Continuous production process and production device of m-methylbenzoyl chloride

Abstract

The invention belongs to the technical field of organic synthesis, and particularly relates to a continuous production process and a production device of m-methylbenzoyl chloride. The continuous production process of m-methylbenzoyl chloride comprises the following steps: adding m-toluic acid and a liquid catalyst into a reaction kettle, dropwise adding thionyl chloride in stages, controlling the temperature and tail gas flow to react, preserving heat after the reaction is finished, and evaporating to remove thionyl chloride at normal pressure and negative pressure to obtain a reaction liquid crude product; the reaction liquid crude product enters a light component removal tower, the material is preheated through a product tower top material, the temperature is increased to 85-90 DEG C from 60-65 DEG C, then the reaction liquid crude product enters the light component removal tower to remove light components, and after heavy components are removed in the product tower, a m-methyl benzoyl chloride finished product is obtained. According to the continuous production process of the m-methylbenzoyl chloride, provided by the invention, the reaction time is shortened, the energy consumption is reduced, the production cost is reduced, and the produced m-methylbenzoyl chloride is high in yield and high in content.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and specifically relates to a continuous production process and a production device of m-toluoyl chloride. Background Art

[0002] In the fine chemical industry, m-toluoyl chloride, as a key chemical raw material, is widely used in many fields such as medicine, pesticides, dyes and photosensitive materials due to its unique chemical properties. As an important intermediate, it is of great significance to promote technological progress and new product development in related industries. However, the traditional m-toluoyl chloride production process has some significant problems, which limit the improvement of production efficiency and the reduction of costs.

[0003] The traditional batch distillation method is to directly feed the crude product into the distillation tower and heat it with steam or other heat sources. This method has the problem of high energy consumption, especially in large-scale production, where energy consumption becomes an important part of production costs. In addition, due to the large fluctuations in the appearance of each batch of products produced, the quality is unstable, which affects the market competitiveness and application scope of the products.

[0004] In the reaction step, the traditional production method usually uses hot water as the heating medium. However, this method results in a slow reaction rate between sulfoxide and m-toluic acid, and a long reaction time is required to achieve the expected chemical conversion rate. This not only prolongs the entire production cycle, reduces production efficiency, but also increases production costs. At the same time, the energy transfer efficiency of hot water heating is low, requiring more energy consumption, further increasing production costs.

[0005] For example, in the existing patent CN101906033A, it is described that m-toluic acid and thionyl chloride are put into a reactor, stirred and heated at a temperature of 70-85°C until no gas is discharged, and the chlorination reaction is completed. However, this temperature range causes the instantaneous amount of tail gas to be too large, the sulfoxide entrainment increases, and the unit consumption is high. At the same time, the reaction time is not described in detail, and although the content of the m-toluoyl chloride product obtained reaches more than 98.5%, there is still room for improvement.

[0006] In addition, in the patent publication CN105348085A, it is described that the use of a thin film evaporator for vacuum distillation has a product yield of 97-98% and a product content of about 99.2%-99.5%. Although this method improves the product content and yield to a certain extent, the cost of using a thin film evaporator for vacuum distillation is high and there is still the problem of high energy consumption.

[0007] Although the patent publication CN105330535A describes the use of a relatively low reaction temperature (20-35° C.), the reaction activity is relatively low at this temperature, and the use of an organic solvent increases the cost of post-processing, which also limits the improvement of production efficiency and the reduction of costs. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art, provide a continuous production process of m-toluoyl chloride, shorten the reaction time, reduce energy consumption, reduce production costs, and produce m-toluoyl chloride with high yield and high content. The present invention also provides a continuous production device of m-toluoyl chloride.

[0009] The continuous production process of m-toluoyl chloride of the present invention comprises the following steps: adding m-toluic acid and a liquid catalyst into a reaction kettle, dripping thionyl chloride in stages, controlling the temperature and tail gas flow rate to react, keeping the temperature after the reaction is completed, removing thionyl chloride under normal pressure and negative pressure to obtain a crude reaction liquid, and preheating the crude reaction liquid to a light removal tower material through the product tower top material, raising the temperature from 60-65° C. to 85-90° C., and then entering a light removal tower to remove light components and a product tower to remove heavy components to obtain a finished m-toluoyl chloride product. The liquid catalyst is DMF.

