Continuous preparation method of herbicide intermediate 2-chloronicotinoyl chloride
By continuously preparing 2-chloronicotinic chloride by controlling the temperature and pressure in the microchannel reactor, the problems of uneven stirring and low heat transfer efficiency in the batch preparation method are solved, and efficient and safe 2-chlorotinic acid smoke are achieved. Acid chloride production.
Patent Information
- Application Number
- CN202411326829.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2025-01-10
AI Technical Summary
In the prior art, the batch preparation method of 2-chloronicotinic chloride has problems such as uneven stirring, low heat transfer efficiency, long reaction time, large power consumption, and poor production capacity and quality.
The continuous preparation method is carried out by a microchannel reactor. By controlling the temperature, flow rate and pressure, 2-chloronic acid and chlorinated reagent are carried out in the microchannel to obtain 2-chloronic acid chloride, which adopts a modular structure. The microchannel reactor, including unit pumps, temperature control modules and backpressure modules, uses specific pipeline materials, with reaction conditions of 25-60℃, 0.1-60mL/min flow rate and 0-5Mpa pressure.
It realizes continuous production with simple operation, short reaction time, small amount of chlorinated reagents, high heat transfer efficiency, high conversion rate, good safety and low energy consumption, and improves production capacity and product purity.
Smart Images
Figure CN119285539A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a continuous preparation method of a herbicide intermediate 2-chloronicotinyl chloride. Background Art
[0002] 2-Chloronicotinyl chloride is an important intermediate for the synthesis of the herbicide nicosulfuron. The current method for preparing 2-chloronicotinyl chloride is to directly synthesize it by acyl chlorination reaction of 2-chloronicotinic acid and a chlorination reagent. Its synthesis method generally adopts an intermittent method of a kettle reactor. The intermittent stirring reactor structure causes uneven material stirring, low heat transfer efficiency, long reaction time, high power consumption, reduced product production capacity, and poor quality assurance. Summary of the invention
[0003] In view of the shortcomings of the prior art, the present invention provides a continuous preparation method of 2-chloronicotinyl chloride, an intermediate of a herbicide: after 2-chloronicotinic acid, a solvent and a chlorination agent pass through a microchannel reactor, 2-chloronicotinyl chloride is continuously obtained from the discharge port of the microchannel reactor by controlling a certain temperature, flow rate and pressure, and the product is obtained by post-processing. This continuous preparation method is simple to operate, short in reaction time, uses less chlorination agent, has good safety, can improve heat transfer efficiency and production capacity, and can also achieve continuous production and reduce energy consumption.
[0004] A continuous preparation method for a herbicide intermediate 2-chloronicotinyl chloride comprises the following steps: continuously feeding 2-chloronicotinic acid and a chlorination agent at a molar ratio of 1:1.1-2, continuously feeding through a feed port of a microchannel reactor at a temperature of 25-60°C, and continuously obtaining 2-chloronicotinyl chloride from a discharge port of the microchannel reactor after an acyl chlorination reaction occurs in a pipeline.
[0005]
[0006] in, The solvent for the chlorination reaction is one of dichloromethane, dichloroethane, chloroform, carbon tetrachloride, cyclohexane, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, methyl tert-butyl ether, 1,4-dioxane, N-methylpyrrolidone and ethyl acetate.
[0007] The chlorination agent is one of thionyl chloride, phosphorus trichloride, phosphorus tribromide, phosphorus pentachloride and phosphorus pentabromide.
[0008] The molar ratio of the 2-chloronicotinic acid to the chlorination agent is 1:1.1-2.0.
[0009] The temperature is 25~60°C.
[0010] The flow rate is 0.1~60mL / min.
[0011] The pressure is 0~5Mpa.
[0012] The microchannel reactor adopts a modular structure, and the reactor consists of a unit pump, a temperature control module, a pipeline module and a back pressure module; the maximum pressure of the unit pump of the microchannel reactor is 20Mpa; the temperature range of the temperature control module is -20~300℃; the pressure adjustment range of the back pressure module is 0-100Mpa; the total volume of the microchannel reactor is 120~1200mL; the microchannel reactor is composed of one or more reactor modules connected in series or in parallel; the pipeline material is Teflon, tetrafluoro, Hastelloy, polyvinyl chloride, 304, 316, and glass.
