阅读说明：本技术 一种利用酸酐-水系制备双（氟磺酰）亚胺的方法 (Method for preparing bis (fluorosulfonyl) imide by using anhydride-water system ) 是由 苏秋铭 张梦 辛伟贤 谢文健 陈新滋 于 2020-06-23 设计创作，主要内容包括：本发明公开了一种利用酸酐-水系制备双(氟磺酰)亚胺的方法,该方法包括以下步骤：在无溶剂体系中,在0～100℃下,双(氟磺酰)亚胺金属盐与强酸酸酐在水参与下反应制备双(氟磺酰)亚胺粗品；再经减压蒸馏得到高纯度的双(氟磺酰)亚胺。本发明提供的制备方法具有方法简单、副反应少、操作条件较温和和适用范围较广等优点。(The invention discloses a method for preparing bis (fluorosulfonyl) imide by using an anhydride-water system, which comprises the following steps: in a solvent-free system, under the temperature of 0-100 ℃, reacting bis (fluorosulfonyl) imide metal salt with strong acid anhydride in the presence of water to prepare a crude bis (fluorosulfonyl) imide product; then the high-purity bis (fluorosulfonyl) imide is obtained by reduced pressure distillation. The preparation method provided by the invention has the advantages of simple method, less side reaction, mild operation conditions, wide application range and the like.)

1. A method for preparing bis (fluorosulfonyl) imide by using an anhydride-water system is characterized by comprising the following steps: in a solvent-free system, under the temperature of 0-100 ℃, reacting bis (fluorosulfonyl) imide metal salt with strong acid anhydride in the presence of water to prepare a crude bis (fluorosulfonyl) imide product; then the high-purity bis (fluorosulfonyl) imide is obtained by reduced pressure distillation.

2. The method for preparing bis (fluorosulfonyl) imide using an acid anhydride-water system as claimed in claim 1, wherein said bis (fluorosulfonyl) imide metal salt is at least one selected from the group consisting of lithium bis (fluorosulfonyl) imide, sodium bis (fluorosulfonyl) imide, potassium bis (fluorosulfonyl) imide, rubidium bis (fluorosulfonyl) imide, cesium bis (fluorosulfonyl) imide, calcium bis (fluorosulfonyl) imide, magnesium bis (fluorosulfonyl) imide, and zinc bis (fluorosulfonyl) imide.

3. The method for preparing bis (fluorosulfonyl) imide from anhydride-water system according to claim 1, wherein said strong acid anhydride is selected from at least one of sulfur trioxide, dinitrogen pentoxide, trifluoroacetic anhydride, and trifluoromethanesulfonic anhydride.

4. The method for preparing bis (fluorosulfonyl) imide from an anhydride-water system as claimed in claim 1, wherein the molar ratio of bis (fluorosulfonyl) imide metal salt to strong acid anhydride is 1: 1-5: 1; the molar ratio of the water to the strong acid anhydride is 1: 1.

5. The method for preparing bis (fluorosulfonyl) imide from anhydride-water system according to claim 1, wherein the reaction temperature of bis (fluorosulfonyl) imide metal salt with strong acid anhydride for preparing bis (fluorosulfonyl) imide is 0-50 ℃ and the reaction time is 0.5-5 h.

6. The method for preparing bis (fluorosulfonyl) imide using an acid anhydride-water system according to claim 1, wherein the temperature of said vacuum distillation is 40 to 180 ℃ and the distillation pressure is 0.1 to 0.8 MPa.

7. The method for preparing bis (fluorosulfonyl) imide using an acid anhydride-water system as claimed in claim 1, wherein the acid anhydride is added first, and then the metal salt of bis (fluorosulfonyl) imide is added; or adding the bis (fluorosulfonyl) imide metal salt, adding the strong acid anhydride, and slowly dripping water under stirring to react.

Technical Field

The invention belongs to the technical field of lithium battery electrolytes in fluorine chemical industry, and particularly relates to a method for preparing bis (fluorosulfonyl) imide by using an anhydride-water system.

