HK1215019B - Synthesis of tetrabutylammonium bis(fluorosulfonyl)imide and related salts - Google Patents

Abstract

The present invention is directed to methods comprising adding ammonia, either as an ammonium salt or as a gas at pressures below 0.01 MPa, to a sulfuryl fluoride solution to form the anion of bis(fluorosulfonyl)amine under conditions well suited for large-scale production. The bis(fluorosulfonyl)amine so produced can be isolated by methods described in the prior art, or isolated as an organic ion pair, such as an alkylammonium solid salt, or as an ionic liquid.

Description

Synthesis of tetrabutylammonium bis (fluorosulfonyl) imide and related salts

Cross Reference to Related Applications

The benefit of U.S. provisional patent application No.61/727,616, filed 11/16/2012, the contents of which are incorporated herein by reference in their entirety.

Technical Field

The present invention relates to a significantly improved tetrabutylammonium bis (fluorosulfonyl) imide, [ Bu₄N]⁺[(FSO₂)₂N]^-And a method for preparing the related salt.

Background

Containing bis (fluorosulfonyl) imide [ (FSO)₂)₂N]^–The compound (b) is useful, for example, in the fields of Lewis acid catalysts, ion transporters, organic compound synthesis, electrolytes and the like.

Various methods for the synthesis of bis (fluorosulfonyl) amines and related compounds have been proposed (see, e.g., Ruff, Inorg. chem.4(10):1446 (1965); Ruff, Inorg. Synth. XI:138(William, ed., McGraw-HillBook Co., 1968); Vij et al, coord. chem. Rev.158:413 (1997); Krumm et al, Inorg. chem.37:6295 (1998); Beran et al, Z.Anorg. Allg. chem.631:55 (2005); U.S. Patent No.8,377,406, U.S. Patent No.5,723,664; and U.S. Patent No.5,874,616; DE Patent No. 1199244). However, these processes may not be suitable for industrial scale production either because of their low yield or because of the need to form, for example, hazardous intermediates and/or the need for corrosive/expensive raw materials.

Improved obtaining [ (FSO)₂)₂N]^–Methods for their preparation and their salts are disclosed in morinaca (US2012/0028067a1 and US2012/0070358a1), incorporated herein by reference in its entirety, by treating SO with ammonia gas in the presence of an aprotic base₂F₂In acetonitrile to obtain [ (FSO) in high yield₂)₂N]^–A salt. As used herein, an "aprotic base" is free of labile hydrogen atoms. For example, diethylamine is a protic base and triethylamine is an aprotic base. Morinaka can control SO using high pressure conditions₂F₂Thereby allowing it to react with high concentrations of ammonia.

Those skilled in the art will recognize that the morinaca process uses reactor pressures above atmospheric. Morinaka describes the high pressure conditions for [ (FSO)₂)₂N]^–Commercial scale synthesis of salts is problematic because large scale synthesis requires large pressurized vessels. Large pressurized vessels for commercial scale synthesis are expensive compared to low cost vessels designed for use at atmospheric pressure or lower. Furthermore, the high-toxicity SO which cannot be detected at all by sensory or conventional means is treated under high pressure₂F₂With added safety issues. To be exposed to SO₂F₂Is fatal to the operator.

Therefore, there is a need for an improved [ (FSO)₂)₂N]^–A process for the synthesis of salts which can be safely and economically scaled up for commercial use.

The present invention is based in part on the Morinaka methodUnder conditions, i.e. at pressures above 0.01MPa, the discovery of gas phase reactor fouling occurred. Fouling is a labor cost increasing problem and foulants must be removed during operation. This goes far beyond simple flushing, as any assembly whose surface contains part of the reactor headspace must be disassembled. The fouling agent is a volatile, toxic, fluoridated slag. Even if the assembly is very clean, fouling can cause equipment failure through corrosion and wear on, for example, the mixing bearings and seals. For [ (FSO)₂)₂N]^–Industrial scale production of salts without fouling the reactor and SO₂F₂Operation under conditions where the risk of leakage is minimal is even more preferred.

