A method for synthesizing 1,4-butanedisulfonyl lactone

Abstract

The application provides a synthesis method of 1,4-butanediol sulfonic acid lactone, and aims to provide a synthesis method of 1,4-butanediol sulfonic acid lactone which uses tetrahydrofuran as a raw material, is low in price and easy to obtain, reduces a chlorination reaction, reduces the generation of by-products, is simple in reaction, easy to operate and high in industrial value, and the technical scheme is that sulfite and tetrahydrofuran are subjected to a free radical addition reaction under the action of a free radical initiator to obtain 4-hydroxybutane sulfonate in one step, and the 4-hydroxybutane sulfonate is acidified and ring-closed to obtain 1,4-butanediol sulfonic acid lactone; and the application relates to the technical field of chemical industry.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to a method for synthesizing 1,4-butanolactone. Background Technology

[0002] With the continuous rise of new energy vehicles, higher requirements are being placed on the performance of lithium-ion batteries. 1,4-Butyrolactone, as an electrolyte additive for lithium-ion batteries, has shown unique properties and can effectively improve the electrochemical performance of lithium-ion batteries. Therefore, the research on the synthesis method of 1,4-butyrolactone has also attracted widespread attention.

[0003] Currently, the synthesis of 1,4-butyryl lactone mainly involves the following methods:

[0004] CN106397392A discloses a method for sulfonating raw material 3-buten-1-ol or 3-buten-1-chloro with a sulfonating agent under the action of an initiator to obtain a first intermediate product, and then adding a strong acid to the first intermediate product for acidification to obtain a second intermediate product; the second intermediate product is then dehydrated and cyclized to obtain 1,4-butanesulfonate lactone. Although the reaction steps of this method are simple, 3-buten-1-ol is expensive, easy to polymerize, requires low-temperature storage, and has high industrialization costs.

[0005] CN109293625A discloses a method using an alcohol compound as a solvent and 4-chlorobutanol and sodium sulfite solution as reaction substrates. The reaction involves vigorous stirring followed by heating to reflux to induce a sulfonation reaction, yielding a mixture A. Mixture A is concentrated to recover the alcohol solvent, then acidified with hydrochloric acid solution. The mixture is heated and concentrated until it becomes viscous, then another alcohol solvent is added, followed by cooling to precipitate sodium chloride crystals. The mixture is filtered, and the filter cake is sodium chloride. The filtrate is concentrated to recover the alcohol solvent, yielding 4-hydroxybutanesulfonic acid. The 4-hydroxybutanesulfonic acid is then dehydrated to obtain industrial-grade 1,4-butanesulfonate lactone. An azeotrope is added to the industrial-grade 1,4-butanesulfonate lactone, and finally, fractionation is performed to obtain high-purity 1,4-butanesulfonate lactone. However, this method uses 4-chloro-1-butanol, which is expensive, and the reaction generates a large number of byproducts, making it unsuitable for industrial production.

[0006] CN109776484A discloses a method in which tetrahydrofuran reacts with acetyl chloride in the presence of zinc powder as a catalyst to produce chlorobutyl acetate, followed by sulfonation, acidification, and dehydration cyclization to obtain 1,4-BS. Although the raw materials are inexpensive, the reaction steps are cumbersome, and acetyl chloride readily reacts with water to form acetic acid and hydrogen chloride, requiring a high-quality storage environment.

[0007] Therefore, it is urgent to find a method for synthesizing 1,4-butyryl lactone with low raw material cost, simple reaction steps, and suitability for industrial production. Summary of the Invention

[0008] To address the problems of expensive raw materials, cumbersome reaction steps, and inconvenience for industrial production in the synthesis of 1,4-butanesulfonate lactone in the prior art, this invention provides a new method for the synthesis of 1,4-butanesulfonate lactone. This reaction uses tetrahydrofuran and sulfite as raw materials, which are inexpensive and readily available. It also reduces chlorination reactions and the generation of byproducts. The reaction is simple and easy to operate, and has high industrial value.

