A method for preparing 1,3-benzenedisulfonic acid and a method for preparing 1,3-benzenedisulfonate

Abstract

The present invention belongs to the technical field of organic synthesis, and in particular to a method for preparing 1,3-benzenedisulfonic acid and a method for preparing 1,3-benzenedisulfonic acid salt. The present invention adopts cage-shaped octaphenylsilsesquioxane as raw material, and prepares 1,3-benzenedisulfonic acid by a one-step sulfonation method using a sulfonating agent. The preparation of raw materials is safe, the reaction temperature is low, the post-processing is simple, the yield is high, and it is suitable for scaled-up production.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for preparing 1,3-benzenedisulfonic acid and a method for preparing 1,3-benzenedisulfonic acid salt. Background Art

[0002] 1,3-Benzenedisulfonate is an important chemical intermediate for the preparation of resorcinol and m-aminophenol. As important organic chemical raw materials, resorcinol and m-aminophenol are widely used in pharmaceuticals, plastics, rubber, wood adhesives, and surfactants. In recent years, researchers have used 1,3-Benzenedisulfonate to prepare covalent sulfur-carbon materials with extremely high sulfur content for use in sodium-sulfur batteries, achieving high ionic / electronic conductivity and good capacity retention. It can also be used as a ligand to synthesize multinuclear bismuth oxide clusters, which are used as structural units in microelectronic materials, catalyst precursors, organic-inorganic hybrid materials, and radiopaque polymers.

[0003] The precursor for preparing 1,3-benzenedisulfonate is 1,3-benzenedisulfonic acid. Currently, the primary method for producing 1,3-benzenedisulfonic acid is to use pure benzene as the raw material, followed by sulfonation with a sulfonating agent such as fuming sulfuric acid or liquid sulfur trioxide. The sulfonation reaction is a two-step process, with the first step at approximately 80°C and the second at approximately 175°C. However, this production method uses highly hazardous raw materials, high reaction temperatures, and a complex preparation method, generating large amounts of waste acid and being environmentally unfriendly. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a method for preparing 1,3-benzenedisulfonic acid and a method for preparing 1,3-benzenedisulfonic acid salt, which has safe raw materials, low reaction temperature and simple processing.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing 1,3-benzenedisulfonic acid, comprising the following steps:

[0007] Under the protection of inert gas, caged octaphenylsilsesquioxane, a soluble solvent for caged octaphenylsilsesquioxane and a sulfonating agent are mixed to carry out a sulfonation reaction to obtain a sulfonation reaction liquid; the temperature of the sulfonation reaction is 40 to 100° C.;

[0008] The sulfonation reaction solution and ice water were mixed to precipitate a solid, which was washed and then freeze-dried to obtain 1,3-benzenedisulfonic acid.

[0009] Preferably, the sulfonating agent is sulfuric acid solution, fuming sulfuric acid solution, chlorosulfonic acid or acetyl sulfate solution; and the ratio of the mass of the cage-shaped octaphenylsilsesquioxane to the volume of the sulfonating agent is 1 g: (2-20) mL.

[0010] Preferably, the soluble solvent of the cage-shaped octaphenylsilsesquioxane includes one or more of dichloromethane, chloroform, 1,2-dichloroethane, pyridine and N,N-dimethylformamide; the ratio of the mass of the cage-shaped octaphenylsilsesquioxane to the volume of the soluble solvent of the cage-shaped octaphenylsilsesquioxane is 1g:(5-50)mL.

[0011] Preferably, the holding time of the sulfonation reaction is 12 to 24 hours.

[0012] Preferably, the inert gas is nitrogen or argon.

[0013] The present invention also provides a method for preparing 1,3-benzenedisulfonate, comprising the following steps:

[0014] The 1,3-benzenedisulfonic acid solution and the alkaline metal compound solution are mixed, and then neutralized, dried, and recrystallized to obtain 1,3-benzenedisulfonic acid salt;

[0015] The 1,3-benzenedisulfonic acid is prepared by the preparation method described in the above technical solution.

[0016] Preferably, the alkaline metal compound is one or more of potassium carbonate, potassium hydroxide, potassium bicarbonate, lithium carbonate, lithium hydroxide, sodium carbonate, sodium hydroxide and sodium bicarbonate.

[0017] Preferably, the mixing of the 1,3-benzenedisulfonic acid solution and the alkaline metal compound solution is performed to adjust the pH value of the 1,3-benzenedisulfonic acid solution to 7-8 using the alkaline metal compound solution.

