Method for efficiently and continuously preparing methylsulfonyl chloride

Abstract

The invention discloses a method for efficiently and continuously preparing methylsulfonyl chloride, which is a process technology for preparing methylsulfonyl chloride by continuously performing oxychlorination on dimethyl disulfide in a reactor with a specific structure by taking dimethyl disulfide as a raw material, chlorine as a chlorinating agent and hydrochloric acid and methylsulfonyl chloride or chloroform as a solvent. The method is low in sulfur value loss, high in product selectivity, mild in condition, short in reaction time, high in product production efficiency, convenient to realize automation and safe and stable in operation, and is a process suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of fine chemicals, in particular to a method for efficiently and continuously preparing methanesulfonyl chloride. Background Art

[0002] Methanesulfonyl chloride is an important intermediate for medicines, pesticides and fine chemicals. Its downstream product, methanesulfonic acid, is an important emerging electroplating solution in the electroplating industry.

[0003] The equation for preparing methylsulfonyl chloride using dimethyl disulfide as raw material is as follows:

[0004]

[0005] Hydrolysis side reaction

[0006] CH3SO2Cl+H2O→CH3SO3H+HCl

[0007] Main impurity side reaction

[0008] CH3SO3Cl+Cl2→ClCH2SO3Cl+HCl

[0009] The reaction is a highly exothermic system, with a heat release of about 651 kJ per mol of reaction, and 8 mol of hydrogen chloride is released; the suitable temperature for industrial batch reaction is 20-30°C; both the raw material dimethyl disulfide and the product methylsulfonyl chloride are insoluble in hydrochloric acid, so the system is a liquid-liquid-gas three-phase reaction system. Therefore, the batch reaction has the following obvious disadvantages:

[0010] The heat transfer area per unit volume of material is small, less than 2.5M2 / M3, resulting in slow chlorine flow rate and long reaction process, with a batch reaction taking 20-25 hours. This results in low production capacity and a high hydrolysis rate of the product methylsulfonyl chloride.

[0011] With an annual production capacity of 10,000 tons of methylsulfonyl chloride, the by-product of 30% hydrochloric acid is more than 45,000 tons. Moreover, these hydrochloric acids contain trace amounts of dimethyl disulfide with an extremely low olfactory threshold, which results in low customer acceptance of the by-product hydrochloric acid. The outlet of the by-product hydrochloric acid is restricted, causing environmental pollution and limiting the release of methylsulfonyl chloride production capacity.

[0012] To produce 10,000 tons of methylsulfonyl chloride per year, more than 20 single reactors are needed. Together with supporting facilities, the equipment occupies an area of ​​at least 3,000 square meters.

[0013] The reaction equipment has a large online liquid holding capacity, with an annual production capacity of 10,000 tons of methylsulfonyl chloride and an online liquid holding capacity of up to 60M3. The raw material dimethyl disulfide is flammable and explosive, and the product methylsulfonyl chloride is highly toxic. Such a large liquid holding capacity poses a huge safety hazard.

[0014] Patent CN02123805 (application number) discloses a method for producing high-purity methylsulfonyl chloride by an intermittent process. Although many safeguard measures have been taken to reduce the above-mentioned disadvantages to a certain extent, it also brings about the disadvantages of complex process, cumbersome equipment, and high labor intensity.

[0015] Predecessors have conducted relatively extensive research on the continuous process. For example, JP 2003342252, DE1811768, US3600136 authorized in 1971, US3993692 authorized in 1976, and patent EP675106 authorized in 1995 have all failed to well solve the drawbacks existing in the batch reaction and have problems in practical applications. There are no reports on industrial applications.

[0016] Patent CN201410020731 (application number) discloses a method for continuously producing high-purity methylsulfonyl chloride by using a rising film reactor. Although this kind of equipment has quite an improvement compared with the previous reaction methods, it has solved the previous problems to a considerable extent and has quite an advantage. However, its stability is poor, starting and stopping are inconvenient, it takes a considerable amount of time from starting up to the system being stable, and a lot of intermediate materials are generated. A very small change in factors has a great impact on the system stability, and occasionally there is a phenomenon of pulse fluctuation, which causes great damage to the equipment.

[0017] In view of the current problems in the production of methylsulfonyl chloride, the present invention proposes a method for efficiently and continuously preparing methylsulfonyl chloride. Summary of the Invention

[0018] To solve the defects existing in the prior art, the present invention proposes a method for efficiently and continuously preparing methylsulfonyl chloride.

