N-phenyl-N-trichloromethylthio benzenesulfonamide and preparation method thereof

Abstract

The invention provides N-phenyl-N-trichloromethylthio benzenesulfonamide and a preparation method thereof, and belongs to the technical field of organic synthesis, and the preparation method comprises the following steps: (1) in the presence of an organic solvent and an acid capturing agent, reacting aniline with trichlorochloromethane to generate an N-phenyl trichloromethylthiamine intermediate; and (2) under an in-situ condition, enabling the N-phenyl trichloromethylthiamine intermediate to react with benzene sulfonyl chloride in a weakly alkaline environment, so as to obtain the N-phenyl-N-(trichloromethylthio) benzene sulfonamide. According to the N-phenyl-N-trichloromethylthio benzenesulfonamide and the preparation method thereof, the process steps are simplified, and the purposes of high product yield, product appearance improvement and less production wastewater are achieved.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, specifically to an N-phenyl-N-trichloromethylthiobenzenesulfonamide and its preparation method. Background Technology

[0002] During rubber processing, rubber compounds are prone to premature cross-linking before reaching the set conditions, a condition commonly known as scorching. Scorching not only shortens processing time but also leads to decreased product performance and increased scrap rates. With the development of modern processes towards higher temperatures and speeds, and the application of components such as reinforcing resins, resorcinol-hexamethylenetetramine systems, and highly reactive carbon black, the scorching problem has become increasingly prominent.

[0003] In existing technologies, scorching is often suppressed by adjusting the vulcanization system. However, this method requires sophisticated equipment and process conditions, is complex to operate, and is not conducive to widespread adoption. In contrast, adding an anti-scorching agent to the formulation is a simple and effective measure that can extend the safe processing time while maintaining product performance.

[0004] N-Phenylacetyl-N-(trichloromethylthio)benzenesulfonamide, as a novel organic sulfur compound, can effectively delay early reactions in vulcanization systems, significantly prolong the scorch time of rubber compounds, and improve the safety of processing. Secondly, the trichloromethylthio substituent group possesses strong thermal stability and steric hindrance, enabling the compound to maintain good anti-scorch effects even under high-temperature, rapid processing conditions. Thirdly, this compound has wide applicability and can be used in various rubber formulation systems, not only avoiding adverse effects on product performance but also improving the mechanical properties and aging resistance of vulcanized rubber. However, current processes using N-phenyl-N-(trichloromethylthio)benzenesulfonamide generate large amounts of wastewater with high COD levels, and the transportation and transshipment of the raw material, perchloromethanethiol, pose significant safety risks. Therefore, developing novel anti-scorch agent processes is of great importance.

[0005] Current methods typically use aniline, benzenesulfonyl chloride, and perchloromethanethiol as raw materials. The process involves first reacting aniline with benzenesulfonyl chloride to form an N-phenylbenzenesulfonamide intermediate, which is then reacted with perchloromethanethiol to obtain N-phenyl-N-(trichloromethylthio)benzenesulfonamide. Existing processes utilize alkaline dissolution for impurity removal and reverse dropping to improve purity and color. However, these processes still generate large amounts of wastewater with high COD values, hindering environmental protection and industrial application. Summary of the Invention

[0006] In view of this, the present invention provides an N-phenyl-N-trichloromethylthiobenzenesulfonamide and its preparation method, which simplifies the process steps, achieves high product yield, improves product appearance, and reduces production wastewater.

[0007] To achieve the above objective, the present invention provides a method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide, comprising the following steps: (1) In the presence of an organic solvent and an acid scavenger, aniline is reacted with trichlorothiomethyl ... (2) Under in-situ conditions, the N-phenyltrichloromethylthioamine intermediate was reacted with benzenesulfonyl chloride in a weakly alkaline environment to obtain N-phenyl-N-(trichloromethylthio)benzenesulfonamide.

[0008] Optionally, the organic solvent includes one or more of dichloromethane, chloroform, 120# solvent oil, and carbon tetrachloride.

[0009] Optionally, the acid scavenger is an organic base, which is one of pyridine, triethylamine, and diisopropylethylamine.

[0010] Optionally, in step (1), the reaction temperature of aniline with trichlorothiochloromethane is -10~15℃ and the time is 1~3h.

[0011] Optionally, in step (2), the reaction temperature of the N-phenyltrichloromethylthioamine intermediate with benzenesulfonyl chloride in a weakly alkaline environment is -5~30℃, and the time is 1~3h.

