 to the filtering device 4 through the delivery pump 5 for filtration, and the filtrate is sent to the microwave reaction kettle 2 to serve as a solvent again, and the filtered substance is 11-bromodecane acid.

[0080] Comparative Example 1:

[0081] Step S1, first set the reaction temperature of the microwave reactor 2 to 40°C, stop microwave radiation, set the reaction time to 30min, and set the stirring speed to 60r / min.

[0082] Step S2, weighing 100 kg of undecylenic acid, 400 kg of a mixed solvent and 1 kg of benzoyl peroxide, feeding them into a batching kettle 1 from a feed port, stirring to form a reaction solution, and feeding them into a microwave reactor 2 from a feed port, wherein the mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

[0083] Step S3, feeding hydrogen bromide gas into the microwave reactor 2 from the gas inlet at the bottom of the microwave reactor 2, wherein the molar ratio of undecylenic acid to hydrogen bromide is 1:1.5.

[0084] Step S4, performing anti-Markovnikov addition in the microwave reactor 2, controlling to stop microwave radiation, and performing conventional stirring reaction for 30 minutes.

[0085] Step S5, feeding the reaction liquid obtained in step S4 into the crystallization kettle 3 from the discharge port of the microwave reactor 2, maintaining the rotation speed of the crystallization kettle agitator at 50r / min, the crystallization temperature at -15°C, the time at 4h, and the gauge pressure at -40KPa for freeze crystallization.

[0086] Step S6, the crystallized product is transported from the discharge port of the crystallization kettle 3 to the filtering device 4 through the delivery pump 5 for filtration, and the filtrate is sent to the microwave reaction kettle 2 to serve as a solvent again, and the filtered substance is 11-bromodecane acid.

[0087] Comparative Example 2:

[0088] The experimental steps of Comparative Example 2 were repeated in Comparative Example 1, with the only difference being that the reaction temperature of the microwave reactor 2 was set to 30° C., and the other conditions remained unchanged, and 11-bromodecane acid was finally prepared.

[0089] Comparative Example 3:

[0090] The experimental steps of Comparative Example 3 were repeated in Comparative Example 1, with the only difference being that the reaction temperature of the microwave reactor 2 was set to 20° C., and the other conditions remained unchanged, and 11-bromodecane acid was finally prepared.

[0091] Comparative Example 4:

[0092] The experimental steps of Comparative Example 4 were repeated in Comparative Example 1, with the only difference being that the reaction temperature of the microwave reactor 2 was set to 10° C., and the other conditions remained unchanged, and 11-bromodecane acid was finally prepared.

[0093] Comparative Example 5:

[0094] The experimental steps of Comparative Example 5 are repeated in Example 1, the only difference being that "the mixed solvent in step S2 is replaced with toluene of equal mass", and the other conditions remain unchanged, and finally 11-bromodecaneic acid is prepared.

[0095] Comparative Example 6:

[0096] The experimental steps of Comparative Example 6 are repeated in Example 2, the only difference being that "the mixed solvent in step S2 is replaced with toluene of equal mass", and the other conditions remain unchanged, and finally 11-bromodecaneic acid is prepared.

[0097] Comparative Example 7:

[0098] The experimental steps of Comparative Example 7 are repeated in Example 3, the only difference being that "the mixed solvent in step S2 is replaced with toluene of equal mass", and the other conditions remain unchanged, and finally 11-bromodecaneic acid is prepared.

[0099] Comparative Example 8:

[0100] The experimental steps of Comparative Example 8 are repeated as those of Comparative Example 1, with the only difference being that "the stirring speed of the microwave reactor 2 for conventional stirring is 100 r / min", and the other conditions remain unchanged, and finally 11-bromodecane acid is prepared.

[0101] Comparative Example 9:

[0102] The experimental steps of Comparative Example 9 are repeated as those of Comparative Example 2, with the only difference being that "the stirring speed of the microwave reactor 2 for conventional stirring is 100 r / min", and the other conditions remain unchanged, and finally 11-bromodecane acid is prepared.

[0103] The undecylenic acid conversion rate and 11-bromodecaneic acid yield and purity results obtained in the above examples and comparative examples are summarized in Tables 1 and 2.