[0010] The thionyl chloride is added dropwise in stages, at least in 2 stages. The thionyl chloride added in the first stage is 1 / 3-1 / 2 of the total weight of thionyl chloride. In the second stage, thionyl chloride is added dropwise to control the tail gas flow rate to 160m 3 / h-190m 3 / h.

[0011] The reaction temperature is 45-67°C and the reaction time is 6-9h.

[0012] The insulation temperature is 70-85℃ and the insulation time is 1-2h.

[0013] The temperature for removing thionyl chloride by negative pressure evaporation is 105-125°C, and the vacuum degree is 87-92 kPa.

[0014] The feed rate into the lightness removal tower is 335L / h-385L / h, and the vacuum degree is adjusted to 97.9kPa±2kPa.

[0015] The heavy components at the bottom of the tower are added to the product tower through the light removal pump, and the flow rate is controlled to be 300L / h-365L / h, and the vacuum degree is 97.9kPa±2kPa.

[0016] The production device adopted in the continuous production process of m-toluoyl chloride comprises a reaction kettle, a light-removal tower and a product tower. The bottom of the reaction kettle is connected with a crude product tank, the crude product tank is connected with a preheater through a crude product feed pump, the preheater is connected with the center of the light-removal tower, and the bottom of the light-removal tower is connected with the center of the product tower through a light-removal pump.

[0017] The top of the reactor is connected to the first-stage reaction condenser, the first-stage reaction condenser is connected to the second-stage reaction condenser, a recovery tank is connected to the pipeline from the second-stage reaction condenser back to the top of the reactor, and a dropping tank is connected to the reactor.

[0018] The top of the light removal tower is connected to the first-stage light removal condenser, the first-stage light removal condenser is connected to the second-stage light removal condenser, the pipeline from the second-stage light removal condenser back to the top of the light removal tower is connected to a front still, and a light removal reboiler is arranged at the bottom of the light removal tower.

[0019] The preheater is connected to the product secondary condenser, the pipeline from the product secondary condenser back to the top of the product tower is connected to the main still, and a product reboiler is arranged at the bottom of the product tower.

[0020] Specifically, the continuous production process of m-toluoyl chloride comprises the following steps:

[0021] (1) Add m-toluic acid and thionyl chloride to the reactor, add liquid catalyst, heat to 45-67°C by steam, then start to drop thionyl chloride in the second stage, and control the tail gas flow rate to 160m 3 / h-190m 3 / h, react for 6-9h, until no tail gas is generated, and then keep warm at 70-85℃ for 50-80min. After the reaction is completed, remove excess thionyl chloride by regular and negative pressure distillation. The temperature of negative pressure thionyl chloride distillation is 105-125℃, and the vacuum degree is 87-92kPa. The crude reaction liquid is obtained and pumped into the crude product intermediate tank.

[0022] (2) The crude reaction liquid is fed from the tower to the light removal tower after passing through the preheater at the top of the product tower, with a feed rate of 335 L / h-385 L / h, and the vacuum degree is adjusted to 97.9 kPa±2 kPa. The light component is extracted to the front still after partial condensation, with an extraction flow rate of 25 L / h-35 L / h, and the rest is refluxed to the light removal tower; the heavy component at the bottom of the light removal tower is added to the product tower through the light removal pump, with a control flow rate of 300 L / h-365 L / h, and the vacuum degree is 97.9 kPa±2 kPa. The temperature at the bottom of the product tower is controlled at 135°C±3°C to fully receive the product of m-methylbenzoyl chloride.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The continuous production process of m-toluoyl chloride of the present invention adopts a distillation feed preheating method, and effectively utilizes the heat of the top material of the product tower to preheat the material about to enter the lightness removal tower. This method can significantly reduce energy consumption, achieve energy recovery, and thus improve production efficiency.

[0025] (2) The continuous production process of m-toluoyl chloride of the present invention uses steam as a heating medium. Its thermal conductivity is good, and the reaction system can be quickly heated at an appropriate temperature, so that thionyl chloride and m-toluic acid react instantly. The reaction is carried out at 20-67° C., thereby increasing the reaction rate and shortening the reaction time. At the same time, the steam heating method has high energy transfer efficiency, reduces energy consumption, and reduces production costs.

