A process for the preparation of methanesulfonic acid

Abstract

The application provides a preparation method of methyl sulfonic acid, which is obtained by reacting raw material dimethyl disulfide with nitrogen oxide, air and water in a certain proportion. The method has high raw material utilization rate, is green and environment-friendly, and is easy to be industrialized. By controlling the content of methyl methyl sulfonate and 1-methyl-2-((methylsulfonyl) methyl) disulfane in the dimethyl disulfide, the colority of the separated product is lower, and the melting range of the product is narrower.

Description

Technical Field

[0001] This invention belongs to the field of alkyl sulfonic acid synthesis, specifically relating to a method for preparing methanesulfonic acid. Background Technology

[0002] Methanesulfonic acid, also known as methanesulfonic acid or methanesulfonic acid (MSA), has shown unique applications in the manufacture of circuit boards for electronic products in recent years, and its use in the electroplating industry is becoming increasingly widespread. Reports on the application of methanesulfonic acid and its salt systems in electroplating are increasing year by year, and the market is growing annually. Methanesulfonic acid and its salts have unique uses as main salts in brush plating of copper, zinc, tin, and cadmium. For example, copper methanesulfonate in brush plating solutions has two types: acidic high-speed copper and high-alkaline copper, which exhibit excellent performance and wide applications, unmatched by other copper salts. Cadmium methanesulfonate is mainly used for electroplating low-hydrogen embrittlement cadmium on ultra-high strength steel, and is widely used in the aerospace industry. In addition, methanesulfonic acid is also an important raw material in pharmaceuticals, pesticides, and chemicals. Methanesulfonic acid is a catalyst for esterification and polymerization reactions, and its uses are also very extensive in inks and coatings as a quick-setting agent.

[0003] In patents US4239696 and US3392095, methanesulfonic acid can be produced by oxidizing methanethiol or dimethyl disulfide with hydrogen peroxide, but the recycling of large amounts of acid and alkali wastewater and exhaust gas emissions is a serious problem.

[0004] Patent document US6531629 describes a method for preparing methanesulfonic acid by direct catalytic oxidation of thiols or dimethyl disulfide with nitric acid. Although this method can satisfactorily produce methanesulfonic acid by catalytic oxidation of methanethiol and dimethyl disulfide with nitric acid, the reaction conditions are mild, but the reaction process is difficult to control, resulting in serious air and water pollution, inconvenient storage and transportation, high raw material prices, which is not conducive to large-scale safe production by small and medium-sized enterprises and does not conform to my country's green, environmentally friendly and sustainable development strategy for chemicals. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing methanesulfonic acid, which has the characteristics of mild reaction conditions, green and environmentally friendly, and easy to industrialize.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A method for preparing methanesulfonic acid involves reacting dimethyl disulfide with nitrogen oxides, air, and water in a certain proportion, without requiring additional catalyst.

[0008] In this invention, the nitrogen oxide is nitric oxide, nitrogen dioxide, or a mixture of the two;

[0009] In this invention, the reaction pressure is 0-2.0 MPaG, and the reaction temperature is 0-200℃, preferably 50-150℃;

[0010] In the method described in this invention, the raw material dimethyl disulfide contains methyl methanesulfonate and / or 1-methyl-2-((methanesulfonyl)methyl)disulfide, and it is necessary to control the total content of methyl methanesulfonate and 1-methyl-2-((methanesulfonyl)methyl)disulfide in the raw material to be 1-1000 ppm.

[0011]

[0012] Methyl methanesulfonate 1-methyl-2-((methanesulfonyl)methyl)dithion

[0013] The main sources of impurities are: 1) those generated during the production of dimethyl disulfide; and 2) those resulting from the transformation of substances during the storage of dimethyl disulfide.

[0014] Methods for controlling impurity content can include, but are not limited to, separation methods such as distillation, extraction, and crystallization. Lowering impurity levels to even lower concentrations will increase separation energy consumption and result in raw material loss.

