A microwave-assisted synthesis process for preparing 11-bromoundecenoic acid

Abstract

This invention discloses a microwave-assisted synthesis process for 11-bromoundecenoic acid. The specific steps are as follows: undecenoic acid is mixed with a nonpolar solvent, an initiator is added, and the mixture is stirred. The resulting preliminary reaction mixture is then transferred to a microwave reactor. After adjusting the microwave power and controlling the temperature, the mixed solution undergoes an anti-Markovnikov addition reaction with hydrogen bromide gas within the microwave reactor to generate a bromoundecenoic acid solution. The resulting addition solution is then transferred to a crystallization vessel for freeze crystallization. The crystallized product is filtered to obtain 11-bromoundecenoic acid. This invention utilizes hydrogen bromide aeration and mechanical stirring in the microwave reactor to increase the gas-liquid mass transfer area and improve mass transfer efficiency. The microwave-assisted synthesis of 11-bromoundecenoic acid achieves molecular-level stirring, significantly shortening the reaction time and effectively increasing the yield of the target product. Simultaneously, the use of a nonpolar solvent with weak microwave absorption effectively avoids the thermal effect generated by microwaves, resulting in an even higher yield of the target product.

Description

Technical Field

[0001] This invention relates to a synthesis process for the rapid reaction of undecenoic acid and hydrogen bromide to synthesize 11-bromoundecanoic acid using microwave assistance. Background Technology

[0002] Nylon 11 (PA11) has the chemical name polyamide 11 and the structure H[NH(CH2)] 10 CO] n PA11, a nylon material with low water absorption and excellent low-temperature impact resistance, plays an irreplaceable role in automotive oil pipelines, electronic appliances, municipal gas pipelines, and offshore oil field development. The development of PA11 in China is constrained by the preparation technology of its polymer monomers; therefore, the synthesis of 11-bromoundecanoic acid is of great significance.

[0003] In the prior art, undecenoic acid is reacted with hydrogen bromide in an anti-Markovnikov addition reaction to prepare bromoundecanoic acid. Benzoyl peroxide or azobisisobutyronitrile is usually used as an initiator, toluene is measured as a reaction solvent, undecenoic acid and the initiator are dissolved in toluene, HBr gas is passed through, after the reaction is completed, it is aged, washed with deionized water until neutral, frozen crystallized and filtered, and air-dried to obtain 11-bromoundecanoic acid. Chinese patent CN202211136892.9 discloses a method for preparing 11-bromoundecanoic acid using undecenoic acid, solvent, composite initiator, and hydrogen bromide as raw materials, employing a tower and batch reactor in series, with a maximum yield of 96.04%. Chinese patent CN201410045612.2 describes a method that prepares a raw material solution by mixing undecenoic acid, toluene, and benzene in a specific ratio, using benzoyl peroxide or azodiethylbutyronitrile as an initiator, and reacting it with hydrogen bromide in a double-batch reactor to generate a 11-bromoundecanoic acid solution, requiring 80 minutes. Both existing methods suffer from drawbacks such as a small gas-liquid mass transfer interface, slow reaction rate, and high operating costs. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the present invention aims to provide an efficient and simple microwave-assisted process for the preparation of 11-bromoundecanoic acid. The solvent used in this invention is a non-polar solvent with weak microwave absorption, which avoids the thermal effects generated by microwaves. The reactants undecenoic acid and hydrogen bromide have a certain degree of polarity, allowing for molecular-level stirring under the influence of a microwave field. Therefore, the method of this invention has the advantages of fast reaction speed and high yield of the target product.

[0005] The technical solution adopted in this invention is as follows:

[0006] A microwave-assisted synthesis process for 11-bromoundecenoic acid includes the following steps:

[0007] 1) Undecenoic acid and a nonpolar solvent are mixed, an initiator is added, and the mixture is stirred in a mixing vessel to obtain a preliminary reaction mixture;

[0008] 2) The mixture in the batching vessel is transferred to the microwave reactor, and hydrogen bromide gas is simultaneously bubbled into the mixture in the microwave reactor. The microwave reactor is equipped with a coil heat exchange device for regulating the reaction temperature. The mixture in the microwave reactor is regulated to the reaction temperature, and the microwave is turned on so that undecenoic acid and hydrogen bromide gas undergo an anti-Markovnikov addition reaction under microwave radiation to generate a solution containing 11-bromoundecanoic acid.

