Synthesis system of 3-methyl-2-nitrobenzoic acid methyl ester

Abstract

The utility model relates to the technical field of synthesis of organic compounds, in particular to a synthesis system of methyl 3-methyl-2-nitrobenzoate, which comprises a reaction kettle, and a sealable feed port is arranged at the top of the reaction kettle; the top of the reaction kettle is connected with an azeotropic pipe which is connected with a rectifying tower, and the bottom of the rectifying tower is provided with a water outlet and connected with a reboiler; the rectifying tower is sequentially connected with the condenser and the receiving tank, the receiving tank is connected with the reaction kettle through a first return pipe, and the receiving tank is connected with the rectifying tower through a second return pipe; the reaction kettle is sequentially connected with the cooling kettle and the centrifuge; a solid outlet of the centrifuge is connected with the washing device; a liquid outlet of the centrifugal machine is connected with a mother liquor tank which is connected with the reaction kettle through a mother liquor pipeline, and a mother liquor pump is arranged on the mother liquor pipeline. According to the utility model, the conversion rate and the reaction efficiency of the synthetic reaction of the 3-methyl-2-nitrobenzoic acid methyl ester can be improved, the purity of the product is improved, the resource utilization rate is improved, and the continuous production of the 3-methyl-2-nitrobenzoic acid methyl ester is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of organic compound synthesis, in particular to a synthesis system of methyl 3-methyl-2-nitrobenzoate. Background Art

[0002] Chlorantraniliprole (chemical formula: C 18 H 14 BrCl2N5O2) is a new insecticide with the advantages of high permeability, conductivity, chemical stability, and high insecticidal activity. It also has no residual effects on agricultural products and mixes well with other pesticides. Methyl 3-methyl-2-nitrobenzoate is an important raw material for the synthesis of K-amine (5-chloro-3-methyl-2-aminobenzamide), an intermediate in the synthesis of chlorantraniliprole, and plays a key role in the production of chlorantraniliprole.

[0003] The conventional production process of methyl 3-methyl-2-nitrobenzoate is as follows: 3-methyl-2-nitrobenzoic acid is added to excess methanol, heated under reflux for a certain period of time under the catalysis of sulfuric acid, most of the methanol is removed, and the crude product is poured into water while hot to obtain a crude product. Then, alkali (NaOH) is added to the hot water to adjust the pH to a weak alkaline state to remove unreacted 3-methyl-2-nitrobenzoic acid, and the product is obtained after solid-liquid separation. The aqueous phase after solid-liquid separation can be re-acidified to obtain unreacted 3-methyl-2-nitrobenzoic acid.

[0004] The existing production process of methyl 3-methyl-2-nitrobenzoate has the following defects: (1) The esterification reaction of 3-methyl-2-nitrobenzoic acid is a reversible reaction with low conversion rate and reaction efficiency. After keeping warm to reaction equilibrium, generally only about 85% of 3-methyl-2-nitrobenzoic acid is converted into products; (2) Sodium sulfate by-product is produced during the process of adding alkali to adjust the pH, and the obtained 3-methyl-2-nitrobenzoic acid product has low purity and needs to be refined before it can meet the use requirements; (3) The consumption of water and sulfuric acid in the reaction process is large, the recycling of waste liquid is difficult, and the resource utilization rate is low; (4) The production process of methyl 3-methyl-2-nitrobenzoate is difficult to carry out continuously. Utility Model Content

[0005] In view of the defects in the production process of methyl 3-methyl-2-nitrobenzoate in the prior art, such as low conversion rate and reaction efficiency, low product purity, low resource utilization rate, and difficulty in carrying out the production process continuously, the utility model provides a synthesis system for methyl 3-methyl-2-nitrobenzoate, which can improve the conversion rate and reaction efficiency of the synthesis reaction of methyl 3-methyl-2-nitrobenzoate, improve the purity of the product, improve resource utilization rate, reduce resource waste, and realize continuous production of methyl 3-methyl-2-nitrobenzoate.

[0006] The technical solution of the utility model is:

[0007] A synthesis system for methyl 3-methyl-2-nitrobenzoate comprises a reactor, wherein a sealable feed port is provided at the top of the reactor; an azeotropic pipe is connected to the top of the reactor, the azeotropic pipe is connected to a distillation tower, a drain port is provided at the bottom of the distillation tower, and a reboiler is connected to the bottom of the distillation tower; the distillation tower is sequentially connected to a condenser and a receiving tank, the receiving tank is connected to the reactor via a first reflux pipe, and the receiving tank is connected to the distillation tower via a second reflux pipe;

[0008] The reactor is connected to the cooling kettle and the centrifuge in sequence. The solid outlet of the centrifuge is connected to the washing device. The liquid outlet of the centrifuge is connected to the mother liquid tank. The mother liquid tank is connected to the reactor through a mother liquid pipeline. A mother liquid pump is provided on the mother liquid pipeline.

[0009] Furthermore, heating devices are respectively provided outside the reactor and the reboiler.

