A method for preparing N-phenyl-N-trichloromethylthiophenyl sulfonamide by one-pot cooking

Abstract

A method for preparing N-phenyl-N-trichloromethylthio phenyl sulfonamide by one-pot method, organic solvent, aniline and catalyst are added to phenylsulfonyl chloride, then slow addition of acid binding agent, incubation for 1-4 h to obtain a reaction solution containing intermediate N-phenyl phenyl sulfonamide; the system is cooled to 0-20℃, slow addition of per-chloromethylthio alcohol, after the end of feeding, continue to react for 1-4 h; then add water to separate the phases, add appropriate amount of water in the organic phase to distill the organic solvent, filter to obtain N-phenyl-N-trichloromethylthio phenyl sulfonamide. The method uses organic solvent as solvent, adopts two-step reaction one-pot method, the process is simple, improves the reaction conversion rate, effectively reduces the generation of by-products, the yield of the product is high, and the quality is good. The used organic solvent and acid binding agent can be recycled and used, which reduces the production cost and greatly reduces the three wastes, and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide by one-pot cooking. Background Technology

[0002] During rubber processing or storage, mechanical heat and high-temperature environments can cause rubber compounds to prematurely vulcanize (crosslink), losing their fluidity and reprocessing ability—a phenomenon known as scorching, which leads to waste. Currently, the most widely used anti-scorching agent in China is CTP. However, under the same compounding system, excessive CTP can decrease some physical properties, such as tensile strength and compression set. Overuse may also cause blooming problems, and its effectiveness is limited in sulfur-free vulcanization systems. N-phenyl-N-trichloromethylthiobenzenesulfonamide (anti-scorching agent E) avoids these problems. Under the same compounding system, it has no adverse effects on the vulcanization performance and physical properties of the rubber compound, exhibits high storage stability and good operability, and meets industrial production safety and hygiene requirements, making it an ideal anti-scorching agent.

[0003] Currently, the main method for synthesizing anti-scorching agent E is to react aniline with benzenesulfonyl chloride under alkaline conditions to obtain the intermediate N-phenylbenzenesulfonamide, and then add alkali and perchloromethanethiol to react and synthesize anti-scorching agent E.

[0004] Chinese patent CN 111548291 B describes a process where, after preparing the intermediate N-phenylbenzenesulfonamide, an organic solvent is added to the system for dissolution, followed by standing and layering to obtain an organic solution containing the intermediate N-phenylbenzenesulfonamide. The need to separate the intermediate complicates the process and requires significant equipment. The first step reaction is carried out in an aqueous solution. Since the solid product and liquid raw materials aniline and benzenesulfonyl chloride are insoluble in water, the intermediate inevitably encapsulates aniline and benzenesulfonyl chloride. Aniline will react with perchloromethanethiol, causing the final product to turn yellow and have an irritating odor. Furthermore, in the examples, sodium hydroxide is used as the acid-binding agent in both steps. Sodium hydroxide is highly alkaline, easily causing the raw materials benzenesulfonyl chloride and perchloromethanethiol to undergo alkaline hydrolysis, generating hydrolysis byproducts and reducing the quality of the raw materials. Material utilization rate; Sodium hydroxide will activate the NH bond of N-phenylbenzenesulfonamide, which will reduce the selectivity of the reaction and lead to the generation of a large amount of N-phenyl-N-benzenesulfonylbenzenesulfonamide byproduct. This will not only reduce the yield of the product, but also seriously affect the quality of the final product due to the large amount of byproduct entering the final product; Although the claims of the patent also make requirements for organic bases such as pyridine and triethylamine, they are not reflected in the examples. The reaction is carried out in water. It is difficult to avoid the encapsulation of raw materials and acid-binding agents by intermediates when using acid-binding agents such as pyridine and triethylamine, and it cannot be carried out by one-pot cooking.