[0009] 3) The reaction solution obtained in step 2) is transported from the outlet of the microwave reactor to the crystallization vessel for freeze crystallization. The crystallized product is transported from the outlet of the crystallization vessel to the filtration device for filtration through a transfer pump to obtain 11-bromoundecenoic acid product.

[0010] Further, the nonpolar solvent mentioned in step 1) is one or more of n-hexane, cyclohexane, methylcyclohexane, petroleum ether, cyclohexanone, and n-heptane, and the mass ratio of undecenoic acid to the nonpolar solvent is 1:3-7, preferably 1:4-5.

[0011] Further, in step 1), the initiator is one or more of benzoyl peroxide, dodecyl peroxide, di-tert-butyl peroxide, and xylene peroxide, and its total amount is 0.5-5% of the mass of undecenoic acid, preferably 0.8-1.2%.

[0012] Furthermore, during step 2), the molar ratio of undecenoic 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 100-5000W, preferably 2000-5000W. The microwave is controlled by a pulse switch, and the running time and stopping time within one microwave radiation cycle are 5-60s, preferably 10-30s.

[0014] Further, in step 2), the reaction temperature in the microwave reactor is 10-40℃, preferably 10-20℃, and the residence time of the mixture in the microwave reactor is 10-60 min, preferably 20-40 min.

[0015] Furthermore, in step 3), the crystallization vessel is equipped with a stirrer and a heat exchange coil. The speed of the stirrer is set to 10 to 100 r / min, the crystallization temperature is -10 to -20℃, the time is 2 to 6 h, and the gauge pressure is -30 to -50 kPa.

[0016] Furthermore, the crystallized product is transported from the outlet of the crystallization vessel to a filtration device via a transfer pump for filtration. The filtration pressure is 0.1 to 0.5 MPa and the temperature is -10 to -20°C. The filtrate is then transported to a batching vessel for reuse.

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

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

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

[0020] By employing the above-described technology, the beneficial effects of the present invention compared to the prior art are as follows:

[0021] 1. This invention increases the gas-liquid mass transfer area and improves mass transfer efficiency by using an aerator and mechanical stirring.

[0022] 2. This invention uses microwave-assisted synthesis of 11-bromoundecanoic acid, which can achieve molecular-level stirring, significantly shorten the reaction time, and effectively improve the yield of the target product.

[0023] 3. This invention uses a nonpolar solvent with weak microwave absorption capacity, 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. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the microwave-assisted synthesis process of 11-bromoundecanoic acid;

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

[0026] Appendix Figure 2 The markings include: 1-Battery mixing vessel; 2-Microwave reactor; 3-Crystallization vessel; 4-Filter; 5-Transfer pump. Detailed Implementation

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

[0028] The structural diagram of the reaction apparatus used in this reaction embodiment is shown below. Figure 2As shown, the system includes a mixing tank 1, a microwave reactor 2, a crystallization tank 3, and a filter 4. The mixing tank 1 has an inlet and an outlet; the outlet is connected to the inlet of the microwave reactor 2. The mixed solution is pumped into the microwave reactor 2 via a transfer pump 5. The microwave reactor 2 has an inlet at the top and an air inlet at the bottom. An aeration device, which can be a tubular, plate, or disc aerator, is installed at the bottom of the microwave reactor. Hydrogen bromide gas is introduced into the bottom of the microwave reactor through the aeration device, and the gas reacts with the undecenoic acid raw material via anti-Markovnikov addition. The outlet of the microwave reactor 2 is connected to the transfer pump 5, and the material is pumped to the crystallization tank 3 for freeze crystallization. The crystallized product is then pumped from the outlet of the crystallization tank 3 to the filter device 4 via the transfer pump 5 for filtration.