[0013] The continuous flow reactor is a three-phase microchannel reactor.
[0014] The invention adopts a continuous method to prepare the intermediate 2-chloronicotinoyl chloride of the herbicide nicosulfuron. Compared with the existing intermittent preparation method, the invention has the advantages of simple operation, small amount of chlorination reagent, short reaction time, high heat transfer efficiency, high conversion rate, good safety, continuous production and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 This is the liquid phase diagram of Example 1.
[0016] Figure 2 This is the liquid phase diagram of Example 2.
[0017] Figure 3 This is the liquid phase diagram of Example 3.
[0018] Figure 4 This is the liquid phase diagram of Example 4.
[0019] Figure 5 This is the liquid phase diagram of Example 5.
[0020] Figure 6 This is the liquid phase diagram of Example 6.
[0021] Figure 7 This is the liquid phase diagram of Example 7.
[0022] Figure 8 This is the liquid phase diagram of Example 8.
[0023] Fig. 9 This is the liquid phase diagram of Comparative Example 1. DETAILED DESCRIPTION
[0024] Example 1 150 g of 2-chloronicotinic acid, 124 g of thionyl chloride and 220 g of ethylene dichloride were mixed and flowed in a microchannel reactor at 3 mL / min, 55°C and 1.0 MPa, and a 2-chloronicotinyl chloride solution was continuously obtained from the outlet of the back pressure valve. The reaction solution was concentrated under normal pressure to obtain 2-chloronicotinyl chloride. Based on the reacted 2-chloronicotinic acid, the yield of 2-chloronicotinyl chloride was 98.5%, and the product purity was 98.81%.
[0025] Example 2 150 g of 2-chloronicotinic acid, 124 g of thionyl chloride and 220 g of ethylene dichloride were mixed and flowed in a microchannel reactor at 3 mL / min, 40°C and 1.0 MPa, and a 2-chloronicotinyl chloride solution was continuously obtained from the outlet of the back pressure valve. The reaction solution was concentrated under normal pressure to obtain 2-chloronicotinyl chloride. Based on the reacted 2-chloronicotinic acid, the yield of 2-chloronicotinyl chloride was 97.47%, and the product purity was 98.95%.
[0026] Example 3 150 g of 2-chloronicotinic acid, 124 g of thionyl chloride and 220 g of ethylene dichloride were mixed and flowed in a microchannel reactor at 5 mL / min, 45°C and 1.0 MPa, and a 2-chloronicotinyl chloride solution was continuously obtained from the outlet of the back pressure valve. The reaction solution was concentrated under normal pressure to obtain 2-chloronicotinyl chloride. Based on the reacted 2-chloronicotinic acid, the yield of 2-chloronicotinyl chloride was 97.26%, and the product purity was 99.41%.
[0027] Example 4 150 g of 2-chloronicotinic acid, 124 g of thionyl chloride and 220 g of ethylene dichloride were mixed and flowed in a microchannel reactor at 8 mL / min, 40°C and 2.0 MPa, and a 2-chloronicotinyl chloride solution was continuously obtained from the outlet of the back pressure valve. The reaction solution was concentrated under normal pressure to obtain 2-chloronicotinyl chloride. Based on the reacted 2-chloronicotinic acid, the yield of 2-chloronicotinyl chloride was 98.58%, and the product purity was 97.83%.
[0028] Example 5 150 g of 2-chloronicotinic acid, 124 g of thionyl chloride and 220 g of ethylene dichloride were mixed and flowed in a microchannel reactor at 10 mL / min, 25°C and 5.0 MPa, and a 2-chloronicotinyl chloride solution was continuously obtained from the outlet of the back pressure valve. The reaction solution was concentrated under normal pressure to obtain 2-chloronicotinyl chloride. Based on the reacted 2-chloronicotinic acid, the yield of 2-chloronicotinyl chloride was 98.03%, and the product purity was 98.71%.