[0009] Therefore, the technical solution provided by this invention is as follows:

[0010] A method for synthesizing 1,4-butanesulfonate lactone involves a one-step free radical addition reaction between sulfite and tetrahydrofuran under the action of a free radical initiator to obtain 4-hydroxybutanesulfonate; acidification and cyclization of 4-hydroxybutanesulfonate yields 1,4-butanesulfonate lactone.

[0011] Furthermore, the above-mentioned method for synthesizing 1,4-butyryl lactone includes the following steps in sequence:

[0012] 1) Add deionized water and sulfite to the autoclave, stir until clear, then add free radical initiator and tetrahydrofuran in sequence, pressurize to a pressure of not less than 1 MPa, heat to a temperature of not less than 100°C, react for 2 to 24 hours, and dehydrate by vacuum distillation until the reaction solution is turbid.

[0013] 2) After the reaction solution in step 1) is cooled to room temperature, a strong acid and an alcohol are added to the reaction solution in step 1). The mixture is stirred at room temperature for 2-4 hours and then filtered. The filtrate is dehydrated by vacuum distillation. The mixture is then heated under vacuum to undergo a cyclization reaction until no more bubbles are generated. The mixture is then distilled to obtain crude 1,4-butyryl lactone. The crude 1,4-butyryl lactone is then purified by distillation to obtain 1,4-butyryl lactone.

[0014] Furthermore, the above-mentioned method for synthesizing 1,4-butyryl lactone includes the following steps in sequence:

[0015] 1) Add deionized water and sulfite to the autoclave, stir until clear, then add free radical initiator and tetrahydrofuran in sequence, raise the pressure to 1-10 MPa, raise the temperature to 100-300℃ and react for 2-24 hours, then dehydrate by vacuum distillation until the reaction solution is turbid.

[0016] 2) After the reaction solution in step 1) cools to room temperature, add strong acid and alcohol to the reaction solution in step 1), stir the reaction at room temperature for 2-4 hours, filter, remove water by vacuum distillation of the filtrate, and then cyclize the solution under vacuum at 110-120℃ until no bubbles are generated. Then raise the temperature to 130-150℃ and distill to obtain crude 1,4-butyryl lactone. After fractional distillation of the crude 1,4-butyryl lactone, 1,4-butyryl lactone is obtained.

[0017] The preferred pressure in step 1) is 1 MPa, 2 MPa, 4 MPa, 5 MPa, 7 MPa, 8 MPa, or 9 MPa, and more preferably 4 MPa, 5 MPa, 7 MPa, or 8 MPa. In this scheme, the reaction pressure has a significant effect on the ring-opening of tetrahydrofuran. Under pressure of 1 to 10 MPa, tetrahydrofuran is more likely to undergo ring-opening, and under the action of a free radical initiator, sulfite is generated to produce 4-hydroxybutane sulfonate, with a high yield.

[0018] The preferred temperatures for step 1) are 100℃, 150℃, 200℃, and 300℃.

[0019] The preferred reaction time for step 1) is 2h, 5h, 10h, 15h, or 24h.

[0020] In this scheme, under pressure of 1-10 MPa and reaction at 100-300℃ for 2-24 hours, both the reaction yield and the reaction efficiency can be ensured, energy consumption can be saved, and side reactions can be prevented.

[0021] Preferably, in the above-mentioned method for synthesizing 1,4-butyryl lactone, the molar ratio of tetrahydrofuran to sulfite is 0.5 to 2.0:1; more preferably, it is 0.5:1, 1:1, 1.2:1, 1.5:1, or 2:1.

[0022] The free radical initiator is 0.1% to 10% of the mass of tetrahydrofuran.

[0023] Preferably, in the above-mentioned method for synthesizing 1,4-butyryl lactone, the sulfite is one of sodium bisulfite, potassium bisulfite, ammonium bisulfite, sodium metabisulfite, potassium metabisulfite, and ammonium metabisulfite.