[0029] The microwave reactor 2 is equipped with a microwave generator with a microwave power of 100-5000W. The microwave reactor 2 is also equipped 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℃. The microwave reactor 2 is also equipped with a stirring device with a stirring speed of 20-100r / min.

[0030] The above-described apparatus synthesizes 11-bromoundecanoic acid using microwave energy, which includes the following steps:

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

[0032] Step S2: Weigh undecenoic acid, solvent and benzoyl peroxide, and feed them into the mixing tank 1 through the feed inlet. Stir to form a reaction solution, and feed it into the microwave reactor 2 through the feed inlet. The mass ratio of n-hexane, petroleum ether and cyclohexane in the solvent is 5:3:2.

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

[0034] Step S4: Start the prepared microwave reactor 2 and carry out the anti-Markovnikov addition in the microwave reactor 2, maintaining the reaction time for 10-60 minutes.

[0035] Step S5: The addition solution is fed into the crystallization vessel 3 from the outlet of the microwave reactor 2. The stirring speed of the crystallization vessel is kept at 10 to 100 r / min, the crystallization temperature is -10 to -20℃, the time is 2 to 6 h, and the gauge pressure is -30 to -50 kPa for freeze crystallization.

[0036] In step S6, the crystallized product is transported from the outlet of the crystallization vessel 3 to the filtration device 4 via the transfer pump 5 for filtration. The filtrate is sent to the batching vessel 1 to serve as a solvent again. The filtered substance is 11-bromoundecanoic acid.

[0037] Using the above-described preparation apparatus and method, the following description will be provided in conjunction with specific embodiments.

[0038] Example 1:

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

[0040] Step S2: Weigh 100 kg of undecenoic acid, 400 kg of mixed solvent and 1 kg of benzoyl peroxide, and feed them into the mixing vessel 1 through the feed inlet. Stir to form a reaction solution, and feed it into the microwave reactor 2 through the feed inlet. The mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

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

[0042] Step S4: Start the pre-set microwave reactor 2 and carry out anti-Markovnikov addition in the microwave reactor 2. The microwave is controlled by a pulse switch. The running time and stop time in one microwave radiation cycle are 20 seconds each, and the reaction time is 30 minutes.

[0043] Step S5: The reaction solution obtained in step S4 is fed into the crystallization vessel 3 from the outlet of the microwave reactor 2. The stirring speed of the crystallization vessel is kept at 50 r / min, the crystallization temperature is -15℃, the time is 4h, and the gauge pressure is -40 kPa for freeze crystallization.

[0044] In step S6, the crystallized product is transported from the outlet of the crystallization vessel 3 to the filtration device 4 via the transfer pump 5 for filtration. The filtrate is then sent to the microwave reactor 2 to serve as a solvent again. The filtered substance is 11-bromoundecanoic acid.

[0045] Example 2:

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

[0047] Step S2: Weigh 100 kg of undecenoic acid, 400 kg of mixed solvent and 1 kg of benzoyl peroxide, and feed them into the mixing vessel 1 through the feed inlet. Stir to form a reaction solution, and feed it into the microwave reactor 2 through the feed inlet. The mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

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

[0049] Step S4: Start the pre-set microwave reactor 2 and carry out anti-Markovnikov addition in the microwave reactor 2. The microwave is controlled by a pulse switch. The running time and stop time in one microwave radiation cycle are 20 seconds each, and the reaction time is 30 minutes.

[0050] Step S5: The reaction solution obtained in step S4 is fed into the crystallization vessel 3 from the outlet of the microwave reactor 2. The stirring speed of the crystallization vessel is kept at 50 r / min, the crystallization temperature is -15℃, the time is 4h, and the gauge pressure is -40 kPa for freeze crystallization.

[0051] In step S6, the crystallized product is transported from the outlet of the crystallization vessel 3 to the filtration device 4 via the transfer pump 5 for filtration. The filtrate is then sent to the microwave reactor 2 to serve as a solvent again. The filtered substance is 11-bromoundecanoic acid.

