A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide

Abstract

The invention belongs to the field of chemical synthesis, and particularly relates to a continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide. The method comprises the following steps: first preparing 2-mercapto-N,N-dimethylnicotinamide, then adding water and hydrochloric acid to the system, filtering out most of sulfur, passing hydrogen chloride, adding activated carbon, removing the remaining sulfur, and obtaining an aqueous solution of 2-mercapto-N,N-dimethylnicotinamide; then feeding an organic solvent and chlorine into a chlorine-passing tubular reactor, and starting to feed the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide into the chlorine-passing tubular reactor after the pressure is stabilized, and after the reaction, the feed liquid enters a layering and liquid separation tank to separate an organic phase and an aqueous phase, and the gas enters a chlorine recovery tank, and the organic phase enters an ammonia-passing tubular reactor, and the material at the outlet of the ammonia-passing tubular reactor enters an acidifying kettle, and after adjusting the pH value with hydrochloric acid, filtering and washing with water are performed to obtain 2-aminosulfonyl-N,N-dimethylnicotinamide.

Description

Technical Field

[0001] The invention belongs to the field of chemical synthesis, and specifically relates to a continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide. Background Art

[0002] 2-Aminosulfonyl-N,N-dimethylnicotinamide is an important intermediate of Nicosulfuron technical, wherein the oxidation of 2-mercapto-N,N-dimethylnicotinamide to 2-chlorosulfonyl-N,N-dimethylnicotinamide by chlorine or sodium hypochlorite solution is the bottleneck of the whole process, especially in industrial production. In this step, the raw material 2-mercapto-N,N-dimethylnicotinamide (I) mainly generates the intermediate state (II) and a small amount of (III) and (IV) during the process of passing chlorine. When chlorine is continuously passed, the intermediate state of the above reaction is further oxidized to 2-chlorosulfonyl-N,N-dimethylnicotinamide. For the intermediate states (III) and (IV), when 2-chlorosulfonyl-N,N-dimethylnicotinamide is generated, the intermediate state (II) and a small amount of (III) and (IV) are further oxidized to 2-chlorosulfonyl-N,N-dimethylnicotinamide. -dimethylnicotinamide, sulfuric acid is generated. 2-Chlorosulfonyl-N,N-dimethylnicotinamide, as a compound with poor stability, reacts with water to generate sulfonic acid. The presence of sulfuric acid accelerates the hydrolysis of 2-chlorosulfonyl-N,N-dimethylnicotinamide. At the same time, excessive chlorine will allow 2-chlorosulfonyl-N,N-dimethylnicotinamide to further remove sulfur dioxide to obtain N,N-dimethyl-2-chloronicotinamide. From the above analysis, it can be seen that in the case of insufficient chlorine, the reaction stays in the intermediate state. Excessive chlorine or excessive local concentration will promote the decomposition of 2-chlorosulfonyl-N,N-dimethylnicotinamide to release sulfur dioxide to obtain the by-product N,N-dimethyl-2-chloronicotinamide. Since 2-mercapto-N,N-dimethylnicotinamide and chlorine are difficult to dissolve in organic solvents, the system requires a mixed solvent system of organic solvents and water. The reaction is exothermic, and high temperature accelerates the hydrolysis of 2-chlorosulfonyl-N,N-dimethylnicotinamide. Therefore, the hydrolysis of 2-chlorosulfonyl-N,N-dimethylnicotinamide becomes more serious as the reaction system is enlarged. Although there are literature reports that the yield of this step can reach more than 95%, the actual yield of this step in the production of Nicosulfuron technical is 70-80%. Therefore, this step reaction is an important breakthrough point for improving the economic benefits of Nicosulfuron.

[0003] The production reaction of 2-aminosulfonyl-N,N-dimethylnicotinamide is as follows:

[0004] Summary of the invention

[0005] In view of the many problems existing in the above-mentioned technologies, the present invention provides a continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, which effectively reduces the generation of sulfuric acid, and uses a tubular reactor to alleviate the hydrolysis of 2-chlorosulfonyl-N,N-dimethylnicotinamide, and the reaction cycle is significantly shortened.

[0006] The technical solution of the present invention is as follows:

[0007] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific preparation method is as follows:

[0008] (1) 2-chloro-N,N-dimethylnicotinamide, sodium sulfide, elemental sulfur and water are reacted to prepare 2-mercapto-N,N-dimethylnicotinamide;

[0009] (2) After the reaction is completed, water is added to the system and the pH of the system is adjusted to 2.5-3.5 with hydrochloric acid, and the system is stirred at 70-80°C. Most of the sulfur is filtered out while hot, and hydrogen chloride is slowly introduced into the system to increase the acidity of the system while the system is kept below 35°C, until the supernatant of the system gradually changes from reddish brown to light yellow, activated carbon is added, and after decolorization, an aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is obtained by filtration; most of the sulfur is filtered out for the first time, and then the sulfur is forced out by increasing the acidity of the system with hydrogen chloride gas, and activated carbon is added. The remaining sulfur is filtered out for the second time. If the two filtrations are combined into one, the sulfur filtered out will be sticky due to the high acidity and will not be easy to filter. However, the sulfur is less in the second time, the pH is lower, the sulfur is sticky, and a larger amount of activated carbon is added, which will not affect the filtration;

[0010] (3) Setting the temperature of the cooling medium of each section of the chlorine-passing tubular reactor to -15--5°C, starting to feed the organic solvent and chlorine into the chlorine-passing tubular reactor, controlling the pressure of the chlorine-passing tubular reactor to 0.05-0.1 MPa, and starting to feed the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide into the chlorine-passing tubular reactor after the pressure is stabilized, and controlling the reaction temperature of the chlorine-passing tubular reactor to -5-5°C by controlling the feeding rate of the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide and the relative gas flow rate of each point of chlorine. After the reaction, the feed liquid enters the stratification and liquid separation tank to separate the organic phase and the aqueous phase, the gas enters the chlorine recovery tank, and the organic phase enters the ammonia-passing tubular reactor. By adjusting the ammonia ventilation rate, the pH of the material at the discharge port is maintained at 8-10. The material at the outlet of the ammonia-passing tubular reactor enters the acidification kettle, and after adjusting the pH to 4-6 with hydrochloric acid, the temperature is maintained at 0-5°C for filtration, and 2-aminosulfonyl-N,N-dimethylnicotinamide is obtained by washing with water.