[0024] Preferably, in the above-mentioned method for synthesizing 1,4-butyryl lactone, the free radical initiator is a peroxide; more preferably, it is one of tert-butanol peroxide, sodium persulfate, and potassium persulfate.

[0025] This scheme uses peroxide as an initiator, which is beneficial for initiating ring-opening reactions.

[0026] Preferably, in the above-mentioned method for synthesizing 1,4-butyryl lactone, the vacuum degree in step 2) is 600-1000 Pa.

[0027] Preferably, in the above-mentioned method for synthesizing 1,4-butyryl lactone, the strong acid is one of hydrochloric acid, concentrated sulfuric acid, nitric acid, and phosphoric acid, or HCl gas may be introduced.

[0028] This technical solution utilizes strong acid to facilitate the acidification of 4-hydroxybutane sulfonate, ensuring the yield of the final product.

[0029] Preferably, in the above-mentioned method for synthesizing 1,4-butyryl lactone, the alcohol is one of methanol, ethanol, propanol, and butanol.

[0030] Tetrahydrofuran is an important raw material for organic synthesis and a high-performance solvent with excellent solubility for many organic and inorganic substances. However, because tetrahydrofuran is a five-membered heterocyclic compound, it is relatively stable and difficult to open, which limits its application as a reaction substrate.

[0031] Sulfites generally refer to the collective term for inorganic sulfites that can produce sulfur dioxide, including sulfur dioxide, sulfur, sulfurous acid, sulfites, bisulfites, metabisulfites, and low-sulfites, which have strong reducing properties.

[0032] This invention uses tetrahydrofuran as a raw material. Under high pressure, free radical initiators such as tert-butanol peroxide, sodium persulfate, and potassium persulfate are used to initiate the hydrolysis and ring-opening reaction of tetrahydrofuran to form free radicals. This effectively solves the problem that tetrahydrofuran is difficult to open due to its low stress and low activity. Combining the strong reducing properties of sulfites, after the tetrahydrofuran ring opens, it directly undergoes a free radical addition reaction with sulfites to generate 4-hydroxybutane sulfonate. The reaction is rapid and does not require chlorination, nor does it produce intermediate chlorination products, thus achieving a "one-step reaction". Then, in an alcohol solvent, the product 1,4-butanesulfonic acid lactone is obtained through strong acid acidification and distillation, with a yield greater than 65%, a purity greater than 99.5%, and a water content less than 160 ppm. The product quality is excellent, meeting the requirements for electronic grade and lithium-ion battery electrolyte additives.

[0033] Compared with existing processes, the raw materials used in this invention are inexpensive and readily available, and the chlorination reaction steps are reduced, thereby reducing the generation of by-products. The reaction is simple and easy to operate, and has industrial value. Attached Figure Description

[0034] Figure 1 The 1,4-butyryl lactone provided in Example 1 of this invention 1 HNMR identification spectrum. Detailed Implementation

[0035] To better understand the technical solution of the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0036] Example 1

[0037] This embodiment provides a method for synthesizing 1,4-butyryl lactone, comprising the following steps:

[0038] 1) Add 150 mL of deionized water and 31.2 g of sodium bisulfite to the autoclave, stir until clear, then add 2.2 g of tert-butanol peroxide (TBHP) and 21.6 g of tetrahydrofuran in sequence, raise the pressure to 4.0 MPa, raise the temperature to 200 °C and react for 5 h, then dehydrate under reduced pressure by distillation until the reaction solution is turbid.

[0039] The chemical equation for this reaction step is as follows:

[0040]

[0041] 2) After the reaction solution cools to room temperature, add 100g concentrated hydrochloric acid and 100g ethanol to the reaction solution from step 1). Stir the reaction at room temperature for 3 hours, then filter. Remove water from the filtrate by vacuum distillation using a water pump. Then, cyclize the solution at 120°C under a vacuum of 800Pa until no more bubbles are generated. Distill at 135°C to obtain crude 1,4-butyryl lactone. Further distillation yields 1,4-butyryl lactone (purity 99.6%, water content 136ppm, acid value (based on HF) 37ppm, yield 81.6%). 1 H NMR spectrum as follows Figure 1 As shown, 1 ¹H NMR (400MHz in CDCl₃) δ 4.40–4.60 (2H), 3.1–3.3 (2H⁺), 2.1–2.3 (2H⁺), 1.7–1.9 (2H), confirming that the product prepared in this application is 1,4-butyryl lactone.

