Method for producing alkali sulfonylimide salt

Abstract

The present invention relates to a process for the preparation of salts of bis(chlorosulfonyl)imides that is economically feasible on an industrial scale and provides high purity products.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to earlier European Patent Application No. 22305259.8, filed March 7, 2022, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to a process for the preparation of salts of bis(chlorosulfonyl)imides that is economically feasible on an industrial scale and provides high purity products. [Background technology]

[0003] Fluorosulfonylimide salts, especially the lithium salt of bis(fluorosulfonyl)imide (LiFSI), are useful compounds for battery electrolytes. Various processes, reactants and intermediates leading to LiFSI are described in the patent literature, notably in Canadian Patent 2 527 802 (Universite de Montreal), which describes several routes for preparing LiFSI, such as the process for preparing LiFSI in one step starting from bis(chlorosulfonyl)imide (HCSI) using anhydrous hydrogen fluoride (HF): [ka] The following are listed.

[0004] One alternative known process for preparing LiFSI is a two-step process that involves fluorination of bis(chlorosulfonyl)imide (HCSI) to bis(fluorosulfonyl)imide (HFSI) using a fluorinating agent, such as anhydrous hydrogen fluoride (HF), followed by fluorination of HFSI to LiFSI using a lithiation agent.

[0005] Another known two-step process for preparing LiFSI uses NHF(HF) as the fluorinating agent. xThe process comprises a first step of fluorination of bis(chlorosulfonyl)imide (HCSI) to ammonium bis(fluorosulfonyl)imide (NHFSI) using 1,4-dichlorophenylsulfonyl, followed by a second step of lithiation of NHFFSI, which then leads to the LiFSI product. Such processes are described, for example, in WO 2017 / 090877 A1 (CLS) and EP 3 170 789 A1 (Nippon Soda Co., Ltd.).

[0006] Another known two-step process for preparing LiFSI involves the lithiation of HCSI in the first step using a lithiation agent to prepare LiCSI as an intermediate product, and then the fluorination of LiCSI to LiFSI using a fluorination agent. For example, Korean Patent No. 20200049164 (CLS) describes a method for preparing LIFSI, which includes the steps of reacting HCSI with various lithiation agents in a (SI) solvent to produce LiCSI, and then reacting it directly with anhydrous fluorination agents without purification. A long list of possible solvents is given in the specification, but dimethyl carbonate is used in the examples.

[0007] As can be seen from the above patent documents, the preparation of bis(fluorosulfonyl)imides, their salts and intermediate products is carried out in a solvent, e.g. an organic solvent, to disperse the reactive entities and to allow them to react. Summary of the Invention

[0008] Applicants have recognized that there remains a need in the art for improved methods for producing intermediate compounds used in the preparation of bis(chlorosulfonyl)imide salts.

[0009] In particular, the applicant is well aware that in the methods disclosed in the prior art, the solvent usually has to be treated to remove residual amounts of water and / or may need to be removed after the reaction. This step to remove the solvent increases the complexity of the industrial process as well as its overall cost.

[0010] With a view to overcoming the abovementioned drawbacks, the Applicant faced himself with the problem of providing a simpler process for the preparation of bis(chlorosulfonyl)imide salts, which does not require, inter alia, the use of solvents.

[0011] Thus, in a first aspect, the present application provides a method for preparing a salt of a bis(chlorosulfonyl)imide, comprising the steps of: (a) providing bis(chlorosulfonyl)imide (HCSI); (b) melting the HCSI provided in step (a) to obtain a molten HCSI; and (c) treating the molten HCSI obtained in step (b) with a compound of formula (I): (I)M + B - (In the formula, M is selected from Na, Li, K, Ce, Rb and Fr; B is Cl; F; carbonate (CO3 2- );Sulfate (SO4 2- carboxylate; silicate, preferably metasilicate; borate, preferably tetraborate; and mixtures thereof; and allowing the reaction to proceed to produce a salt of a bis(chlorosulfonyl)imide. Including, wherein the process, in particular steps (b) to (d), is carried out in the absence of a solvent; It concerns the method.