Disclosure of Invention

It is an object of the present invention to provide a process wherein SO is added in the presence of an aprotic base₂F₂The headspace above the solution was slowly and continuously injected with ammonia (NH)₃) Can be safely and commercially realized under the pressure of less than 0.01 MPa. [ (FSO) obtained by this method₂)₂N]^–The salt yield was greater than or equal to that reported by morinaca. In addition, reactor fouling is eliminated by operating at this lower pressure.

It is a further object of the invention to provide a process in which NH₃Adding to SO in the form of a salt₂F₂For example, with ammonium salts (e.g. NH)₄F) Into NH₃. By NH₃The addition of salts allows safe use of reactor pressures above 0.01 MPa. The yield was the same as injecting gas at lower pressure and no fouling occurred.

It is still another object of the present invention to provide a method for preparing bis (fluorosulfonyl) imide anion (M)⁺ _n[(FSO₂)₂N^–]_m) A process for preparing a salt, wherein M⁺Is an inorganic or organic cation and n and m are 1 to 4, comprising:

adding ammonia to sulfonyl fluoride (SO) in a closed reactor in the presence of an aprotic base₂F₂) While maintaining the pressure in the sealed reactor below 0.01MPa (75 torr) to produce a solution containing product ions [ (FSO)₂)₂N]^-(ii) ("FSI") in solution;

subjecting said mixture to a reaction comprising product ions [ (FSO)₂)₂N]^-("FSI") solution was added to M-containing solution⁺A solution of a salt, and;

isolating the resulting bis (fluorosulfonyl) imide-containing anion (M)⁺ _n[(FSO₂)₂N^–]_m) A salt.

Drawings

FIG. 1 shows a SO₂F₂And NH₃Reaction scheme of the reaction.

Detailed Description

In general, SO₂F₂And NH₃The reaction of (3) takes place only in liquid solution and not in gas phase. However, reactor fouling indicates that surface reactions can occur. SO (SO)₂F₂And NH₃Some of the relevant reactions of (a) are shown in figure 1.

SO₂F₂And NH₃The initial reaction of (2) is a vigorous amino defluorination (aminodefluorination) to give fluorosulfonamide FSO₂NH₂. Then FSO₂NH₂Can be reacted in one of several ways: second amino defluorination to give the sulfonamide (route 1), or deprotonation to give the fluorosulfonamide anion (FSO)₂NH^-Paths 2 and 3). Dissolved FSO₂NH^-Is an intermediate product that can make the inventive product herein and morinaca. FSO₂NH^-Sufficiently inert to allow FSO₂NH₂Can be isolated in high yield by acidification of the intermediate tank (see, e.g., U.S. patent application 2012/028292a 1). FSO₂NH^-Through reaction with SO₂F₂Further slowly reacting to obtain (FSO)₂)₂NH, which is rapidly deprotonated to give the product anion (FSO)₂)₂N^-And separated as ion pairs.

Ammonia was used as a reactant:

gaseous NH₃With dissolved SO₂F₂The reaction is highly exothermic and very fast, and gaseous NH₃The rate of addition must be carefully controlled. In a preferred embodiment, the SO is added to a vigorously stirred mixture₂F₂To the solution of (a) is slowly added gaseous NH₃For a period of at least 90 minutes, or more preferably two hours or more. The rate of addition is generally adjusted according to the degree of temperature rise above the initial temperature. In some embodiments, the NH is added₃The temperature rise from the initial static temperature is maintained at + -5 deg.C or less, more preferably + -2 deg.C or less. Effective cooling of the reactor is required in order to remove the heat of reaction.