[0042] The chemical equation for this reaction step is as follows:

[0043]

[0044] Example 2

[0045] This embodiment provides a method for synthesizing 1,4-butyryl lactone, comprising the following steps:

[0046] 1) Add 200 mL of deionized water and 37.5 g of sodium bisulfite to a high-pressure reactor, stir until clear, then add 0.2 g of sodium persulfate and 21.6 g of tetrahydrofuran in sequence, raise the pressure to 1.0 MPa, raise the temperature to 100 °C and react for 24 h, then dehydrate under reduced pressure by distillation until the reaction solution is turbid.

[0047] 2) After the reaction solution cools to room temperature, add 100g of concentrated hydrochloric acid and 100g of ethanol to the reaction solution in step 1). Stir the reaction at room temperature for 3 hours, then filter. After removing water from the filtrate by vacuum distillation using a water pump, cyclize the solution at 110°C under a vacuum of 600Pa until no more bubbles are generated. Then, distill at 140°C to obtain crude 1,4-butyryl lactone. After fractional distillation, 1,4-butyryl lactone is obtained. (Purity 98.7%, water content 154ppm, acid value (based on HF) 46ppm, yield 65.4%).

[0048] The chemical equation for the reaction in this example is the same as that in Example 1.

[0049] Example 3

[0050] 1) Add 160 mL of deionized water and 35.7 g of potassium bisulfite to a high-pressure reactor. Stir until clear, then add 1.08 g of potassium persulfate and 10.8 g of tetrahydrofuran in sequence. Increase the pressure to 2.0 MPa, heat to 100 °C and react for 24 h. Then, dehydrate under reduced pressure by distillation until the reaction solution becomes turbid.

[0051] The chemical equation for this reaction step is as follows:

[0052]

[0053] 2) After the reaction solution cools to room temperature, add 100g of concentrated hydrochloric acid and 100g of ethanol to the reaction solution in step 1). Stir the reaction at room temperature for 2 hours, then filter. After removing water from the filtrate by vacuum distillation using a water pump, cyclize the solution at 115°C under a vacuum of 800Pa until no more bubbles are generated. Then, distill at 135°C to obtain crude 1,4-butyryl lactone. Further distillation yields crude 1,4-butyryl lactone. (Purity 99.6%, water content 142ppm, acid value (based on HF) 43ppm, yield 69.7%).

[0054] The chemical equation for this reaction step is as follows:

[0055]

[0056] Example 4

[0057] This embodiment provides a method for synthesizing 1,4-butyryl lactone, comprising the following steps:

[0058] 1) Add 400 mL of deionized water and 29.7 g of ammonium bisulfite to a high-pressure reactor, stir until clear, then add 4.32 g of tert-butanol peroxide and 43.2 g of tetrahydrofuran in sequence. Increase the pressure to 7.0 MPa, increase the temperature to 100 °C and react for 15 h. Then, dehydrate under reduced pressure by distillation until the reaction solution is turbid.

[0059] The chemical equation for this reaction step is as follows:

[0060]

[0061] 2) After the reaction solution cools to room temperature, add 14.7g of concentrated sulfuric acid and 100g of ethanol to the reaction solution in step 1). Stir the reaction at room temperature for 4 hours, then filter. After removing water from the filtrate by vacuum distillation using a water pump, cyclize the solution at 112°C under a vacuum of 800Pa until no more bubbles are generated. Then, distill at 150°C to obtain crude 1,4-butyryl lactone. Further distillation yields crude 1,4-butyryl lactone (purity 99.5%, water content 141ppm, acid value (based on HF) 39ppm, yield 75.3%).