[0012] The salt of bis(chlorosulfonyl)imide obtained by the process of the present invention is characterized by undetectable amounts of solvent, which makes it suitable for many applications, especially as an intermediate for the preparation of LiFSI used in battery applications.

[0013] Advantageously, the process of the present invention is carried out in molten HCSI, which serves to disperse the compound of formula (I) in the absence of solvents and diluents.In other words, the process of the present invention is a solvent-free process, which means that no solvents and / or diluents are added to the reaction mixture during the reaction.This is advantageous because, firstly, it avoids the step to remove the solvent, thus reducing the complexity of the industrial process and its overall cost, and secondly, it also avoids the preliminary step of treating the solvent to reduce its water content. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In this application: - the expression "of" is to be understood as including limiting values; - any description, even if made in relation to a particular embodiment, is applicable to and interchangeable with other embodiments of the invention; - when an element or component is said to be included in and / or selected from a list of enumerated elements or components, in related embodiments expressly contemplated herein, the element or component can also be any one of the individual enumerated elements or components, or can also be selected from a group consisting of any two or more of the explicitly enumerated elements or components; it is to be understood that any element or component enumerated in a list of elements or components may be omitted from such list; - any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited range, as well as the endpoints of the range, and equivalents thereof; - the term "solvent" is intended to mean a compound that exhibits the following three cumulative properties: 1 / is present throughout the reaction and is optionally added during the process; 2 / does not change during the process, in other words is non-reactive towards the reactants involved; and 3 / must be removed at the end of the process if the reaction product must be in its pure form. For clarity, the molten HCSI used in the process of the present invention does not fall within this definition and is not intended as a "solvent" or "diluent" as mentioned above. Solvents typically used in such processes are well known and have been extensively described in the literature. Such solvents may be aprotic, e.g. polar aprotic solvents, cyclic and acyclic carbonates, such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, cyclic and acyclic esters, such as gamma-butyrolactone, gamma-valerolactone, methyl formate, methyl acetate, methyl propionate, ethyl acetate, ethyl propionate, isopropyl acetate, propyl propionate, butyl acetate, cyclic and acyclic ethers, such as diethyl ether, diisopropyl ether, methyl tert-butyl ether, dimethoxymethane, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxane, 4-methyl-1,3-dioxane, 1,4-dioxane, amide compounds, such as N,N-dimethylformamide, N-methyloxazolidinone, sulfoxide and sulfone compounds, such as sulfolane, 3-methylsulfolane, dimethylsulfoxide, and cyano-, nitro-, chloro- or alkyl-substituted alkanes or aromatic hydrocarbons, such as acetonitrile, valeronitrile, adiponitrile, benzonitrile, nitromethane, nitrobenzene may be selected from the group consisting of:

[0015] In the context of the present invention, the starting HCSI as provided in step (a) can be purified by known methods, for example by: - by reacting chlorosulfonyl isocyanate (ClSO2NCO) with chlorosulfonic acid (ClSO2OH); - by reacting cyanogen chloride (CNCl) with sulfur trioxide (SO3) and with chlorosulfonic acid (ClSO2OH); or - By reacting sulfamic acid (NH2SO2OH) with thionyl chloride (SOCl2) and with chlorosulfonic acid (ClSO2OH), It can be manufactured.

[0016] In one embodiment, the starting HCSI is produced by reacting chlorosulfuric acid (ClSO2OH) with chlorosulfonyl isocyanate (ClSO2NCO). According to this embodiment, step (i) consists in preparing a reaction mixture comprising the HCSI, a heavy fraction and a light fraction in a reactor by reacting chlorosulfonyl isocyanate (ClSO2NCO) with chlorosulfonic acid (ClSO2OH).

[0017] In another embodiment, the starting HCSI is prepared by reacting sulfamic acid (NHSOOH), chlorosulfonic acid (ClSOOH) and thionyl chloride (SOCl). The applied sulfamic acid can be ground to a certain particle size and dried under vacuum to reduce its water content and accelerate the kinetics of the conversion, significantly shortening the reaction time.

[0018] In another embodiment, the starting HCSI is produced by reacting cyanogen chloride, CNCl, with sulfur trioxide (SO3) and chlorosulfonic acid (ClSO2OH).