[0052] Example 3:

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

[0054] Step S2: Weigh 100 kg of undecenoic acid, 400 kg of mixed solvent and 1 kg of benzoyl peroxide, and feed them into the mixing vessel 1 through the feed inlet. Stir to form a reaction solution, and feed it into the microwave reactor 2 through the feed inlet. The mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

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

[0056] Step S4: Start the pre-set microwave reactor 2 and carry out anti-Markovnikov addition in the microwave reactor 2. The microwave is controlled by a pulse switch. The running time and stop time in one microwave radiation cycle are 20 seconds each, and the reaction time is 30 minutes.

[0057] Step S5: The reaction solution obtained in step S4 is fed into the crystallization vessel 3 from the outlet of the microwave reactor 2. The stirring speed of the crystallization vessel is kept at 50 r / min, the crystallization temperature is -15℃, the time is 4h, and the gauge pressure is -40 kPa for freeze crystallization.

[0058] In step S6, the crystallized product is transported from the outlet of the crystallization vessel 3 to the filtration device 4 via the transfer pump 5 for filtration. The filtrate is then sent to the microwave reactor 2 to serve as a solvent again. The filtered substance is 11-bromoundecanoic acid.

[0059] Example 4:

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

[0061] Step S2: Weigh 100 kg of undecenoic acid, 400 kg of mixed solvent and 1 kg of benzoyl peroxide, and feed them into the mixing vessel 1 through the feed inlet. Stir to form a reaction solution, and feed it into the microwave reactor 2 through the feed inlet. The mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

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

[0063] Step S4: Start the pre-set microwave reactor 2 and carry out anti-Markovnikov addition in the microwave reactor 2. The microwave is controlled by a pulse switch. The running time and stop time in one microwave radiation cycle are 20 seconds each, and the reaction time is 30 minutes.

[0064] Step S5: The reaction solution obtained in step S4 is fed into the crystallization vessel 3 from the outlet of the microwave reactor 2. The stirring speed of the crystallization vessel is kept at 50 r / min, the crystallization temperature is -15℃, the time is 4h, and the gauge pressure is -40 kPa for freeze crystallization.

[0065] In step S6, the crystallized product is transported from the outlet of the crystallization vessel 3 to the filtration device 4 via the transfer pump 5 for filtration. The filtrate is then sent to the microwave reactor 2 to serve as a solvent again. The filtered substance is 11-bromoundecanoic acid.

[0066] Example 5:

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

[0068] Step S2: Weigh 100 kg of undecenoic acid, 400 kg of mixed solvent and 1 kg of benzoyl peroxide, and feed them into the mixing vessel 1 through the feed inlet. Stir to form a reaction solution, and feed it into the microwave reactor 2 through the feed inlet. The mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

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

[0070] Step S4: Start the pre-set microwave reactor 2 and carry out anti-Markovnikov addition in the microwave reactor 2. The microwave is controlled by a pulse switch. The running time and stop time in one microwave radiation cycle are 20 seconds each, and the reaction time is 30 minutes.

[0071] Step S5: The reaction solution obtained in step S4 is fed into the crystallization vessel 3 from the outlet of the microwave reactor 2. The stirring speed of the crystallization vessel is kept at 50 r / min, the crystallization temperature is -15℃, the time is 4h, and the gauge pressure is -40 kPa for freeze crystallization.

[0072] In step S6, the crystallized product is transported from the outlet of the crystallization vessel 3 to the filtration device 4 via the transfer pump 5 for filtration. The filtrate is then sent to the microwave reactor 2 to serve as a solvent again. The filtered substance is 11-bromoundecanoic acid.

[0073] Example 6:

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

[0075] Step S2: Weigh 100 kg of undecenoic acid, 400 kg of mixed solvent and 1 kg of benzoyl peroxide, and feed them into the mixing vessel 1 through the feed inlet. Stir to form a reaction solution, and feed it into the microwave reactor 2 through the feed inlet. The mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

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

[0077] Step S4: Start the pre-set microwave reactor 2 and carry out anti-Markovnikov addition in the microwave reactor 2. The microwave is controlled by a pulse switch. The running time and stop time in one microwave radiation cycle are 20 seconds each, and the reaction time is 30 minutes.