[0062] The chemical equation for this reaction step is as follows:

[0063]

[0064] Example 5

[0065] This embodiment provides a method for synthesizing 1,4-butyryl lactone, comprising the following steps:

[0066] 1) Add 190 mL of deionized water and 29.7 g of ammonium bisulfite to a high-pressure reactor. Stir until clear, then add 4.32 g of sodium persulfate and 21.6 g of tetrahydrofuran in sequence. Increase the pressure to 8.0 MPa, heat to 200 °C and react for 20 h. Then, dehydrate under reduced pressure by distillation until the reaction solution becomes turbid.

[0067] 2) After the reaction solution cools to room temperature, add 18.9 g of nitric acid and 100 g of methanol to the reaction solution in step 1). Stir the reaction at room temperature for 3 hours, then filter. After removing water from the filtrate by vacuum distillation using a water pump, cyclize the solution at 118°C under a vacuum of 1000 Pa until no more bubbles are generated. Then, distill at 148°C to obtain crude 1,4-butyryl lactone. After fractional distillation, 1,4-butyryl lactone is obtained. (Purity 99.6%, water content 145 ppm, acid value (based on HF) 43 ppm, yield 80.9%).

[0068] The chemical equation for the reaction in this example is the same as that in Example 4.

[0069] Example 6

[0070] This embodiment provides a method for synthesizing 1,4-butyryl lactone, comprising the following steps:

[0071] 1) Add 200 mL of deionized water and 29.7 g of ammonium bisulfite to a high-pressure reactor, stir until clear, then add 2.6 g of potassium persulfate and 25.92 g of tetrahydrofuran in sequence, raise the pressure to 9.0 MPa, raise the temperature to 300 °C and react for 2 h, then dehydrate under reduced pressure by distillation until the reaction solution is turbid.

[0072] 2) After the reaction solution cools to room temperature, add 10.8 g of phosphoric acid and 100 g of ethanol to the reaction solution in step 1). Stir the reaction at room temperature for 3 hours, then filter. After removing water from the filtrate by vacuum distillation using a water pump, cyclize the solution at 113°C under a vacuum of 800 Pa until no more bubbles are generated. Then, distill at 132°C to obtain crude 1,4-butyryl lactone. Further distillation yields crude 1,4-butyryl lactone. (Purity 99.7%, water content 147 ppm, acid value (based on HF) 37 ppm, yield 69.7%).

[0073] The chemical equation for the reaction in this example is the same as that in Example 1.

[0074] Example 7

[0075] This embodiment provides a method for synthesizing 1,4-butyryl lactone, comprising the following steps:

[0076] 1) Add 100 mL of deionized water and 28.8 g of sodium metabisulfite to the autoclave, stir until clear, then add 2.2 g of tert-butanol peroxide and 21.6 g of tetrahydrofuran in sequence, raise the pressure to 5.0 MPa, raise the temperature to 150 °C and react for 10 h, then dehydrate under reduced pressure by distillation until the reaction solution is turbid.

[0077] The chemical equation for this reaction step is as follows:

[0078] Na₂S₂O₅ + H₂O = 2NaHSO₃

[0079]

[0080] 2) After the reaction solution cools to room temperature, add 100g of concentrated hydrochloric acid and 100g of propanol to the reaction solution in step 1). Stir the reaction at room temperature for 3 hours, then filter. After removing water from the filtrate by vacuum distillation using a water pump, cyclize the solution at 114°C under a vacuum of 800Pa until no more bubbles are generated. Then, distill at 150°C to obtain crude 1,4-butyryl lactone. After fractional distillation, 1,4-butyryl lactone is obtained. (Purity 99.5%, water content 138ppm, acid value (based on HF) 41ppm, yield 78.4%).