[0019] The present invention includes the following steps:

[0020] S1. Using dimethyl disulfide as a substrate, the solvent for dissolving the substrate dimethyl disulfide is chloroform or methylsulfonyl chloride. The mass ratio of the chloroform or methylsulfonyl chloride solvent to dimethyl disulfide is 0 - 5:1. Hydrochloric acid is the source of the solvent and the water required for the reaction, and chlorine gas or liquid chlorine is the oxidant. Methylsulfonyl chloride is continuously oxidized in a microchannel continuous flow reactor with different structures; when the oxidant is chlorine gas, the molar ratio of chlorine gas to dimethyl disulfide is 1.0 - 2:1; the concentration of the hydrochloric acid is 30 - 40%, and the mass ratio of hydrochloric acid to the substrate dimethyl disulfide is 1 - 20:1; the chlorine gas or liquid chlorine is first mixed with hydrochloric acid and then reacts with the dimethyl disulfide solution;

[0021] S2. At a certain temperature, hydrochloric acid is continuously pumped into the microchannel reactor module by a metering pump, and chlorine gas or liquid chlorine is continuously introduced. After being fully mixed with hydrochloric acid in the reactor, a chloroform solution of dimethyl disulfide is continuously pumped into the reactor by a metering pump for reaction. The reaction temperature is controlled by an external circulation heat exchange system; the pressure of the chlorine gas or liquid chlorine entering the feed port of the reactor is 1 - 15 bar; the reaction temperature is 0 - 100 °C; this reaction system is a liquid-liquid-gas three-phase reaction system, different from the two-phase system. The inventor unexpectedly found that the mixing order of the two materials has a huge impact on the reaction result.

[0022] S3. Control the feed ratio by the method of feeding through a flow meter and a metering pump, and control the residence time of the material mixing reaction by controlling the flow rate and changing the microchannel length of the microchannel reactor module; the reaction residence time is 0.1 - 30 s;

[0023] S4. After the reaction is completed, the material flows out from the end of the reactor, undergoes gas-liquid separation. The gas is washed and absorbed to produce by-product hydrochloric acid, and the liquid is extracted with chloroform, the solvent is concentrated and recovered, and the product is obtained by rectification. The solvent is recycled, or the liquid is directly separated into layers. The oil layer is rectified to obtain the product methylsulfonyl chloride, and the aqueous phase is recycled back to the reaction system as hydrochloric acid.

[0024] The method for preparing methylsulfonyl chloride using a microchannel reactor, characterized in that the oxidant in step S1 is chlorine gas, and the molar ratio of chlorine gas to dimethyl disulfide is 1.0 - 1.1:1.

[0025] The method for preparing methylsulfonyl chloride using a microchannel reactor, characterized in that the pressure of the chlorine gas or liquid chlorine entering the feed port of the reactor in step S2 is 5 - 10 bar.

[0026] The method for preparing methylsulfonyl chloride using a microchannel reactor, characterized in that the mass ratio of the chloroform or methylsulfonyl chloride solvent to dimethyl disulfide in step S1 is 0.5 - 2:1.

[0027] The method for preparing methylsulfonyl chloride using a microchannel reactor, characterized in that the mass ratio of the hydrochloric acid to the substrate dimethyl disulfide in step S1 is 2 - 5:1.

[0028] The method for preparing methylsulfonyl chloride using a microchannel reactor, characterized in that the reaction temperature in step S2 is 0 - 60 °C.

[0029] The method for preparing methylsulfonyl chloride using a microchannel reactor, characterized in that the reaction residence time in step S3 is 3 - 10 s.

[0030] The described method for preparing methylsulfonyl chloride using a microchannel reactor is characterized in that the liquid obtained by gas-liquid separation of the reaction liquid in step S4 is subjected to solvent extraction, and the extract is concentrated and rectified to obtain the product, or the liquid obtained by gas-liquid separation of the reactants directly separates the oil layer, and the oil layer is rectified to obtain the product. The extraction solvent is selected from one or more of chloroform, dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene.

[0031] The described method for preparing methylsulfonyl chloride using a microchannel reactor is characterized in that all the reaction processes in steps S1-S3 are continuously carried out in a microchannel reactor module with a specific structure. The microchannel reactor module is divided into an enhanced mass transfer structure and a straight channel structure. Among them, the micro-structure of the enhanced mass transfer module is a diamond structure, a heart structure, a triangular structure, or a circular structure, and the micro-structure of the straight channel module is a cylindrical structure or a rectangular structure.

