Preparation method of methylene disulfonic acid, methylene methanedisulfonate and preparation method of methylene methanedisulfonate

Abstract

The invention discloses a preparation method of methylene disulfonic acid, methylene methanedisulfonate and a preparation method of methylene methanedisulfonate. The preparation method of methylene disulfonic acid comprises the step of sulfonating acetic acid to prepare methylene disulfonic acid. According to the preparation method of the methylene disulfonic acid, the acetic acid serves as the raw material, the prepared methylene disulfonic acid is high in purity and yield and few in impurity, methylene methanedisulfonate further prepared from the methylene disulfonic acid has the advantages of being high in purity, few in impurity, high in yield and the like, the methylene methanedisulfonate can serve as an additive of a battery electrolyte, and the battery performance is improved. And moreover, the reaction conditions are mild, the process is simple, the cost is low, and industrial production can be realized.

Description

Technical Field

[0001] The present application relates to the field of electrolyte additives, and in particular to a preparation method of methylene disulfonic acid, methylene methane disulfonate and a preparation method thereof. Background Art

[0002] Methylene methanedisulfonate (MMDS) is an additive commonly used in lithium-ion battery electrolytes. It can prevent manganese ions dissolved at high temperatures from being adsorbed on the negative electrode surface, inhibit the increase in impedance, and effectively improve the battery's cycle characteristics. It is especially suitable for power batteries with positive electrode material systems such as lithium manganese oxide, lithium iron phosphate, and lithium cobalt oxide.

[0003] However, the current method for preparing methylene methane disulfonate has defects such as many by-products, low yield and high cost, which hinders its industrial production. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one purpose of the present application is to propose a method for preparing methylene disulfonic acid, methylene disulfonate and a method for preparing the same. The method for preparing methylene disulfonic acid of the present application uses acetic acid as a raw material, and the methylene disulfonic acid prepared has high purity and yield, and few impurities. The methylene disulfonic acid further prepared from the methylene disulfonic acid has the characteristics of high purity, few impurities, high yield, etc., and is beneficial as an additive for battery electrolyte to improve battery performance. In addition, the reaction conditions are mild, the process is simple, the cost is low, and industrial production can be realized.

[0005] In a first aspect of the present application, the present application provides a method for preparing methylene disulfonic acid. According to an embodiment of the present application, the method for preparing methylene disulfonic acid comprises the step of sulfonating acetic acid to prepare the methylene disulfonic acid.

[0006] According to the preparation method of methylene disulfonic acid in the embodiment of the present application, acetic acid is used as a raw material and subjected to sulfonation treatment to generate methylene disulfonic acid. Since acetic acid has high reaction selectivity, the reaction byproducts are few, the methylene disulfonic acid has high purity and few impurities, and the methylene disulfonic acid methylene ester further prepared from the methylene disulfonic acid has the characteristics of high purity, few impurities, high yield, etc., which is conducive to being used as an additive for battery electrolyte to improve battery performance.

[0007] According to the embodiments of the present application, the above-mentioned method for preparing methylene disulfonic acid may also have the following additional technical features:

[0008] According to an embodiment of the present application, a sulfonation reagent is used to react with acetic acid to carry out the sulfonation treatment, and the sulfonation reagent includes at least one of chlorosulfonic acid, concentrated sulfuric acid, sulfur trioxide, oleum and aminosulfonic acid.

[0009] According to an embodiment of the present application, the molar ratio of the sulfonating agent to acetic acid used in the sulfonation treatment is (1.8-2.6):1; and / or the temperature of the sulfonation treatment is 30°C-130°C, preferably 50°C-80°C; and / or the time of the sulfonation treatment is 8h-24h, preferably 13h-18h.

[0010] In the second aspect of the present application, the present application proposes a method for preparing methylene methane disulfonate, which comprises dehydrating and esterifying the methylene disulfonic acid prepared by the method described in the first aspect to obtain the methylene methane disulfonate.

[0011] According to an embodiment of the present application, the dehydration esterification treatment includes: mixing the methylene disulfonic acid, a condensation reagent, a dehydrating agent and a solvent to react.

[0012] According to an embodiment of the present application, the dehydrating agent includes: at least one of sulfur trioxide, polyphosphoric acid, boron trioxide and oleum;

[0013] and / or, the solvent comprises a halogenated alkane;

[0014] And / or, the condensation reagent includes: at least one of anhydrous formaldehyde, paraformaldehyde and trioxymethylene.