[0081] The chemical equation for this reaction step is as follows:

[0082]

[0083] Comparative Example 1

[0084] This comparative example provides a method for synthesizing 1,4-butyryl lactone, comprising the following steps:

[0085] 1) Add 150 mL of deionized water and 31.2 g of sodium bisulfite to the autoclave, stir until clear, then add 2.2 g of hydrogen peroxide and 21.6 g of tetrahydrofuran in sequence, raise the pressure to 4.0 MPa, raise the temperature to 200 °C and react for 5 h, then dehydrate under reduced pressure by distillation until the reaction solution is turbid.

[0086] 2) After the reaction solution cools to room temperature, add 100g of concentrated hydrochloric acid and 100g of ethanol to the reaction solution in step 1). Stir the reaction at room temperature for 3 hours and then filter. After removing water from the filtrate by vacuum distillation using a water pump, raise the temperature to 110-120℃ under a vacuum of 800Pa to carry out the cyclization reaction until no bubbles are generated. Then raise the temperature to 130-150℃ and distill to detect the formation of 1,4-butyric acid lactone.

[0087] Comparative Example 2

[0088] This comparative example provides a method for synthesizing 1,4-butyryl lactone, comprising the following steps:

[0089] 1) Add 160ml of deionized water and 35.7g of potassium bisulfite to the autoclave, stir until clear, then add 1.08g of potassium persulfate and 10.8g of tetrahydrofuran in sequence. Increase the pressure to 0.1Mpa, heat to 100℃ and react for 24h. Then, dehydrate under reduced pressure by distillation until the reaction solution is turbid.

[0090] 2) After the reaction solution cools to room temperature, add 100g of concentrated hydrochloric acid and 100g of ethanol to the reaction solution in step 1). Stir the reaction at room temperature for 3 hours, then filter. After removing water from the filtrate by vacuum distillation using a water pump, cyclize the solution at 120°C under a vacuum of 800Pa until no more bubbles are generated. Then, distill at 135°C to obtain crude 1,4-butyryl lactone. After fractional distillation, 1,4-butyryl lactone is obtained. (Purity 99.6%, water content 147ppm, acid value (as HF) 48pm, yield 10.1%).

[0091] Comparative Example 3

[0092] This comparative example provides a method for synthesizing 1,4-butyryl lactone, comprising the following steps:

[0093] 1) Add 150 mL of deionized water and 31.2 g of sodium bisulfite to the autoclave, stir until clear, then add 2.2 g of tert-butanol peroxide (TBHP) and 21.6 g of tetrahydrofuran in sequence, raise the pressure to 4.0 MPa, raise the temperature to 90 °C and react for 5 h, then dehydrate under reduced pressure by distillation until the reaction solution is turbid.

[0094] The chemical equation for this reaction step is as follows:

[0095]

[0096] 2) After the reaction solution cools to room temperature, add 100g concentrated hydrochloric acid and 100g ethanol to the reaction solution from step 1). Stir the reaction at room temperature for 3 hours, then filter. Remove water from the filtrate by vacuum distillation using a water pump. Then, cyclize the solution at 120°C under a vacuum of 800Pa until no more bubbles are generated. Finally, distill at 135°C to obtain crude 1,4-butyryl lactone. Further distillation yields 1,4-butyryl lactone (purity 99.6%, water content 136ppm, acid value (based on HF) 37ppm, yield 55.6%). 1 H NMR spectrum as follows Figure 1 As shown, 1 ¹H NMR (400MHz in CDCl₃) δ 4.40–4.60 (2H), 3.1–3.3 (2H⁺), 2.1–2.3 (2H⁺), 1.7–1.9 (2H), confirming that the product prepared in this application is 1,4-butyryl lactone.

[0097] The chemical equation for this reaction step is as follows:

[0098]

[0099] As can be seen from Examples 1-7, the yield is highest when the molar ratio of tetrahydrofuran to sulfite is 1:1, and increasing the initiator dosage also helps to increase the yield.

[0100] Through Examples 1-7 and Comparative Example 1, it can be seen that when the technical solution provided in this application uses hydrogen peroxide as an initiator, it does not generate 1,4-butyryl lactone. The possible reason is that the strong oxidizing property of hydrogen peroxide reacts with sulfite, resulting in no free radical generation, thus causing sulfite not to react with tetrahydrofuran.