[0026] (3) The continuous production process of m-toluoyl chloride of the present invention does not add organic solvent, thus avoiding the occurrence of side reactions and reducing production energy consumption. The obtained product content is above 99.6% and the yield is above 99.2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the continuous production process of m-toluoyl chloride of the present invention.

[0028] In the figure: 1. Reactor; 2. First-stage reaction condenser; 3. Second-stage reaction condenser; 4. Dropping tank; 5. Crude product tank; 6. Recovery tank; 7. Crude product feed pump; 8. Light removal tower; 9. First-stage light removal condenser; 10. Light removal reboiler; 11. Fore still; 12. Light removal second-stage condenser; 13. Light removal pump; 14. Product tower; 15. Preheater; 16. Main still; 17. Product reboiler; 18. Product second-stage condenser. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific embodiments.

[0030] The devices used in the following embodiments are as follows: Figure 1 As shown, the production device used in the continuous production process of m-toluoyl chloride includes a reactor 1, a light removal tower 8, and a product tower 14. The bottom of the reactor 1 is connected to a crude product tank 5, and the crude product tank 5 is connected to a preheater 15 through a crude product feed pump 7. The preheater 15 is connected to the middle of the light removal tower 8, and the bottom of the light removal tower 8 is connected to the middle of the product tower 14 through a light removal pump 13.

[0031] The top of the reactor 1 is connected to the first-stage reaction condenser 2, the first-stage reaction condenser 2 is connected to the second-stage reaction condenser 3, the pipeline from the second-stage reaction condenser 3 back to the top of the reactor is connected to a recovery tank 6, and the reactor 1 is connected to a dropping tank 4.

[0032] The top of the de-lightening tower 8 is connected to the first-stage de-lightening condenser 9, the first-stage de-lightening condenser 9 is connected to the second-stage de-lightening condenser 12, the pipeline from the second-stage de-lightening condenser 12 returning to the top of the de-lightening tower 8 is connected to a front still 11, and a de-lightening reboiler 10 is arranged at the bottom of the de-lightening tower 8.

[0033] The preheater 15 is connected to a product secondary condenser 18 . A main still 16 is connected to a pipeline from the product secondary condenser 18 back to the top of the product tower 14 . A product reboiler 17 is provided at the bottom of the product tower 14 .

[0034] The working process of the production device is as follows: the raw materials are added to the reactor 1, and the dropping speed is controlled according to the process requirements by the dropping tank 4. During the reaction, the generated gas enters the reaction primary condenser 2 through the top of the reactor for preliminary condensation. The gas that is not completely condensed continues to enter the reaction secondary condenser 3 for further condensation. The condensed liquid part is collected in the recovery tank 6 to recover the unreacted raw materials or by-products, and the rest is returned to the reactor 1 to continue to participate in the reaction. After the reaction is completed, the crude product at the bottom of the reactor 1 enters the crude product tank 5 through a pipeline. The crude product is transported to the preheater 15 for preheating by the crude product feed pump 7 to improve the light removal efficiency. The preheated crude product enters the light removal tower 8, and the light components are separated from m-toluoyl chloride by distillation in the tower. The light components escape from the top of the light removal tower 8 and are condensed in turn through the light removal primary condenser 9 and the light removal secondary condenser 12. The condensed light components are collected in the front still 11, and the rest are refluxed to the light removal tower 8 for continued heat exchange. The bottom of the light removal tower 8 is used to transport the m-toluoyl chloride after light removal to the product tower 14 through the light removal pump 13. The m-toluoyl chloride after light removal enters the product tower 14, and the m-toluoyl chloride is separated from the heavy components by further distillation in the tower. The gas escaping from the top of the product tower 14 enters the product secondary condenser 18 for condensation. The condensed liquid is collected in the main still 16 as the final product m-toluoyl chloride. The bottom of the product tower 14 is provided with a product reboiler 17 for providing heat to maintain the distillation process in the tower. The final product m-toluoyl chloride is collected in the main still 16.