[0018] Preferably, before the drying, the method further comprises: subjecting the reaction liquid obtained from the neutralization reaction to rotary evaporation; the temperature of the rotary evaporation is 70-80° C.; the speed of the rotary evaporation is 80-100 rpm; and the time of the rotary evaporation is 20-40 min.

[0019] Preferably, the drying temperature is 70-90° C. and the drying time is 8-12 hours.

[0020] The present invention provides a method for preparing 1,3-benzenedisulfonic acid, comprising the following steps: under inert gas protection, mixing a caged octaphenylsilsesquioxane, a soluble solvent for the caged octaphenylsilsesquioxane, and a sulfonating agent, conducting a sulfonation reaction to obtain a sulfonation reaction liquid; the sulfonation reaction temperature is 40 to 100°C; the sulfonation reaction liquid is mixed with ice water to precipitate a solid, the solid is washed, and then freeze-dried to obtain 1,3-benzenedisulfonic acid. The present invention uses caged octaphenylsilsesquioxane as a raw material and uses a sulfonating agent to perform a one-step sulfonation process to prepare 1,3-benzenedisulfonic acid. The preparation method has safe raw materials, a low reaction temperature, simple post-processing, a high yield (70 to 80%), and is suitable for scale-up production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 FT-IR spectrum of dipotassium 1,3-benzenedisulfonic acid salt obtained in Examples 1 and 2;

[0022] Figure 2 The 1,3-benzenedisulfonic acid dipotassium salt obtained in Examples 1 and 2 is 1 H-NMR spectrum;

[0023] Figure 3 This is the ESI-MS spectrum of 1,3-benzenedisulfonic acid dipotassium salt obtained in Examples 1 and 2;

[0024] Figure 4 The XRD patterns of dipotassium 1,3-benzenedisulfonic acid salt obtained in Examples 1 and 2 are shown. DETAILED DESCRIPTION

[0025] The present invention provides a method for preparing 1,3-benzenedisulfonic acid, comprising the following steps:

[0026] Under the protection of inert gas, caged octaphenylsilsesquioxane, a soluble solvent for caged octaphenylsilsesquioxane and a sulfonating agent are mixed to carry out a sulfonation reaction to obtain a sulfonation reaction liquid; the temperature of the sulfonation reaction is 40 to 100° C.;

[0027] The sulfonation reaction solution and ice water were mixed to precipitate a solid, which was washed and then freeze-dried to obtain 1,3-benzenedisulfonic acid.

[0028] Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used, and commercially available products known to those skilled in the art can be used.

[0029] The invention mixes cage-shaped octaphenylsilsesquioxane, a soluble solvent of cage-shaped octaphenylsilsesquioxane and a sulfonating agent under the protection of an inert gas to obtain a mixed liquid.

[0030] In the present invention, the preparation method of the cage-shaped octaphenylsilsesquioxane is based on the literature "Mechanistic Insights into the Synthesis of Fully Condensed PolyhedralOctaphenylsilsesquioxane" (Qin Z, Yang R, Zhang W, et al.Mechanistic Insights into the Synthesis of Fully Condensed Polyhedral Octaphenylsilsesquioxane[J]. Chinese Journal of Chemistry, 2019, 37(10)), the raw materials used for preparation are: phenyltrimethoxysilane PTMS (≥99%, Jingzhou Jianghan Chemical Co., Ltd.), acetone, anhydrous ethanol, deionized water, and potassium hydroxide purchased from Beijing Tongguang Fine Chemical Co., Ltd.; the specific preparation method of the cage-shaped octaphenylsilsesquioxane (OPS) is as follows: in a 500mL three-necked round-bottom flask equipped with a reflux condenser and a magnetic stirrer in an oil bath, PTMS (19.83g) and acetone (100mL) are stirred for 30min, then, deionized water (5mL) and potassium hydroxide (0.2g) are added, and then the mixture is heated to 65℃ and reacted for 24h. The crude product is filtered and washed with anhydrous ethanol to remove unreacted substances, and then filtered and dried in a vacuum oven at 120℃ for 8h, and finally 12.29g of OPS is collected with a yield of 95.43%.