Precisely controlled SO₂F₂And/or NH₃Addition of (c) can be maintained, for example, using mass flow controllers, caliper gauges (caliper gauges), and the like. In some embodiments, NH₃(and/or SO)₂F₂Addition) rate is controlled by internal reactor pressure, reactor temperature, or other variable conditions.

Within certain limits, NH₃And SO₂F₂The order and rate of addition of (c) can be varied. At NH₃There must be a large molar excess of SO in the reactor during the addition₂F₂. For example, NH may be added at a continuous rate₃To contain SO₂F₂To achieve 70 torr (0.0093MPa), additional SO₂F₂The addition is carried out in a pressure-dependent manner using, for example, a gate valve. In a preferred embodiment, both reagents are added simultaneously at a controlled rate. For example, when the reactor pressure is below, e.g., 70 torr, additional SO may be added₂F₂。

NH₃The rate of addition of (c) may vary as a function of the degree of agitation of the reactor contents: better agitation in the reactor allows for NH₃Faster addition. NH should be controlled₃At a rate to reduce the formation of by-products. For a 2 gallon reactor with maximum agitation rate, a two hour addition time is sufficient to provide a yield of 95% or more. Although within the scope of the invention, NH is added at a constant rate under similar conditions₃More than one hour results in reduced yields and the formation of large amounts of insoluble by-products.

Preferably, the aprotic base (B) is capable of acting as an anion with preparation (i.e., BH)⁺(FSO₂)₂N^-,BH⁺FSO₂NH^-And BH⁺F^-) The ion pairs of (a) remain dissolved. Morinaca describes exemplary non-reactive bases (and many ineffective bases) that do not describe TMPDA, which is the base that has been found to be most useful for the process. Trialkylamines are the preferred bases, more preferably TMPDA. TMPDA can maximize reactor load, is inexpensive and recyclable. TMPDA produced a clear canned liquid so the reactor could be reused after a simple flush. TMPDA is used as a process base to produce concentrates with low melting points and broad solubility. TMPDA has a mild boiling point so that it can be reused.

Acceptable solvents include ethers (e.g., diethyl ether, tetrahydrofuran, etc.), nitriles (e.g., acetonitrile, butyronitrile, etc.), esters (e.g., ethyl acetate, etc.), halogenated hydrocarbons (e.g., dichloromethane, etc.), and tertiary amides (e.g., N-Dimethylacetamide (DMA), N-methylpyrrolidone (NMP), Tetramethylurea (TMU), dimethylacryl urea (DMPU), etc.. more preferably, the solvent having a higher polarity₂F₂Solvents which dissolve well therein are more preferred.

Theoretical NH₃And SO₂F₂In a ratio of 1: 2. In practice, a molar ratio of 1.008:2 has been used. Higher molar ratios can also be used without any advantage and increase the likelihood of by-product formation.

Alkali and SO₂F₂Is 3: 2. In practice, TMPDA and SO₂F₂The molar ratio was 1.03:1 (equivalent ratio 2.06:1 or 4:2) and yields of 85-95% were obtained. The ratio can be reduced to near theoretical levels without substantially affecting yield, provided that the base is specific to NH₃More strongly basic, i.e. TMPDA having two nitrogen atoms is more than NH₃Stronger bases.

The amount of solvent depends on the solubility of the product. The low polarity solvent does not give a reactor load of 1 mole without forming pot solids (potsolids), and much lower loads are needed to prevent this. More polar solvent can give more than 1 mole loading. Acetonitrile and TMPDA were used as solvent and base, respectively, with a 1.1 molar loading to yield a clear liquid and no formation of a canned solid. Solids begin to form at greater than about 1.1 moles of the solvent/base combination.

NH was carried out at-10 ℃ and 70 torr using acetonitrile and TMPDA as solvent and base, respectively₃At one molar equivalent of SO₂F₂High yields were still obtained when the addition was completed before (example 3). This indicates the addition of NH₃Is partially free (i.e. as NH) during the addition₄F) (see FIG. 1). Example 3 SO addition₂F₂Also indicates the intermediate FSO₂NH₂Is partially free, under these conditions, reversible pathway 2 is performed instead of irreversible pathway 1 (see FIG. 1).