[0011] The pressure of the chlorine-passing tubular reactor is 0.05-0.1MPa. The pressure is controlled to make the solubility of chlorine higher. Too much pressure will affect the stability of the feed, especially the stability of the chlorine feed. The pH of the outlet of the ammonia-passing tubular reactor is 8-10. If the pH is too low, the reaction is not complete. If it is too high, it will need to be neutralized with hydrochloric acid, which is wasteful and the nitrogen in the wastewater exceeds the standard. The acidification end point pH of the acidification kettle is 4-6. If the pH is too high, the ammonia is not neutralized cleanly and the product has a strong odor. If the pH is too low, the product color will turn yellow. In addition, there will be pH index requirements for external sales, which are basically weak acid, weak base or neutral. If the pH is unqualified, it needs to be washed with water, which affects the yield.

[0012] Preferably, the molar ratio of sodium sulfide, elemental sulfur and 2-chloro-N,N-dimethylnicotinamide is 0.6-0.7:1.0-1.1:1, and the mass ratio of water to 2-chloro-N,N-dimethylnicotinamide is 0.3-0.5:1.

[0013] Preferably, in step (1), the reaction temperature is 125-135° C. and the reaction time is 3-5 h.

[0014] Preferably, in step (2), water in an amount of 4-6 times the mass of 2-chloro-N,N-dimethylnicotinamide is added, and the stirring time is 0.5-1.5 h; activated carbon in an amount of 2-5% of the mass of 2-chloro-N,N-dimethylnicotinamide is added, the decolorization temperature is 30-35° C., and the decolorization time is 0.5-1.5 h.

[0015] Preferably, the mass ratio of the amount of the organic solvent used in step (3) to the 2-mercapto-N,N-dimethylnicotinamide aqueous solution is 0.4-0.8:1, and the organic solvent is one of dichloroethane and dichloromethane. Further preferably, the mass ratio of the amount of the organic solvent used in step (3) to the 2-mercapto-N,N-dimethylnicotinamide aqueous solution is 0.5-0.6:1.

[0016] Preferably, in step (3), the molar ratio of chlorine gas to 2-mercapto-N,N-dimethylnicotinamide is 2.9-3.5: 1. Further preferably, in step (3), the molar ratio of chlorine gas to 2-mercapto-N,N-dimethylnicotinamide is 3.2-3.3: 1.

[0017] Preferably, the reaction temperature of the chlorine gas tubular reactor in step (3) is -2-2°C. Too high a temperature will produce more impurities, while too low a temperature will result in high energy consumption and the risk of mercapto crystals precipitating and clogging the pipeline.

[0018] Preferably, three chlorine feeding points are arranged on the chlorine-passing tubular reactor, and the pre-feeding temperature of the chlorine-passing tubular reactor is set to be below -10°C.

[0019] The invention uses 2-chloro-N, N-dimethylnicotinamide, sodium sulfide and elemental sulfur as raw materials to react and prepare 2-mercapto-N, N-dimethylnicotinamide. After the reaction is completed, water is added to the system, and the pH value of the system is adjusted with hydrochloric acid to maintain the temperature and stir. The sulfur is filtered out while hot. The system temperature is maintained and hydrochloric acid gas is slowly introduced to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changes from reddish brown to light yellow. Activated carbon is added, and the 2-mercapto-N, N-dimethylnicotinamide aqueous solution is obtained by filtering after decolorization. The temperature of the cooling medium of each section of the tubular reactor is set, chlorine gas and an organic solvent are introduced into the chlorine-passing tubular reactor, and the chlorine-passing tubular reactor is controlled. The reaction vessel pressure is increased, and the aqueous solution of 2-mercapto-N, N-dimethylnicotinamide is fed after the pressure is stabilized. The reaction temperature of the chlorine-passing tubular reactor is controlled by controlling the feeding speed of the aqueous solution of 2-mercapto-N, N-dimethylnicotinamide and the relative gas flow rate of each point of chlorine. After the reaction, the feed liquid enters the stratification and liquid separation tank to separate the organic phase and the aqueous phase. The gas enters the chlorine recovery tank, and the organic phase enters the ammonia-passing tubular reactor. The pH value of the material at the discharge port is controlled by adjusting the ammonia ventilation rate. The material at the outlet of the ammonia-passing tubular reactor enters the acidification kettle, and after adjusting the pH value with hydrochloric acid, it is filtered and washed with water to obtain 2-aminosulfonyl-N, N-dimethylnicotinamide.

[0020] The invention solves the problem of hydrolysis or decomposition of 2-chlorosulfonyl-N,N-dimethylnicotinamide from two aspects. Firstly, pH is adjusted, most of sulfur is filtered out while hot, hydrochloric acid gas is introduced into a 2-mercapto-N,N-dimethylnicotinamide solution, excess sulfur in the 2-mercapto-N,N-dimethylnicotinamide is forced out, and the sulfur is removed by decolorization with activated carbon. By removing sulfur twice, the generation of sulfuric acid in the chlorine gas passing process is reduced; then, a continuous reaction device is used to pass a chlorine tubular reactor to shorten the contact time of 2-chlorosulfonyl-N,N-dimethylnicotinamide with chlorine and water, and the hydrolysis and decomposition of 2-chlorosulfonyl-N,N-dimethylnicotinamide are alleviated; finally, a continuous production device is used to pass an ammonia tubular reactor in the ammoniation stage to realize a mode in which 2-chlorosulfonyl-N,N-dimethylnicotinamide is produced and consumed at the same time. When tubular reactors are applied to production, the amplification effect is far lower than that of kettle reactors, which significantly improves the reaction efficiency of this step. By operating two tubular reactors in parallel, namely a chlorine-passing tubular reactor and an ammonia-passing tubular reactor, the annual production capacity demand of 1,000 tons of 2-aminosulfonyl-N,N-dimethylnicotinamide can be met.