[0019] According to the method of the present invention, in step (b), the HCSI is in a molten state (also called liquid state) and is heated to its melting temperature (Tm HCSI ) is heated above

[0020] Preferably, step (b) is carried out at a temperature (Tb) suitable to melt the HCSI and maintain it in the molten state while avoiding its decomposition.

[0021] Step (b) is to measure the melting temperature (Tm) of HCSI (Tm HCSI In this case, Tb ≧ Tm HCSI For example, Tb is the melting point Tm of HCSI (Tm HCSI ) plus 5°C or more. In this case, Tb ≥ Tm HCSI As another example, Tb is the melting point Tm of HCSI (Tm HCSI ) plus 10°C or more. In this case, Tb ≥ Tm HCSI It's +10.

[0022] One of skill in the art will appreciate that the Tm of HCSI is affected by the presence and amount of impurities.

[0023] Preferably, the temperature (Tb) at which step (b) is carried out is at least 30° C., such as at least 37° C., such as at least 38° C., at least 40° C., at least 45° C. or even at least 50° C. In any case, the temperature (Tb) at which step (b) is carried out is below the decomposition temperature of the HCSI.

[0024] Preferably, under step (c), said compound of formula (I) is added either gradually or all at once.

[0025] Alternatively, the melt (HCSI) is added, either gradually or all at once, to said compound of formula (I) previously loaded into the reactor.

[0026] Those skilled in the art will appreciate that other ingredients or reactants, either in powder or liquid form, can be added to the reaction environment based on the needs or circumstances.

[0027] In some embodiments, the molar ratio of HCSI to compound of formula (I) ranges from 0.001:1 to 20:1, particularly from 0.1:1 to 10:1, more particularly from 0.5:1 to 5:1, and even more particularly is about 1:1.

[0028] Preferably, in said compound of formula (I), M is selected from Na, Li and K.

[0029] Even more preferably, M is Li. According to this embodiment, the compound of formula (I) will be referred to as "compound LiX".

[0030] According to this embodiment, the compound LiX used in the method of the present invention is a component that does not generate water or soluble species over the course of the reaction.

[0031] In some embodiments, the compound LiX is lithium chloride (LiCl), lithium fluoride (LiF), lithium carbonate (Li2CO3), lithium sulfate (Li2SO4), lithium carboxylate (Li n (RCO2) n ), Li2SiO3, Li2B4O7 and mixtures thereof.

[0032] Even more preferably, said compound LiX is anhydrous lithium chloride (LiCl) in solid form.

[0033] Depending on the circumstances, said steps (b) and (c) can be carried out at the same temperature or at different temperatures.

[0034] Those skilled in the art will understand that the choice of compound of formula (I) will affect the temperature at which step (c) is carried out. The detailed description of step (c) as provided later in this specification refers to the step in which in compound (I), M is Li, and therefore the salt as obtained at the end of step (C) is lithium bis(chlorosulfonyl)imide (LiCSI).

[0035] Preferably, when step (c) is carried out at a temperature (Tc) at which LiCSI is in liquid form, it is carried out at a temperature below the melting point (Tm) of LiCSI (Tm LiCSI In this case, Tc ≥ Tm LiCSI For example, Tc is the melting point Tm of LiCSI (Tm LiCSI ) plus 5°C or more. In this case, Tc ≥ Tm LiCSI +5. As another example, Tc is the melting point Tm of LiCSI (Tm LiCSI ) plus 10°C or more. In this case, Tc ≥ Tm LiCSI It's +10.

[0036] Alternatively and more preferably, step (c) is carried out while the HCSI is in a molten state, i.e., Tc≧Tm HCSI and LiCSI is at least partially in solid form, i.e., Tc≦Tm LiCSI According to this embodiment, Tc is the melting point Tm of LiCSI (Tm LiCSI ) minus 5°C or less. In this case, Tc≦Tm LiCSI -5. As another example, Tc is the melting point Tm of LiCSI (Tm LiCSI ) minus 10 degrees Celsius or less. In this case, Tc ≦ Tm LiCSI In other words, according to these embodiments, the temperature Tc at which step (c) is performed is less than the melting point (Tm HCSI ) and the melting point of LiCSI (Tm LiCSI )

[0037] Preferably, the temperature (Tc) at which step (c) is carried out is 37° C. or higher, such as 50° C. or higher, 60° C. or higher, 80° C. or higher, or even 100° C. or higher. In some embodiments, the temperature (Tc) at which step (c) is carried out is 220° C. or lower, such as 218° C. or lower, 215° C. or lower, 212° C. or lower, or even 210° C. or higher.