[0015] During the reaction, dimethyl disulfide is oxidized to generate methanesulfonic acid and thiomethyl radicals. Under the reaction conditions, thiomethyl radicals readily react with methanesulfonic acid to form a polymer of methanesulfonic acid (degree of polymerization 2-10). The presence of one or more of methyl methanesulfonate or 1-methyl-2-((methanesulfonyl)methyl)disulfide can greatly inhibit the polymerization reaction between thiomethyl radicals and methanesulfonic acid, thereby increasing the reaction yield. Simultaneously, it was unexpectedly discovered that when dimethyl disulfide contains a certain amount of methyl methanesulfonate or one or more of 1-methyl-2-((methanesulfonyl)methyl)disulfide, the separated product has a lower color and a narrower melting range.

[0016] The method for preparing methanesulfonic acid involves continuously adding dimethyl disulfide, nitrogen oxides, air, and water to a reaction vessel to carry out the reaction.

[0017] In one specific embodiment, the method is as follows: water is initially used to line the bottom of the reactor and a certain temperature is controlled. Then, nitrogen oxides, air and water are introduced into the reactor in a certain proportion. After the flow rates of nitrogen oxides, air and water stabilize, dimethyl disulfide is added into the reactor at a certain rate, and continuous discharge begins at the same time. A constant pressure is controlled, and after a period of time, a methanesulfonic acid reaction solution with a stable composition can be obtained.

[0018] In this invention, the molar ratio of nitrogen oxides to dimethyl disulfide is (0.5-20):1, the volume ratio of air to nitrogen oxides is (0.8-15):1, and the molar ratio of water (excluding the bottom layer) to dimethyl disulfide is (12-350):1.

[0019] In this invention, nitrogen oxides and air are introduced below the liquid surface during the reaction process.

[0020] In this invention, dimethyl disulfide is added below the liquid surface after being dispersed in a porous material.

[0021] In this invention, the residence time of the material during the continuous reaction process is 0.05-40h (residence time of material = mass of reaction liquid after stabilization / total mass flow rate of feed material), preferably 0.3-20h.

[0022] Compared with the prior art, the solution described in this invention has the following advantages:

[0023] 1) No external catalyst is added, which reduces the catalyst post-treatment or catalyst recycling process, resulting in a significant cost advantage.

[0024] 2) The reaction conditions are relatively mild, and the equipment and material costs are low during the scale-up process.

[0025] 3) Improved raw material utilization and reduced by-product content lowered production costs. Detailed Implementation

[0026] The following embodiments will further illustrate the method provided by the present invention, but the present invention is not limited to the listed embodiments, and should also include any other known modifications within the scope of the claims of the present invention.

[0027] Dimethyl disulfide: Shanghai Maclean Biochemical Technology Co., Ltd., purity 98%.

[0028] In the examples, the contents of methyl methanesulfonate and 1-methyl-2-((methanesulfonyl)methyl)dithion were controlled by distillation separation.

[0029] The content determination method for methyl methanesulfonate and 1-methyl-2-((methanesulfonyl)methyl)dithion was as follows: Gas chromatography was used. The analytical conditions were: Agilent 7890A gas chromatograph with a DB-5-MS-UI column for online determination; a two-stage temperature program was used, with an initial temperature of 50℃, held for 1 minute, then increased to 80℃ at a rate of 5℃ / min; then increased to 250℃ at a rate of 10℃ / min. High-purity argon was used as the carrier gas with a split ratio of 100:1. The injection temperature was 250℃, and the detector was an FID detector at 250℃.

[0030] The qualitative test method for methyl methanesulfonate or 1-methyl-2-((methanesulfonyl)methyl)dithion is NMR equipment:

[0031] The 1H NMR spectrum of methyl methanesulfonate is: 1H NMR (DMSO, 400 M Hz) δ = 3.18 (s, 3H), δ = 3.87 (s, 3H).

[0032] The 1H NMR spectrum of 1-methyl-2-((methanesulfonyl)methyl)dithion is as follows: HNMR (DMSO, 400MHz) δ=2.31(s,3H), δ=2.85(s,3H), δ=4.68(s,2H).