At NH₃The elevated pressure during addition produces fouling and the solids soaked with solvent and base make all areas of the interior surface not liquid wet. Two gallons (7.57 liters) of parr with overhead stirrer at about 0.1MPa (1 atm) per reaction in each of these reactionsThe headspace of the reactor will foul. All piping, check valves, and agitation assemblies that were vented into the headspace were fouled. The reactor needs to be disassembled and cleaned after each run. The stirring assembly is not easily cleaned and is generally not reusable after three runs, due to fouling wear and/or bearing swelling, or corrosion, i.e. leaching of carbon from the bearing into the fouling material. Although PTFE ("Teflon^TM") bearings alleviate the corrosion problem, but the problem of wear still remains.

Fouling only occurs at NH₃The addition was eliminated by using a reactor pressure of less than 0.01Mpa (75 torr). The pressure in the reactor may be at NH₃After addition, increases, which makes fouling no longer a problem. The pressure can be increased by increasing the temperature, more preferably by adding SO₂F₂Or a combination of the two.

The reactor temperature depends on the stage of the reaction and the solvent used and to some extent on the vapor pressure of the solvent and the base. For example, acetonitrile has a significant vapor pressure above about 10 ℃. When acetonitrile is used as solvent, NH₃Is carried out at a temperature of between-30 and +20 ℃ and preferably between-15 and +5 ℃. Within the scope of the invention, NH can be carried out at elevated temperature (40 ℃) using higher-boiling solvents and bases₃Or (2) is added. Non-volatile bases, such as polymers of tertiary amines, and the like, may be used within the scope of the present invention.

If a volatile solvent is used (e.g. acetonitrile), NH is added once₃The temperature is increased to +10 to +40 deg.C, more preferably 24-28 deg.C, by introducing SO for timely completion of the reaction₂F₂The reactor pressure was increased to below 0.1MPa (750 torr) (path 3 in fig. 1). Higher pressures may be used but are preferably below atmospheric pressure for safety. In a suitably degassed reaction, SO is accompanied by₂F₂At full consumption, the end pressure will be close to the vapor pressure of the solvent. The contents were then removed from the reactor as a clear liquid.

In a preferred embodiment, the reactor can be reused without extensive cleaning.

In a preferred embodiment, the reaction is sufficiently complete at pressures below 0.01MPa if a suitable high boiling point solvent/base combination is used.

Ammonium salts were used as reactants:

in another preferred embodiment of the invention, NH is introduced₃As ammonium salts (e.g. NH)₄F) Scale formation is inhibited. An additional equivalent of base is required. In this example, the reactor pressure may be greater than 0.1MPa, up to 0.3MPa, but for safety the reactor pressure is preferably less than 0.1 MPa. A pressure slightly below atmospheric pressure is most preferred. Ammonium fluoride is preferred over other salts because the by-products are generally more readily soluble in the process solvent. For example, although ammonium chloride is not preferred within the scope of the present invention, it produces an insoluble by-product and contaminated product (comparative example 1).

Ammonium fluoride is insoluble in most aprotic organic solvents. In addition, NH is suspended under process conditions, for example in the presence of TMPDA₄The conversion of F to free ammonia is very slow even with a finely divided solid. This makes NH₃Slowly added to the tank and any NH was prevented₃Escaping into the headspace. A clear canned liquid free of fouling was obtained. The yield of product isolated in this embodiment of the invention was the same as that obtained using ammonia (examples 1 and 2).

In a particular embodiment of the invention, temperatures of 0-50 deg.C, more preferably 24-28 deg.C, may be used.

By using the above improvements, commercially viable scaling-up can be achieved at acceptable cost and increased safety.