[0010] Furthermore, a first flow valve is provided on the first reflux pipe, and a second flow valve is provided on the second reflux pipe, which can adjust the liquid flow rates of the first reflux pipe and the second reflux pipe.

[0011] Furthermore, a discharge valve is provided on the receiving tank, which can be opened to discharge part of the liquid when there is too much liquid in the receiving tank to maintain stable pressure in the system.

[0012] Furthermore, the reactor is connected to the cooling reactor through a product pipeline, and a product pump is provided on the product pipeline.

[0013] Furthermore, the reaction kettle and the cooling kettle are respectively provided with stirring devices, which can make the solutions in the reaction kettle and the cooling kettle mixed evenly, thereby improving the reaction efficiency.

[0014] Furthermore, the washing device is provided with a waste liquid outlet, which is connected to the mother liquid tank through a waste liquid pipeline. The washing waste liquid can be passed into the mother liquid tank for recycling, thereby improving the utilization rate of the washing waste liquid.

[0015] Furthermore, the materials of the reactor, receiving tank and mother liquid tank are acid-resistant alloys; the material of the condenser is selected from glass lining, glass, graphite or silicon carbide; the material of the reboiler is selected from acid-resistant alloys, glass lining, ceramics, glass, steel-lined PTFE tube, graphite, silicon carbide or fiberglass reinforced plastics, which can avoid corrosion caused by excessive acidity of the liquid in the synthesis of 3-methyl-2-nitrobenzoic acid methyl ester.

[0016] The beneficial effects of the present invention are:

[0017] 1. The synthesis system of methyl 3-methyl-2-nitrobenzoate provided by the utility model can realize azeotropic distillation of methanol and 3-methyl-2-nitrobenzoic acid, remove water from the reaction system in real time during the reaction process, shift the equilibrium of the originally reversible esterification reaction to the right, and make more 3-methyl-2-nitrobenzoic acid undergo esterification, thereby greatly improving the conversion rate and reaction efficiency of the synthesis reaction of methyl 3-methyl-2-nitrobenzoate.

[0018] 2. The synthesis system of the utility model can directly obtain the fine product of 3-methyl-2-nitrobenzoic acid methyl ester during the azeotropic distillation process, eliminating the step of adding sodium hydroxide solution to the crude 3-methyl-2-nitrobenzoic acid methyl ester for neutralization and purification, and does not produce sodium sulfate as a by-product, thereby improving the purity of the product.

[0019] 3. When using the synthesis system of the present application to synthesize methyl 3-methyl-2-nitrobenzoate, there is no need to repeatedly add water or sulfuric acid. All the waste liquid generated by the reaction is collected in a mother liquor tank and finally transported back to the reactor through the mother liquor pipeline for a cyclic reaction, which can improve resource utilization; the catalyst sulfuric acid in the reaction system can be reused, reducing resource waste.

[0020] 4. The utility model can realize the continuous production of methyl 3-methyl-2-nitrobenzoate, further improving the reaction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] Figure 1 Schematic diagram of the structure of the synthesis system in Example 1.

[0023] In the figure, 1-reactor, 11-azeotropic tube, 2-distillation tower, 21-reboiler, 3-condenser, 4-receiving tank, 41-first reflux pipe, 42-second reflux pipe, 5-cooling kettle, 6-centrifuge, 7-washing device, 8-mother liquor tank, 81-mother liquor pipeline. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will be combined with the drawings of the embodiments of the present invention to clearly and completely describe the technical solutions of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0025] Example 1

[0026] A synthesis system for methyl 3-methyl-2-nitrobenzoate comprises a reactor 1, wherein the reactor 1 is provided with a stirring device and a sealable feed port is provided at the top of the reactor 1; an azeotropic pipe 11 is connected to the top of the reactor 1, the azeotropic pipe 11 is connected to a distillation tower 2, a drain port is provided at the bottom of the distillation tower 2, a reboiler 21 is connected to the bottom of the distillation tower 2, and heating devices are respectively provided on the outside of the reactor 1 and the reboiler 21; the distillation tower 2 is sequentially connected to a condenser 3 and a receiving tank 4, the receiving tank 4 is connected to the reactor 1 via a first reflux pipe 41, and the receiving tank 4 is connected to the distillation tower 2 via a second reflux pipe 42, the first reflux pipe 41 is provided with a first flow valve, the second reflux pipe 42 is provided with a second flow valve, and the receiving tank 4 is provided with a discharge valve;

[0027] The reactor 1 is connected to the cooling kettle 5 through a product pipeline. The cooling kettle 5 is provided with a stirring device. A product pump is provided on the product pipeline. The cooling kettle 5 is connected to a centrifuge 6.

[0028] The solid outlet of the centrifuge 6 is connected to the washing device 7, and the washing device 7 is provided with a waste liquid outlet, which is connected to the mother liquid tank 8 through a waste liquid pipeline;

[0029] The liquid outlet of the centrifuge 6 is connected to the mother liquid tank 8, which is connected to the reactor 1 through a mother liquid pipeline 81, and a mother liquid pump is provided on the mother liquid pipeline 81;

[0030] The materials of the reactor 1, the receiving tank 4 and the mother liquid tank 8 are acid-resistant alloys, the material of the condenser 3 is glass-lined, and the material of the reboiler 21 is acid-resistant alloys.