[0038] Each of step (b) and / or step (c) may be carried out at atmospheric pressure or under reduced pressure, for example, each of step (b) and step (c) may be carried out under vacuum or at about 1 atmosphere, preferably 1 atmosphere.

[0039] In embodiments where the temperature (Tc) at which step (c) is carried out varies between the melting point of HCSI (Tm1) and the melting point of LiCSI (Tm2), the molar ratio of HCSI to compound LiX is preferably such that HCSI is the excess reactant, so that unconverted HCSI allows the final reaction medium to be processed for further LiCSI filtration, for example, the molar ratio of HCSI to compound LiX is 2:1.

[0040] In other embodiments where the temperature (Tc) at which step (c) is carried out is equal to or greater than the melting point (Tm2) of LiCSI, the molar ratio of HCSI to compound LiX is preferably such that compound LiX is an excess reactant, such that HCSI can be completely converted and compound LiX can be filtered to provide isolated LiCSI, for example, the molar ratio of HCSI to compound LiX is 1:1.05.

[0041] Preferably, when LiCl is used, hydrogen chloride (HCl) formed as a by-product during step (b) and / or step (c) is continuously removed from the reaction vessel throughout step (b) and / or step (c). For example, HCl removal is performed under vacuum or by stripping with an inert gas (such as nitrogen, helium or argon). The sparged HCl can be further recycled.

[0042] Preferably, the process according to the invention comprises, after step (c), a step (d) which comprises separating the salt of bis(chlorosulfonyl)amide from the reaction mixture. When the process comprises step (d), the HCSI remaining after the reaction can be reused. The remaining HCSI is preferably in a molten state.

[0043] This separation step can be carried out by any separation means known to those skilled in the art. Separation can be carried out, for example, by filtration, for example under pressure or under vacuum, or by decantation. The mesh size of the filtration medium can be, for example, 2 μm or less, 0.45 μm or less, or 0.22 μm or less. The separated product can be washed once or several times with a suitable solvent. The separation step can be carried out once or repeated two or more times if necessary.

[0044] Some or all of the steps of the method according to the invention are advantageously carried out in equipment capable of withstanding the corrosion of the reaction medium.

[0045] For this purpose, alloys based on molybdenum, chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum, carbon and tungsten sold under the Hastelloy® brand or under the names Inconel® or Monel® are also available. TMMaterials that are corrosion resistant are selected for the parts that come into contact with the reaction medium, such as alloys of nickel, chromium, iron and manganese to which copper and / or molybdenum have been added, more particularly Hastelloy C276 or Inconel 600, 625 or 718 alloys, sold by AB 12000. Austenitic steels may also be selected, more particularly stainless steels, such as 304, 304L, 316 or 316L stainless steels. Steels are used that have a nickel content of at most 22% by weight, preferably between 6% and 20% by weight, more preferentially between 8% and 14% by weight. 304 and 304L steels have a nickel content that varies between 8% and 12% by weight, and 316 and 316L steels have a nickel content that varies between 10% and 14% by weight. More particularly, 316L steel is selected. Equipment made of or coated with polymeric compounds that are resistant to corrosion of the reaction medium may also be used. In particular, materials such as PTFE (polytetrafluoroethylene or Teflon) or PFA (perfluoroalkyl resin) may be mentioned. Glass and glass-lined as well as elastomer devices may also be used. It would not be outside the scope of the invention to use equivalent materials. The material for filtration must be compatible with the medium used. Fluorinated polymers (PTFE, PFA), loaded fluorinated polymers (Viton™), as well as polyester (PET), polyurethane, polypropylene, polyethylene, cotton, and other compatible materials may be used.