[0021] In summary, the beneficial effects of the present invention are:

[0022] (1) By removing sulfur twice, the generation of sulfuric acid during the chlorine gas flow is reduced, and the hydrolysis of 2-chlorosulfonyl-N,N-dimethylnicotinamide is alleviated;

[0023] (2) Using a chlorine-passing tubular reactor instead of a kettle reactor, and achieving multi-point reaction and multi-point heat release by introducing chlorine at multiple points, effectively alleviating local overheating and effectively alleviating the hydrolysis of 2-chlorosulfonyl-N,N-dimethylnicotinamide;

[0024] (3) Using a chlorine-passing tubular reactor, by adjusting the concentration of the 2-mercapto-N,N-dimethylnicotinamide solution, the chlorine ratio at each site, the system pressure and other measures, 2-chlorosulfonyl-N,N-dimethylnicotinamide can be effectively prevented from contacting with excess chlorine, thereby promoting its decomposition;

[0025] (4) When using a kettle reactor, in order to alleviate the situation of local chlorine over-concentration and over-temperature, it is necessary to control the speed of chlorine flow. This process takes 4-6 hours. The use of a chlorine-flowing tubular reactor greatly shortens the residence time of 2-chlorosulfonyl-N,N-dimethylnicotinamide in the system to less than 30 seconds. Therefore, the hydrolysis and decomposition problems of 2-chlorosulfonyl-N,N-dimethylnicotinamide are alleviated again. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure is the product of the chlorine-passing reaction of Comparative Example 1;

[0027] Figure 2 The spectrum of the product of Comparative Example 1 after passing ammonia;

[0028] Figure 3 The spectrum of the chlorine gas reaction product of Example 1;

[0029] Figure 4 This is the spectrum of the product after passing ammonia in Example 1. DETAILED DESCRIPTION

[0030] The following is a further detailed description of the above contents of the present invention through specific implementation methods in the form of embodiments, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies implemented based on the above contents of the present invention belong to the scope of the present invention, and unless otherwise specified, the following embodiments are all completed using conventional existing technologies.

[0031] The chlorine-passing tubular reactor and the ammonia-passing tubular reactor described below may be tubular reactors available in the prior art, and the basic parameters that may be specifically selected are: a tube diameter of 2.5 cm, a length of each tube of 10 m, a chlorine feed interface being provided at the initial position of the tube diameter; and a mass fraction of the sodium sulfide described below being 60%.

[0032] Example 1

[0033] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific steps of which are:

[0034] 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur and 200kg of water were reacted at 125℃ for 3h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction was completed, 2000kg of water was added to the system and the pH of the system was adjusted to 2.5-3.5 with 600kg of hydrochloric acid. The system was stirred at 70℃ for 1h, and the sulfur was filtered out while hot. 20kg of hydrochloric acid gas (hydrogen chloride) was slowly introduced into the system to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changed from reddish brown to brown. The mixture was turned to light yellow, 20 kg of activated carbon was added, and the mixture was decolorized at 30 ° C for 1 hour, and then filtered to obtain an aqueous solution of 2-mercapto-N, N-dimethylnicotinamide; the concentration of the aqueous solution of 2-mercapto-N, N-dimethylnicotinamide (mass concentration) was detected to be 10.8%, and the temperature of the cooling medium in each section of the chlorine-passing tubular reactor was set to -5 ° C. First, the discharge valve of the chlorine-passing tubular reactor, the inlet and outlet valves of the stratified liquid separation tank, and the inlet and outlet valves of the ammonia-passing tubular reactor were opened. When the temperature of the first pipeline at the feed end of the chlorine-passing tubular reactor dropped to below -10 ° C (i.e., the chlorine-passing pipe) After the temperature in the reactor is controlled below -10°C), the feed valve of the chlorine-passing tubular reactor is opened to start feeding dichloromethane and chlorine. The flow rate of dichloromethane is 160kg / h, and the flow rate of the chlorine total valve is 51.0kg / h. The pressure of the chlorine-passing tubular reactor is adjusted to 0.05±0.005MPa. After the pressure is stable, the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is fed at a flow rate of 400kg / h. By controlling the relative gas flow rate of each chlorine feeding point, the reaction temperature of each section of the chlorine-passing tubular reactor is controlled at -2-2°C. After the reaction, the feed liquid enters the stratification and liquid separation tank to separate the organic phase and the aqueous phase, the gas enters the chlorine recovery tank, and the organic phase enters the ammonia gas pipe reactor. By adjusting the ammonia gas flow rate, the pH of the material at the outlet is maintained at 8-8.5. The material at the outlet of the ammonia gas pipe reactor enters the acidification kettle. After accumulating a certain amount, hydrochloric acid is used to adjust the pH to 4-4.5, and the temperature is maintained at 0°C for filtration. After washing with 300kg of water, 2-aminosulfonyl-N,N-dimethylnicotinamide is obtained. The mass after drying is 512kg, the content is 98.0%, and the yield of the two steps of chlorine and ammonia is 92.5%.

[0035] Example 2

[0036] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific steps of which are:

