Method for preparing methylene methyldisulfonate by one-pot method

Abstract

The invention discloses a method for preparing methylene methyldisulfonate through a one-pot method, and belongs to the technical field of electrolytes.The method is characterized by comprising the following steps that firstly, methanesulfonic acid is added into a three-neck bottle, then liquid sulfur trioxide or fuming sulfuric acid is added, and the temperature is increased to 130-170 DEG C; 2, preserving heat for 6-8 hours, cooling, and adding an inert solvent; 3, paraformaldehyde is added, and the temperature is raised to 40-90 DEG C; step 4, slowly dropwise adding a water binding agent, and after dropwise adding, keeping the temperature for 2-6 hours to carry out cyclization reaction; 5, after the reaction is finished, cooling to 40-90 DEG C, and standing to separate out an upper organic layer; step 6, cooling to 10-30 DEG C, and carrying out suction filtration; and step 7, drying under reduced pressure at 40 DEG C to obtain the methylene methyldisulfonate. The method has the effects of effectively solving the problem that a large amount of waste phosphoric acid is generated in the existing methylene methyldisulfonate preparation method technology, improving the productivity and reducing the cost.

Description

Technical Field

[0001] The present application relates to the technical field of electrolytes, and more specifically to a one-pot method for preparing methylene disulfonate. Background Art

[0002] Methylene disulfonate has a unique disulfonate cyclic structure and can be used as an electrolyte additive for lithium batteries. Adding a small amount of methylene disulfonate to the electrolyte of lithium-ion batteries can effectively inhibit the rise of impedance, effectively improve the battery cycle performance and extend the battery life. Therefore, methylene disulfonate is increasingly used in the battery field, especially for power lithium batteries, especially lithium manganate batteries.

[0003] Methylene disulfonate is a chemical with the appearance of white or off-white crystals or crystalline powder. It is referred to as MMDS, with the molecular formula of C2H4O6S2, CAS.NO: 99591-74-9, and its structural formula is as follows: Figure 1 shown.

[0004] At present, the preparation method of methylene disulfonate mainly uses methylene disulfonic acid and polyformaldehyde as reaction raw materials, and generates methylene disulfonate under the action of water-binding agents such as phosphorus pentoxide and phosphorus trichloride.

[0005] The existing preparation process of methanedisulfonic acid as a reaction raw material is: using dibromomethane (dichloromethane) and sodium sulfite as starting materials to generate sodium methylenedisulfonate, then reacting with barium chloride to generate barium methylenedisulfonate, and then acidifying with a strong acid such as concentrated sulfuric acid to obtain an aqueous solution of methanedisulfonic acid, and finally removing water by distillation to obtain methanedisulfonic acid with a low water content, and then continuing high-temperature distillation to obtain methylene methanedisulfonate with a high content, and generating a large amount of distillation residue. The disadvantages are: a long process route, a large amount of solid waste, a low yield, a high cost, and it is not conducive to industrial production.

[0006] In view of this, a process suitable for industrial preparation of high-purity methylene disulfonate is studied in the art. Summary of the invention

[0007] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for preparing methylene dimethyl sulfonate by a one-pot process, which has the advantages of being simple to operate, high in yield, high in efficiency and suitable for large-scale one-pot preparation of methylene dimethyl sulfonate to meet the requirements of industrial production.

[0008] To achieve the above object, the present invention provides the following technical solution: a method for preparing methylene disulfonate by a one-pot process, characterized in that it comprises the following steps:

[0009] Step 1: Add methanesulfonic acid into a three-necked flask, then add liquid sulfur trioxide, and heat to 130-170°C;

[0010] Step 2, keep warm for 6-8 hours, cool down and add inert solvent;

[0011] Step 3, adding paraformaldehyde and heating to 40-90°C;

[0012] Step 4, slowly dropwise add the water-binding agent, and after the dropwise addition is complete, heat preservation is performed for 2-6 hours to carry out the cyclization reaction;

[0013] Step 5: After the reaction is completed, the temperature is lowered to 40-90°C, and the upper organic layer is separated;

[0014] Step 6, cooling to 10-30°C and filtering;

[0015] Step 7, drying under reduced pressure at 40° C. to obtain methylene disulfonate.