[0046] All raw materials used in the process according to the invention, including the reactants, may preferably exhibit very high purity standards: preferably, their content of metal components such as Na, K, Ca, Mg, Fe, Cu, Cr, Ni, Zn is less than 10 ppm, more preferably less than 5 ppm, or even less than 2 ppm.

[0047] The bis(chlorosulfonyl)imide salt as obtained at the end of the process of the invention can be advantageously used for other reactions etc.

[0048] According to a preferred embodiment, when compound (I) contains M such as Li, the lithium salt obtained by the process of the invention can be used for the preparation of LiFSI.

[0049] Alternatively, the LiCSI salt as obtained at the end of the process of the present invention can be contacted with one or more organic solvents to obtain crystallized LiCSI.

[0050] In a second aspect, the present invention relates to a salt of bis(chlorosulfonyl)imide obtained by the process described above, characterized in that its organic solvent content is less than 100 ppm.

[0051] In some preferred embodiments, the amount of solvent in the bis(chlorosulfonyl)imide salt is less than 100 ppm, for example less than 90 ppm, less than 80 ppm, less than 70 ppm, less than 60 ppm, less than 50 ppm, less than 40 ppm, less than 30 ppm, less than 20 ppm, less than 10 ppm, or even less than 1 ppm. This is an advantageous feature of the salt obtained by the process of the present invention. The residual solvent content can be measured by gas chromatography (GC) or by headspace sud chromatography.

[0052] The bis(chlorosulfonyl)imide salt as obtained at the end of the process of the invention may be in the molten state or in crystalline form.

[0053] In a third aspect, the present invention relates to the use of the lithium salt of bis(chlorosulfonyl)imide obtained by the process described above for the preparation of lithium bis(fluorosulfonyl)imide (LiFSI).

[0054] In a further aspect, the present invention relates to a process for the preparation of a salt of a bis(fluorosulfonyl)imide, comprising steps (a), (b), (c) and optionally (d) as disclosed above and, after said step (c) or said step (d), a step (e) of contacting said salt of a bis(chlorosulfonyl)amide as obtained in step (c) or in step (d) with at least one fluorinating agent, wherein steps (a) to (d) are carried out in the absence of a solvent. It concerns the method.

[0055] Preferably, the at least one fluorinating agent is prepared from anhydrous HF or from a fluorinating agent having the formula: (i) KF(HF) p (wherein p is 0 or 1); (ii) NaF(HF) p (wherein p is 0 or 1); (iii) X2F(HF) p (wherein X2 is an onium cation and p is 0 or 1); (iv) NH4F(HF) p (wherein p varies from 0 to 10); (v) LiF; (vi)ZnF2 The compound is selected from the group consisting of:

[0056] To the extent that the disclosures of any patents, patent applications, and publications incorporated herein by reference conflict with the statements of this application to the extent that any term may be unclear, the statements of this application shall control.

Claims

1. A method for producing a salt of bis(chlorosulfonyl)imide, comprising the steps of: (a) providing bis(chlorosulfonyl)imide (HCSI); (b) melting the bis(chlorosulfonyl)imide (HCSI) provided in step (a) to obtain molten bis(chlorosulfonyl)imide (HCSI); and (c) treating the molten bis(chlorosulfonyl)imide (HCSI) obtained in step (b) with a compound of formula (I): (I)M ＋ B － (In the formula, M is selected from Na, Li, K, Ce, Rb and Fr; B is Cl; F; carbonate (CO ３ ２－ ); sulfate (SO ４ ２－ ); carboxylates; silicates, preferably metasilicates; borates, preferably tetraborates; and mixtures thereof. and allowing the reaction to proceed to produce a salt of a bis(chlorosulfonyl)imide. Including; The process is carried out in the absence of a solvent. method.

2. Step (c) adding said compound of formula (I) to said molten HCSI, either gradually or all at once; or - loading the compound of formula (I) into a reactor and adding the molten HCSI, either gradually or all at once; The method of claim 1 , comprising:

3. The process according to claim 1 or 2, wherein the molar ratio of HCSI to said compound of formula (I) is from 0.001:1 to 20:1, preferably from 0.1:1 to 10:

1.

