Process for production of bis (chlorosulfonyl) imides

Abstract

The invention relates to a process for the preparation of bis (chlorosulfonyl) imide (HCSI), said process comprising the steps of (i) providing to a reactor a composition (H) comprising a chlorosulfonyl isocyanate in an amount (CSI-1), a chlorosulfonic acid in an amount (CSA-1) and HSCI in an amount (HCSI-1) of up to 20 wt.%, based on the total weight of the composition (H), and (ii) heating said composition (H). The invention also relates to a process for recycling a composition (H) as defined above, said process comprising feeding said composition (H) to a reactor and heating said composition (H) at a temperature of less than 150 DEG C.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from the prior European patent application No. 22305803.3 filed on June 1, 2022, the entire contents of which are hereby incorporated by reference for all purposes. Technical Field

[0003] The present disclosure relates to a method for producing bis(chlorosulfonyl)imide (HCSI). Background Art

[0004] Bis(fluorosulfonyl)imide (HFSI), its corresponding salts and ionic liquids containing FSI anions have been shown to be useful in a variety of applications, including but not limited to as electrolytes in lithium-ion batteries and supercapacitors. Bis(fluorosulfonyl)imide is a relatively strong acid and can form a variety of stable metal salts. The lithium salt of bis(fluorosulfonyl)imide (LiFSI) has been shown to be particularly useful in batteries and supercapacitors. Bis(chlorosulfonyl)imide (HCSI) is known to be the most important starting material for the preparation of HFSI.

[0005] There are many methods for producing HCSI. One of the known methods is called the "isocyanate route", which includes the steps of: (i) reacting chlorosulfonyl isocyanate with chlorosulfonic acid to prepare a reaction mixture containing HCSI, a heavy fraction and a light fraction, and (ii) distilling the reaction mixture to separate each of the light fraction, HCSI and the heavy fraction.

[0006] The separated light fraction, as obtained at the end of the process, is a hazardous waste, since it is highly corrosive. Therefore, the waste management costs of the isocyanate route are currently relatively high.

[0007] Chinese Patent Application No. 106044728 (in the name of QUZHOU CHEMSPECCHEMICAL CO., LTD.) teaches a method for preparing imido-disulfuryl fluoridelithium salt. Example 4 indicates that HCSI is produced by an isocyanate route. Specifically, chlorosulfonic acid is mixed with concentrated sulfuric acid and the mixture is heated to 105°C-115°C. Then, chlorosulfonyl isocyanate is added dropwise. After the addition, the temperature is gradually increased to 120°C-130°C. After the reaction, only the excess chlorosulfonyl isocyanate is separated from the main fraction for recycling, while most of the fraction is not treated.

[0008] WO 2009 / 123328 (Nippon Catalytic Chem Ind) provides a method for preparing fluorosulfonyl imide (such as N-(fluorosulfonyl)-N-(fluoroalkylsulfonyl)imide, di(fluorosulfonyl)imide) and its salt, which comprises the step of fluorinating a chlorinated precursor. Example 2 of the document teaches a method for preparing bis(chlorosulfonyl)imide (HCSI) by reacting chlorosulfonic acid (CSA) with chlorosulfonyl isocyanate (CSI), and the target bis(chlorosulfonyl)imide (HCSI) is separated from the reaction medium by reduced pressure distillation. Summary of the invention

[0009] The applicant believes that there is still a need for an improved environmentally friendly process for producing HCSI, characterized by easy handling and recycling of light fractions, low production of non-recyclable / non-recoverable products, low waste management costs, while increasing HCSI yield.

[0010] It has now been found that a composition (H) comprising chlorosulfonyl isocyanate, chlorosulfonic acid and HCSI, previously considered to be a waste stream after separation from the reaction mixture of the above-mentioned isocyanate route, can be used to prepare HCSI.