[0005] Chinese patent CN 112094209 B uses water as the reaction medium, and regardless of whether sodium hydroxide, sodium bicarbonate, or sodium carbonate is used as the acid-binding agent, the production of N-phenyl-N-benzenesulfonylbenzenesulfonamide byproducts is unavoidable. In this patent, a large amount of alkali solution is added after the synthesis of the intermediate to form a sodium salt, which then dissolves in water. The byproduct is insoluble in water and can be removed by filtration, adding an extra step. Although this avoids the byproduct entering the final product, it does not change the poor selectivity of this step. Secondly, by directly adding perchloromethanethiol to the sodium salt of the intermediate, the pH of the system drops rapidly as the reaction proceeds and perchloromethanethiol partially hydrolyzes. The sodium salt of the intermediate precipitates due to the decrease in pH, inevitably leading to the formation of a solid product containing part of the intermediate. This results in not only a low product yield but also poor product quality.

[0006] Chinese patent CN 114957049 B uses aniline itself as an acid-binding agent. The intermediate formed after the reaction of aniline with benzenesulfonyl chloride contains aniline hydrochloride. This hydrochloride needs to be removed by filtration and washing before it can be transferred to another reactor and alkali added to form a sodium salt, which is then used to react with perchloromethanethiol. This process is complex, lengthy, and also increases the need for recovering excess aniline. Using the intermediate sodium salt in the reaction with perchloromethanethiol also makes it difficult to avoid intermediate precipitation and encapsulation, resulting in low product yield and poor quality.

[0007] Chinese patent CN 115784946 B employs a one-pot synthesis method, bypassing the separation of the intermediate N-phenylbenzenesulfonamide. While this simplifies the process, byproducts generated in the first step reaction can enter the second step, affecting product quality. Our extensive experiments have observed that during the first step's reaction of aniline with benzenesulfonyl chloride to synthesize the intermediate N-phenylbenzenesulfonamide, the precipitated intermediate consistently clumps together, encapsulating aniline and benzenesulfonyl chloride. Residual aniline also reacts with perchloromethanethiol, impacting product yield and appearance. In the second step, the intermediate sodium salt reacts with perchloromethanethiol; this patented technology similarly struggles to avoid intermediate precipitation and encapsulation, leading to lower product yield and poorer quality. Summary of the Invention

[0008] To address the problems of harsh reaction conditions, high energy consumption, low yield, low purity, and safety hazards in the existing synthesis of anti-scorching agent E, this invention provides a method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide using a one-pot cooking method.

[0009] To achieve the above-mentioned objectives, the specific technical solution of this invention is as follows: A method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide by one-pot cooking, the method comprising the following steps: (1) Add the organic solvent, aniline, and catalyst to the reaction vessel; (2) Slowly add benzenesulfonyl chloride at 10-15℃. After the benzenesulfonyl chloride is added, slowly add the acid-binding agent. After the acid-binding agent is added, keep the reaction at the temperature for 1-4 hours to obtain a reaction solution containing the intermediate N-phenylbenzenesulfonamide. (3) Cool the above reaction solution containing intermediates to 5-10°C, slowly add perchloromethanethiol, and continue the reaction for 1-4 hours after the perchloromethanethiol is added; add water to the above system to form a phase, add an appropriate amount of water to the organic phase for distillation to recover the organic solvent, and filter to obtain N-phenyl-N-trichloromethanethiol benzenesulfonamide. The solvent can be used directly. Add alkali to the aqueous phase to neutralize and recover the acid-binding agent. The acid-binding agent can be used directly.

[0010] Furthermore, in step (1), the catalyst is one or more of 4-dimethylaminopyridine, tetrabutylammonium bromide, and tetrabutylammonium chloride, preferably 4-dimethylaminopyridine, and its amount is 0.1 to 1% of the mass of aniline.

[0011] Furthermore, in step (1), the organic solvent can be one or more of cyclohexane, n-hexane, dichloromethane, dichloroethane, chloroform, trichloroethylene, and 120# solvent oil, preferably dichloromethane, and the mass ratio of dichloromethane to aniline is 7.0 to 15.0:1, preferably 7.0 to 10.0:1.

[0012] Furthermore, in step (2), the molar ratio of aniline to benzenesulfonyl chloride is 1:1.0 to 1.2, preferably 1:1.1 to 1.12.