[0031] In the present invention, the sulfonating agent is preferably a sulfuric acid solution, a fuming sulfuric acid solution, chlorosulfonic acid or an acetyl sulfate solution, more preferably chlorosulfonic acid; the mass concentration of the sulfuric acid solution is preferably 99%; the mass concentration of the fuming sulfuric acid solution is preferably 20-60%, more preferably 20-40%; the acetyl sulfate solution comprises concentrated sulfuric acid and acetic anhydride; the volume ratio of the concentrated sulfuric acid to acetic anhydride is preferably 1:(1-2), more preferably 1:1; the acetyl sulfate solution is prepared by mixing concentrated sulfuric acid and acetic anhydride, reacting at 0°C for 0.5-2h, to obtain the acetyl sulfate solution.

[0032] In the present invention, the ratio of the mass of the cage-shaped octaphenylsilsesquioxane to the volume of the sulfonating agent is preferably 1 g: (2 to 20) mL, more preferably 1 g: (5 to 10) mL.

[0033] In the present invention, the soluble solvent of the cage-shaped octaphenylsilsesquioxane preferably includes one or more of dichloromethane, chloroform, 1,2-dichloroethane, pyridine and N,N-dimethylformamide, more preferably 1,2-dichloroethane; the preferred ratio of the mass of the cage-shaped octaphenylsilsesquioxane to the volume of the soluble solvent of the cage-shaped octaphenylsilsesquioxane is 1 g: (5 to 50) mL, more preferably 1 g: (10 to 20) mL.

[0034] In the present invention, the inert gas is preferably nitrogen or argon, more preferably nitrogen.

[0035] In the present invention, the mixing of the caged octaphenylsilsesquioxane, the soluble solvent of the caged octaphenylsilsesquioxane and the sulfonating agent is preferably performed by first mixing the caged octaphenylsilsesquioxane and the soluble solvent of the caged octaphenylsilsesquioxane and stirring, and then dropwise adding the sulfonating agent under the stirring condition; the stirring temperature is preferably 0 to 4° C., more preferably 0° C.; the stirring speed is preferably 350 to 400 rad / min, more preferably 400 rad / min; and the dropping rate is preferably 1 to 2 mL / min, more preferably 1 mL / min.

[0036] After obtaining the mixed solution, the present invention performs a sulfonation reaction on the mixed solution to obtain a sulfonation reaction solution.

[0037] In the present invention, the temperature of the sulfonation reaction is 40 to 100° C., preferably 50 to 80° C.; the holding time of the sulfonation reaction is preferably 12 to 24 hours, more preferably 12 to 20 hours.

[0038] In the present invention, the sulfonation reaction is preferably carried out under stirring and reflux conditions; the stirring speed is preferably 350 to 400 rad / min, more preferably 400 rad / min.

[0039] During the sulfonation reaction, the phenyl group of the cage-shaped octaphenylsilsesquioxane is connected to two sulfonic acid groups to generate 1,3-benzenedisulfonic acid.

[0040] After obtaining the sulfonation reaction liquid, the present invention mixes the sulfonation reaction liquid with ice water to precipitate solids.

[0041] In the present invention, the process of mixing the sulfonation reaction liquid and ice water is preferably to add ice water to the sulfonation reaction liquid; the volume ratio of the sulfonation reaction liquid to ice water is preferably 1:(4-5), more preferably 1:5.

[0042] The invention adds ice water to the sulfonation reaction liquid mainly to precipitate solids in the sulfonation reaction liquid, and can also decompose excess chlorosulfonic acid, dissolve broken siloxane, or dilute concentrated sulfuric acid.

[0043] After the solid is precipitated, the sulfonation reaction solution after the solid is precipitated is preferably filtered to obtain the solid.

[0044] The present invention has no particular limitation on the filtration process, and any filtration process well known in the art may be used.

[0045] After the filtration, the present invention washes the solid.

[0046] In the present invention, the reagent used for the washing is preferably deionized water; and the washing is preferably performed until the pH value of the washing liquid is neutral.

[0047] After the washing, the present invention freeze-dries the washed solid to obtain 1,3-benzenedisulfonic acid.

[0048] Before the freeze-drying, the present invention preferably pre-freezes the washed solid; the pre-freezing temperature is preferably -10 to -20°C, more preferably -20°C; the pre-freezing time is preferably 4 to 8 hours, more preferably 5 hours.

[0049] The freeze-drying equipment is preferably a freeze dryer; the freeze-drying pressure is preferably 0.01 to 0.05 MPa, more preferably 0.01 MPa; the freeze-drying temperature is preferably -30 to -50°C, more preferably -40°C; the present invention has no special limitation on the freeze-drying time, as long as the water is sublimated and dried out.