[0032] The beneficial effects of the present invention are:

[0033] 1. The heat transfer area per unit volume of the microchannel equipment used is 2500 M2 / M3, which is 1000 times that of the kettle-type equipment, and the mass transfer coefficient is 1000 times that of the kettle-type equipment.

[0034] 2. The reaction time is short, only 3-10 s, the production capacity is large, and the production efficiency is high. The hydrolysis rate of methylsulfonyl chloride is low, less than 0.5%.

[0035] 3. The equipment occupies a small area. For an annual production capacity of 10,000 tons of methylsulfonyl chloride, only less than 30 M2 of reaction area is required. Due to the thoroughness of the reaction, the post-treatment equipment and process are also simplified.

[0036] 4. The holdup is small. For an annual production capacity of 10,000 tons of methylsulfonyl chloride, the holdup of the reaction system is only less than 500 L, which is less than one percent of the holdup of the traditional kettle type.

[0037] 5. This reaction system is convenient for realizing automatic control, ensuring safety in production in essence, making the product quality stable, having a low labor cost, only requiring a heat exchange medium with a temperature almost the same as the reaction temperature, having high heat exchange efficiency and low power consumption.

[0038] 6. The reaction conversion is thorough, and both dimethyl disulfide and chlorine are well utilized. The content of dimethyl disulfide and chlorine in the by-product hydrochloric acid has been reduced to extremely low limits; the selectivity is good, and both the hydrolysis reaction and the side reaction of chloromethylsulfonyl chloride are effectively inhibited, showing obvious advantages both economically and in terms of essential environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention.

[0040] In the accompanying drawings:

[0041] Figure 1 is a schematic process flow diagram of the present invention;

[0042] Figure 2 is a schematic structural diagram of the continuous flow tubular reactor device used in the present invention;

[0043] Figure 3 is a schematic structural diagram of the continuous flow microchannel reactor module of the present invention;

[0044] Figure 4 is a schematic structural diagram of the mass transfer enhanced and straight channel microstructures of the microchannel module of the present invention.

[0045] In the figure: 1, hydrochloric acid solution raw material tank; 2, chlorine vaporizer; 3, hydrochloric acid solution metering pump; 4, dimethyl disulfide solution raw material tank; 5, dimethyl disulfide solution metering pump; 6, premixing zone; 7, reaction zone; 8, cooling zone; 9, product collection zone; 10, tail gas caustic soda absorption zone. Specific embodiments

[0046] The following describes the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for explaining and illustrating the present invention and are not used to limit the present invention.

[0047] Example: As Figure 1 , Figure 2 , Figure 3 , Figure 4 shown, the method for efficiently and continuously preparing methylsulfonyl chloride of the present invention includes the following steps:

[0048] S1. Using dimethyl disulfide as the substrate, chloroform as the solvent for dissolving dimethyl disulfide, hydrochloric acid as the solvent and the source of water required for the reaction, and chlorine gas or liquid chlorine as the oxidant, continuously oxidize to prepare methylsulfonyl chloride in a microchannel continuous flow reactor with different structures;

[0049] S2. At a certain temperature, hydrochloric acid is continuously pumped into the microchannel reactor module by a metering pump, and chlorine gas or liquid chlorine is continuously introduced. After being fully mixed with hydrochloric acid in the reactor, the chloroform solution of dimethyl disulfide is continuously pumped into the reactor by a metering pump for reaction, and the reaction temperature is controlled by an external circulation heat exchange system;

[0050] S3. Control the feed ratio by the method of feeding through a flow meter and a metering pump, and control the residence time of the material mixing reaction by controlling the flow rate and changing the microchannel length of the microchannel reactor module;

[0051] S4. After the reaction is completed, the material flows out from the end of the reactor, undergoes gas-liquid separation, the gas is washed and absorbed to produce by-product hydrochloric acid, the liquid is extracted with chloroform, the solvent is concentrated and recovered, and the product is obtained by rectification. The solvent is recycled, or the liquid is directly separated into layers, the oil layer is rectified to obtain the product methylsulfonyl chloride, and the aqueous phase is recycled back to the reaction system as hydrochloric acid.

[0052] Among them, the oxidant described in step S1 is chlorine gas, and the molar ratio of chlorine gas to dimethyl disulfide is 1.0 - 2:1, preferably 1.0 - 1.1:1.