[0016] Preferably, the weight ratio of the inert solvent to methanesulfonic acid is (18-30):1.

[0017] Preferably, the inert solvent is any one of dichloromethane, dichloroethane and dimethyl carbonate.

[0018] Preferably, the water-binding agent is any one of liquid sulfur trioxide and oleum (10%-65%).

[0019] Preferably, the molar ratio of the reactants of methanesulfonic acid: paraformaldehyde: sulfur trioxide is 1:(1.1-2):(3-5).

[0020] Preferably, the reaction temperature of the cyclization reaction is 40-90°C.

[0021] Preferably, the vacuum degree required for the reduced pressure drying is less than -0.097 MPa and the temperature is less than 40°C.

[0022] Preferably, the sulfur trioxide can be replaced by oleum.

[0023] The chemical reaction mechanism of the above-mentioned method for preparing methylene disulfonate can be represented by chemical reaction formula 1: cyclization reaction.

[0024] Chemical reaction formula 1:

[0025]

[0026] Cyclization reaction:

[0027]

[0028] In summary, the present invention has the following advantages:

[0029] The process can save costs, simplify operations, reduce the generation and treatment of three wastes, and the final product can obtain high-purity methylene disulfonate with a total yield of more than 90%, which is of great significance for the large-scale preparation of methylene disulfonate. The present invention can utilize cheap and readily available raw materials, simple operations, mild operating conditions, low risks, low costs, and high efficiency to synthesize methylene disulfonate, which meets the requirements of large-scale industrial production and has significant application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the structural formula of methylene disulfonate;

[0031] Figure 2 is a flow chart of Embodiment 1;

[0032] Figure 3 is a flow chart of Embodiment 2;

[0033] Figure 4 It is a flow chart of embodiment 3. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0035] Embodiment 1, as Figure 2 As shown, a one-pot method for preparing methylene disulfonate comprises the following steps:

[0036] 1) Preparation of methylene disulfonic acid:

[0037] Add methanesulfonic acid (9.6 g, 0.1 mol) to a three-necked flask, then add liquid sulfur trioxide (16 g, 0.2 mol), raise the temperature to 140-150°C, keep warm for 6 hours, cool to 50°C, and proceed to the next step;

[0038] 2) Preparation of methylene disulfonate:

[0039] Add 176.2 g of ethylene dichloride and paraformaldehyde (3.6 g, 0.12 mol) into a three-necked flask, raise the temperature to 70-80 ° C, slowly add sulfur trioxide (16 g, 0.2 mol), keep warm for 3 hours after the addition is complete, cool to 70 ° C, separate the upper organic layer, and then cool to 20-25 ° C through circulating water and brine, filter, and dry at a temperature of less than 40 ° C and a vacuum degree of less than -0.097 MPa to obtain methylene disulfonate (17.1 g, 0.091 mol) with a molar yield of 91% and a purity of more than 99.5%.

[0040] Embodiment 2, as Figure 3As shown, a one-pot method for preparing methylene disulfonate comprises the following steps:

[0041] 1) Preparation of methylene disulfonic acid:

[0042] Add methanesulfonic acid (9.6 g, 0.1 mol) to a three-necked flask, then add 24.6 g 65% oleum (converted to 16 g sulfur trioxide, 0.2 mol), heat to 150-160°C, keep warm for 7 hours, cool to 40°C, and proceed to the next step;

[0043] 2) Preparation of methylene disulfonate:

[0044] Add 200g of dichloromethane and paraformaldehyde (6g, 0.2mol) into a three-necked flask, raise the temperature to 40°C, slowly drop 80g of 25% fuming sulfuric acid (converted into 20g of sulfur trioxide, 0.25mol), keep warm for 4 hours after the addition is complete, separate the layers while hot, separate the upper organic layer, cool it to 15-20°C through circulating water and brine, filter it with suction, dry it at a temperature of less than 40°C and a vacuum degree of less than -0.097MPa, and obtain methylene disulfonate (17.3g, 0.092mol) with a molar yield of 92% and a purity of more than 99.5%.