The canned liquids obtained in the examples of the present invention may be processed as described below to isolate the product.

Product ion [ (FSO)₂)₂N]^-(“FSI ") can be isolated, for example, as a metal salt, organic salt, or other salt. Solid salts are preferred over ionic liquids, although they are also within the scope of the present invention. In some embodiments, C₁-C₅Tetraalkylammonium salts are used to precipitate FSI, e.g. tetrabutylammonium bromide (Bu)₄NBr). In some embodiments, the quaternary ammonium hydroxide (e.g., Bu)₄NOH, etc.) are preferred. Bu₄This product of NFSI has a melting point of about 99 ℃, enabling it to be handled under ambient conditions, is insoluble in water, slightly soluble in cold methanol, very soluble in hot methanol. This enables a very large recovery of FSI to be achieved resulting in higher separation yields than reported by morinaca. Another salt, Me₄N⁺FSI^-(by Me)₄NCl) produced an initial precipitate with 10-17 ppm chloride (by ion chromatography) and, after a second recrystallization from distilled water, contained an undetectable amount of chlorine (<10 ppm). However, FSI as Me₄Recovery of NFSI is approximately comparable to Bu₄The recovery rate of NFSI is 10 percent lower. The solid alkylammonium salts obtained according to the invention are very pure and can be dried to very low water contents.

Examples

Example 1

A1 liter, 4-neck round bottom flask was equipped with a stirrer, air inlet, pressure compensating dropping funnel and thermometer, and charged with ACS grade ammonium fluoride (16.06g, 0.43mol) and 1-methyl-2-pyrrolidone (NMP, 462 g). The dropping funnel was charged with 1, 3-bis (dimethylamino) propane (TMPDA, 120g, 0.92 mol). The flask was then sealed and evacuated under dynamic vacuum with magnetic stirring, so both TMPDA and NMP were vented. After a few seconds at 20 torr, the vacuum was stopped and the flask was charged with SO₂F₂The gas is allowed to flow until a steady pressure of 700 torr is reached. TMPDA was then added dropwise over a period of 10 seconds to the stirred flask contents, the flask contents were stirred under 25 ℃ water bath conditions and SO was added continuously at a set pressure (700 Torr)₂F₂. After 21 hours, the amount of SO was calculated₂F₂(87.7g, 87.7mol) were all added and the reactor pressure was 347 Torr. No solids were observed in the headspace of the flask. The flask was then assembled for vacuum distillation and the solvent and some base were distilled off (1.6 torr, 65 ℃ water bath, 53 ℃ distillation head). The flask contents (203g), a clear yellow oil, were slowly poured into a stirred warm water solution (1.5kg) of tetrabutylammonium bromide (161g, 0.5 mol). The solid thus obtained was suction-filtered, compressed with a rubber barrier and dissolved in a hot methanol solution. The solution was fine filtered hot (poisefiltered), diluted to a total of 1 liter with water (40mL) and cooled to-25 ℃. The crystals thus obtained were collected by filtration and dried in a vacuum oven at 45 ℃ to constant weight. The yield was 154.3g (0.36mol, 85%) and the melting point was 97-99 ℃.

Example 2

A2 liter stainless steel reactor (Parr instruments, Morin, IL) was charged with ACS grade ammonium fluoride (NH)₄F,36.2g,0.98mol), TMPDA (327g,2.5mol) and acetonitrile (842 g). The reactor was sealed and vented to 57 torr pressure before stirring was initiated. Sulfonyl fluoride (208.8g,2.05mol) was added continuously with gentle stirring at a set pressure of 650-750 torr. The temperature was slowly raised from 12 ℃ to 25 ℃ and the remaining SO₂F₂The temperature was maintained between 25 ℃ and 27 ℃ for about 24 hours during the addition. Excess gas was pumped out and the reactor was opened. No solids were found in the reactor headspace. The contents were saturated with ammonia gas and the solid obtained was filtered off and washed with acetonitrile. The combined filtrates were concentrated to a clear yellow oil (306g) and treated with tetrabutylammonium bromide as before to obtain the product in two portions from methanol, 360.6g (0.85mol, 87%) with a melting point of 98.5-99.5 ℃.