[0050] The present invention also provides a method for preparing 1,3-benzenedisulfonate, comprising the following steps:

[0051] The 1,3-benzenedisulfonic acid solution and the alkaline metal compound solution are mixed, and then neutralized, dried, and recrystallized to obtain 1,3-benzenedisulfonic acid salt;

[0052] The 1,3-benzenedisulfonic acid is prepared by the preparation method described in the above technical solution.

[0053] In the present invention, the solution of 1,3-benzenedisulfonic acid and the solution of an alkaline metal compound are mixed to carry out a neutralization reaction to obtain a neutralization reaction solution.

[0054] In the present invention, the preparation method of the 1,3-benzenedisulfonic acid solution is to dissolve the 1,3-benzenedisulfonic acid in boiling water to obtain the 1,3-benzenedisulfonic acid solution.

[0055] In the present invention, the temperature of the boiling water is preferably 80-100° C., more preferably 80-90° C.; the ratio of the mass of the 1,3-benzenedisulfonic acid to the volume of the boiling water is preferably 1 g:(5-15 mL), more preferably 1 g:10 mL.

[0056] In the present invention, the mixing of the 1,3-benzenedisulfonic acid solution and the alkaline metal compound solution is preferably performed by adjusting the pH value of the 1,3-benzenedisulfonic acid solution to 7-8 using the alkaline metal compound solution.

[0057] In the present invention, the alkaline metal compound is preferably one or more of potassium carbonate, potassium hydroxide, potassium bicarbonate, lithium carbonate, lithium hydroxide, sodium carbonate, sodium hydroxide and sodium bicarbonate, more preferably potassium bicarbonate; the concentration of the solution of the alkaline metal compound is preferably 0.05 to 0.1 mol / L, more preferably 0.1 mol / L.

[0058] Before the drying, the present invention preferably further comprises: subjecting the reaction liquid obtained from the neutralization reaction to rotary evaporation; the temperature of the rotary evaporation is preferably 70 to 80°C, more preferably 80°C; the rotation speed of the rotary evaporation is preferably 80 to 100 rpm, more preferably 90 to 100 rpm; the time of the rotary evaporation is preferably 20 to 40 min, more preferably 30 min.

[0059] The present invention adopts rotary evaporation to remove water.

[0060] After the rotary evaporation, the present invention dries the product after the rotary evaporation to obtain dry matter.

[0061] In the present invention, the drying temperature is preferably 70 to 90° C., more preferably 80° C.; the drying time is preferably 8 to 12 hours, more preferably 12 hours.

[0062] After obtaining the dry matter, the present invention recrystallizes the dry matter to obtain 1,3-benzenedisulfonate.

[0063] In the present invention, the recrystallization is preferably performed by mixing the dry matter and water to prepare a saturated solution, followed by cooling crystallization, filtering and drying to obtain 1,3-benzenedisulfonate.

[0064] In the present invention, the mixing temperature is preferably 80-100°C, more preferably 90-100°C; the cooling crystallization is preferably naturally cooled to room temperature and then allowed to stand; the room temperature is preferably 20-25°C, more preferably 25°C; the standing time is preferably 8-14h, more preferably 12h.

[0065] The saturated solution described in the present invention is a solution obtained by adding dry matter into solvent water. When the dry matter can no longer dissolve, the resulting solution is a saturated solution.

[0066] In the present invention, the filtration is preferably suction filtration; the suction filtration is preferably water pump filtration; the pressure of the suction filtration is preferably 0.01-0.05 MPa, more preferably 0.01 MPa; the drying temperature is preferably 70-90°C, more preferably 80°C; the drying time is preferably 8-14h, more preferably 12h; the drying equipment is preferably a blast oven.

[0067] The 1,3-benzenedisulfonate prepared by the present invention has a structural formula as shown in Formula I:

[0068]

[0069] In formula I, X is one or more of K, Li and Na.

[0070] The 1,3-benzenedisulfonate prepared by the invention has good thermal stability and chemical structure stability, and the reaction conditions are mild, easy to control, simple to operate and suitable for expanded production.

[0071] The technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention, but they should not be understood as limiting the scope of protection of the present invention.