[0045] Embodiment 3, as shown in the figure, a method for preparing methylene disulfonate by a one-pot process comprises the following steps:

[0046] 1) Preparation of methylene disulfonic acid:

[0047] Add methanesulfonic acid (9.6 g, 0.1 mol) to a three-necked flask, then add 24.6 g 65% oleum (converted to 16 g sulfur trioxide, 0.2 mol), heat to 150-160°C, keep warm for 8 hours, cool to 50°C, and proceed to the next step;

[0048] 2) Preparation of methylene disulfonate:

[0049] Add 200g of dimethyl carbonate and paraformaldehyde (4.5g, 0.15mol) into a three-necked flask, heat to 80-90°C, slowly drop sulfur trioxide (16g, 0.2mol), keep warm for 6 hours after the addition is complete, cool to 70°C, separate the upper organic layer, cool to 20-25°C through circulating water and brine, filter with suction, dry at a temperature of less than 40°C and a vacuum degree of less than -0.097MPa to obtain methylene disulfonate (17.3g, 0.092mol), with a molar yield of 92% and a purity of more than 99.5%.

[0050] The beneficial effects of the present invention are as follows:

[0051] The process saves costs, simplifies operations, reduces the generation and treatment of three wastes, and the final product can obtain high-purity methylene disulfonate with a total yield of more than 90%, which is of great significance for the large-scale preparation of methylene disulfonate. The present invention can utilize cheap and readily available raw materials, simple operations, mild operating conditions, low risks, low costs, and high efficiency to synthesize methylene disulfonate, meets the requirements of large-scale industrial production, and has significant application value.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the design concept of the present invention should be included in the protection scope of the present invention.

Claims

1. A one-pot method for preparing methylene disulfonate, characterized in that: The steps include: Step 1: Add methanesulfonic acid into a three-necked flask, then add liquid sulfur trioxide, and heat to 130-170°C; Step 2, keep warm for 6-8 hours, cool down and add inert solvent; Step 3, adding paraformaldehyde and heating to 40-90°C; Step 4, slowly dropwise add the water-binding agent, and after the dropwise addition is complete, heat preservation is performed for 2-6 hours to carry out the cyclization reaction; Step 5: After the reaction is completed, the temperature is lowered to 40-90°C, and the upper organic layer is separated; Step 6, cooling to 10-30°C and filtering; Step 7, drying under reduced pressure at 40° C. to obtain methylene disulfonate.

2. The method for preparing methylene disulfonate by a one-pot process according to claim 1, wherein: The weight ratio of the inert solvent to methanesulfonic acid is (18-30):

1.

3. A one-pot method for preparing methylene disulfonate according to claim 2, characterized in that: The inert solvent is any one of dichloromethane, dichloroethane and dimethyl carbonate.

4. The method for preparing methylene disulfonate by a one-pot process according to claim 1, wherein: The water-binding agent is any one of liquid sulfur trioxide or fuming sulfuric acid (10%-65%).

5. The method for preparing methylene disulfonate by a one-pot process according to claim 4, characterized in that: The molar ratio of the reactants of methanesulfonic acid: paraformaldehyde: sulfur trioxide is 1:(1.1-2):(3-5).

6. The method for preparing methylene disulfonate by a one-pot process according to claim 1, characterized in that: The reaction temperature of the cyclization reaction is 40-90°C.

7. The method for preparing methylene disulfonate by a one-pot process according to claim 1, characterized in that: The vacuum degree required for the reduced pressure drying is less than -0.097MPa and the temperature is less than 40°C.

8. The method for preparing methylene disulfonate by a one-pot process according to claim 1, characterized in that: The sulfur trioxide may be replaced with oleum.

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