[0013] Furthermore, in step (2), the acid-binding agent is pyridine, triethylamine, or 3-methylpyridine, preferably triethylamine; the molar ratio of the acid-binding agent to aniline is 1:2.0 to 3.0, preferably 1:2.0 to 2.3, and the addition time of triethylamine is 1 to 4 hours, preferably 2 to 3 hours.

[0014] Furthermore, in step (3), the molar ratio of aniline to perchloromethanethiol is 1:1.0 to 1.5, preferably 1:1.1 to 1.2, the feeding temperature of perchloromethanethiol is 0 to 20°C, preferably 5 to 10°C, and the feeding time is 1 to 5 hours, preferably 2 to 3 hours.

[0015] The reaction process in the above synthesis method is as follows:

[0016] The innovativeness and beneficial effects of this invention are as follows: 1. The process is simple. The entire process uses a one-pot cooking method in the same solvent, without the need for dissolution, filtration, extraction and other operations, which saves equipment and simplifies the process.

[0017] 2. Good Selectivity: First, an organic solvent, aniline, and catalyst are added to the reaction vessel. Then, benzenesulfonyl chloride is slowly added to the system. Approximately half of the aniline reacts with benzenesulfonyl chloride to form an intermediate, while the other half reacts with hydrochloric acid to form aniline hydrochloride. About half of the benzenesulfonyl chloride remains in the system. Next, a basic acid-binding agent is slowly added to the system. The aniline hydrochloride neutralizes to form aniline while simultaneously reacting with the remaining benzenesulfonyl chloride to form an intermediate. The system remains nearly neutral, preventing further reaction between benzenesulfonyl chloride and the intermediate to form N-phenyl-N-benzenesulfonylbenzenesulfonamide byproducts. Therefore, the reaction exhibits good selectivity.

[0018] 3. High yield and good quality: The use of organic solvents and organic amines as acid-binding agents avoids the hydrolysis of benzenesulfonyl chloride and perchloromethanethiol, greatly improving the utilization rate of raw materials. It also effectively avoids the formation of intermediates that are insoluble in water, which would cause aniline and benzenesulfonyl chloride to be trapped, thus effectively solving the problem of residual aniline reacting with perchloromethanethiol to form byproducts that affect product quality. At the same time, it also solves the problem of intermediate precipitation being trapped by the product in the second step of the reaction, which affects the yield and product quality.

[0019] 4. Economic and environmentally friendly post-treatment: After adding water to the phase, the acid-binding agent in the system can be recovered, and the organic solvent can be recycled after distillation, which further reduces the cost. Attached Figure Description

[0020] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0021] Figure 1 This is the HPLC chromatogram of the intermediate solid precipitated after the first step of the reaction in Example 1.

[0022] Figure 2 This is the HPLC chromatogram of the solid product precipitated after the second step of the reaction in Example 1.

[0023] Figure 3 This is the HPLC chromatogram of the intermediate solid precipitated after the first step of the reaction in Comparative Example 1.

[0024] Figure 4 The image shows the HPLC spectrum of the mother liquor after the first step of the reaction in Comparative Example 1.

[0025] Figure 5 This is the HPLC chromatogram of the solid product precipitated after the second step of the reaction in Comparative Example 1.

[0026] Figure 6 This is the HPLC chromatogram of the intermediate solid precipitated after the first step of the reaction in Comparative Example 2.

[0027] Figure 7 This is the HPLC spectrum of the mother liquor after the first step of the reaction in Comparative Example 2.

[0028] Figure 8 This is the HPLC chromatogram of the solid product precipitated after the second step of the reaction in Comparative Example 2.

[0029] Figure 9 This is the HPLC chromatogram of the intermediate solid precipitated after the first step of the reaction in Comparative Example 3.

[0030] Figure 10 The image shows the HPLC spectrum of the mother liquor after the first step of the reaction in Comparative Example 3.