[0015] According to an embodiment of the present application, the solvent includes: at least one of dichloroethane and tetrachloroethane.

[0016] According to an embodiment of the present application, the molar ratio of the methylene disulfonic acid, the condensation agent and the dehydrating agent is 1:(1.0-1.5):(1.0-2);

[0017] And / or, the mass ratio of the dehydrating agent to the solvent is 1:(2-20);

[0018] And / or, the temperature of the dehydration esterification treatment is 50°C to 130°C.

[0019] According to an embodiment of the present application, the dehydration esterification treatment further comprises:

[0020] The crude methylene disulfonate obtained by the dehydration esterification treatment is allowed to stand for stratification, and the organic layer solution is collected;

[0021] The organic layer solution is distilled to obtain a concentrated solution;

[0022] The concentrated solution is subjected to crystallization treatment, and crystals are collected to obtain the methylene methanedisulfonate.

[0023] According to an embodiment of the present application, the temperature of the distillation treatment is 30°C to 40°C.

[0024] And / or, the pressure of the distillation treatment is -0.12MPa to -0.06MPa;

[0025] And / or, the temperature of the crystallization treatment is 3°C to 8°C.

[0026] In the third aspect of the present application, the present application proposes methylene methane disulfonate, which is prepared according to the preparation method of methylene methane disulfonate described in the second aspect of the present application.

[0027] According to an embodiment of the present application, the methylene methanedisulfonate satisfies at least one of the following conditions:

[0028] The content of methylene methane disulfonate is not less than 99.7%;

[0029] The free acid content is not more than 100ppm;

[0030] The moisture content is not more than 100ppm;

[0031] Chroma not greater than 50 Hazen;

[0032] The content of a single metal ion is no more than 1ppm.

[0033] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0035] Figure 1 and Figure 2 The schematic diagrams of the process for preparing methylene methane disulfonate products according to one embodiment of the present application are shown respectively;

[0036] Figure 3 shows a chromatogram of methylene disulfonic acid according to Example 1 of the present application;

[0037] Figure 4 shows the hydrogen nuclear magnetic resonance spectrum of methylene methanedisulfonate according to Example 1 of the present application;

[0038] Figure 5 The carbon nuclear magnetic resonance spectrum of methylene methanedisulfonate according to Example 1 of the present application is shown. DETAILED DESCRIPTION

[0039] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0040] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0041] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this application.

[0042] In the present application, the terms "comprise" or "include" are open expressions, that is, including the contents specified in the present application but not excluding other contents.

[0043] At present, the existing methods for synthesizing MMDS are mainly the following:

[0044] 1. Sodium methylene disulfonate is obtained by reacting dihaloalkane with sodium sulfite, and then methylene disulfonic acid is obtained by precipitation, acidification, dehydration and drying, and then reacted with polyoxymethylene in the presence of a dehydrating agent to generate MMDS. This method requires high temperature and high pressure reaction, has high requirements for equipment, and has safety risks; the post-processing process of synthesizing methylene disulfonic acid is complicated, and a large amount of sodium halide hazardous waste will be generated, and the cost of three waste treatment is high.

[0045] 2. Using methane disulfonic acid to react with a silver reagent to obtain silver methane disulfonate, and then reacting with diiodomethane to obtain MMDS. The silver carbonate and diiodomethane used in this method are expensive and not suitable for industrial production.

[0046] 3. Methanesulfonic acid is reacted with a sulfonating agent to obtain methylene disulfonic acid, which is then reacted with a condensation agent to obtain the product MMDS through a dehydration condensation reaction. The raw material methanesulfonic acid of this method is relatively expensive and the cost is high.

[0047] In view of this, see Figure 1 The present application adopts acetic acid as a raw material, and the methylene disulfonic acid obtained by sulfonation treatment has high purity and yield and few impurities. The methylene disulfonic acid is further dehydrated and esterified to obtain methylene disulfonate, which has the characteristics of high purity, few impurities, high yield, etc., and is beneficial as an additive for battery electrolyte to improve battery performance. In addition, acetic acid is easy to obtain and cheap as a raw material, the reaction conditions are mild, the process is simple, the cost is low, and industrial production can be realized.