[0037] 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur and 200kg of water were reacted at 135℃ for 3h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction was completed, 3000kg of water was added to the system and the pH of the system was adjusted to 2.5-3.5 with 600kg of hydrochloric acid. The system was stirred at 80℃ for 1h, and the sulfur was filtered out while hot. 20kg of hydrochloric acid gas was slowly introduced into the system to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changed from reddish brown to Light yellow, add 20kg of activated carbon, decolorize at 35℃ for 1h, and then filter to obtain an aqueous solution of 2-mercapto-N,N-dimethylnicotinamide; detect the concentration of the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide to be 8.5%, set the temperature of the cooling medium in each section of the chlorine tubular reactor to -8℃, first open the discharge valve of the chlorine tubular reactor, the inlet and outlet valves of the stratified liquid separation tank, and the inlet and outlet valves of the ammonia tubular reactor, and open the feed valve of the chlorine tubular reactor after the temperature of the first pipeline at the feed end of the chlorine tubular reactor drops below -10℃ (The chlorine-passing tubular reactor is provided with three chlorine feeding points, and feeding valves are provided at the chlorine feeding points), dichloromethane and chlorine are started to be fed, the flow rate of dichloroethane is 250kg / h, the flow rate of the chlorine total valve is 53kg / h, the pressure of the tubular reactor is adjusted to 0.06±0.005MPa, and after the pressure is stabilized, the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is started to be fed, and the flow rate is 500kg / h. By controlling the relative gas flow rate of each chlorine feeding point, the reaction temperature of each section of the chlorine-passing tubular reactor is controlled at -3-1°C, and the reaction is The liquid after reaction enters a stratification and liquid separation tank to separate the organic phase and the aqueous phase, the gas enters a chlorine recovery tank, the organic phase enters an ammonia gas pipe reactor, the pH of the material at the outlet is maintained at 8-8.5 by adjusting the ammonia gas flow rate, the material at the outlet of the ammonia gas pipe reactor enters an acidification kettle, after a certain amount is accumulated, the pH is adjusted to 4.5-5 with hydrochloric acid, the temperature is maintained at 2°C, and 2-aminosulfonyl-N,N-dimethylnicotinamide is obtained by washing with 300kg of water. The mass after drying is 508kg, the content is 97.8%, and the yield of the two steps of chlorine and ammonia is 92.6%.

[0038] Example 3

[0039] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific steps of which are:

[0040] 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur, and 200kg of water were reacted at 130℃ for 4h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction was completed, 2500kg of water was added to the system and the pH of the system was adjusted to 2.5-3.5 with about 600kg of hydrochloric acid. The system was stirred at 85℃ for 1h, and the sulfur was filtered out while hot. 20kg of hydrochloric acid gas was slowly introduced into the system to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changed from reddish brown to brown. to light yellow, add 20 kg of activated carbon, decolorize at 30°C for 1 hour, and then filter to obtain an aqueous solution of 2-mercapto-N,N-dimethylnicotinamide; the concentration of the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is detected to be 9.6%, and the temperature of the cooling medium in each section of the chlorine-passing tubular reactor is set to -12°C. First, open the discharge valve of the chlorine-passing tubular reactor, the inlet and outlet valves of the stratified liquid separation tank, and the inlet and outlet valves of the ammonia-passing tubular reactor. After the temperature of the first pipeline at the feed end of the chlorine-passing tubular reactor drops below -10°C, open the feed valve of the chlorine-passing tubular reactor The chlorine gas tubular reactor was set with three chlorine feeding points, and feeding valves were set at the chlorine feeding points. Dichloromethane and chlorine were fed in. The flow rate of dichloromethane was 225 kg / h, and the flow rate of the chlorine total valve was 57 kg / h. The pressure of the tubular reactor was adjusted to 0.08±0.005 MPa. After the pressure was stable, an aqueous solution of 2-mercapto-N,N-dimethylnicotinamide was fed in. The flow rate was 450 kg / h. The reaction temperature of each section of the chlorine gas tubular reactor was controlled at -4-0°C by controlling the relative gas flow rate of each chlorine feeding point. After the reaction, the feed liquid enters a layer separation tank to separate the organic phase and the aqueous phase, the gas enters a chlorine recovery tank, and the organic phase enters an ammonia gas pipe reactor. The pH of the material at the outlet is maintained at 8-8.5 by adjusting the ammonia gas flow rate. The material at the outlet of the ammonia gas pipe reactor enters an acidification kettle. After a certain amount of accumulation, the pH is adjusted to 4.5-5 with hydrochloric acid, and the temperature is maintained at 5° C. Filtering, washing with 300 kg of water to obtain 2-aminosulfonyl-N, N-dimethylnicotinamide, which has a mass of 522 kg after drying, a content of 97.9%, and a two-step yield of chlorine and ammonia is 94.2%.

[0041] Example 4

[0042] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific steps of which are:

[0043] 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur, and 200kg of water were reacted at 130℃ for 3h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction was completed, 3000kg of water was added to the system and the pH of the system was adjusted to 2.5-3.5 with about 600kg of hydrochloric acid. The system was stirred at 85℃ for 1h, and the sulfur was filtered out while hot. The system was kept below 35℃ and 20kg of hydrochloric acid gas was slowly introduced to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changed from reddish brown to brown. to light yellow, add 20 kg of activated carbon, decolorize at 32 ° C for 1 hour, and then filter to obtain an aqueous solution of 2-mercapto-N, N-dimethylnicotinamide; the concentration of the aqueous solution of 2-mercapto-N, N-dimethylnicotinamide is detected to be 8.7%, and the temperature of the cooling medium in each section of the chlorine-passing tubular reactor is set to -15 ° C. First, open the discharge valve of the chlorine-passing tubular reactor (the chlorine-passing tubular reactor is provided with three chlorine feeding points, and the chlorine feeding points are all provided with feed valves), the inlet and discharge valves of the stratified liquid separation tank and the inlet and discharge valves of the ammonia-passing tubular reactor, and wait for the chlorine-passing tubular reactor to pass. After the temperature of the first pipeline at the feed end of the reactor drops below -10°C, the feed valve of the chlorine-passing tubular reactor is opened to start feeding dichloromethane and chlorine. The dichloromethane flow rate is 300kg / h, and the chlorine total valve flow rate is 58kg / h. The pressure of the tubular reactor is adjusted to 0.08±0.005MPa. After the pressure stabilizes, the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is fed at a flow rate of 500kg / h. By controlling the relative gas flow rate of each chlorine feeding point, the reaction temperature of each section of the chlorine-passing tubular reactor is controlled at -6--2°C. After the reaction, the feed liquid enters a layer separation tank to separate the organic phase and the aqueous phase, the gas enters a chlorine recovery tank, and the organic phase enters an ammonia gas pipe reactor. The pH of the material at the outlet is maintained at 8-8.5 by adjusting the ammonia gas flow rate. The material at the outlet of the ammonia gas pipe reactor enters an acidification kettle. After a certain amount of accumulation, the pH is adjusted to 4.5-5 with hydrochloric acid, and the temperature is maintained at 3° C. Filtering, washing with 300 kg of water to obtain 2-aminosulfonyl-N, N-dimethylnicotinamide, which has a mass of 530 kg after drying, a content of 98.2%, and a two-step yield of chlorine and ammonia is 95.0%.