[0012] Optionally, the molar ratio of aniline to chloroform is (0.8~1.2):1.

[0013] Optionally, the molar ratio of benzenesulfonyl chloride to aniline is (1.0~1.5):1.

[0014] Optionally, the concentration of aniline in the organic solvent is 10-21 wt%.

[0015] Optionally, the method further includes the following steps: adding an alkaline aqueous solution to neutralize the byproduct hydrogen chloride in step (1), wherein the molar ratio of aniline to base is 1:(1~1.5).

[0016] To achieve the above objectives, the present invention also provides a method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide, which yields N-phenyl-N-trichloromethylthiobenzenesulfonamide.

[0017] The above-described technical solution of the present invention has at least the following beneficial effects: 1. Simplified process: The entire preparation process can be carried out in situ, avoiding the separation and purification of intermediates in traditional processes, reducing steps and shortening the process flow; 2. Improved yield and purity: Reduced intermediate losses significantly improved the yield and purity of the target product, and improved the product's appearance; 3. Environmentally friendly: Wastewater discharge is reduced by about 90%, COD index drops significantly, effectively reducing environmental burden. Attached Figure Description

[0018] Figure 1 This is a high-performance liquid chromatogram of the product in Example 1 of the present invention; Figure 2 This is a high-performance liquid chromatogram of the product in Example 2 of the present invention; Figure 3 This is a high-performance liquid chromatogram of the product in Example 3 of the present invention; Figure 4 This is a high-performance liquid chromatogram of the product in Example 4 of the present invention; Figure 5 This is a high-performance liquid chromatogram of the product in Comparative Example 1 of the present invention; Figure 6 This is a high-performance liquid chromatogram of the product in Comparative Example 2 of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings of the embodiments of the present invention. Figures 1-6 The technical solutions of the embodiments of the present invention will be clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0020] The reaction process of this invention is as follows: Step (1): Aniline reacts with trichlorothioyl chloride Reaction equation: C6H5NH2 + CCl3SCl → C6H5NH–SCCl3 + HCl Product: N-phenyltrichloromethylthionine Step 2: Reaction of the intermediate with benzenesulfonyl chloride Reaction equation: C6H5NH–SCCl3 + C6H5SO2Cl → C6H5N(SCCl3)(SO2C6H5) + HCl Product: N-phenyl-N-(trichloromethylthio)benzenesulfonamide During the reaction, the lone pair of electrons on aniline acts as a nucleophile, attacking the sulfur atom of CCl3SCl to form an N-S bond; simultaneously, a Cl atom leaves. -The formation of HCl and the protonation byproduct of aniline requires neutralization by an acid scavenger. Reason: The S-Cl bond in CCl3SCl has high electronegativity / polarization, and sulfur is sensitive to nucleophiles; aniline, even when incompletely protonated, possesses sufficient nucleophilicity, resulting in high selectivity at low temperatures. The acid scavenger (organic base) immediately neutralizes the generated HCl, preventing aniline from being protonated (and losing its nucleophilicity), thus maintaining a high conversion rate. The nitrogen on the formed NS-substituted product retains its lone pair of electrons, and nitrogen performs a nucleophilic attack on the sulfonyl chloride, forming a (N-SO2-Ph) bond and releasing a Cl- atom. - .

[0021] Example 1 1. In a 250 mL three-necked flask, add 9.3 g (0.1 mol) aniline and 100 mL dichloromethane. Place the mixture under stirring and cool to -5 °C under nitrogen protection. While maintaining stirring, slowly add 15.0 g (0.1 mol) perchloromethanethiol dropwise over 30 min, simultaneously adding 12.1 g (0.12 mol) triethylamine as an acid scavenger. Maintain the reaction temperature between -5 °C and 5 °C for 2 h. TLC analysis showed that aniline was completely converted to the N-phenyltrichloromethanethiamine intermediate, which did not require separation.

[0022] 2. In the same reaction system, slowly add 21.4 g (0.12 mol) benzenesulfonyl chloride, control the temperature at 0-20℃, maintain the system under weakly alkaline conditions, and continue the reaction for 2 h.

[0023] 3. After the reaction is complete, the reaction solution is washed with water, dried with anhydrous sodium sulfate, concentrated under reduced pressure, and then purified by column chromatography to obtain an off-white crystalline product.