[0053] Among them, the pressure of the chlorine gas or liquid chlorine entering the feed port in the reactor in step S2 is 1 - 15 bar, preferably 5 - 10 bar.

[0054] Among them, the chloroform described in step S1 is a solvent for dissolving dimethyl disulfide. The solvent for dissolving the substrate dimethyl disulfide is one or more of chloroform, dichloroethane, dichloromethane, carbon tetrachloride, chlorobenzene, and methylsulfonyl chloride. Preferably, the mass ratio of the solvent of chloroform or methylsulfonyl chloride to dimethyl disulfide is 0 - 5:1, preferably 0.5 - 2:1.

[0055] Among them, the concentration of the hydrochloric acid described in step S1 is 0 - 40%, preferably 30 - 40%. The mass ratio of hydrochloric acid to the substrate dimethyl disulfide is 1 - 20:1, preferably 2 - 5:1.

[0056] Among them, the reaction temperature in step S2 is 0 - 100 °C, preferably the reaction temperature is 0 - 60 °C, and more preferably 10 - 50 °C.

[0057] Among them, the reaction residence time in step S3 is 0.1 - 30 s, preferably the residence time is 3 - 10 s.

[0058] Among them, for the liquid obtained by gas-liquid separation of the reaction solution in step S4, after solvent extraction, the extract is concentrated and rectified to obtain the product, or the liquid obtained by gas-liquid separation of the reactants is directly separated into the oil layer, and the oil layer is rectified to obtain the product. The extraction solvent can be one or more of chloroform, dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene.

[0059] Among them, the chlorine gas or liquid chlorine in step S1 is first mixed with hydrochloric acid and then reacts with the dimethyl disulfide solution.

[0060] Among them, the entire reaction process in steps S1 - S3 is continuously carried out in a microchannel reactor module with a specific structure. The microchannel reactor module is divided into an enhanced mass transfer type structure and a straight channel structure. Among them, the microstructures of the enhanced mass transfer type module include a diamond structure, a heart shape structure, a triangular structure, and a circular structure, and the microstructures of the straight channel module include a cylindrical structure and a rectangular structure.

[0061] Working principle:

[0062] The present invention uses a microchannel reactor. The microchannel continuous flow reactor is a new generation of reactor that has been newly developed in recent years and gradually applied to production, with excellent heat transfer, mass transfer, and mixing performance. For the liquid-liquid-gas three-phase highly exothermic system for the preparation of methylsulfonyl chloride, the microchannel reactor is the most suitable, which can simultaneously solve the problems of mixing, mass transfer, and heat transfer of various previous reactors, and realize the good application of the microchannel reactor in the process of preparing methylsulfonyl chloride from dimethyl disulfide.

[0063] The specific embodiments are as follows:

[0064] Example 1

[0065] (1) Refer to Figure 2 Determine the connection mode of the tubular reactor. The microchannel type is (3b + 3b + 3a) enhanced channel structure module + enhanced channel structure module + direct current channel module, and the heat exchange medium is high and low temperature heat transfer oil.

[0066] (2) The raw material dimethyl disulfide is dissolved in 1 times the mass of chloroform. The mixed solution enters the reactor at a flow rate of 8 g / min, 36% hydrochloric acid enters the reactor at a flow rate of 8 g / min, chlorine enters at a flow rate of 560 ml / min, the chlorine feed port pressure is 8.5 bar, the reaction temperature is 40 °C, and it is cooled to 10 °C and enters the receiving area. It runs continuously for 10 hours, and gas-liquid separation is carried out. The received liquid is layered, the water layer is extracted with chloroform, the extraction liquids are combined, concentrated, and rectified to obtain 5780 g of product with a purity of 99.8% and a yield of 99%. It is analyzed that about 0.5% of the yield is lost in the rectification process, about 0.2% of the yield is hydrolyzed into methylsulfonic acid, 0.1% of the yield is lost in the by-product hydrogen chloride, and no reduced sulfide is detected.

[0067] The liquid holdup of the reactor system is about 200 ml, the residence time is about 3 s, and the floor area of the reaction system is less than 0.4 M2.

[0068] For this set of reactors of this scale, calculated according to an annual operation of 7200 hours, the annual output of methylsulfonyl chloride is about 4.16 tons.

[0069] Example 2

[0070] (1) Refer to Figure 2 Determine the connection mode of the tubular reactor. The microchannel type is (3a + 3b + 3a) direct current channel module + enhanced channel structure module + direct current channel module, and the heat exchange medium is high and low temperature heat transfer oil.