4. 4. The method according to any one of claims 1 to 3, wherein in the compound of formula (I), M is selected from Na, Li and K, and / or B is selected from Cl, F, carbonate and sulfate.

5. - step (b) is carried out at a temperature of at least 30°C, preferably at least 38°C; and / or - steps (b) and (c) are carried out at the same temperature or at different temperatures; and / or - each of steps (b) and (c) is carried out at atmospheric pressure or under reduced pressure; and / or step (c) is carried out at a temperature of at least 37° C. and at most 220° C.; and / or the molar ratio of HCSI to said compound of formula (I) is in the range of 0.001:1 to 20:1, in particular 0.1:1 to 10:1, more in particular 0.5:1 to 5:1; The method according to any one of claims 1 to 4.

6. In the compound of formula (I), M is Li [compound LiX], and the salt of bis(chlorosulfonyl)imide is LiCSI: Step (c) is to determine the melting temperature (Tm １ ) and the melting point of LiCSI (Tm ２ ) wherein the molar ratio of HCSI to compound of formula (I) is preferably such that HCSI is an excess reactant, preferably the molar ratio of HCSI to compound LiX is 2:1; or step (c) is carried out at a temperature equal to or greater than the melting point (Tm2) of LiCSI, said molar ratio of HCSI to compound of formula (I) being such that the compound LiX is the excess reactant, preferably said molar ratio of HCSI to compound LiX being 1:1.05; The method according to any one of claims 1 to 5.

7. The compound of formula (I) can be used in the preparation of lithium chloride (LiCl), lithium fluoride (LiF), lithium carbonate (Li ２ CO ３ ), lithium sulfate (Li ２ SO ４ ), lithium carboxylate (Li ｎ (R.C.O. ２ ) ｎ ), Li ２ SiO ３ , Li ２ B ４ O ７ The method according to any one of claims 1 to 6, wherein the compound is selected from the group consisting of: and mixtures thereof.

8. 8. The method according to claim 7, wherein said compound of formula (I) is LiCl, preferably in anhydrous and solid form.

9. 9. The method of claim 8, wherein hydrogen chloride (HCl) formed as a by-product during step (b) and / or step (c) is continuously removed from the reaction vessel throughout step (b) and / or step (c).

10. 10. The process of claim 9, wherein HCl removal is accomplished by stripping using a stream of inert gas in the reaction vessel sky or within the liquid reaction mixture.

11. 11. The process according to any one of claims 1 to 10, comprising after step (c) a step (d) comprising separating the salt of the bis(chlorosulfonyl)amide from the reaction mixture.

12. A salt of bis(chlorosulfonyl)imide obtainable by the process according to any one of claims 1 to 11, characterized in that its organic solvent content, as measured by gas chromatography, is less than 100 ppm.

13. 13. The salt of bis(chlorosulfonyl)imide according to claim 12, which is a lithium salt of bis(chlorosulfonyl)imide.

14. 14. Use of the lithium salt of bis(chlorosulfonyl)imide according to claim 13 as an intermediate compound in the preparation of lithium bis(fluorosulfonyl)imide (LiFSI).

15. A method for producing a salt of a bis(fluorosulfonyl)imide, comprising the steps of: (a) providing bis(chlorosulfonyl)imide (HCSI); (b) melting the bis(chlorosulfonyl)imide (HCSI) provided in step (a) to obtain molten bis(chlorosulfonyl)imide (HCSI); and (c) treating the molten bis(chlorosulfonyl)imide (HCSI) obtained in step (b) with a compound of formula (I): (I)M ＋ B － (In the formula, M is selected from Na, Li, K, Ce, Rb and Fr; B is Cl; F; carbonate (CO ３ ２－ ); sulfate (SO ４ ２－ ); carboxylates; silicates, preferably metasilicates; borates, preferably tetraborates; and mixtures thereof. and allowing the reaction to proceed to produce a salt of a bis(chlorosulfonyl)imide; (d) optionally separating said salt of bis(chlorosulfonyl)amide from the reaction mixture; (e) contacting said salt of bis(chlorosulfonyl)amide as obtained in step (c) or in step (d) with at least one fluorinating agent; Including, Steps (a) to (d) are carried out in the absence of a solvent; method.

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