[0031] Figure 11 This is the HPLC chromatogram of the solid product precipitated after the second step of the reaction in Comparative Example 3. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention. Example

[0033] This invention provides a method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide using a one-pot cooking method. The synthesis method includes the following steps: Step 1: Add 200g of dichloromethane, 20g of aniline, and 0.2g of 4-dimethylaminopyridine to the reaction vessel and mix thoroughly.

[0034] Step 2: At 13°C, add 41.72g of benzenesulfonyl chloride to the above solution over a period of 1 hour.

[0035] Step 3: Add 42.39g of pyridine to the reaction solution from Step 2. The addition time is 3 hours. After the addition is complete, a reaction solution containing the intermediate is obtained.

[0036] Step 4: Lower the system temperature to 5℃ and add 45.9g of perchloromethanethiol dropwise over 3 hours. After the perchloromethanethiol addition is complete, continue the reaction for another 2 hours. Add water to the above system as the phase, add 150g of water to the organic phase, and distill to recover the organic solvent. Filter to obtain N-phenyl-N-trichloromethylthiobenzenesulfonamide, and dry to obtain 78.88g of white powder with a purity of 99.7% and a yield of 95.7%.

[0037] HPLC detection results are as follows Figure 1 (3.8 min aniline, 4.7 min intermediate, 8.5 min byproduct).

[0038] Figure 1 The image shows the HPLC chromatogram of the intermediate solid precipitated after the first step of the reaction, which contains 0.064% aniline, 98.7% intermediate, and 0.8% byproduct.

[0039] Figure 2 The image shows the HPLC chromatogram of the solid product precipitated after the second reaction step (4.7 min intermediate, 15.7 min anti-scorching agent E), with an intermediate content of 0.165% and a product content of 99.7%. Example

[0040] This invention provides a method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide using a one-pot cooking method. The synthesis method includes the following steps: Step 1: Add 300g of dichloromethane, 20g of aniline, and 0.2g of 4-dimethylaminopyridine to the reaction vessel and mix thoroughly.

[0041] Step 2: At 13°C, add 39.83g of benzenesulfonyl chloride to the above solution over a period of 1 hour.

[0042] Step 3: Add 45.63g of triethylamine to the reaction solution from Step 2. The addition time is 4 hours. After the addition is complete, keep the reaction at 25°C for 4 hours to obtain a reaction solution containing the intermediate.

[0043] Step 4: Lower the system temperature to 5℃ and add 47.9g of perchloromethanethiol dropwise over 3 hours. After the perchloromethanethiol addition is complete, continue the reaction for another 2 hours. Add water to the above system as the phase, add 150g of water to the organic phase, and distill to recover the organic solvent. Filter to obtain N-phenyl-N-trichloromethylthiobenzenesulfonamide, and dry to obtain 79.46g of white powder with a purity of 99.6% and a yield of 96.3%. Example

[0044] This invention provides a method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide using a one-pot cooking method. The synthesis method includes the following steps: Step 1: Add 300g cyclohexane, 20g aniline, and 0.2g tetrabutylammonium bromide to a flask and mix thoroughly.

[0045] Step 2: At 15°C, add 39.83g of benzenesulfonyl chloride to the above solution over a period of 1 hour.

[0046] Step 3: Add 46.72g of triethylamine to the reaction solution from Step 2. The addition time is 3 hours. After the addition is complete, keep the reaction at 25°C for 4 hours to obtain a reaction solution containing the intermediate.

[0047] Step 4: Lower the system temperature to 10℃ and add 47.9g of perchloromethanethiol dropwise over 3 hours. After the perchloromethanethiol addition is complete, continue the reaction for another 2 hours. Add water to the above system as the phase, add 150g of water to the organic phase, and distill to recover the organic solvent. Filter to obtain N-phenyl-N-trichloromethanethiobenzenesulfonamide, and dry to obtain 79g of white powder with a purity of 99.8% and a yield of 96%. Example

[0048] This invention provides a method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide using a one-pot cooking method. The synthesis method includes the following steps: Step 1: Add 300g cyclohexane, 20g aniline, and 0.2g tetrabutylammonium bromide to a flask and mix thoroughly.