[0033] Colorimetric testing method: The experimental instrument and model are Hach Lico 690, 11mm, and the test unit is Hazen;

[0034] Melting range test method: The experimental instrument was a Netzsch differential scanning calorimeter, the DSC heating rate was 10℃ / min, and the test atmosphere was nitrogen.

[0035] Example 1

[0036] Take a 500mL PTFE-lined steel reactor, add 230.0g of pure water, start stirring at 2000rpm and 130℃, then introduce nitrogen dioxide into the reactor at a rate of 20L / h, introduce air into the reactor at a rate of 70L / h, and add water at a rate of 500g / h. Add dimethyl disulfide (purity 99.6%, with a total content of methyl methanesulfonate and 1-methyl-2-((methanesulfonyl)methyl)disulfide of 20ppm) through a liquid distributor into the reactor at a rate of 18g / h, controlling the reactor holdup to 340g. Continuously collect the reaction liquid, controlling the gas collection rate to maintain the reactor pressure at 1.1MPaG. Continue running for 36h. After stabilization, the conversion rate of the raw material dimethyl disulfide is >99.9%, and the yield of the product methanesulfonic acid is 98.7%.

[0037] The above reaction solution was subjected to vacuum distillation at a pressure of 5-20 kPaA to remove dilute nitric acid and nitrogen oxides. The crude product was then purified by vacuum distillation at a pressure of 10-200 PaA. Pure methanesulfonic acid with a purity of 99.9%, a color of 10 Hazen, and a melting range of 20.07-20.19 °C was obtained at the top of the column.

[0038] Example 2

[0039] Take a 500mL PTFE-lined steel reactor, add 230.0g of pure water, start stirring at 1000rpm and 50℃, then introduce nitrogen dioxide into the reactor at a rate of 30L / h, introduce air into the reactor at a rate of 25L / h, and add water at a rate of 50g / h. Add dimethyl disulfide (purity 99.1%, with a total of methyl methanesulfonate and 1-methyl-2-((methanesulfonyl)methyl)disulfide of 750ppm) through a liquid distributor into the reactor at a rate of 18g / h, controlling the reactor holdup to 260g. Continuously collect the reaction liquid, controlling the gas collection rate to maintain the reactor pressure at 0.5MPaG. Continue running for 24h. After stabilization, the conversion rate of the raw material dimethyl disulfide is >99.9%, and the yield of the product methanesulfonic acid is 98.3%.

[0040] The above reaction solution was subjected to vacuum distillation at a pressure of 5-20 kPaA to remove dilute nitric acid and nitrogen oxides. The crude product was then purified by vacuum distillation at a pressure of 10-200 PaA. Pure methanesulfonic acid with a purity of 99.8%, a color of 12 Hazen, and a melting range of 20.04-20.23 °C was obtained at the top of the column.

[0041] Example 3

[0042] Take a 20L PTFE-lined steel reactor, add 8000.5g of pure water, start stirring at 1600rpm and 90℃, then introduce nitric oxide into the reactor at a rate of 16L / h, introduce air into the reactor at a rate of 160L / h, and add water at a rate of 100g / h. Dimethyl disulfide (purity 98.4%, of which the total amount of methyl methanesulfonate and 1-methyl-2-((methanesulfonyl)methyl)disulfide is 430ppm) is introduced into the reactor through a liquid distributor at a rate of 18g / h, controlling the liquid holdup in the reactor to 13.1kg. Then, continuously collect the reaction liquid, control the gas collection rate to keep the reactor pressure at 0.1MPaG, and run continuously for 240h. After stabilization, the conversion rate of the raw material dimethyl disulfide is >99.9%, and the yield of the product methanesulfonic acid is 98.8%.

[0043] The above reaction solution was subjected to vacuum distillation at a pressure of 5-20 kPaA to remove dilute nitric acid and nitrogen oxides. The crude product was then purified by vacuum distillation at a pressure of 10-200 PaA. Pure methanesulfonic acid with a purity of 99.6%, a color of 13 Hazen, and a melting range of 20.00-20.28 °C was obtained at the top of the column.