[0024] Yield = Actual product mass / Theoretical product mass; Product purity is determined by HPLC.

[0025] The product was analyzed and the following results were obtained: yield 92%, purity 98.5% (HPLC determination, chromatogram shown). Figure 1 The product appears as uniform, off-white crystals.

[0026] Note: This method enables the efficient synthesis of the target compound under mild conditions, avoids intermediate separation steps, improves process efficiency, and effectively improves product appearance.

[0027] Example 2 1. Add 9.3 g (0.1 mol) aniline and 100 mL chloroform to a 250 mL three-necked flask, place under stirring, and cool the reaction system to -5 °C under nitrogen protection. While maintaining stirring, slowly add 15.0 g (0.1 mol) perchloromethylthiol dropwise over 30 min, simultaneously adding 12.1 g (0.12 mol) triethylamine as an acid scavenger. Maintain the reaction temperature between -5 °C and 5 °C for 2 h. TLC analysis showed that aniline was completely converted to the N-phenyltrichloromethylthiamine intermediate, which did not require separation.

[0028] 2. In the same reaction system, slowly add 21.4 g (0.12 mol) benzenesulfonyl chloride, control the temperature at 0~20℃, maintain the system under weakly alkaline conditions, and continue the reaction for 2 h.

[0029] 3. After the reaction is complete, the reaction solution is washed with water, dried with anhydrous sodium sulfate, concentrated under reduced pressure, and then purified by column chromatography to obtain an off-white crystalline product.

[0030] Yield = Actual product mass / Theoretical product mass; Product purity is determined by HPLC.

[0031] The product was analyzed and the following results were obtained: yield 90%, purity 97.8% (HPLC determination, chromatogram shown). Figure 2 The product is a light-colored crystal.

[0032] Note: This demonstrates that the process of the present invention has good adaptability to different solvent systems and can stably obtain the target compound with high yield and high purity.

[0033] Example 3 1. Add 0.1 mol aniline and 120 mL of 120# solvent oil to a 250 mL three-necked flask and cool to -10 °C under nitrogen protection. Slowly add 0.12 mol perchloromethylthiol dropwise while stirring, and simultaneously add 0.15 mol pyridine as an acid scavenger. React for 3 h to obtain N-phenyltrichloromethylthiamine intermediate.

[0034] 2. In the same reaction system, continue to add 0.15 mol of benzenesulfonyl chloride dropwise, control the reaction temperature at 0-25 °C, maintain the weak alkalinity of the system, and continue the reaction for 2 h.

[0035] 3. After the reaction was completed, the reaction solution was washed with water, dried with anhydrous sodium sulfate, concentrated under reduced pressure, and purified by column chromatography to obtain the target product as a white powder.

[0036] Yield = Actual product mass / Theoretical product mass; Product purity is determined by HPLC.

[0037] The product was analyzed and the following results were obtained: yield 89%, purity 97.3% (HPLC determination, chromatogram shown). Figure 3 The product appears as a uniform white powder crystal.

[0038] Note: Under high feed ratio conditions, this method can still maintain high yield and purity, and the reaction system is stable, proving that the method of the present invention has good scalability and is suitable for pilot-scale and industrial production.

[0039] Example 4 1. Add 0.1 mol of aniline to a 250 mL three-necked flask and dissolve it in 80 mL of carbon tetrachloride. Stir at 0 °C. Slowly add 0.1 mol of perchloromethanethiol and simultaneously add 0.12 mol of diisopropylethylamine as an acid scavenger. React for 1.5 h to generate an intermediate.

[0040] 2. In the same reaction system, continue to add 0.13 mol of benzenesulfonyl chloride dropwise, keep the temperature between 5 and 25 °C, maintain weakly alkaline conditions, and react for 2 h.

[0041] 3. The target product, needle-shaped crystals, was obtained by extraction, drying, and vacuum concentration.

[0042] Yield = Actual product mass / Theoretical product mass; Product purity is determined by HPLC.

[0043] The product was analyzed and the following results were obtained: yield 91%, purity 98.0% (HPLC determination, chromatogram shown). Figure 4 The product appears as well-formed white needle-like crystals.

[0044] Note: This method demonstrates that diisopropylethylamine can also serve as a highly efficient acid scavenger, effectively neutralizing the byproduct HCl and maintaining system stability. This further verifies the flexibility and versatility of this process in the selection of acid scavengers.