[0044] Example 5

[0045] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific steps of which are:

[0046] 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur, and 200kg of water were reacted at 125℃ for 3h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction was completed, 2500kg of water was added to the system and the pH of the system was adjusted to 2.5-3.5 with about 600kg of hydrochloric acid. The system was stirred at 85℃ for 1h, and the sulfur was filtered out while hot. 20kg of hydrochloric acid gas was slowly introduced into the system to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changed from reddish brown to brown. to light yellow, add 20 kg of activated carbon, decolorize at 30 ° C for 1 hour, and then filter to obtain an aqueous solution of 2-mercapto-N, N-dimethylnicotinamide; detect the concentration of the aqueous solution of 2-mercapto-N, N-dimethylnicotinamide to be 9.5%, set the temperature of the cooling medium in each section of the chlorine-passing tubular reactor to -15 ° C, first open the discharge valve of the chlorine-passing tubular reactor (the chlorine-passing tubular reactor is provided with three chlorine feeding points, and the chlorine feeding points are all provided with feed valves), the inlet and discharge valves of the stratified liquid separation tank and the inlet and discharge valves of the ammonia-passing tubular reactor, and wait for the chlorine-passing tubular reactor to pass. After the temperature of the first pipeline at the feed end of the reactor drops below -10°C, the feed valve of the chlorine-passing tubular reactor is opened to start feeding dichloromethane and chlorine. The dichloromethane flow rate is 315kg / h, and the chlorine total valve flow rate is 62kg / h. The pressure of the tubular reactor is adjusted to 0.10±0.005MPa. After the pressure stabilizes, the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is fed at a flow rate of 450kg / h. By controlling the relative gas flow rate of each chlorine feeding point, the reaction temperature of each section of the chlorine-passing tubular reactor is controlled at -6--2°C. After the reaction, the feed liquid enters a layer separation tank to separate the organic phase and the aqueous phase, the gas enters a chlorine recovery tank, and the organic phase enters an ammonia gas pipe reactor. The pH of the material at the outlet is maintained at 8.5-9 by adjusting the ammonia gas flow rate. The material at the outlet of the ammonia gas pipe reactor enters an acidification kettle. After a certain amount of accumulation, the pH is adjusted to 5-5.5 with hydrochloric acid, and the temperature is maintained at 0°C for filtration. After washing with 300kg of water, 2-aminosulfonyl-N,N-dimethylnicotinamide is obtained. The mass after drying is 520kg, the content is 98.4%, and the yield of the two steps of passing chlorine and passing ammonia is 95.3%.

[0047] Example 6

[0048] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific steps of which are:

[0049] 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur, and 200kg of water were reacted at 128℃ for 4h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction was completed, 3000kg of water was added to the system and the pH of the system was adjusted to 2.5-3.5 with about 600kg of hydrochloric acid. The system was stirred at 85℃ for 1h, and the sulfur was filtered out while hot. The system was kept below 35℃ and 20kg of hydrochloric acid gas was slowly introduced to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changed from reddish brown to brown. to light yellow, add 20 kg of activated carbon, decolorize at 30 ° C for 1 hour, and then filter to obtain an aqueous solution of 2-mercapto-N, N-dimethylnicotinamide; the concentration of the aqueous solution of 2-mercapto-N, N-dimethylnicotinamide is detected to be 8.6%, and the temperature of the cooling medium in each section of the chlorine-passing tubular reactor is set to -15 ° C. First, open the discharge valve of the chlorine-passing tubular reactor (the chlorine-passing tubular reactor is provided with three chlorine feeding points, and the chlorine feeding points are all provided with feed valves), the inlet and discharge valves of the stratified liquid separation tank and the inlet and discharge valves of the ammonia-passing tubular reactor, and wait for the chlorine-passing tubular reactor to pass. After the temperature of the first pipeline at the feed end of the reactor drops below -10°C, the feed valve of the chlorine-passing tubular reactor is opened to start feeding dichloromethane and chlorine. The dichloromethane flow rate is 400kg / h, and the chlorine total valve flow rate is 62kg / h. The pressure of the tubular reactor is adjusted to 0.08±0.005MPa. After the pressure stabilizes, the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is fed at a flow rate of 500kg / h. By controlling the relative gas flow rate of each chlorine feeding point, the reaction temperature of each section of the chlorine-passing tubular reactor is controlled at -6--2°C. After the reaction, the feed liquid enters a layer separation tank to separate the organic phase and the aqueous phase, the gas enters a chlorine recovery tank, and the organic phase enters an ammonia gas pipe reactor. The pH of the material at the outlet is maintained at 8.5-9 by adjusting the ammonia gas flow rate. The material at the outlet of the ammonia gas pipe reactor enters an acidification kettle. After a certain amount of accumulation, the pH is adjusted to 5.5-6 with hydrochloric acid, and the temperature is maintained at 0° C. Filtering, washing with 300 kg of water to obtain 2-aminosulfonyl-N, N-dimethylnicotinamide, which has a mass of 528 kg after drying, a content of 98.1%, and a two-step yield of chlorine and ammonia is 95.5%.