[0049] Step 2: At 15°C, add 39.83g of benzenesulfonyl chloride to the above solution over a period of 1 hour.

[0050] Step 3: Add 42.39g of pyridine to the reaction solution from Step 2. The addition time is 3 hours. After the addition is complete, keep the reaction at 25°C for 3 hours to obtain a reaction solution containing the intermediate.

[0051] Step 4: Lower the system temperature to 10℃ and add 47.9g of perchloromethanethiol dropwise over 3 hours. After the perchloromethanethiol addition is complete, continue the reaction for another 2 hours. Add water to the above system to form a water phase. Add 150g of water to the organic phase and distill to recover the organic solvent. Filter to obtain N-phenyl-N-trichloromethanethiobenzenesulfonamide. Dry to obtain 77.48g of white powder with a purity of 99.7% and a yield of 94%. Comparative Example 1 (Implemented according to Chinese Patent CN 112094209 B) 1. Add 11.7g of aniline and 36.7g of 15wt% sodium hydroxide aqueous solution to the flask within 30 minutes and mix thoroughly.

[0052] 2. Add 33g of benzenesulfonyl chloride dropwise at 80℃. After 1.5h, the addition of benzenesulfonyl chloride is completed. Continue to keep the reaction at the temperature for another 1h. The pH value is measured to be approximately 6, indicating that the synthesis of the intermediate is complete.

[0053] 3. After the intermediate synthesis is complete, add 61.5g of 9wt% sodium hydroxide solution to the flask, maintain the temperature inside the vessel at 40℃, stir for 1 hour, and then filter the alkaline solution of the intermediate.

[0054] 16g of perchloromethanethiol was mixed thoroughly with 65g of 120# solvent oil and added dropwise at 60℃ over 3-4 hours. After the addition was complete, the reaction was continued at this temperature for another 1.5 hours. After the reaction was finished, the mixture was filtered and dried to obtain the target product. Agglomeration occurred during the condensation process. The final product yield was 88.16%, and the product purity was 82.8%. The HPLC chromatograms for each reaction stage are shown below. Figure 3 (3.8 min aniline, 4.7 min intermediate, 8.5 min byproduct).

[0055] Figure 3 The image shows the HPLC chromatogram of the intermediate solid precipitated after the first step of the reaction. The content of aniline is 6.8%, the content of intermediate is 85%, and the content of byproduct is 4.6%. The results show that the intermediate contains a large amount of aniline, and the strong alkaline sodium hydroxide will activate the intermediate. The intermediate will further react with benzenesulfonyl chloride to generate N-phenyl-N-benzenesulfonylbenzenesulfonamide byproduct.

[0056] Figure 4 The image shows the HPLC spectrum of the mother liquor after the first step reaction (2.3 min benzenesulfonic acid, 4.7 min intermediate), in which the benzenesulfonic acid content is 50%. Benzenesulfonic acid is derived from the hydrolysis of benzenesulfonyl chloride. The reduction in raw materials after the hydrolysis of benzenesulfonic acid leads to a decrease in product yield.

[0057] Figure 5 The image shows the HPLC chromatogram of the solid product precipitated after the second reaction step (2.3 min benzenesulfonic acid, 4.7 min intermediate, 14.3 min anti-scorching agent E). The benzenesulfonic acid content is 4.5%, the intermediate content is 10.2%, the N-phenyl-N-benzenesulfonylbenzenesulfonamide byproduct content is 4.6%, and the final product, N-phenyl-N-trichloromethylthiobenzenesulfonamide, has a content of only 82.8%. It is evident that directly adding perchloromethanethiol to the sodium salt of the intermediate causes a rapid decrease in the pH of the system as the reaction proceeds and perchloromethanethiol partially hydrolyzes. This leads to the precipitation of the sodium salt of the intermediate due to the decreased pH, inevitably resulting in the solid product containing part of the intermediate. This not only results in a low yield but also poor quality. Furthermore, the disubstituted byproducts from the first reaction step are also incorporated into the final product, affecting its appearance and purity. Comparative Example 2 (Implemented according to Chinese Patent CN 111548291 B) 1. Add 9.3g aniline, 12.5g 32wt% sodium hydroxide solution, and 0.3g TBAB to a flask, dilute with 200g water, and mix well.