[0048]

[0049] To this end, in the first aspect of the present application, the present application proposes a method for preparing methylene disulfonic acid. According to an embodiment of the present application, the method for preparing methylene disulfonic acid comprises the steps of sulfonating acetic acid to prepare the methylene disulfonic acid, which will be described in detail below.

[0050] In the reaction process of acetic acid and sulfonating agent to generate methylene disulfonic acid through sulfonation treatment, acetic acid has high reaction selectivity, which is helpful to directly generate the target product without going through complex intermediates or side reaction pathways, so that the obtained reactant containing methylene disulfonic acid has less by-products. In addition, the reaction conditions of the sulfonation treatment are mild, which is conducive to more selective interaction between molecules, maintains the stability of the substrate, and avoids the decomposition or rearrangement of the substrate due to overly harsh conditions to produce by-products. Further, since there are few by-products in the reactant containing methylene disulfonic acid, the introduction of by-products into methylene disulfonate products can be reduced, so that the methylene disulfonate products have high purity and few impurities, which is conducive to being used as an additive for battery electrolyte and improving battery performance. In addition, the reactant containing methylene disulfonic acid can be directly used to generate methylene disulfonate without intermediate treatment.

[0051] According to an embodiment of the present application, a sulfonation reagent is used to react with acetic acid to carry out the sulfonation treatment, and the sulfonation reagent includes at least one of chlorosulfonic acid, concentrated sulfuric acid, sulfur trioxide, oleum (chemical formula H2S2O7, also known as pyrosulfuric acid or persulfuric acid) and aminosulfonic acid. The sulfonation reagent can introduce a sulfonic acid group (-S0 H) into acetic acid to generate methylene disulfonic acid, and has the advantages of high conversion efficiency and less by-products.

[0052] According to an embodiment of the present application, the molar ratio of the sulfonating agent to acetic acid used in the sulfonation treatment is (1.8-2.6):1, for example, it can be 1.8:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1 or 2.6:1 or a range value formed by any two values ​​as endpoint values. The sulfonating agent and acetic acid satisfy the above ratio, so that the two can react fully, reduce the unreacted substrate and sulfonating agent residues, and improve the utilization rate of raw materials. In addition, the reaction rate can be controlled to reduce the heat accumulation or side reactions caused by too fast reaction.

[0053] According to an embodiment of the present application, the temperature of the sulfonation treatment is 30°C to 130°C, for example, 30°C, 35°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 130°C or any two values ​​as the range value formed by the endpoint values. The temperature of the sulfonation treatment meets the above conditions, so that the sulfonation reagent and acetic acid can fully react, the yield of methylene disulfonic acid can be increased, and the generation of by-products can be reduced. In some embodiments, the temperature of the sulfonation treatment is 50°C to 80°C. As a result, the reaction conditions are mild, which is conducive to more selective interactions between molecules, maintains the stability of the substrate, and reduces the phenomenon of substrate decomposition or rearrangement due to overly harsh conditions, and the generation of by-products.

[0054] According to an embodiment of the present application, the time of the sulfonation treatment is 8h to 24h, for example, it can be 8h, 10h, 12h, 13h, 15h, 18h, 20h, 22h, 24h or any two values ​​as the range value formed by the endpoint value. The time of the sulfonation treatment meets the above conditions, so that the sulfonation reagent and acetic acid can fully react, the yield of methylene disulfonic acid can be improved, and the phenomenon of by-product generation caused by product decomposition or rearrangement can be reduced. In some embodiments, the time of the sulfonation treatment is 13h to 18h. Thus, the yield and purity of methylene disulfonic acid can be further improved, and by-product generation can be reduced.

[0055] In the second aspect of the present application, the present application proposes a method for preparing methylene methane disulfonate, which comprises dehydrating and esterifying the methylene disulfonic acid prepared by the method for preparing methylene disulfonic acid described in the first aspect to obtain the methylene methane disulfonate.

[0056] According to an embodiment of the present application, the dehydration esterification treatment includes: reacting the methylene disulfonic acid, a condensation reagent, a dehydrating agent and a solvent. The specific reaction formula is as follows:

[0057] By adding a solvent to the dehydration esterification treatment system, the reaction materials are mixed evenly, the reaction is easy to control, the dehydrating agent can be reduced from directly contacting with methylene disulfonic acid to cause carbonization, and the reaction activity is high, thereby reducing the occurrence of side reactions.