Example 3

A2 liter stainless steel reactor was charged with TMPDA (375g, 2.88mol) and acetonitrile (750g), cooled to-10 ℃ and vented with stirringEmpty to 19 torr. Adding SO to the reactor₂F₂Until the exit pressure was 70 torr, and ammonia (23.4g, 1.37mol) was fed to the reactor at that pressure and temperature over 2 hours. After the addition of ammonia gas was complete, 117g (1.15mol) of SO were added₂F₂. The temperature of the reactor was then increased to 25 ℃ and an additional 165g of SO was added at a pressure of 250-500 torr₂F₂The reactor contents were stirred overnight. The excess gas was pumped out and the reactor was opened. A small amount of solids could be observed on the exposed condenser tubes but no solids were found in the reactor headspace. The product was treated with tetrabutylammonium bromide as described above and yielded a single crop of product (487g, 1.15mol, 84%) with a melting point of 97-101 ℃.

Comparative example 1

A2 liter stainless steel reactor (Parr instruments, Morin, IL) was charged with ACS grade ammonium chloride (NH)₄Cl, 43g, 0.8mol), TMPDA (259g, 1.99mol) and acetonitrile (838 g). The reactor was sealed and vented to 122 torr pressure before stirring was initiated. The reactor temperature reached 25 ℃ and sulfuryl chloride (162.4g,1.59mol) was added continuously over 18 hours at a set pressure of 650-750 torr with gentle stirring at 25-27 ℃. The excess gas was pumped out and the reactor was opened. There was some build-up of solids at the reactor headspace interface. A certain amount of precipitated solid was filtered off and washed with acetonitrile. The combined filtrates were concentrated to a clear yellow oil (321g) and treated with tetrabutylammonium bromide as before to give the product from methanol, only one crop (226g) was collected, which had a broader melting point range of 98-120+ ° c, indicating contamination.

Comparative example 2

A2 gallon (7.57L) stainless steel high pressure reactor (Parr instruments, Molin, IL) was charged with acetonitrile (3.72kg) and tetramethyl-1, 3-propanediamine (TMPDA, 1.50kg, 11.5 mol). The reactor was evacuated with gentle stirring (mediumstirring) until a static vacuum of 43-45 torr was maintained at 10 ℃ for at least 10 minutes. Sulfuryl fluoride (SO) by pressure-gated immersion tube₂F₂) Pass into the reactor until a set pressure of 760 torr is reached. AddingAfter the end of the addition, a total of 227.5g of SO were added₂F₂The reactor temperature rose from 11 ℃ to 14 ℃. The agitation rate was set to 80% of the maximum rate and NH was added at a constant rate over a period of 3 hours₃Gas (96g, 5.63mol) was allowed to rise to a temperature of 23-25 deg.C, with cooling as necessary to maintain the temperature in this range. Adding SO at a set pressure₂F₂Is continued for the entire period of time. NH (NH)₃After the addition of (3), SO is added₂F₂Until the theoretical weight (1.14kg, 11.2mol) was added. The reactor was then stirred at a reduced stirring rate for 10 hours, during which time the pressure dropped from 760 torr to 123 torr and the temperature dropped from 25 ℃ to 15 ℃. The reactor contents, a clear pale yellow liquid, were transferred under reduced pressure through a dip tube to a large rotary evaporator and the sealed reactor was again rinsed through the dip tube with 1kg of acetonitrile. The combined liquids were concentrated at 60C/150 torr to 60C/80 torr to give 2.886kg of a viscous liquid residue which was added at a constant rate to a vigorously stirred solution of tetrabutylammonium bromide (2kg,6.2mol) in warm (31 ℃) water (10kg) for more than 14 minutes. The glass vessel was rinsed with 3X 25mL of methanol and added to the stirred tank, and the tank was stirred for an additional 20 minutes. The solid obtained was collected by suction filtration and rubber barrier compression. The wet solid (3.245kg) was removed from warm methanol (4.93kg), fine filtered, and cooled to-20 ℃. The crystalline product was collected by filtration, and the filter cake was washed twice with cold methanol and dried to constant weight in a dynamic vacuum at 45 ℃. The yield was 1.992kg (4.71mol, 84.4%) of the product as a white crystalline product with a melting point of 97 ℃ to 99 ℃. The second crop (208.2g, 0.49mol, 8.8%) had a melting point of 97 ℃ to 99 ℃ and was obtained by concentration of the filtrate. The remaining filtrate was combined with the aqueous residue from the first separation of the product and further rotary evaporated at 60 ℃ (rotovaped down) and the solid obtained was separated from methanol and recrystallized as before to yield a third crop of product (44.6g, 0.1mol, 1.9%) with a melting point of 97 ℃ -99 ℃. The overall yield was 2.245kg (5.31mol, 95.1%). After removal of the contents, the reactor was opened and a large amount of solids were found to be deposited in the reactor headspace, gas inlet pipe and check valve.