[0072] Example 1

[0073] Under the protection of inert gas (nitrogen), 100 mL of 1,2-dichloroethane, 20g of cage-shaped octaphenylsilsesquioxane, maintaining the temperature at 0°C, stirring at 400 rad / min, then adding 80mL of chlorosulfonic acid dropwise at 1mL / min, and carrying out a sulfonation reaction at 80°C, stirring at 400 rad / min, and refluxing for 12h to obtain a sulfonation reaction solution; 900mL of ice water was added to 180mL of the sulfonation reaction solution to precipitate a solid, which was filtered to obtain a precipitate, and the precipitate was washed with deionized water until the pH value of the washing solution was neutral. The washed precipitate was pre-frozen at -20°C for 5h, and then placed in a freeze dryer at a pressure of 0.01MPa and a temperature of -40°C for freeze drying until the water was completely sublimated and dried to obtain 1,3-benzenedisulfonic acid (yield: 70%);

[0074] 34 g of 1,3-benzenedisulfonic acid was dissolved in 340 mL of boiling water at 80°C to obtain a solution, and the pH value was adjusted to 7.0 with potassium bicarbonate solution (mass concentration of 0.1 mol / L). After rotary evaporation at 80°C at 100 rpm for 40 min, the solution was dried in a blast oven at 80°C for 12 h, and then recrystallized. After mixing with water at 90°C to prepare a saturated solution, the solution was naturally cooled to 25°C and allowed to stand for 12 h. The solution was filtered with a water pump at a pressure of 0.01 MPa, and then dried in a blast oven at 80°C for 12 h to obtain a white crystalline powder of 1,3-benzenedisulfonic acid dipotassium salt (yield 70%).

[0075] Example 2

[0076] Under the protection of inert gas (nitrogen), 250 mL of 1,2-dichloroethane, 50g of cage-shaped octaphenylsilsesquioxane, maintaining the temperature at 0°C, stirring at 400rad / min, then adding 160mL of chlorosulfonic acid dropwise at 2mL / min, and carrying out a sulfonation reaction at 80°C, stirring at 400rad / min, and refluxing for 18h to obtain a sulfonation reaction solution; 2000mL of ice water was added to 410mL of the sulfonation reaction solution to precipitate a solid, which was filtered to obtain a precipitate, and the precipitate was washed with deionized water until the pH value of the washing solution was neutral. The washed precipitate was pre-frozen at -20°C for 4h, and then placed in a freeze dryer at a pressure of 0.01MPa and a temperature of -40°C for freeze drying until the water was completely removed by sublimation drying to obtain 1,3-benzenedisulfonic acid (yield 80%);

[0077] 97 g of 1,3-benzenedisulfonic acid was dissolved in 600 mL of boiling water at 80°C to obtain a solution, and the pH value was adjusted to 7.0 with potassium bicarbonate solution (mass concentration of 0.1 mol / L). After rotary evaporation at 80°C at 100 rpm for 40 min, the solution was dried in a blast oven at 80°C for 12 h, and then recrystallized. After mixing with water at 80°C to prepare a saturated solution, the solution was naturally cooled to 25°C and allowed to stand for 12 h. The solution was filtered with a water pump at a pressure of 0.01 MPa, and then dried in a blast oven at 80°C for 12 h to obtain a white crystalline powder of 1,3-benzenedisulfonic acid dipotassium salt (yield 80%).

[0078] Performance Testing

[0079] (1) The 1,3-benzenedisulfonic acid dipotassium salt obtained in Examples 1 and 2 was subjected to infrared spectroscopy (FT-IR) testing. The results were as follows: Figure 1 shown.

[0080] Depend on Figure 1 It can be seen that 1193, 1032cm -1is the stretching vibration absorption peak of O=S=O; 800, 697cm -1 It is meta-substituted benzene, =CH out-of-plane vibration absorption peak; 3068cm -1 The stretching vibration absorption peak of the unsaturated CH of the benzene ring is located at 1,3-benzenedisulfonate, which proves that 1,3-benzenedisulfonate was successfully synthesized.

[0081] (2) The 1,3-benzenedisulfonic acid dipotassium salt obtained in Examples 1 and 2 was subjected to hydrogen nuclear magnetic resonance ( 1 H-NMR) test, the results are as follows Figure 2 shown.