[0058] 2. Add 18.5g of benzenesulfonyl chloride dropwise at -15℃. After 2 hours, the benzenesulfonyl chloride is added. Then, raise the temperature to 20℃ and continue the reaction for 2 hours. Finally, raise the temperature to 75℃ and continue the reaction for 2 hours. The pH value is measured to be approximately 7, indicating that the synthesis of the intermediate is complete.

[0059] 3. Add 69g of 120# solvent oil to the intermediate and heat to 102℃. Stir thoroughly until the solid is completely dissolved. Let stand and separate into layers to obtain a solvent oil mother liquor containing N-phenylbenzenesulfonamide.

[0060] 4. Add 13.5g of 32wt% sodium hydroxide solution and 0.3g of TBAB to the solvent oil of N-phenylbenzenesulfonamide, stir and cool down to below 0℃, then slowly add 21.2g of perchloromethanethiol dropwise for 1 hour. After the addition of perchloromethanethiol is completed, first raise the temperature to 50℃ and react for 2 hours, then continue to raise the temperature to 80℃ and react for 2 hours. Check that the pH is ≈9, and then stop the reaction.

[0061] 5. Extraction was performed at 110℃ for 30 min, followed by standing for 20 min to separate the layers, yielding an organic phase and a salt-containing mother liquor. The lower salt-containing mother liquor was separated, and the organic layer was cooled to -5℃ for 2 h to crystallize. The crystals were then filtered and dried to obtain pure N-phenyl-N-trichloromethylthiobenzenesulfonamide, with a yield of 91.5% and a purity of 90.71%. Agglomeration also occurred during the condensation process. HPLC chromatograms of each reaction stage are shown below. Figure 6 .

[0062] Figure 6 The image shows the HPLC chromatogram of the intermediate solid precipitated after the first step of the reaction (3.8 min aniline, 4.7 min intermediate, 8.5 min byproduct), in which the aniline content is 7.21%, the intermediate content is 83.52%, and the byproduct content is 5.47%.

[0063] Figure 7 The image shows the HPLC chromatogram of the mother liquor after the first step of the reaction (2.3 min benzenesulfonic acid, 3.8 min aniline, 4.7 min intermediate), in which the content of benzenesulfonic acid is 64.4%, the content of aniline is 11.28%, and the content of intermediate is 17.87%.

[0064] Figure 8 The image shows the HPLC chromatogram of the solid product precipitated after the second reaction step (4.7 min intermediate, 14.3 min anti-scorching agent E), with an intermediate content of 6.23% and a product content of 90.71%. The HPLC chromatogram shows that conventional methods convert the intermediate to its corresponding sodium salt in a strong alkali environment before reacting it with perchloromethanethiol to generate the product. This reaction generates hydrochloric acid, and the hydrolysis of perchloromethanethiol also releases a large amount of acidic substances, causing a rapid decrease in the system's pH. This leads to the intermediate precipitating from the water and being encapsulated in the final product, resulting in a low yield and poor product quality. Comparative Example 3 (Implemented according to Chinese Patent CN 115784946 B) 1. Mix 14.0g of aniline, 15.2g of sodium bicarbonate, 1.1g of tetrabutylammonium bromide and 168ml of water until homogeneous.

[0065] 2. At 25°C, 28.4 g of benzenesulfonyl chloride was added dropwise to the above emulsion over a period of 3 hours. After the addition was complete, the mixture was kept at this temperature for 3 hours to obtain a reaction solution containing the intermediate.

[0066] 3. Cool the above reaction solution to 0℃, then add 91 ml of 2.8 mol / L NaOH solution and 39.1 g of perchloromethanethiol dropwise over 3 hours. Maintain the reaction solution temperature at 5℃ during the dropwise addition. After the addition is complete, hydrolyze the solution at 100℃ for 1 hour. Filter, collect the filter cake, wash, and dry to obtain 54.3 g of N-phenyl-N-trichloromethylthiobenzenesulfonamide, with a purity of 86.83% and a yield of 83.79%. HPLC chromatogram is shown below. Figure 9 (3.8 min aniline, 4.7 min intermediate, 8.5 min byproduct).