[0050] Example 7

[0051] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific steps of which are:

[0052] 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur, and 200kg of water were reacted at 130℃ for 5h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction was completed, 2500kg of water was added to the system and the pH of the system was adjusted to 2.5-3.5 with about 600kg of hydrochloric acid. The system was stirred at 85℃ for 1h, and the sulfur was filtered out while hot. The system was kept below 35℃ and 20kg of hydrochloric acid gas was slowly introduced to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changed from reddish brown to brown. to light yellow, add 20 kg of activated carbon, decolorize at 35 ° C for 1 hour, and then filter to obtain an aqueous solution of 2-mercapto-N, N-dimethylnicotinamide; the concentration of the aqueous solution of 2-mercapto-N, N-dimethylnicotinamide is detected to be 9.7%, and the temperature of the cooling medium in each section of the chlorine-passing tubular reactor is set to -15 ° C. First, open the discharge valve of the chlorine-passing tubular reactor (the chlorine-passing tubular reactor is provided with three chlorine feeding points, and the chlorine feeding points are all provided with feed valves), the inlet and outlet valves of the stratified liquid separation tank and the inlet and outlet valves of the ammonia-passing tubular reactor, and wait for the chlorine-passing tubular reactor to pass. After the temperature of the first pipeline at the feed end of the reactor drops below -10°C, the feed valve of the chlorine-passing tubular reactor is opened to start feeding dichloromethane and chlorine. The dichloromethane flow rate is 230kg / h, and the chlorine total valve flow rate is 57kg / h. The pressure of the tubular reactor is adjusted to 0.07±0.005MPa. After the pressure stabilizes, the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is fed at a flow rate of 500kg / h. By controlling the relative gas flow rate of each chlorine feeding point, the reaction temperature of each section of the chlorine-passing tubular reactor is controlled at -6--2°C. After the reaction, the feed liquid enters a layer separation tank to separate the organic phase and the aqueous phase, the gas enters a chlorine recovery tank, and the organic phase enters an ammonia-passing tubular reactor. The pH of the material at the outlet is maintained at 8.5-9 by adjusting the ammonia ventilation rate. The material at the outlet of the ammonia-passing tubular reactor enters an acidification kettle. After a certain amount of accumulation, the pH is adjusted to 5-5.5 with hydrochloric acid, and the temperature is maintained at 4° C. Filtering, washing with 300 kg of water to obtain 2-aminosulfonyl-N, N-dimethylnicotinamide, which has a mass of 536 kg after drying, a content of 98.2%, and a two-step yield of chlorine and ammonia passing of 96.0%.

[0053] Example 8

[0054] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific steps of which are:

[0055] 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur, and 200kg of water were reacted at 132℃ for 3h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction was completed, 3000kg of water was added to the system and the pH of the system was adjusted to 2.5-3.5 with about 600kg of hydrochloric acid. The system was stirred at 85℃ for 1h, and the sulfur was filtered out while hot. The system was kept below 35℃ and 20kg of hydrochloric acid gas was slowly introduced to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changed from reddish brown to brown. to light yellow, add 20 kg of activated carbon, decolorize at 30°C for 1 hour, and then filter to obtain an aqueous solution of 2-mercapto-N,N-dimethylnicotinamide; the concentration of the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is detected to be 8.6%, and the temperature of the cooling medium in each section of the chlorine-passing tubular reactor is set to -15°C. First, open the discharge valve of the chlorine-passing tubular reactor, the inlet and outlet valves of the stratified liquid separation tank, and the inlet and outlet valves of the ammonia-passing tubular reactor. After the temperature of the first pipeline at the feed end of the chlorine-passing tubular reactor drops below -10°C, open the feed valve of the chlorine-passing tubular reactor. The chlorine gas tubular reactor is provided with three chlorine gas feeding points, and feeding valves are provided at the chlorine gas feeding points. Dichloromethane and chlorine are fed in. The flow rate of dichloromethane is 250 kg / h, and the flow rate of the chlorine gas total valve is 57 kg / h. The pressure of the tubular reactor is adjusted to 0.08±0.005 MPa. After the pressure is stable, the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is fed in. The flow rate is 500 kg / h. The reaction temperature of each section of the chlorine gas tubular reactor is controlled at -6--2°C by controlling the relative gas flow rate of each chlorine gas feeding point. After the reaction, the feed liquid enters a layer separation tank to separate the organic phase and the aqueous phase, the gas enters a chlorine recovery tank, and the organic phase enters an ammonia gas pipe reactor. The pH of the material at the outlet is maintained at 8.5-9 by adjusting the ammonia gas flow rate. The material at the outlet of the ammonia gas pipe reactor enters an acidification kettle. After a certain amount of accumulation, the pH is adjusted to 5-5.5 with hydrochloric acid, and the temperature is maintained at 0° C. Filtering, washing with 300 kg of water to obtain 2-aminosulfonyl-N, N-dimethylnicotinamide, which has a mass of 529 kg after drying, a content of 98.5%, and a two-step yield of chlorine and ammonia is 96.1%.

[0056] Example 9

[0057] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific steps of which are:

[0058] 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur and 200kg of water were reacted at 127℃ for 3h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction was completed, 2500kg of water was added to the system and the pH of the system was adjusted to 2.5-3.5 with about 600kg of hydrochloric acid. The system was stirred at 85℃ for 1h, and the sulfur was filtered out while hot. 20kg of hydrochloric acid gas was slowly introduced into the system to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changed from reddish brown to The mixture was light yellow, 20 kg of activated carbon was added, and the mixture was decolorized at 30 ° C for 1 hour, and then filtered to obtain an aqueous solution of 2-mercapto-N, N-dimethylnicotinamide; the concentration of the aqueous solution of 2-mercapto-N, N-dimethylnicotinamide was detected to be 9.5%, and the temperature of the cooling medium in each section of the chlorine-passing tubular reactor was set to -155 ° C. First, the discharge valve of the chlorine-passing tubular reactor was opened (three chlorine feeding sites were set in the chlorine-passing tubular reactor, and the feed valves were set at the chlorine feeding sites), the inlet and outlet valves of the stratified liquid separation tank and the inlet and outlet valves of the ammonia-passing tubular reactor were opened, and the chlorine-passing tubular reactor was opened. After the temperature of the first pipeline at the feed end of the reactor drops below -10°C, the feed valve of the chlorine-passing tubular reactor is opened to start feeding dichloromethane and chlorine. The dichloromethane flow rate is 230kg / h, and the chlorine total valve flow rate is 58kg / h. The pressure of the tubular reactor is adjusted to 0.07±0.005MPa. After the pressure stabilizes, the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is fed at a flow rate of 450kg / h. By controlling the relative gas flow rate of each chlorine feeding point, the reaction temperature of each section of the chlorine-passing tubular reactor is controlled at -6--2°C. After the reaction, the feed liquid enters a layer separation tank to separate the organic phase and the aqueous phase, the gas enters a chlorine recovery tank, and the organic phase enters an ammonia gas pipe reactor. The pH of the material at the outlet is maintained at 9-9.5 by adjusting the ammonia gas flow rate. The material at the outlet of the ammonia gas pipe reactor enters an acidification kettle. After a certain amount of accumulation, the pH is adjusted to 5-5.5 with hydrochloric acid, and the temperature is maintained at 4° C. Filtering, washing with 300 kg of water to obtain 2-aminosulfonyl-N, N-dimethylnicotinamide, which has a mass of 521 kg after drying, a content of 98.1%, and a two-step yield of chlorine and ammonia is 95.2%.