[0082] Depend on Figure 2 As can be seen, there are 4 groups of resonance peaks in the characteristic region of the benzene ring. The unsplit singlet at 8.12ppm corresponds to the uncoupled hydrogen on the meta-substituted benzene ring, the two doublets at 7.92 and 7.91ppm correspond to the para-hydrogen of SO3K, and the triplet at 7.75-7.42ppm corresponds to the meta-hydrogen of the two SO3K groups. The area integration of the characteristic peaks of the benzene ring gives a ratio of 1:2:1. According to the number of hydrogen atoms on the phenyl group, 1 The H-NMR spectrum supports the meta-substitution form on the benzene ring.

[0083] (3) Electrospray mass spectrometry (ESI-MS) was used to test the 1,3-benzenedisulfonic acid dipotassium salt obtained in Examples 1 and 2. The results are as follows: Figure 3 shown.

[0084] Depend on Figure 3 It can be seen that a molecular ion peak appears at 294.90919m / z, which is obtained by removing potassium ions from the product with a relative molecular mass of 313.87234. 1 The H-NMR spectrum shows that the product obtained in Example 1 is a single dipotassium salt of 1,3-benzenedisulfonic acid, and the structural formula is shown below:

[0085]

[0086] (4) X-ray diffraction (XRD) test was performed on the 1,3-benzenedisulfonic acid dipotassium salt obtained in Examples 1 and 2. The results are as follows: Figure 4 shown.

[0087] Depend on Figure 4 It can be seen that dipotassium 1,3-benzenedisulfonate is a crystalline compound.

[0088] (5) Thermogravimetric (TG) test was performed on the dipotassium salt of 1,3-benzenedisulfonic acid in Example 1. The initial decomposition temperature of the dipotassium salt of 1,3-benzenedisulfonic acid was 550°C, and the residual carbon rate was 47%, indicating that the salt has good thermal stability and chemical structure stability.

[0089] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing 1,3-benzenedisulfonic acid, characterized in that: The following steps are involved: Under the protection of inert gas, caged octaphenylsilsesquioxane, a soluble solvent for caged octaphenylsilsesquioxane and a sulfonating agent are mixed to carry out a sulfonation reaction to obtain a sulfonation reaction liquid; the temperature of the sulfonation reaction is 40 to 100° C.; The sulfonation reaction solution is mixed with ice water to precipitate a solid, and the solid is washed and freeze-dried to obtain 1,3-benzenedisulfonic acid; The sulfonating agent is chlorosulfonic acid.

2. The preparation method according to claim 1, characterized in that The ratio of the mass of the cage-shaped octaphenylsilsesquioxane to the volume of the sulfonating agent is 1 g: (2 to 20) mL.

3. The preparation method according to claim 1, characterized in that The soluble solvent of the cage-shaped octaphenylsilsesquioxane includes one or more of dichloromethane, chloroform, 1,2-dichloroethane, pyridine and N,N-dimethylformamide; the ratio of the mass of the cage-shaped octaphenylsilsesquioxane to the volume of the soluble solvent of the cage-shaped octaphenylsilsesquioxane is 1g:(5-50)mL.

4. The preparation method according to claim 1, characterized in that The holding time of the sulfonation reaction is 12 to 24 hours.

5. The preparation method according to claim 1, characterized in that The inert gas is nitrogen or argon.

6. A method for preparing 1,3-benzenedisulfonate, characterized in that: The following steps are involved: 1,3-benzenedisulfonic acid is prepared according to the preparation method according to any one of claims 1 to 5; The 1,3-benzenedisulfonic acid solution and the alkaline metal compound solution are mixed, and then subjected to a neutralization reaction, drying and recrystallization in sequence to obtain 1,3-benzenedisulfonic acid salt.

7. The preparation method according to claim 6, characterized in that The alkaline metal compound is one or more of potassium carbonate, potassium hydroxide, potassium bicarbonate, lithium carbonate, lithium hydroxide, sodium carbonate, sodium hydroxide and sodium bicarbonate.

8. The preparation method according to claim 6, characterized in that The step of mixing the 1,3-benzenedisulfonic acid solution and the alkaline metal compound solution is to adjust the pH value of the 1,3-benzenedisulfonic acid solution to 7-8 using the alkaline metal compound solution.

9. The preparation method according to claim 6, characterized in that Before the drying, the method further comprises: subjecting the reaction liquid obtained from the neutralization reaction to rotary evaporation; the temperature of the rotary evaporation is 70-80° C.; the speed of the rotary evaporation is 80-100 rpm; and the time of the rotary evaporation is 20-40 minutes.

10. The preparation method according to claim 6, characterized in that The drying temperature is 70-90° C.; the drying time is 8-12 hours.

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