[0045] Comparative Example 1 1. Add 0.1 mol aniline and 100 mL dichloromethane to a 250 mL three-necked flask, stir at room temperature (about 20 °C), slowly add 0.12 mol benzenesulfonyl chloride, and react for 2 h to generate N-phenylbenzenesulfonamide intermediate.

[0046] 2. The obtained intermediate was reacted with 0.12 mol of perchloromethanethiol under alkaline conditions and heated at 40 °C for 3 h.

[0047] 3. The target product is obtained through conventional extraction, drying and concentration.

[0048] Yield = Actual product mass / Theoretical product mass; Product purity is determined by HPLC.

[0049] The product was analyzed, and the following results were obtained: yield 75%, purity 94.2% (HPLC determination, chromatogram shown). Figure 5 The product is a light yellow solid with poor crystallinity. The wastewater discharge is large, and the COD value is significantly higher, approximately 10 times that of the method described in this invention.

[0050] Note: This traditional method involves intermediate separation and multiple reaction steps, which is complex and inefficient, resulting in decreased yield, unsatisfactory product appearance and quality, and a significant environmental burden.

[0051] Comparative Example 2 1. Add 0.1 mol aniline and 100 mL dichloromethane to a 250 mL three-necked flask, stir at -5 °C, and slowly add 0.1 mol perchloromethanethiol dropwise, without adding an acid scavenger. React for 2 h to obtain the intermediate.

[0052] 2. Continue to add 0.12 mol benzenesulfonyl chloride to the same reaction system, control the temperature at 0-20 °C, and react for 2 hours.

[0053] 3. After post-processing, the target product is obtained.

[0054] Yield = Actual product mass / Theoretical product mass; Product purity is determined by HPLC.

[0055] The product was analyzed and the following results were obtained: yield 68%, purity 90.1% (HPLC determination, chromatogram shown). Figure 6 The product appears as grayish-yellow crystals, accompanied by obvious byproducts.

[0056] Note: Because the byproduct HCl could not be neutralized in time during the reaction, the system became acidified, the reaction rate decreased significantly, and side reactions occurred. This not only reduced the yield and purity but also caused a significant deterioration in the appearance quality of the product, demonstrating the necessity of the acid scavenger in the process of this invention.

[0057] Table 1 summarizes the results of Examples 1-4 and Comparative Examples 1-2.

[0058]

[0059] Depend on Figures 1-6 As can be seen from Table 1, the preparation process in the embodiments of the present invention is simple, the amount of wastewater is less than that in the comparative example, the product yield and purity are higher than those in the comparative example, and the appearance of the product is more aesthetically pleasing than that in the comparative example.

[0060] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide, characterized in that, Includes the following steps: (1) In the presence of an organic solvent and an acid scavenger, aniline is reacted with trichlorothiomethyl ... (2) Under in-situ conditions, the N-phenyltrichloromethylthioamine intermediate was reacted with benzenesulfonyl chloride in a weakly alkaline environment to obtain N-phenyl-N-(trichloromethylthio)benzenesulfonamide.

2. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide according to claim 1, characterized in that, The organic solvent includes one or more of dichloromethane, chloroform, 120# solvent oil, and carbon tetrachloride.

3. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide according to claim 1, characterized in that, The acid-scavenging agent is an organic base, which is one of pyridine, triethylamine, and diisopropylethylamine.

4. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide according to claim 3, characterized in that, The molar ratio of aniline to organic base is 1:(1~1.5).

5. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide according to claim 1, characterized in that, In step (1), the reaction temperature of aniline with trichlorothiochloromethane is -10~15℃ and the time is 1~3h.

6. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide according to claim 1, characterized in that, In step (2), the reaction temperature of the N-phenyltrichloromethylthioamine intermediate with benzenesulfonyl chloride in a weakly alkaline environment is -5~30℃, and the time is 1~3h.

7. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide according to claim 1, characterized in that, The molar ratio of aniline to chloromethane trichlorothiocyanate is (0.8~1.2):

1.

8. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide according to claim 1, characterized in that, The molar ratio of benzenesulfonyl chloride to aniline is (1.0~1.5):

1.

9. The method for preparing N-phenyl-N-trichloromethylthiobenzenesulfonamide according to claim 1, characterized in that, The concentration of aniline in the organic solvent is 10-21 wt%.

10. An N-phenyl-N-trichloromethylthiobenzenesulfonamide prepared by the method of any one of claims 1-9.

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