[0067] Figure 9 The image shows the HPLC chromatogram of the intermediate solid precipitated after the first step of the reaction, which contains 2.62% aniline, 89.45% intermediate, and 7.3% byproduct.

[0068] Figure 10 The image shows the HPLC chromatogram of the mother liquor after the first step of the reaction (2.3 min benzenesulfonic acid, 3.8 min aniline, 4.7 min intermediate), with benzenesulfonic acid content of 25.41%, aniline content of 24.52%, and intermediate content of 40.15%. The reaction in alkaline aqueous solution inevitably leads to the hydrolysis of benzenesulfonyl chloride.

[0069] Figure 11 The image shows the HPLC chromatogram of the solid product precipitated after the second reaction step (4.7 min intermediate, 14.3 min anti-scorching agent E), with an intermediate content of 9.75% and a product content of 86.83%. Furthermore, the aniline remaining in the first reaction step can react with perchloromethanethiol, causing the product to turn yellow and have an irritating odor. The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide by one-pot cooking, characterized in that, The process includes the following steps: adding organic solvent, aniline, and catalyst to a reaction vessel, slowly adding benzenesulfonyl chloride, and then slowly adding an acid-binding agent after the benzenesulfonyl chloride is added. After the acid-binding agent is added, the reaction is maintained at a constant temperature for 1-4 hours to obtain a reaction solution containing the intermediate N-phenylbenzenesulfonamide. The system is then cooled to 0-20°C, and perchloromethanethiol is slowly added. After the perchloromethanethiol is added, the reaction continues for 1-4 hours. Then, water is added to the organic phase, and an appropriate amount of water is added to the organic phase for distillation to recover the organic solvent. The mixture is then filtered to obtain N-phenyl-N-trichloromethanethiol benzenesulfonamide.

2. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide by one-pot cooking as described in claim 1, characterized in that: The organic solvent is one or more of cyclohexane, n-hexane, dichloromethane, dichloroethane, chloroform, trichloroethylene, and 120# solvent oil, and the mass ratio of the organic solvent to aniline is 7-15:

1.

3. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide by one-pot cooking as described in claim 1, characterized in that: The catalyst is one or more of 4-dimethylaminopyridine, tetrabutylammonium bromide, and tetrabutylammonium chloride, and its amount is 0.1 to 1% of the mass of aniline.

4. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide by one-pot cooking as described in claim 3, characterized in that: The organic solvent is dichloromethane, and the mass ratio of dichloromethane to aniline is 7-10:1; the catalyst is 4-dimethylaminopyridine.

5. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide by one-pot cooking as described in claim 1, characterized in that: The benzenesulfonyl chloride is fed at a temperature of 0–20°C, and after the benzenesulfonyl chloride is fed, the temperature is kept at 20–25°C for 1–4 hours. The molar ratio of aniline to benzenesulfonyl chloride is 1:1.0–1.

2.

6. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide by one-pot cooking as described in claim 1, characterized in that: The acid-binding agent is pyridine, triethylamine, or 3-methylpyridine, and the molar ratio of aniline to the acid-binding agent is 1:2.0 to 3.0; the acid-binding agent is added over a period of 1 to 4 hours.

7. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide by one-pot cooking as described in claim 1, characterized in that: The molar ratio of aniline to perchloromethanethiol is 1:1.0 to 1.5, the feeding temperature of perchloromethanethiol is 0 to 20°C, and the feeding time is 1 to 5 hours.

8. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide by one-pot cooking as described in claim 7, characterized in that: The molar ratio of aniline to perchloromethanethiol is 1:1.1 to 1.2, the feeding temperature of perchloromethanethiol is 5 to 10°C, and the feeding time is 2 to 3 hours.

Images