[0101] Through Examples 1-7 and Comparative Example 2, it can be seen that the pressure in the technical solution provided by this application has a significant impact on the yield of the final product. The reason is that tetrahydrofuran is relatively stable and it is difficult to undergo ring-opening reaction under normal pressure, so there are fewer ring-opening products, resulting in a relatively low yield of the final product.

[0102] Through Examples 1-7 and Comparative Example 3, it can be seen that temperature has a significant impact on the yield of the final product in the technical solution provided in this application. The reason is that tetrahydrofuran is relatively stable and it is difficult to undergo ring-opening reaction at low temperatures, so there are fewer ring-opening products, resulting in a relatively low yield of the final product.

Claims

1. A method for the synthesis of 1,4-butane sultone, characterized in that, Sulfite and tetrahydrofuran occur free radical addition reaction under the action of free radical initiator to obtain 4-hydroxybutane sulfonate in one step; 4-hydroxybutane sulfonate is acidified and cyclized to obtain 1,4-butane sulfonic acid lactone; The reaction pressure of the free radical addition reaction is not less than 1 Mpa, and the temperature is not less than 100 DEG C. The free radical initiator is a peroxide; the peroxide is one of t-butyl hydroperoxide, sodium persulfate and potassium persulfate.

2. The method of synthesizing 1,4-butane sultone according to claim 1, characterized in that, The steps are as follows: 1) adding deionized water and sulfite into an autoclave, stirring until clear, then adding free radical initiator and tetrahydrofuran in sequence, increasing the pressure to not less than 1 Mpa, increasing the temperature to not less than 100 DEG C, then reacting for 2-24 hours, and dehydrating by distillation under reduced pressure until the reaction liquid is turbid; 2) after the reaction liquid in step 1) is cooled to room temperature, strong acid and alcohol are added into the reaction liquid in step 1), stirring at room temperature for 2-4 hours, then filtering, removing water by distillation under reduced pressure, then cyclizing under vacuum until no bubbles are generated, and then distilling to obtain 1,4-butane sulfonic acid lactone crude product, and rectifying the 1,4-butane sulfonic acid lactone crude product to obtain 1,4-butane sulfonic acid lactone.

3. The method of synthesis of 1,4-butane sultone according to claim 1 or 2, characterized in that, The molar ratio of tetrahydrofuran to sulfite is 0.5-2.0:1; the mass of the free radical initiator is 0.1%-10% of the mass of tetrahydrofuran.

4. The method of synthesis of 1,4-butane sultone according to claim 1 or 2, characterized in that, The sulfite is at least one of sodium bisulfite, potassium bisulfite, ammonium bisulfite, sodium metabisulfite, potassium metabisulfite and ammonium metabisulfite.

5. The method for synthesizing 1,4-butyryl lactone according to claim 2, characterized in that, The pressure in step 1) is 1-10 Mpa.

6. The method for synthesizing 1,4-butyryl lactone according to claim 2, characterized in that, The reaction temperature in step 1) is 100-300 DEG C.

7. The method for synthesizing 1,4-butyryl lactone according to claim 2, characterized in that, The reaction temperature in step 2) is 110-120 DEG C.

8. The method for synthesizing 1,4-butyryl lactone according to claim 2, characterized in that, The distillation temperature in step 2) is 130-150 DEG C.

9. The method for synthesizing 1,4-butyryl lactone according to claim 2, characterized in that, The vacuum degree in step 2) is 600-1000 Pa.

10. The method for synthesizing 1,4-butyryl lactone according to claim 2, characterized in that, The strong acid is one of hydrochloric acid, concentrated sulfuric acid, nitric acid and phosphoric acid.

11. The method for synthesizing 1,4-butyryl lactone according to claim 2, characterized in that, The alcohol is one of methanol, ethanol, propanol and butanol.

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