[0071] (2) The raw material dimethyl disulfide is dissolved in chloroform with a mass ratio of 2:1. The mixed solution enters the reactor at a flow rate of 9 g / min, 36% hydrochloric acid enters the reactor at a flow rate of 15 g / min, and chlorine gas enters at a flow rate of 460 ml / min. The pressure at the chlorine gas inlet is 8.5 bar, the reaction temperature is 15 °C, and after cooling to 10 °C, it enters the receiving area. It runs continuously for 10 hours, and then gas-liquid separation is carried out. The received liquid is layered, the aqueous layer is extracted with chloroform, the extracted liquids are combined, concentrated, and rectified to obtain 4300 g of product with a purity of 99.8% and a yield of 98%. It is analyzed that about 0.5% of the yield is lost during the rectification process, about 0.3% of the yield is hydrolyzed into methylsulfonic acid, about 0.9% of the yield forms chloromethylsulfonyl chloride, 0.1% of the yield is lost in the by-product hydrogen chloride, and the content of dimethyl disulfide in the by-product hydrogen chloride is about 50 ppm.

[0072] The liquid holdup in the reactor system is about 200 ml, the residence time is about 4 s, and the floor area of the reaction system is less than 0.4 m².

[0073] For this set of reactors of this scale, calculated based on an annual operation of 7200 hours, the annual output of methylsulfonyl chloride is about 3.1 tons.

[0074] Example 3

[0075] (1) Refer to Figure 2 Determine the connection method of the tubular reactor. The microchannel type is (3b + 3b + 3a) enhanced channel structure module + enhanced channel structure module + direct flow channel module, and the heat exchange medium is high and low temperature heat transfer oil.

[0076] (2) The raw material dimethyl disulfide is dissolved in chloroform with a mass ratio of 1:1. The mixed solution enters the reactor at a flow rate of 8 g / min, 36% hydrochloric acid enters the reactor at a flow rate of 8 g / min, and chlorine gas enters at a flow rate of 560 ml / min. Different from Example (1), the dimethyl disulfide solution is fed in the premixing area, and chlorine gas is fed in the reaction area. The pressure at the chlorine gas inlet is 8.5 bar, the reaction temperature is 40 °C, and after cooling to 10 °C, it enters the receiving area. It runs continuously for 1 hour, and then gas-liquid separation is carried out. The received liquid is layered, the aqueous layer is extracted with chloroform, the extracted liquids are combined, concentrated, and rectified to obtain 516 g of product with a purity of 98.5% and a yield of 88%.

[0077] Example 4

[0078] (1) Refer to Figure 2 Determine the connection method of the tubular reactor. The microchannel type is (3b + 3b + 3a) enhanced channel structure module + enhanced channel structure module + direct flow channel module, and the heat exchange medium is high and low temperature heat transfer oil.

[0079] (2) The raw material dimethyl disulfide is dissolved in chloroform with a mass ratio of 1:1. The mixed solution enters the reactor at a flow rate of 8 g / min, 36% hydrochloric acid enters the reactor at a flow rate of 8 g / min, and chlorine gas enters at a flow rate of 560 ml / min. Different from Example (1), the dimethyl disulfide solution is fed in the premixing zone, and hydrochloric acid is fed in the reaction zone. The pressure at the chlorine gas inlet is 8.5 bar, the reaction temperature is 40 °C, and after cooling to 10 °C, it enters the receiving zone. It runs continuously for 1 hour, and gas-liquid separation is carried out. The received liquid is stratified, the aqueous layer is extracted with chloroform, the extracted liquids are combined, concentrated, and rectified to obtain 454 g of product with a purity of 96.5% and a yield of 77.6%.

[0080] In this example, there is a spark flash explosion phenomenon in the premixing zone.

[0081] In summary, the present invention completely solves the problems in the existing production methods, such as uneven mixing, insufficient reaction of raw materials, high residual content of oxidizable substances in the product sulfonyl chloride, and serious sulfur value loss in the by-product hydrogen chloride. It also solves the problems of difficult heat removal of reaction heat caused by external cooling of the reactor, high reaction temperature, many side reactions, and poor selectivity. Moreover, the microchannel reactor adopted in the present invention has a small liquid holdup in the system, high safety and good stability compared with the falling film reactor. And due to the good mixing and mass transfer effect, the utilization rate of chlorine gas is greatly improved, chlorine gas can be fed in an equivalent amount, and the residual chlorine and residual reduced sulfur in the reaction tail gas can be effectively controlled at the same time.