[0059] Example 10

[0060] A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, the specific steps of which are:

[0061] 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur and 200kg of water were reacted at 130℃ for 3h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction was completed, 3000kg of water was added to the system and the pH of the system was adjusted to 2.5-3.5 with about 600kg of hydrochloric acid. The system was stirred at 85℃ for 1h, and the sulfur was filtered out while hot. 20kg of hydrochloric acid gas was slowly introduced into the system to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changed from reddish brown to Light yellow, add 20 kg of activated carbon, decolorize at 35 ° C for 1 hour, and then filter to obtain an aqueous solution of 2-mercapto-N, N-dimethylnicotinamide; the concentration of the aqueous solution of 2-mercapto-N, N-dimethylnicotinamide is detected to be 8.7%, and the temperature of the cooling medium in each section of the chlorine-passing tubular reactor is set to -15 ° C. First, open the discharge valve of the chlorine-passing tubular reactor (the chlorine-passing tubular reactor is provided with three chlorine feeding points, and the chlorine feeding points are all provided with feed valves), the inlet and outlet valves of the stratified liquid separation tank and the inlet and outlet valves of the ammonia-passing tubular reactor, and wait for the chlorine-passing tubular reactor to pass. After the temperature of the first pipeline at the feed end of the reactor drops below -10°C, the feed valve of the chlorine-passing tubular reactor is opened to start feeding dichloromethane and chlorine. The dichloromethane flow rate is 250kg / h, and the chlorine total valve flow rate is 58kg / h. The pressure of the tubular reactor is adjusted to 0.07±0.005MPa. After the pressure stabilizes, the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide is fed at a flow rate of 500kg / h. By controlling the relative gas flow rate of each chlorine feeding point, the reaction temperature of each section of the chlorine-passing tubular reactor is controlled at -6--2°C. The reaction liquid enters a stratification and liquid separation tank to separate the organic phase and the aqueous phase, the gas enters a chlorine recovery tank, the organic phase enters an ammonia-passing tubular reactor, the pH of the material at the outlet is maintained at 9.5-10 by adjusting the ammonia ventilation rate, the material at the outlet of the ammonia-passing tubular reactor enters an acidification kettle, after a certain amount is accumulated, the pH is adjusted to 5-5.5 with hydrochloric acid, the temperature is maintained at 0°C, and filtration is performed, and 2-aminosulfonyl-N,N-dimethylnicotinamide is obtained by washing with 300kg of water. The mass after drying is 530kg, the content is 98.6%, and the yield of the two steps of passing chlorine and passing ammonia is 95.3%.

[0062] Comparative Example 1

[0063] A batch-type preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide in a reactor, the specific steps of which are:

[0064] 500 kg of 2-chloro-N, N-dimethylnicotinamide, 225 kg of sodium sulfide, 88 kg of elemental sulfur, and 200 kg of water were added to a reaction kettle, and the mixture was reacted at 125°C for 3 h to prepare 2-mercapto-N, N-dimethylnicotinamide. After the reaction was completed, 2000 kg of water was added to the system, and the pH of the system was adjusted to 2.5-3.5 with about 600 kg of hydrochloric acid. 20 kg of activated carbon was added, and the mixture was decolorized at 75°C for 1 h, and then filtered to obtain an aqueous solution of 2-mercapto-N, N-dimethylnicotinamide. Detection of 2-mercapto-N, N-dimethyl The concentration of nicotinamide aqueous solution is 10.8%, 1420 kg of dichloromethane is added, the temperature is controlled at -5-0°C, 445 kg of chlorine is slowly passed, and the chlorine passing time is controlled to be 7 hours. After the chlorine passing is completed, the liquids are separated, the temperature is maintained at -5-0°C, ammonia is passed into the organic phase until the pH of the system is 8-8.5, and after adjusting the pH to 4-4.5 with hydrochloric acid, the temperature is maintained at 0°C and filtered, and 2-aminosulfonyl-N,N-dimethylnicotinamide is washed with 300 kg of water to obtain 2-aminosulfonyl-N,N-dimethylnicotinamide. The mass after drying is 378.3 kg, the content is 97.8%, and the yield of the two steps of passing chlorine and ammonia is 68.2%.

[0065] Comparative Example 2

[0066] A batch-type preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide in a reactor, the specific steps of which are:

[0067] Add 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur, and 200kg of water to the reactor, react at 130℃ for 4h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction is completed, add 2000kg of water to the system and adjust the pH of the system to 2.5-3.5 with about 600kg of hydrochloric acid, keep stirring at 75℃ for 1h, filter out the sulfur while hot, keep the system below 35℃ and slowly pass 20kg of hydrochloric acid gas to increase the acidity of the system and force out the elemental sulfur as much as possible until the supernatant of the system gradually changes from reddish brown to light yellow, add 20kg of activated carbon, decolorize at 30℃ for 1h, and then filter The method comprises the following steps: obtaining an aqueous solution of 2-mercapto-N,N-dimethylnicotinamide; detecting the aqueous solution concentration of 2-mercapto-N,N-dimethylnicotinamide to be 10.8%, adding 4000 kg of dichloromethane, controlling the temperature at -5-0°C, slowly passing 445 kg of chlorine, and controlling the passing time of chlorine for 6 hours; separating the liquids after the passing of chlorine, maintaining the temperature at -5-0°C, passing ammonia gas to the organic phase until the pH value of the system is 8-8.5, adjusting the pH value to 4-4.5 with hydrochloric acid, filtering the organic phase while maintaining the temperature at 5°C, and washing the organic phase with 300 kg of water to obtain 2-aminosulfonyl-N,N-dimethylnicotinamide, which has a mass of 418.5 kg after drying, a content of 98.0%, and a two-step yield of passing chlorine and ammonia of 75.6%.