These examples illustrate possible embodiments of the invention. While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

All documents cited herein, including published journal articles or abstracts, or published related U.S. or foreign patent applications, or foreign patents, or any other documents, are incorporated by reference herein in their entirety, including all data, tables, figures, and text presented in the cited documents.

Claims (9)

1. Preparation of bis (fluorosulfonyl) imide-containing anion [ (FSO)₂)₂N]^–A method of salt, wherein the method comprises:

in the presence of an aprotic base, sulfonyl fluoride (SO) is reacted in a sealed reactor₂F₂) To a suspension, pellet or other form of solid ammonium fluoride in a solvent, and

isolating the salt.

2. The method of claim 1, whichWherein ammonium fluoride is added to the solution containing sulfonyl fluoride (SO)₂F₂) The step of (a) comprises:

providing solid ammonium fluoride to a solvent in a sealed reactor;

providing an aprotic base and an initial amount of sulfonyl fluoride (SO) in a sealed reactor₂F₂) (ii) a And

continuously adding additional amount of SO₂F₂Until a predetermined stoichiometry is reached while maintaining a pressure in the sealed reactor equal to or lower than 0.3 MPa.

3. The method of claim 1, further comprising applying a vacuum to the sealed reactor.

4. The method of claim 1, wherein the solvent is selected from the group consisting of acetonitrile, propionitrile, diethyl ether, tetrahydrofuran, butyronitrile, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, tetramethylurea, dimethylpropylurea, dimethylvinylurea, and combinations thereof.

5. The process of claim 1, wherein the aprotic base is N, N' -tetramethyl-1, 3-propanediamine.

6. The method of claim 1, wherein ammonium fluoride and SO₂F₂Is in a molar ratio of 1:3 to 1.1: 2.

7. The method of claim 1, wherein sulfonyl fluoride (SO) is added₂F₂) In the step (2), the reaction is maintained at a temperature ranging from-30 ℃ to +50 ℃.

8. The method of claim 1, the step of isolating the salt obtained comprising adding a solution of a salt containing an organic cation.

9. The method of claim 1, wherein sulfonyl fluoride (SO)₂F₂) By reaction with ammonium fluoride to prepare a compound containing an anion [ (FSO)₂)₂N]^-And the method further comprises:

will contain [ (FSO)₂)₂N]^-With a solution containing M^x+Mixing solutions of a salt to prepare the salt, wherein the salt is M^x+ _m[(FSO₂)₂N]^– _n,M⁺Is an inorganic or organic cation, and x, n and m are integers from 1 to 4.