[0029] Example 6 150 g of 2-chloronicotinic acid, 124 g of thionyl chloride and 220 g of ethylene dichloride were mixed and flowed in a microchannel reactor at 15 mL / min, 25°C and 5.0 MPa, and a 2-chloronicotinyl chloride solution was continuously obtained from the outlet of the back pressure valve. The reaction solution was concentrated under normal pressure to obtain 2-chloronicotinyl chloride. Based on the reacted 2-chloronicotinic acid, the yield of 2-chloronicotinyl chloride was 97.79%, and the product purity was 98.75%.
[0030] Example 7 150 g of 2-chloronicotinic acid, 124 g of thionyl chloride and 220 g of ethylene dichloride were mixed and flowed in a microchannel reactor at 25 mL / min, 55°C and 3.5 MPa, and a 2-chloronicotinyl chloride solution was continuously obtained from the outlet of the back pressure valve. The reaction solution was concentrated under normal pressure to obtain 2-chloronicotinyl chloride. Based on the reacted 2-chloronicotinic acid, the yield of 2-chloronicotinyl chloride was 96.81%, and the product purity was 99.87%.
[0031] Example 8 150 g of 2-chloronicotinic acid, 124 g of thionyl chloride and 220 g of ethylene dichloride were mixed and flowed in a microchannel reactor at 30 mL / min, 25°C and 5 MPa, and a 2-chloronicotinyl chloride solution was continuously obtained from the outlet of the back pressure valve. The reaction solution was concentrated under normal pressure to obtain 2-chloronicotinyl chloride. Based on the reacted 2-chloronicotinic acid, the yield of 2-chloronicotinyl chloride was 98.70%, and the product purity was 97.40%.
[0032] Comparative Example 1 150 g of 2-chloronicotinic acid, 124 g of thionyl chloride and 220 g of ethylene dichloride were mixed and reacted in a reactor at 85° C. for 5 hours. The yield of 2-chloronicotinyl chloride was 81.6% based on the reacted 2-chloronicotinic acid, and the product purity was 79.68%.
Claims
1. A continuous preparation method of 2-chloronicotinyl chloride, a herbicide intermediate, characterized in that: The steps include: 2-Chloronicotinic acid and a chlorination agent are dissolved in an organic solvent respectively as raw material liquids, the two raw material liquids are fully mixed through a microchannel premixer, and then enter a microchannel reactor, where an acyl chlorination reaction occurs in the pipeline, and the reaction liquid continuously obtains a 2-chloronicotinic acid chloride solution through a back pressure valve outlet.
2. The continuous preparation method of the herbicide intermediate 2-chloronicotinyl chloride according to claim 1, characterized in that: The molar ratio of 2-chloronicotinic acid to the chlorination agent is 1:1.1-2; the chlorination agent is one of thionyl chloride, phosphorus trichloride, phosphorus tribromide, phosphorus pentachloride and phosphorus pentabromide.
3. The continuous preparation method of the herbicide intermediate 2-chloronicotinyl chloride according to claim 1, characterized in that: The organic solvent is any one of dichloromethane, dichloroethane, chloroform, carbon tetrachloride, cyclohexane, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, methyl tert-butyl ether, 1,4-dioxane, N-methylpyrrolidone and ethyl acetate.
4. The continuous preparation method of the herbicide intermediate 2-chloronicotinyl chloride according to claim 1, characterized in that: After being mixed in the premixer, the mixture enters the microchannel reactor at a rate of 0.1-60 mL / min for reaction at a temperature of 25-60° C. At the same time, the pressure in the microchannel reactor is controlled at 1-5 MPa by a back pressure valve.
5. The continuous preparation method of the herbicide intermediate 2-chloronicotinyl chloride according to claim 1, characterized in that: In order to promote the reaction to proceed fully, a second microchannel reactor is set after the microchannel reactor. The reaction materials enter the second microchannel reactor from the previous microchannel reactor, and the temperature in the second microchannel reactor is 10-20°C higher than that of the previous microchannel reactor.
6. The continuous preparation method of the herbicide intermediate 2-chloronicotinyl chloride according to claim 1, characterized in that: The pipeline material of the microchannel reactor is any one of Teflon, tetrafluoroethylene, Hastelloy, polyvinyl chloride, 304, 316, and glass.