[0068] Comparative Example 3

[0069] A batch-type preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide in a reactor, the specific steps of which are:

[0070] Add 500kg of 2-chloro-N,N-dimethylnicotinamide, 225kg of sodium sulfide, 88kg of elemental sulfur, and 200kg of water to the reactor, react at 135℃ for 5h to prepare 2-mercapto-N,N-dimethylnicotinamide. After the reaction is completed, add 2000kg of water to the system and adjust the pH of the system to 2.5-3.5 with about 600kg of hydrochloric acid, keep stirring at 80℃ for 1h, filter out the sulfur while hot, keep the system below 35℃ and slowly pass 20kg of hydrochloric acid gas to increase the acidity of the system and force out the elemental sulfur as much as possible, until the supernatant of the system gradually changes from reddish brown to light yellow, add 20kg of activated carbon, decolorize at 35℃ for 1h, and then pass through The aqueous solution of 2-mercapto-N, N-dimethylnicotinamide was filtered to obtain an aqueous solution; the concentration of the aqueous solution of 2-mercapto-N, N-dimethylnicotinamide was detected to be 10.8%, 4000 kg of dichloromethane was added, the temperature was controlled at 0-2°C, 445 kg of chlorine was slowly passed, and the chlorine passing time was controlled to be 8 hours. After the chlorine passing was completed, the liquids were separated, the temperature was maintained at -5-0°C, ammonia was passed through the organic phase until the pH of the system was 8-8.5, hydrochloric acid was used to adjust the pH to 4-4.5, and the temperature was maintained at 0°C for filtration, and 2-aminosulfonyl-N, N-dimethylnicotinamide was washed with 300 kg of water to obtain 2-aminosulfonyl-N, N-dimethylnicotinamide, which had a mass of 400.3 kg after drying, a content of 98.1%, and a two-step yield of 72.4% for passing chlorine and ammonia.

Claims

1. A continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide, characterized in that: The specific preparation method comprises the following steps: (1) 2-Chloro-N,N-dimethylnicotinamide, sodium sulfide, elemental sulfur and water are reacted to prepare 2-mercapto-N,N-dimethylnicotinamide; (2) After the reaction is completed, water is added to the system and the pH of the system is adjusted to 2.5-3.5 with hydrochloric acid. The system is stirred at 70-80°C, and most of the sulfur is filtered out while hot. Hydrogen chloride is slowly introduced into the system while the temperature is kept below 35°C until the supernatant of the system gradually changes from reddish brown to light yellow. Activated carbon is added, and the system is decolorized and filtered to obtain an aqueous solution of 2-mercapto-N,N-dimethylnicotinamide; (3) Setting the temperature of the cooling medium of each section of the chlorine-passing tubular reactor to -15- -5°C, starting to feed the organic solvent and chlorine into the chlorine-passing tubular reactor, controlling the pressure of the chlorine-passing tubular reactor to 0.05-0.1MPa, and starting to feed the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide into the chlorine-passing tubular reactor after the pressure stabilizes, and controlling the reaction temperature of the chlorine-passing tubular reactor to -2-2°C by controlling the feeding rate of the aqueous solution of 2-mercapto-N,N-dimethylnicotinamide and the relative gas flow rate of each point of chlorine. After the reaction, the feed liquid enters the liquid separator to separate the organic phase and the aqueous phase, the gas enters the chlorine recovery tank, and the organic phase enters the ammonia-passing tubular reactor. By adjusting the ammonia ventilation rate, the pH of the material at the discharge port is maintained at 8-10. The material at the outlet of the ammonia-passing tubular reactor enters the acidification kettle, and after adjusting the pH to 4-6 with hydrochloric acid, the temperature is maintained at 0-5°C for filtration, and 2-aminosulfonyl-N,N-dimethylnicotinamide is obtained by washing with water; In the step (2), 4-6 times the mass of 2-chloro-N,N-dimethylnicotinamide of water is added, the stirring time is 0.5-1.5 hours, 2-5% of the mass of 2-chloro-N,N-dimethylnicotinamide of activated carbon is added, the decolorization temperature is 30-35°C, and the decolorization time is 0.5-1.5 hours; In the step (3), the mass ratio of the amount of the organic solvent to the 2-mercapto-N,N-dimethylnicotinamide aqueous solution is 0.4-0.8:1, and the organic solvent is one of dichloroethane and dichloromethane; In step (3), the molar ratio of chlorine gas to 2-mercapto-N,N-dimethylnicotinamide is 2.9-3.5:1; The chlorine-passing tubular reactor is provided with three chlorine feeding sites, and the pre-feeding temperature of the chlorine-passing tubular reactor is set to be below -10°C.

2. The continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide according to claim 1, characterized in that: The molar ratio of the sodium sulfide, elemental sulfur and 2-chloro-N,N-dimethylnicotinamide is 0.6-0.7:1.0-1.1:1, and the mass ratio of water to 2-chloro-N,N-dimethylnicotinamide is 0.3-0.5:

1.

3. The continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide according to claim 1, characterized in that: In the step (1), the reaction temperature is 125-135° C. and the reaction time is 3-5 h.

4. The continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide according to claim 1, characterized in that: In the step (3), the mass ratio of the organic solvent to the 2-mercapto-N,N-dimethylnicotinamide aqueous solution is 0.5-0.6:

1.

5. The continuous preparation method of 2-aminosulfonyl-N,N-dimethylnicotinamide according to claim 1, characterized in that: In the step (3), the molar ratio of chlorine gas to 2-mercapto-N,N-dimethylnicotinamide is 3.2-3.3:1.

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