[0031] The steps of synthesizing methyl 3-methyl-2-nitrobenzoate using the synthesis system of Example 1 include:

[0032] (1) Add 3-methyl-2-nitrobenzoic acid, sulfuric acid and excess methanol into the reactor 1 through the feed port, and seal the feed port;

[0033] (2) Turn on the stirring device in the reactor 1 and the heating device outside the reactor 1, stir and heat the solution in the reactor 1 to a boiling state, and the mixed vapor of methanol and water enters the distillation tower 2 through the azeotropic tube 11;

[0034] (3) Methanol is added to the reboiler 21, and the heating device outside the reboiler 21 is turned on to heat the reboiler 21. The water vapor in the mixed steam condenses into liquid in the distillation tower 2 and falls to the bottom of the distillation tower 2 and is discharged through the drain port; the methanol vapor enters the condenser 3 from the top of the distillation tower 2, and under the action of the condenser 3, the methanol vapor condenses into liquid and enters the receiving tank 4;

[0035] (4) A portion of the methanol in the receiving tank 4 is refluxed to the reactor 1 through the first reflux pipe 41 to keep the liquid level in the reactor 1 basically stable; another portion of the methanol is refluxed to the distillation tower 2 through the second reflux pipe 42 to replenish the methanol in the reboiler 21; when the amount of methanol entering the receiving tank 4 is too much, the discharge valve on the receiving tank 4 is opened to discharge a portion of the methanol to maintain a stable pressure in the synthesis system;

[0036] (5) After the reactor 1 has reacted for a period of time, the product pump is turned on to transfer the material in the reactor 1 into the cooling kettle 5 for cooling;

[0037] (6) The cooled material is sent to the centrifuge 6 for centrifugation. The solid product obtained by centrifugation is sent to the washing device 7 through the solid outlet, and is eluted with anhydrous methanol to obtain a qualified 3-methyl-2-nitrobenzoic acid methyl ester product. The waste liquid generated by the elution is sent to the mother liquid tank 8 through the waste liquid outlet and the waste liquid pipeline; the liquid obtained by centrifugation is sent to the mother liquid tank 8 through the liquid outlet;

[0038] (7) Turn on the mother liquid pump and transport the liquid in the mother liquid tank 8 back to the reactor 1 through the mother liquid pipeline 81. Then, add 3-methyl-2-nitrobenzoic acid into the reactor 1 through the feed port, and seal the feed port.

[0039] (8) Repeat steps (2) to (7) to continue synthesizing methyl 3-methyl-2-nitrobenzoate.

[0040] Although the present invention has been described in detail with reference to the accompanying drawings and in conjunction with preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, persons of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall fall within the scope of the present invention. Any changes or substitutions that can be easily conceived by persons skilled in the art within the technical scope disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A synthesis system for methyl 3-methyl-2-nitrobenzoate, comprising a reactor, characterized in that: A sealable feed port is provided on the top of the reactor; an azeotropic tube is connected to the top of the reactor, which is connected to a distillation tower; a drain port is provided at the bottom of the distillation tower, which is connected to a reboiler; the distillation tower is sequentially connected to a condenser and a receiving tank, which is connected to the reactor via a first reflux pipe, and the receiving tank is connected to the distillation tower via a second reflux pipe; The reactor is connected to the cooling kettle and the centrifuge in sequence. The solid outlet of the centrifuge is connected to the washing device. The liquid outlet of the centrifuge is connected to the mother liquid tank. The mother liquid tank is connected to the reactor through a mother liquid pipeline. A mother liquid pump is provided on the mother liquid pipeline.

2. The synthesis system according to claim 1, wherein: The reactor and the reboiler are respectively provided with heating devices outside.

3. The synthesis system according to claim 1, wherein: The first return pipe is provided with a first flow valve, and the second return pipe is provided with a second flow valve.

4. The synthesis system according to claim 1, wherein: The receiving tank is provided with a discharge valve.

5. The synthesis system according to claim 1, wherein: The reaction kettle is connected to the cooling kettle through a product pipeline, and a product pump is provided on the product pipeline.

6. The synthesis system according to claim 1, wherein: The reaction kettle and the cooling kettle are respectively provided with stirring devices.

7. The synthesis system according to claim 1, wherein: The washing device is provided with a waste liquid outlet, which is connected to the mother liquid tank through a waste liquid pipeline.

8. The synthesis system according to claim 1, wherein: The materials of the reactor, receiving tank and mother liquid tank are acid-resistant alloy; the material of the condenser is selected from glass lining, glass, graphite or silicon carbide; the material of the reboiler is selected from acid-resistant alloy, glass lining, ceramic, glass, steel-lined PTFE tube, graphite, silicon carbide or fiberglass reinforced plastic.

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