[0078] Step S5: The reaction solution obtained in step S4 is fed into the crystallization vessel 3 from the outlet of the microwave reactor 2. The stirring speed of the crystallization vessel is kept at 50 r / min, the crystallization temperature is -15℃, the time is 4h, and the gauge pressure is -40 kPa for freeze crystallization.

[0079] In step S6, the crystallized product is transported from the outlet of the crystallization vessel 3 to the filtration device 4 via the transfer pump 5 for filtration. The filtrate is then sent to the microwave reactor 2 to serve as a solvent again. The filtered substance is 11-bromoundecanoic acid.

[0080] Comparative Example 1:

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

[0082] Step S2: Weigh 100 kg of undecenoic acid, 400 kg of mixed solvent and 1 kg of benzoyl peroxide, and feed them into the mixing vessel 1 through the feed inlet. Stir to form a reaction solution, and feed it into the microwave reactor 2 through the feed inlet. The mass ratio of n-hexane, petroleum ether and cyclohexane in the mixed solvent is 5:3:2.

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

[0084] Step S4: Perform anti-Markovnikov addition in microwave reactor 2, control and stop microwave radiation, and carry out conventional stirring reaction for 30 minutes.

[0085] Step S5: The reaction solution obtained in step S4 is fed into the crystallization vessel 3 from the outlet of the microwave reactor 2. The stirring speed of the crystallization vessel is kept at 50 r / min, the crystallization temperature is -15℃, the time is 4h, and the gauge pressure is -40 kPa for freeze crystallization.

[0086] In step S6, the crystallized product is transported from the outlet of the crystallization vessel 3 to the filtration device 4 via the transfer pump 5 for filtration. The filtrate is then sent to the microwave reactor 2 to serve as a solvent again. The filtered substance is 11-bromoundecanoic acid.

[0087] Comparative Example 2:

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

[0089] Comparative Example 3:

[0090] The experimental procedure of Comparative Example 3 was repeated with that of Comparative Example 1, except that the reaction temperature of microwave reactor 2 was set to 20°C. All other conditions remained the same, and 11-bromoundecanoic acid was finally prepared.

[0091] Comparative Example 4:

[0092] The experimental procedure of Comparative Example 4 was repeated with that of Comparative Example 1, except that the reaction temperature of the microwave reactor 2 was set to 10°C. All other conditions remained the same, and 11-bromoundecanoic acid was finally prepared.

[0093] Comparative Example 5:

[0094] The experimental steps of Comparative Example 5 were repeated in Example 1, except that the mixed solvent in step S2 was replaced with an equal mass of toluene, and the other conditions remained unchanged, and 11-bromoundecanoic acid was finally prepared.

[0095] Comparative Example 6:

[0096] The experimental steps of Comparative Example 6 were repeated in Example 2, except that "the mixed solvent in step S2 was replaced with an equal mass of toluene", and the other conditions remained unchanged, and 11-bromoundecanoic acid was finally prepared.

[0097] Comparative Example 7:

[0098] The experimental steps of Comparative Example 7 were repeated in Example 3, except that the mixed solvent in step S2 was replaced with an equal mass of toluene, and the other conditions remained unchanged, and 11-bromoundecanoic acid was finally prepared.

[0099] Comparative Example 8:

[0100] The experimental procedure of Comparative Example 8 was repeated with that of Comparative Example 1, except that the stirring speed of the microwave reactor 2 was 100 r / min. All other conditions remained the same, and 11-bromoundecanoic acid was finally prepared.

[0101] Comparative Example 9:

[0102] The experimental procedure of Comparative Example 9 was repeated with that of Comparative Example 2, except that the stirring speed of the microwave reactor 2 was 100 r / min. All other conditions remained the same, and 11-bromoundecanoic acid was finally prepared.