Background

Bis (fluorosulfonyl) imide (CAS: 14984-73-7) having the formula HN (SO)₂F)₂Simple and easyCalled HFSI. HFSI is a strong acid, the salt of which has wide application in catalysis, electrolyte, fluorinating agent and other aspects, particularly, the lithium salt of the HFSI has high thermal stability, is not decomposed below 200 ℃, has good chemical stability and is obviously superior to lithium hexafluorophosphate (LiPF)₆). Therefore, the HFSI becomes an important product in the research of lithium battery electrolyte, and has the advantage of environmental friendliness due to the fact that the HFSI is a very good acidic catalyst, so that the HFSI has important economic and social values.

Bis (fluorosulfonyl) imide is an important raw material for preparing lithium bis (fluorosulfonyl) imide. The prior art for the preparation and extraction of bis (fluorosulfonyl) imide from the literature is known as follows:

patents US4315935, CN102786452, etc. disclose HFSI synthesis methods, which are to synthesize bis (chlorosulfonyl) imide (HClSI) first with chlorosulfonic acid, thionyl chloride and sulfamic acid, and then fluorinate with fluorinating agent to obtain bis (fluorosulfonyl) imide (HFSI). The method for synthesizing HFSI is complex in process, and adopts a fluorinating agent SbF₃、BiF₃The like is expensive, has particularly high toxicity, and generates a reaction byproduct of SbCl₃Easy sublimation, distilling out with HFSI during reduced pressure distillation, difficult purification of HFSI; and ZnF is selected₂Then a large amount of amine-containing wastewater is generated in the later period, and HF is more dangerous, so that the reaction difficulty is increased again due to high toxicity and high corrosivity. The HFSI material obtained by the method has high toxicity and danger, high consumption and large amount of waste.

The literature (Journal of Fluorine Chemistry 127(2006)193-199) reports the preparation of bis (perfluorooctylsuccinimide) from bis (perfluorooctylsulfonyl) imide triethylamine salt by using an acidic cation exchange resin, obtained by sublimation at 0.2mmHg at 120-160 ℃ after the reaction. The method is only useful for preparing the bis (perfluoroalkyl sulfonyl) imine by acidifying the triethylamine salt of the bis (perfluoroalkyl sulfonyl) imine, so the method has great limitation and low applicability.

U.S. Pat. Nos. 8337797, 9156692, 5916475, Inorg. Synth.11,138-43(1968) and others disclose the preparation of HFSI by the mixed heating reaction of urea and fluorosulfonic acid, and the recovery of the generated HFSI by vacuum distillation. However, this method uses a Polytetrafluoroethylene (PTFE) reactor, which is expensive, has a yield of only 40%, has a strong corrosiveness, is expensive, has few suppliers, and has a small difference between the boiling points of fluorosulfonic acid and HFSI, and it is difficult to separate HFSI from excess or unreacted fluorosulfonic acid by vacuum distillation, so it is difficult to obtain HFSI with high purity.

The research of Chinese patent CN105523529A reports that in polar aprotic solvent, potassium bis (fluorosulfonyl) imide reacts with sufficient amount of strong acid to prepare crude bis (fluorosulfonyl) imide, and then high-purity HFSI is obtained by reduced pressure distillation. The strong acids used are shown in the patent to be perchloric acid, hydroiodic acid, chlorosulfonic acid, fluorosulfonic acid and trifluoroacetic acid. Experiments show that chlorosulfonic acid is easy to generate side reaction when participating in the reaction, and high-purity HFSI is not easy to obtain. Perchloric acid, hydroiodic acid, fluorosulfonic acid and trifluoroacetic acid are expensive and have high requirements on equipment, which is not favorable for industrial production. The research of the Chinese patent CN104961110B reports that HFSI is obtained by blowing hydrogen chloride gas into a solution after the solution is prepared by using alkali metal salt of bis (fluorosulfonyl) imide as a solute. The method is difficult to control the pressure of the whole reaction equipment, consumes more hydrogen chloride gas, has higher requirements on the equipment, and needs a large amount of alkali liquor to treat exhaust gas at the later stage, so that a large amount of waste liquid needs to be treated.

In the literature (organic Chemistry32(1993) 5007-5010; organic Chemistry23(1984)3720-3723) 5.0g of dried sodium bis (perfluoroalkylsulfonyl) imide was dissolved in 43g of concentrated sulfuric acid (100%) and placed in a sublimator under high vacuum at 60 ℃ to give 4.2g of bis (perfluoroalkylsulfonyl) imide. However, in the method, the HFSI is difficult to sublimate due to the selection of 100% concentrated sulfuric acid, and is easy to decompose in the heating process, so that a plurality of byproducts are obtained, and the purification is difficult in the later period.