[0035] Example 1

[0036] The continuous production process of m-toluoyl chloride comprises the following steps:

[0037] (1) Add 2500 kg of m-toluic acid and 1380 kg of thionyl chloride to the reactor, add 250 mL of DMF, heat to 65 °C with steam, then start to dropwise add 1020 kg of thionyl chloride in the second stage, and control the tail gas flow rate to 167 m 3 / h, react for 6.5h, until no tail gas is generated, and then keep warm at 80℃ for 60min. After the reaction is completed, remove excess thionyl chloride by regular and negative pressure distillation. The temperature of negative pressure thionyl chloride distillation is 120℃, and the vacuum degree is 89kPa. The crude reaction liquid is obtained and pumped into the crude product intermediate tank.

[0038] (2) The crude reaction liquid is fed from the light-removal tower to the light-removal tower after passing through the preheater at the top of the product tower, with a feed rate of 335 L / h and a vacuum degree of 97.9 kPa. The light component is condensed by a condenser and then extracted to the front still, with an extraction flow rate of 34 L / h, and the rest is refluxed to the light-removal tower; the heavy component at the bottom of the light-removal tower is added to the product tower through a light-removal pump, with a controlled flow rate of 310 L / h and a vacuum degree of 98.5 kPa. The temperature at the bottom of the product tower is controlled at 136° C. to fully receive the product of m-toluoyl chloride, with a yield of 99.22%. After testing, the chromatographic content of m-toluoyl chloride is 99.61%.

[0039] Example 2

[0040] The continuous production process of m-toluoyl chloride comprises the following steps:

[0041] (1) Add 3000 kg of m-toluic acid and 917 kg of thionyl chloride to the reactor, add 300 mL of DMF, heat to 55 °C with steam, then start to dropwise add 1835 kg of thionyl chloride in the second stage, and control the tail gas flow rate to 175 m 3 / h, react for 8.5h, until no tail gas is generated, and then keep warm at 70℃ for 75min. After the reaction is completed, remove excess thionyl chloride by regular and negative pressure distillation. The temperature of negative pressure thionyl chloride distillation is 115℃, and the vacuum degree is 90kPa. The crude reaction liquid is obtained and pumped into the crude product intermediate tank.

[0042] (2) The crude reaction liquid is fed from the light-removal tower to the light-removal tower after passing through the preheater at the top of the product tower, with a feed rate of 360 L / h and a vacuum degree of 98.1 kPa. The light component is condensed by a condenser and then extracted to the front still, with an extraction flow rate of 30 L / h, and the rest is refluxed to the light-removal tower; the heavy component at the bottom of the light-removal tower is added to the product tower through a light-removal pump, with a controlled flow rate of 355 L / h and a vacuum degree of 97.9 kPa. The temperature at the bottom of the product tower is controlled at 135° C. to fully receive the product of m-toluoyl chloride, with a yield of 99.24%. After testing, the chromatographic content of m-toluoyl chloride is 99.63%.

[0043] Example 3

[0044] The continuous production process of m-toluoyl chloride comprises the following steps:

[0045] (1) Add 1500 kg of m-toluic acid and 874 kg of thionyl chloride to the reactor, add 300 mL of DMF, heat to 47 °C with steam, then start to dropwise add 503 kg of thionyl chloride in the second stage, and control the tail gas flow rate to 177 m 3 / h, react for 6h, until no tail gas is generated, and then keep warm at 61℃ for 120min. After the reaction is completed, remove excess thionyl chloride by regular and negative pressure distillation. The temperature of negative pressure thionyl chloride distillation is 120℃, and the vacuum degree is 91kPa. The crude reaction liquid is obtained and pumped into the crude product intermediate tank.

[0046] (2) The crude reaction liquid is fed from the light-removal tower to the light-removal tower after passing through the preheater at the top of the product tower, with a feed rate of 370 L / h and a vacuum degree of 98.9 kPa. The light component is condensed by a condenser and then taken out to the front still, with a flow rate of 35 L / h, and the rest is refluxed into the light-removal tower; the heavy component at the bottom of the light-removal tower is added to the product tower through a light-removal pump, with a flow rate of 355 L / h and a vacuum degree of 98.2 kPa to 98.9 kPa. The temperature at the bottom of the product tower is controlled at 134° C. to fully receive the product of m-toluoyl chloride, with a yield of 99.23%. After testing, the chromatographic content of m-toluoyl chloride is 99.62%.