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

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

[0105]

[0106]

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

[0108]

Claims

1. A microwave-assisted synthesis process for 11-bromoundecenoic acid, characterized in that, Includes the following steps: 1) Undecenoic acid and a nonpolar solvent are mixed, an initiator is added, and the mixture is stirred in a mixing vessel to obtain a preliminary reaction mixture; 2) The mixture in the batching vessel is transferred to the microwave reactor, and hydrogen bromide gas is bubbled into the mixture in the microwave reactor. The microwave reactor is equipped with a coil heat exchange device for regulating the reaction temperature. The mixture in the microwave reactor is regulated to the reaction temperature, and the microwave is turned on so that undecenoic acid and hydrogen bromide gas undergo an anti-Markovnikov addition reaction under microwave radiation to generate a solution containing 11-bromoundecanoic acid. 3) The reaction solution obtained in step 2) is transported from the outlet of the microwave reactor to the crystallization vessel for freeze crystallization. The crystallized product is transported from the outlet of the crystallization vessel to the filtration device for filtration through a transfer pump to obtain 11-bromoundecenoic acid product. The nonpolar solvent mentioned in step 1) is a mixture of n-hexane, cyclohexane, and petroleum ether, and the mass ratio of undecenoic acid to the nonpolar solvent is 1:3-7; In step 2), the microwave power is set to 2000~5000W, and the microwave is controlled by a pulse switch. The running time and stopping time within one microwave radiation cycle are 10~30s each. Step 2) The reaction temperature in the microwave reactor is 20℃, and the residence time of the mixture in the microwave reactor is 20-40 min.

2. The process for microwave-assisted synthesis of 11-bromoundecenoic acid as described in claim 1, characterized in that, The mass ratio of undecenoic acid to nonpolar solvent is 1:4-5.

3. The process for microwave-assisted synthesis of 11-bromoundecenoic acid as described in claim 1, characterized in that, In step 1), the initiator is one or a mixture of benzoyl peroxide, dodecyl peroxide, di-tert-butyl peroxide, and xylene peroxide, and the total amount is 0.5 to 5% of the mass of undecenoic acid.

4. The process for microwave-assisted synthesis of 11-bromoundecenoic acid as described in claim 3, characterized in that, In step 1), the total amount of initiator is 0.8-1.2% of the mass of undecenoic acid.

5. The process for microwave-assisted synthesis of 11-bromoundecenoic acid as described in claim 1, characterized in that, In step 2), the molar ratio of undecenoic acid to hydrogen bromide is controlled at 1:1-5.

6. The process for microwave-assisted synthesis of 11-bromoundecenoic acid as described in claim 5, characterized in that, In step 2), the molar ratio of undecenoic acid to hydrogen bromide is controlled at 1:1.5-2.

7. The process for microwave-assisted synthesis of 11-bromoundecenoic acid as described in claim 1, characterized in that, In step 3), the crystallization vessel is equipped with a stirrer and a heat exchange coil. The speed of the stirrer 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 microwave-assisted synthesis of 11-bromoundecenoic acid as described in claim 1, characterized in that, The crystallized product is transported from the outlet of the crystallization vessel to the filtration device via a transfer pump for filtration. The filtration pressure is 0.1~0.5MPa and the temperature is -10~-20℃. The filtrate is then transported to the batching vessel for reuse.

9. The process for microwave-assisted synthesis of 11-bromoundecenoic acid as described in claim 1, characterized in that, The microwave reactor is equipped with an aeration device at the bottom, which can be a tubular, plate, or disc aerator. 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. The magnetrons are connected to a microwave generator, which is controlled by a microwave pulse control system. The microwave reactor is equipped with an internal coil heat exchange device.

10. The process for microwave-assisted synthesis of 11-bromoundecenoic acid as described in claim 1, characterized in that, The microwave reactor is equipped with a stirrer with a stirring speed of 20-100 r / min.

11. The process for microwave-assisted synthesis of 11-bromoundecenoic acid as described in claim 10, characterized in that, The stirring speed is 40-60 r / min.

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