[0044] Example 4

[0045] Take a 2.0L PTFE-lined steel reactor, add 300.0g of pure water, start stirring at 1600rpm and 140℃. Then, introduce a mixture of nitric oxide and nitrogen dioxide gas (nitric oxide:nitric dioxide volume ratio = 1:3) into the reactor at a rate of 80L / h, introduce air into the reactor at a rate of 65L / h, and add water at a rate of 1000g / h. Add dimethyl disulfide (purity 99.2%, of which the total amount of methyl methanesulfonate and 1-methyl-2-((methanesulfonyl)methyl)disulfide is 430ppm) into the reactor through a liquid distributor at a rate of 18g / h, control the liquid holdup in the reactor to 500g, and then continuously collect the reaction liquid. Control the gas collection rate to keep the reactor pressure at 1.8MPaG. Continue running for 30h. After stabilization, the conversion rate of the raw material dimethyl disulfide is >99.9%, and the yield of the product methanesulfonic acid is 98.5%.

[0046] The above reaction solution was subjected to vacuum distillation at a pressure of 5-20 kPaA to remove dilute nitric acid and nitrogen oxides. The crude product was then purified by vacuum distillation at a pressure of 10-200 PaA. Pure methanesulfonic acid with a purity of 99.7%, a color of 12 Hazen, and a melting range of 20.03-20.25 °C was obtained at the top of the column.

[0047] Comparative Example 1

[0048] Take a 500mL PTFE-lined steel reactor, add 230.0g of pure water, start stirring at 2000rpm and 130℃, then introduce nitrogen dioxide into the reactor at a rate of 20L / h, introduce air into the reactor at a rate of 70L / h, and add water at a rate of 500g / h. Dimethyl disulfide (purity 99.7%, of which the total amount of methyl methanesulfonate and 1-methyl-2-((methanesulfonyl)methyl)disulfide is 1600ppm) is introduced into the reactor through a liquid distributor at a rate of 18g / h, controlling the liquid holdup in the reactor to 340g. Then, the reaction liquid is continuously collected by overflow, and the gas collection rate is controlled to maintain the reactor pressure at 1.1MPaG. After continuous operation for 36h, the conversion rate of the raw material dimethyl disulfide is >99.9%, and the yield of the product methanesulfonic acid is 90.4%.

[0049] The above reaction solution was subjected to vacuum distillation at a pressure of 5-20 kPaA to remove dilute nitric acid and nitrogen oxides. The crude product was then purified by vacuum distillation at a pressure of 10-200 PaA. Pure methanesulfonic acid with a purity of 97.8%, a color of 42 Hazen, and a melting range of 19.58-21.03 °C was obtained at the top of the column.

Claims

1. A method for preparing methanesulfonic acid, characterized in that, The raw material dimethyl disulfide is reacted with nitrogen oxides, air, and water in a certain proportion to obtain the product; the nitrogen oxides are nitric oxide, nitrogen dioxide, or a mixture of the two. The total content of methyl methanesulfonate and 1-methyl-2-((methanesulfonyl)methyl)dithioethane in the raw material dimethyl disulfide is 1-1000 ppm.

2. The method according to claim 1, wherein, The molar ratio of the nitrogen oxides to dimethyl disulfide is (0.5-20):

1.

3. The method according to any one of claims 1-2, wherein, The volume ratio of air to nitrogen oxides is (0.8-15):

1.

4. The method according to claim 1, wherein, The molar ratio of water to dimethyl disulfide is (12-350):

1.

5. The method according to claim 1, wherein, The reaction pressure is 0-2.0 MPaG.

6. The method according to claim 1 or 5, wherein, The reaction temperature is 0-200℃.

7. The method according to claim 1, wherein, The method is as follows: water is initially used to line the bottom of the reactor and the temperature is controlled. Then, nitrogen oxides, air and water are introduced into the reactor in proportion. After the flow rates of nitrogen oxides, air and water stabilize, dimethyl disulfide is added into the reactor and continuous discharge begins. The pressure is controlled to obtain a methanesulfonic acid reaction solution.

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