Disclosure of Invention

Aiming at the defects in the prior art, the invention discovers a new process after intensive research: reacting bis (fluorosulfonyl) imide (MFSI) with strong acid anhydride in the presence of water, wherein the reaction is carried out in a solvent-free manner, and after the reaction is finished, carrying out reduced pressure distillation to obtain high-purity HFSI. The method has the advantages of simple operation, less side reaction and low cost.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing bis (fluorosulfonyl) imide from an anhydride-water system, comprising the steps of: in a solvent-free system, under the temperature of 0-100 ℃, bis (fluorosulfonyl) imide metal salt (MFSI) and strong acid anhydride react under the participation of water to prepare a crude bis (fluorosulfonyl) imide product; then the high-purity bis (fluorosulfonyl) imide (HFSI) is obtained by reduced pressure distillation.

Preferably, the bis (fluorosulfonyl) imide metal salt is selected from the group consisting of lithium bis (fluorosulfonyl) imide (LiFSI), sodium bis (fluorosulfonyl) imide (NaFSI), potassium bis (fluorosulfonyl) imide (KFSI), rubidium bis (fluorosulfonyl) imide (RbFSI), cesium bis (fluorosulfonyl) imide (CsFSI), calcium bis (fluorosulfonyl) imide (Ca (FSI)₂) Bis (fluorosulfonyl) imide magnesium (Mg (FSI))₂) Bis (fluorosulfonyl) imide zinc (Zn (FSI))₂) At least one of (1).

Preferably, the strong acid anhydride is selected from sulfur trioxide (SO)₃) Dinitrogen pentoxide (N)₂O₅) Trifluoroacetic anhydride ((CF)₃CO)₂O), trifluoromethanesulfonic anhydride ((CF)₃SO₂)₂O).

Preferably, the molar ratio of the bis (fluorosulfonyl) imide metal salt to the strong acid anhydride is 1: 1-5: 1; the molar ratio of the water to the strong acid anhydride is 1: 1.

Preferably, the reaction temperature for preparing the bis (fluorosulfonyl) imide by reacting the bis (fluorosulfonyl) imide metal salt with the strong acid anhydride is 0-50 ℃, and the reaction time is 0.5-5 h.

Preferably, the temperature of the reduced pressure distillation is 40-180 ℃, and the distillation pressure is 0.1-0.8 MPa.

Preferably, in the reaction process, the acid anhydride can be strengthened firstly, and then the bis (fluorosulfonyl) imide metal salt can be added; or adding the bis (fluorosulfonyl) imide metal salt, adding the strong acid anhydride, and slowly dripping water under stirring to react.

In the novel process for preparing bis (fluorosulfonyl) imide by using an anhydride-water system, on one hand, the anhydride of a strong acid is commonly used for substitution reaction and is changed into an acyl protecting group or is used as a catalyst, and no document reports that the anhydride is used as a raw material for preparing bis (fluorosulfonyl) imide (HFSI). On the other hand, water is not generally added in the process of preparing the bis (fluorosulfonyl) imide, after all, HFSI is an important intermediate for synthesizing lithium bis (fluorosulfonyl) imide serving as a lithium battery additive, water is not allowed in the process, water can participate in the reaction, and finally the obtained HFSI is also an anhydrous high-purity product. In addition, the invention adopts solvent-free reaction, thus not only saving cost, but also reducing the difficulty of post-treatment.

The invention has the technical effects that:

1. the reaction selects a plurality of bis (fluorosulfonyl) imide salts, which indicates that the invention has wide application.

2. The solvent-free reaction is selected for the reaction, the post-treatment is simple, and the cost is low.

3. The reaction uses a strong acid anhydride to react with equivalent water, and the reaction rate and the reaction exotherm can be controlled by the rate of water addition.

4. After the reaction, the final product is obtained by direct reduced pressure distillation, and has good quality and high purity.

Therefore, the invention provides the HFSI with high efficiency, high quality and high purity, which is suitable for industrial production.

Detailed Description

In order to make the above objects of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to specific examples, but the scope of the present invention is not limited to the following examples.