[0058] According to an embodiment of the present application, the dehydrating agent includes at least one of sulfur trioxide, polyphosphoric acid, boron trioxide and oleum. The use of the above dehydrating agent is conducive to the formation of methylene methane disulfonate, with high yield and purity of homogeneous reaction, less by-products and mild reaction conditions.

[0059] According to an embodiment of the present application, the solvent includes a halogenated alkane. Halogenated alkane will not participate in the dehydration esterification reaction, and as a solvent, will not chemically react with the reactant or product, has good chemical stability, and helps to maintain the selectivity of the reaction. In addition, halogenated alkane has good solubility, and both methylene disulfonic acid and dehydrating agent can be dissolved therein, thereby promoting the uniform conduct of the reaction. In addition, halogenated alkane has a moderate boiling point, which is convenient for removal from the reaction mixture by distillation or evaporation, and helps to separate and purify the product.

[0060] According to an embodiment of the present application, the solvent includes: at least one of dichloroethane and tetrachloroethane. Dichloroethane and / or tetrachloroethane and a dehydrating agent, especially sulfur trioxide, can make the dehydration esterification process under mild reaction conditions, and the yield and purity of methylene disulfonate are high. In addition, dichloroethane and sulfur trioxide can achieve azeotropy during the vacuum distillation process, which is convenient for removal and improves the purity of methylene disulfonate.

[0061] According to an embodiment of the present application, the condensation reagent includes at least one of anhydrous formaldehyde, paraformaldehyde, and trioxymethylene. Thus, the yield and purity of methylene disulfonate can be further improved, and the reaction conditions are mild.

[0062] According to an embodiment of the present application, the molar ratio of the methylene disulfonic acid, the condensation agent and the dehydrating agent is 1: (1.0-1.5): (1.0-2), for example, it can be 1: (1.0-1.4): (1.0-2), 1: (1.0-1.3): (1.0-2), 1: (1.0-1.2): (1.0-2), 1: (1.0-1.5): (1.0-1.9), 1: (1.0-1.5): (1.0-1.5), 1: (1.0-1.5): (1.0-1.3), 1: (1.0-1.5): (1.0-1.2), 1: (1.0-1.2): (1.0-1.2), etc. Thus, the yield and purity of methylene disulfonate can be further improved.

[0063] According to an embodiment of the present application, the mass ratio of the dehydrating agent to the solvent is 1:(2-20), for example, it can be 1:2, 1:4, 1:5, 1:10, 1:15, 1:20 or a range formed by any two values ​​as endpoint values. Thus, the reaction rate can be further increased, the generation of by-products can be reduced, and the yield and purity of methylene disulfonate can be increased.

[0064] According to an embodiment of the present application, the temperature of the dehydration esterification treatment is 50°C to 130°C, for example, 50°C, 60°C, 70°C, 80°C, 85°C, 90°C, 100°C, 120°C, 130°C or any two values ​​as the range formed by the endpoint values. The temperature of the dehydration esterification treatment meets the above conditions, and the methylene disulfonic acid, the condensation reagent and the dehydrating agent can be fully reacted, thereby increasing the yield of methylene disulfonate and reducing the generation of by-products.

[0065] According to the embodiments of the present application, see Figure 2 The dehydration and esterification treatment further includes: S300 static stratification, S400 distillation treatment and S500 crystallization treatment, which will be described in detail below.

[0066] S300 static stratification

[0067] In this step, the crude methylene disulfonate obtained by the dehydration esterification treatment is allowed to stand for stratification, and the organic layer solution is collected. The methylene disulfonate is dissolved in the organic layer, and the organic layer is separated by standing.

[0068] S400 Distillation Process

[0069] In this step, the organic layer solution is distilled to obtain a concentrated solution. The distillation process can mainly remove the dehydrating agent and the solvent.

[0070] According to an embodiment of the present application, the temperature of the distillation treatment is 30°C to 40°C, for example, 30°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C or a range formed by any two values ​​as endpoint values. Thus, it is beneficial for the dehydrating agent and the solvent to azeotrope to achieve the purpose of removal, and the decomposition or rearrangement of methylene disulfonate can be avoided, thereby improving the yield and purity of methylene disulfonate.

[0071] According to an embodiment of the present application, the pressure of the distillation treatment is -0.12MPa to -0.06MPa, for example, -0.07MPa, -0.08MPa, -0.09MPa, -0.10MPa, -0.11MPa, -0.12MPa or a range formed by any two values ​​as endpoint values. Thus, it is beneficial for the dehydrating agent and the solvent to azeotrope to achieve the purpose of removal, and the decomposition or rearrangement of methylene methane disulfonate can be avoided, thereby improving the yield and purity of methylene methane disulfonate.