[0104] Table 1 Conversion rate of undecylenic acid and yield and purity of 11-bromodencanoic acid in different microwave powers or solvents

[0105]

[0106]

[0107] Table 2 Conversion rate of undecylenic acid and yield and purity of 11-bromodencanoic acid at different microwave powers or stirring speeds

[0108]

Claims

1. A process for microwave-assisted synthesis of 11-bromodencenoic acid, characterized in that: The following steps are involved: 1) Undecylenic acid and a non-polar solvent are mixed, an initiator is added, and the mixture is stirred and mixed in a batching kettle to obtain a mixed solution for a preliminary reaction; 2) conveying the mixed liquid in the batching kettle to a microwave reactor, and simultaneously blowing hydrogen bromide gas into the mixed liquid in the microwave reactor, wherein the microwave reactor is provided with a coil heat exchange device for adjusting the reaction temperature, adjusting the mixed liquid in the microwave reactor to the reaction temperature, turning on the microwave, and allowing the undecylenic acid and the hydrogen bromide gas to undergo an anti-Markovnikov addition reaction under the action of microwave radiation, thereby generating a solution containing 11-bromodencanoic acid; 3) The reaction solution obtained in step 2) is transported from the discharge port of the microwave reactor to a crystallization reactor for freezing and crystallization. The crystallized product is transported from the discharge port of the crystallization reactor to a filtration device through a delivery pump for filtration to obtain a 11-bromodencenoic acid product.

2. The process for preparing 11-bromodencenoic acid by microwave-assisted synthesis according to claim 1, characterized in that: In step 1), the non-polar solvent is a mixture of one or more of n-hexane, cyclohexane, methylcyclohexane, petroleum ether, cyclohexanone, and n-heptane, and the mass ratio of undecylenic acid to the non-polar solvent is 1:3-7, preferably 1:4-5.

3. The process for preparing 11-bromodencenoic acid by microwave-assisted synthesis according to claim 1, characterized in that: In step 1), the initiator is a mixture of one or more of benzoyl peroxide, dodecyl peroxide, di-tert-butyl peroxide, and ditoluoyl peroxide, and the total amount thereof is 0.5-5% of the mass of undecylenic acid, preferably 0.8-1.2%.

4. The process for preparing 11-bromodencenoic acid by microwave-assisted synthesis according to claim 1, characterized in that: During the reaction in step 2), the molar ratio of undecylenic acid to hydrogen bromide is controlled at 1:1-5, preferably 1:1.5-2.

5. The process for preparing 11-bromodencenoic acid by microwave-assisted synthesis according to claim 1, characterized in that: In step 2), the microwave power is set to 100-5000 W, preferably 2000-5000 W, and the microwave is controlled by a pulse switch. The running time and the stopping time in one cycle of microwave radiation are 5-60 s respectively, preferably 10-30 s.

6. A process for preparing 11-bromodencenoic acid by microwave-assisted synthesis as claimed in claim 1, characterized in that: Step 2) The reaction temperature in the microwave reactor is 10-40° C., preferably 10-20° C., and the residence time of the mixed solution in the microwave reactor is 10-60 min, preferably 20-40 min.

7. A process for preparing 11-bromodencenoic acid by microwave-assisted synthesis as claimed in claim 1, characterized in that: In step 3), the crystallization kettle is equipped with an agitator and a heat exchange coil, the speed of the agitator of the crystallization kettle is set to 10~100 r / min, the crystallization temperature is -10~-20℃, the time is 2~6h, and the gauge pressure is -30~-50 KPa.

8. The process for preparing 11-bromodencenoic acid by microwave-assisted synthesis according to claim 1, characterized in that: The crystallized product is transported from the discharge port of the crystallization kettle to a filtration device through a delivery pump for filtration, the filtration pressure is 0.1-0.5 MPa, and the temperature is -10--20°C; the filtrate is transported to the batching kettle for reuse.

9. A process for preparing 11-bromodencenoic acid by microwave-assisted synthesis as claimed in claim 1, characterized in that: The bottom of the microwave reactor is provided with an aeration device, which is a tubular, plate or disc aerator, and hydrogen bromide gas is introduced into the bottom of the microwave reactor through the aeration device; one or more magnetrons are evenly arranged around the side wall of the microwave reactor, and the magnetrons are connected to a microwave generator, which is controlled by a microwave pulse control system; the microwave reactor is provided with an inner coil heat exchange device.

10. The process for preparing 11-bromodencenoic acid by microwave-assisted synthesis according to claim 1, characterized in that: The microwave reactor is equipped with a stirrer with a stirring speed of 20-100 r / min, preferably 40-60 r / min.

Images