[0082] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for efficiently and continuously preparing methylsulfonyl chloride, characterized in that, It includes the following steps: S1. Using dimethyl disulfide as the substrate, the solvent for dissolving the substrate dimethyl disulfide is chloroform or methylsulfonyl chloride, the mass ratio of the chloroform or methylsulfonyl chloride solvent to dimethyl disulfide is 0 - 5:1, hydrochloric acid is the source of the solvent and the water required for the reaction, chlorine gas or liquid chlorine is the oxidant, and methylsulfonyl chloride is continuously prepared by continuous oxidation in a microchannel continuous flow reactor with different structures; when the oxidant is chlorine gas, the molar ratio of chlorine gas to dimethyl disulfide is 1.0 - 2:1; the concentration of the hydrochloric acid is 30 - 40%, and the mass ratio of hydrochloric acid to the substrate dimethyl disulfide is 1 - 20:1; the chlorine gas or liquid chlorine is first mixed with hydrochloric acid and then reacts with the dimethyl disulfide solution; S2. At a certain temperature, hydrochloric acid is continuously pumped into the microchannel reactor module by a metering pump, chlorine gas or liquid chlorine is continuously introduced, after being fully mixed with hydrochloric acid in the reactor, the chloroform solution of dimethyl disulfide is continuously pumped into the reactor by a metering pump for reaction, and the reaction temperature is controlled by an external circulation heat exchange system; the pressure of the chlorine gas or liquid chlorine entering the feed port of the reactor is 1 - 15 bar; the reaction temperature is 0 - 100 °C; S3. Control the feed ratio by the method of feeding through a flowmeter and a metering pump, and control the residence time of the material mixing reaction by controlling the flow rate and changing the microchannel length of the microchannel reactor module; the reaction residence time is 0.1 - 30 s; S4. After the reaction is completed, the material flows out from the end of the reactor, undergoes gas-liquid separation, the gas is washed and absorbed to produce by-product hydrochloric acid, the liquid is extracted with chloroform, the solvent is concentrated and recovered, and the product is obtained by rectification, the solvent is recycled, or the liquid is directly stratified, the oil layer is rectified to obtain the product methylsulfonyl chloride, and the aqueous phase is recycled back to the reaction system as hydrochloric acid.

2. The method for efficiently and continuously preparing methylsulfonyl chloride according to claim 1, characterized in that, In step S1, the oxidant is chlorine gas, and the molar ratio of chlorine gas to dimethyl disulfide is 1.0 - 1.1:

1.

3. The method for efficiently and continuously preparing methylsulfonyl chloride according to claim 1, wherein In step S2, the pressure of the chlorine gas or liquid chlorine entering the feed port of the reactor is 5 - 10 bar.

4. A method for efficiently and continuously preparing methylsulfonyl chloride according to claim 1, characterized in that, In step S1, the mass ratio of the chloroform or methylsulfonyl chloride solvent to dimethyl disulfide is 0.5 - 2:

1.

5. The method for efficiently and continuously preparing methylsulfonyl chloride according to claim 1, characterized in that, In step S1, the mass ratio of hydrochloric acid to the substrate dimethyl disulfide is 2 - 5:

1.

6. The method for efficiently and continuously preparing methylsulfonyl chloride according to claim 1, wherein In step S2, the reaction temperature is 0 - 60 °C.

7. A method for efficiently and continuously preparing methylsulfonyl chloride according to claim 1, characterized in that, In step S3, the reaction residence time is 3 - 10 s.

8. A method for efficiently and continuously preparing methylsulfonyl chloride according to claim 1, characterized in that, For the liquid obtained by gas-liquid separation of the reaction solution in step S4, after solvent extraction, the extract is concentrated and rectified to obtain the product, or the liquid obtained by gas-liquid separation of the reactant is directly separated to obtain the oil layer, and the oil layer is rectified to obtain the product; the extraction solvent is selected from one or more of chloroform, dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene.

9. A method for efficiently and continuously preparing methylsulfonyl chloride according to any one of claims 1-8, characterized in that, All the reaction processes in steps S1 - S3 are continuously carried out in a microchannel reactor module with a specific structure. The microchannel reactor module is divided into an enhanced mass transfer type structure and a straight channel structure. Among them, the micro-structure of the enhanced mass transfer type module is a rhombus structure, a heart shape structure, a triangular structure, or a circular structure, and the micro-structure of the straight channel module is a cylindrical structure or a rectangular structure.

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