[0072] S500 Crystallization Treatment

[0073] In this step, the concentrated solution is subjected to crystallization treatment, and crystals are collected to obtain the methylene methane disulfonate. Through the crystallization treatment, impurities can be removed and the purity of the methylene methane disulfonate can be improved.

[0074] According to an embodiment of the present application, the temperature of the crystallization treatment is 3°C to 8°C, for example, 3°C, 5°C, 6°C, 7°C, 8°C or a range formed by any two values ​​as endpoints. Thus, the purity and yield of methylene methane disulfonate can be further improved.

[0075] It should be noted that the features and advantages described above for the first aspect are also applicable to the preparation method of methylene methanedisulfonate, and will not be described in detail here.

[0076] In the third aspect of the present application, the present application proposes a methylene disulfonate, wherein the methylene disulfonate is prepared according to the preparation method of methylene disulfonate described in the second aspect of the present application. The methylene disulfonate of the present application has the characteristics of high purity, few impurities, high yield, etc., and is conducive to being used as an additive for battery electrolyte to improve battery performance.

[0077] According to an embodiment of the present application, the methylene methanedisulfonate satisfies at least one of the following conditions:

[0078] The content of methylene methane disulfonate is not less than 99.7%;

[0079] The free acid content is not more than 100ppm;

[0080] The moisture content is not more than 100ppm;

[0081] Chroma not greater than 50 Hazen;

[0082] The content of a single metal ion is no more than 1ppm.

[0083] In some embodiments, the content of methylene methanedisulfonate is not less than 99.7%, for example, it can be 99.7%, 99.8%, 99.9%, 99.99%, etc., which can be measured by conventional means and instruments such as gas chromatography.

[0084] In some embodiments, the free acid content is no more than 100 ppm, for example, it can be 100 ppm, 80 ppm, 60 ppm, 50 ppm, 40 ppm, 20 ppm, 10 ppm, 5 ppm, 1 ppm, 0.1 ppm, etc., and can be measured by conventional means and instruments such as acid-base titration.

[0085] In some embodiments, the moisture content is no greater than 100 ppm, for example, it may be 100 ppm, 80 ppm, 60 ppm, 50 ppm, 40 ppm, 20 ppm, 10 ppm, 5 ppm, 1 ppm, 0.1 ppm, etc., and can be measured by conventional instruments and means such as a moisture meter.

[0086] In some embodiments, the chromaticity is no greater than 50 Hazen, for example, it may be 50 Hazen, 40 Hazen, 30 Hazen, 20 Hazen, 10 Hazen, 5 Hazen, 1 Hazen, etc., and can be specifically measured by combining conventional instruments and means such as a colorimeter or a spectrophotometer.

[0087] In some embodiments, the content of a single metal ion is no more than 1 ppm, for example, it can be 1 ppm, 0.8 ppm, 0.5 ppm, 0.2 ppm, 0.1 ppm, 0.05 ppm, 0.02 ppm, 0.01 ppm, etc. It can be specifically measured by combining instruments such as atomic absorption spectrometer, electrically coupled plasma atomic emission spectrometer, X-ray fluorescence spectrometer and conventional technical means.

[0088] The above-mentioned methylene disulfonate content, free acid content, moisture content and single metal ion content are measured based on the total mass of the methylene disulfonate product. The methylene disulfonate product that meets the above conditions has high purity, few impurities, low acidity and chromaticity, and is conducive to being used as an additive for battery electrolyte to improve battery performance.

[0089] It should be noted that the characteristics and advantages described above for the preparation method of methylene methanedisulfonate are also applicable to the methylene methanedisulfonate, and will not be repeated here.

[0090] The scheme of the present application will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If no specific technology or conditions are indicated in the embodiments, the technology or conditions described in the literature in this area or the product specification are carried out. The reagents used or the instruments that do not indicate the manufacturer are all conventional products that can be obtained commercially.

[0091] Example 1

[0092] (1) Add 60.05 g of acetic acid to a dry reaction kettle at room temperature, slowly dropwise add 160.12 g of sulfur trioxide (the molar ratio of acetic acid to sulfur trioxide is 1:2), and after the dropwise addition, heat to 50° C. and react for 18 h to obtain methylene disulfonic acid. Ion chromatography detection shows that the yield of methylene disulfonic acid is 89.52%.