[0047] Comparative Example 1

[0048] Add 3000kg of m-toluic acid, 2500kg of dichloroethane and 3500kg of tetrahydrofuran to the reactor, stir evenly to make them fully dissolved, then slowly add 2805kg of thionyl chloride, keep warm and stir at 30℃ for 15.5 hours. After the reaction is completed, first remove the solvent and excess thionyl chloride by atmospheric distillation, then distill under reduced pressure to obtain the product, the chromatographic content is 99.34%, and the calculated yield is 95.6%. The temperature of the reduced pressure distillation is 133℃ and the pressure is -0.095MPa.

[0049] Of course, the above contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the embodiments of the present invention. The present invention is not limited to the above examples, and equal changes and improvements made by ordinary technicians in the technical field within the essential scope of the present invention should all fall within the scope of the patent coverage of the present invention.

Claims

1. A continuous production process for m-toluoyl chloride, characterized in that: Add m-toluic acid and liquid catalyst into the reactor, add thionyl chloride dropwise in stages, control the temperature and tail gas flow rate to react, keep warm after the reaction, evaporate thionyl chloride under normal pressure and negative pressure to obtain a crude reaction liquid, the crude reaction liquid enters the light removal tower material and is preheated by the product tower top material, the temperature is increased from 60-65°C to 85-90°C, and then enters the light removal tower to remove light components and the product tower to remove heavy components to obtain the finished m-toluyl chloride.

2. The continuous production process of m-toluoyl chloride according to claim 1, wherein: The thionyl chloride is added dropwise in stages, at least in 2 stages. The thionyl chloride added in the first stage is 1 / 3-1 / 2 of the total weight of thionyl chloride. In the second stage, thionyl chloride is added dropwise to control the tail gas flow rate to 160m 3 / h-190m 3 / h.

3. The continuous production process of m-toluoyl chloride according to claim 1, wherein: The reaction temperature is 45-67°C and the reaction time is 6-9h.

4. The continuous production process of m-toluoyl chloride according to claim 1, characterized in that: The insulation temperature is 70-85℃ and the insulation time is 1-2h.

5. The continuous production process of m-toluoyl chloride according to claim 1, characterized in that: The temperature for removing thionyl chloride by negative pressure evaporation is 105-125°C, and the vacuum degree is 87-92 kPa.

6. The continuous production process of m-toluoyl chloride according to claim 1, characterized in that: The feed rate into the lightness removal tower is 335L / h-385L / h, and the vacuum degree is adjusted to 97.9kPa±2kPa.

7. The continuous production process of m-toluoyl chloride according to claim 1, characterized in that: The heavy components at the bottom of the tower are added to the product tower through the light removal pump, and the flow rate is controlled to be 300L / h-365L / h, and the vacuum degree is 97.9kPa±2kPa.

8. A production device adopted in the continuous production process of m-toluoyl chloride according to any one of claims 1 to 7, characterized in that: The invention comprises a reaction kettle (1), a light-removal tower (8), and a product tower (14). The bottom of the reaction kettle (1) is connected to a crude product tank (5), the crude product tank (5) is connected to a preheater (15) via a crude product feed pump (7), the preheater (15) is connected to the center of the light-removal tower (8), and the bottom of the light-removal tower (8) is connected to the center of the product tower (14) via a light-removal pump (13).

9. The production device adopted in the continuous production process of m-toluoyl chloride according to claim 8, characterized in that: The top of the reactor (1) is connected to the primary reaction condenser (2), the primary reaction condenser (2) is connected to the secondary reaction condenser (3), a recovery tank (6) is connected to the pipeline from the secondary reaction condenser (3) back to the top of the reactor, and the reactor (1) is connected to a dropping tank (4).

10. The production device adopted in the continuous production process of m-toluoyl chloride according to claim 8, characterized in that: The top of the light removal tower (8) is connected to a first-stage light removal condenser (9), the first-stage light removal condenser (9) is connected to a second-stage light removal condenser (12), a pipeline from the second-stage light removal condenser (12) back to the top of the light removal tower (8) is connected to a front still (11), and a light removal reboiler (10) is provided at the bottom of the light removal tower (8); The preheater (15) is connected to the product secondary condenser (18), and the pipeline from the product secondary condenser (18) back to the top of the product tower (14) is connected to the main still (16), and the bottom of the product tower (14) is provided with a product reboiler (17).

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