[0093] (2) Add 395.60 g of ethylene dichloride to another reaction kettle at room temperature, slowly add 79.12 g of sulfur trioxide, stir for 1 hour, add 176.17 g of methylene disulfonic acid and 29.68 g of polyformaldehyde (CH2O), and reflux at 83°C for 5 hours. At this time, the pressure gauge shows no pressure. After the reaction is completed, stand and separate the layers. Collect the organic layer and perform vacuum distillation at a pressure of -0.095 MPa and a temperature of 35°C. Collect the concentrated solution. After concentration, cool to 5°C for crystallization to obtain 136.36 g of methylene disulfonate.

[0094] Example 2

[0095] The methylene methanedisulfonate product was prepared according to the method of Example 1, except that in step (1), the amount of sulfur trioxide added was 184 g, and the corresponding molar ratio of acetic acid to sulfur trioxide was 1:2.3.

[0096] Example 3

[0097] The methylene methane disulfonate product was prepared according to the method of Example 1, except that in step (1), the amount of sulfur trioxide added was 208 g, and the corresponding molar ratio of acetic acid to sulfur trioxide was 1:2.6.

[0098] Example 4

[0099] The methylene methanedisulfonate product was prepared according to the method of Example 1, except that in step (1), the amount of sulfur trioxide added was 144 g, and the corresponding molar ratio of acetic acid to sulfur trioxide was 1:1.8.

[0100] Example 5

[0101] The methylene methanedisulfonate product was prepared according to the method of Example 1, except that in step (1), the amount of sulfur trioxide added was 120 g, and the corresponding molar ratio of acetic acid to sulfur trioxide was 1:1.5.

[0102] Example 6

[0103] The methylene methanedisulfonate product was prepared according to the method of Example 1, except that in step (1), the amount of sulfur trioxide added was 104 g, and the corresponding molar ratio of acetic acid to sulfur trioxide was 1:1.3.

[0104] Example 7

[0105] The methylene methanedisulfonate product was prepared according to the method of Example 1, except that in step (1), sulfur trioxide was replaced by chlorosulfonic acid, the added amount was 233.05 g, and the corresponding molar ratio of acetic acid to chlorosulfonic acid was 1:2.

[0106] Example 8

[0107] The methylene methanedisulfonate product was prepared according to the method of Example 1, except that in step (1), sulfur trioxide was replaced by oleum (CAS: 8014-95-7), the added amount was 365.31 g, and the corresponding molar ratio of acetic acid to oleum was 1:2.

[0108] Example 9

[0109] The methylene disulfonate product was prepared according to the method of Example 1, except that in step (1), the reaction temperature was 80°C.

[0110] Example 10

[0111] The methylene disulfonate product was prepared according to the method of Example 1, except that in step (1), the reaction temperature was 30°C.

[0112] Embodiment 11

[0113] The methylene disulfonate product was prepared according to the method of Example 1, except that in step (1), the reaction temperature was 130°C.

[0114] Example 12

[0115] The methylene disulfonate product was prepared according to the method of Example 1, except that in step (1), the reaction temperature was 150°C.

[0116] Example 13

[0117] The methylene disulfonate product was prepared according to the method of Example 1, except that in step (1), the reaction temperature was 10°C.

[0118] Embodiment 14

[0119] The methylene disulfonate product was prepared according to the method of Example 1, except that in step (1), the reaction time was 24 h.

[0120] Embodiment 15

[0121] The methylene disulfonate product was prepared according to the method of Example 1, except that in step (1), the reaction time was 8 h.

[0122] Example 16

[0123] The methylene disulfonate product was prepared according to the method of Example 1, except that in step (1), the reaction time was 13 h.

[0124] Embodiment 17

[0125] The methylene disulfonate product was prepared according to the method of Example 1, except that in step (1), the reaction time was 5 h.

[0126] Embodiment 18

[0127] The methylene disulfonate product was prepared according to the method of Example 1, except that in step (1), the reaction time was 30 h.

[0128] Test Case

[0129] The methylene disulfonate content, free acid content, moisture content, chromaticity, single metal ion (Cu, Fe, Zn, Cr, Na, K, Pb, Co, Ni, Ca, Al, Ag) content, yield of the methylene disulfonate prepared in Examples 1 to 18 and the yield of the reactant containing methylene disulfonic acid (referred to as methylene disulfonic acid yield) prepared in step (1) were measured respectively. The methylene disulfonate content was measured by gas chromatography, the free acid content was measured by acid-base titration, the chromaticity was measured by a colorimeter, and the metal ions were measured by an ICP-AES analyzer.

[0130] The results are shown in Table 1. Examples 1 to 18 use acetic acid as a raw material, which can improve the purity of methylene disulfonate in the product, reduce impurities such as free acid, colored substances and metal ions, and have high yields of methylene disulfonic acid and methylene disulfonate. Taking Example 1 as an example, Figure 3 shows the chromatogram of methylene disulfonic acid, Figure 4 and Figure 5 The hydrogen nuclear magnetic resonance spectrum and carbon nuclear magnetic resonance spectrum of methylene methanedisulfonate are shown respectively.

[0131] Table 1 Characteristics of methylene disulfonate products

[0132]

[0133] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for preparing methylene disulfonic acid, characterized in that: The method comprises the step of subjecting acetic acid to sulfonation to prepare the methylene disulfonic acid.

2. The method for preparing methylene disulfonic acid according to claim 1, characterized in that: The sulfonation treatment is carried out by reacting a sulfonating agent with acetic acid, wherein the sulfonating agent comprises at least one of chlorosulfonic acid, concentrated sulfuric acid, sulfur trioxide, fuming sulfuric acid and aminosulfonic acid.

3. The method for preparing methylene disulfonic acid according to claim 1 or 2, characterized in that: The molar ratio of the sulfonating agent to acetic acid used in the sulfonation treatment is (1.8-2.6):1; and / or the temperature of the sulfonation treatment is 30°C-130°C, preferably 50°C-80°C; and / or the time of the sulfonation treatment is 8h-24h, preferably 13h-18h.

4. A method for preparing methylene methanedisulfonate, characterized in that: The method comprises subjecting the methylene disulfonic acid prepared by the method according to any one of claims 1 to 3 to a dehydration esterification treatment to obtain the methylene disulfonate.

5. The method for preparing methylene methanedisulfonate according to claim 4, characterized in that: The dehydration esterification treatment comprises: mixing the methylene disulfonic acid, a condensation agent, a dehydrating agent and a solvent to react.

6. The method for preparing methylene methanedisulfonate according to claim 5, characterized in that: The dehydrating agent comprises: at least one of sulfur trioxide, polyphosphoric acid, boron trioxide and oleum; and / or, the solvent comprises a halogenated alkane; And / or, the condensation reagent includes: at least one of anhydrous formaldehyde, paraformaldehyde and trioxymethylene.

7. The method for preparing methylene methanedisulfonate according to claim 6, characterized in that: The solvent includes at least one of dichloroethane and tetrachloroethane.

8. The method for preparing methylene methanedisulfonate according to claim 4, characterized in that: The molar ratio of the methylene disulfonic acid, the condensation agent and the dehydrating agent is 1:(1.0-1.5):(1.0-2); And / or, the mass ratio of the dehydrating agent to the solvent is 1:(2-20); And / or, the temperature of the dehydration esterification treatment is 50°C to 130°C.

9. The method for preparing methylene methanedisulfonate according to claim 4, characterized in that: The dehydration esterification treatment further comprises: The crude methylene disulfonate obtained by the dehydration esterification treatment is allowed to stand for stratification, and the organic layer solution is collected; The organic layer solution is distilled to obtain a concentrated solution; The concentrated solution is subjected to crystallization treatment, and crystals are collected to obtain the methylene methanedisulfonate.

10. The method for preparing methylene methanedisulfonate according to claim 9, characterized in that: The distillation temperature is 30°C to 40°C. And / or, the pressure of the distillation treatment is -0.12MPa to -0.06MPa; And / or, the temperature of the crystallization treatment is 3°C to 8°C.

11. A methylene methanedisulfonate, characterized in that: Prepared according to the method according to any one of claims 4 to 10.

12. Methylene methanedisulfonate according to claim 11, characterized in that: The methylene methanedisulfonate satisfies at least one of the following conditions: The content of methylene methane disulfonate is not less than 99.7%; The free acid content is not more than 100ppm; The moisture content is not more than 100ppm; Chroma not greater than 50 Hazen; The content of a single metal ion is no more than 1ppm.

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