[0011] The applicant has unexpectedly found that recycling the composition (H) for the synthesis of HCSI successfully increases the final yield of HCSI. Advantageously, the applicant has found that the composition (H) can be recycled as a supplement to fresh chlorosulfonyl isocyanate and chlorosulfonic acid or used as such to prepare HCSI without using additional reactants. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Comparison of DSC results of HCSI synthesized in Examples 1 to 4. DETAILED DESCRIPTION

[0013] In this application:

[0014] - the expression "between ... and ..." is to be understood as including the limit values;

[0015] - any description (even those relating to a specific embodiment) is applicable to and interchangeable with other embodiments of the invention;

[0016] - the expression "isocyanate route" is intended to indicate a reaction comprising at least the steps of: (i) reacting chlorosulfonyl isocyanate with chlorosulfonic acid to prepare a reaction mixture comprising HCSI, a heavy fraction and a light fraction, and (ii) distilling the reaction mixture to separate each of the light fraction, HCSI and the heavy fraction;

[0017] - When an element or component is said to be included in and / or selected from a list of listed elements or components, it should be understood that in the relevant embodiments explicitly considered herein, the element or component may also be any of these listed independent elements or components, or may also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component listed in the list of elements or components may be omitted from this list; and

[0018] - Any recitation of numerical ranges by endpoints herein includes all numbers subsumed within the recited range as well as the endpoints of that range and equivalents thereof.

[0019] In a first aspect, the present invention relates to a method for preparing bis(chlorosulfonyl)imide (HCSI), the method comprising the following steps:

[0020] (i) providing a composition (H) into a reactor, which comprises chlorosulfonyl isocyanate in an amount of (CSI-1), chlorosulfonic acid in an amount of (CSA-1), and HCSI in an amount of (HCSI-1) up to 20 wt. % based on the total weight of the composition (H), and

[0021] (ii) heating the composition (H) to obtain a mixture (M1) comprising HCSI in an amount of (HCSI-2), wherein (HCSI-2) is higher than (HCSI-1).

[0022] Preferably, the molar ratio of the amount of chlorosulfonyl isocyanate (CSI-1) to the amount of chlorosulfonic acid (CSA-1) is equal to, for example, 1.00:1.01, 1.00:1.02, 1.00:1.03, 1.00:1.04, 1.00:1.05, 1.00:1.06, 1.00:1.07, 1.00:1.08, 1.00:1.09, 1.00:1.10, or any range between these values.

[0023] Preferably, composition (H) comprises HCSI in an amount of at most 15 wt.%, more preferably at most 12 wt.%, at most 10 wt.%, at most 8 wt.%, at most 5 wt.%, at most 2 wt.% or at most 1 wt.% (HCSI-1), based on the total weight of composition (H).

[0024] Preferably, composition (H) comprises HCSI in an amount of at least 0.01 wt.%, more preferably at least 0.05 wt.% (HCSI-1), based on the total weight of composition (H).

[0025] The presence and amount of CSA, CSI and HCSI in composition (H) and other compositions mentioned in this specification can be determined, for example, using spectroscopic analysis techniques such as Raman or near infrared.

[0026] Advantageously, the composition (H) is separated from one or more reaction mixtures of the isocyanate route as defined above. The composition (H) may also be referred to as a "light fraction". Thus, advantageously, the process according to the present disclosure significantly reduces the waste management costs of the isocyanate route, since the separated light fraction can be recycled and reused.

[0027] Composition (H) may be heated in step (ii) in the presence or absence of an additional catalyst.

[0028] Optionally, composition (H) is heated in the presence of a catalyst.

[0029] The catalyst is not particularly limited. The catalyst can be an acid, and is preferably a protonic acid and / or a Lewis acid. Lewis acid is generally based on Lewis acid-base theory, and generally refers to a substance that accepts an electron pair. The Lewis acid can be selected from the group consisting of: NiCl2, FeCl2, FeCl3, CoCl3, ZnCl2 and MnCl2. Protonic acid generally refers to a molecule or ion that can release a proton (hydrogen ion, H+). The protonic acid can be concentrated sulfuric acid and / or oleum. Concentrated sulfuric acid generally refers to a sulfuric acid solution with a mass percentage of ≥70%, more specifically a sulfuric acid solution with a mass percentage of ≥98%. Oleum (HSO4.xSO3) generally refers to a sulfuric acid solution of sulfur trioxide, more specifically a sulfuric acid solution of sulfur trioxide with a mass percentage of ≥20%.

[0030] According to an embodiment, the catalyst may be added to the composition (H). For example, the catalyst is added to the composition (H) during step (i) or before starting step (ii).

[0031] Alternatively, the catalyst may be generated in situ. For example, as step (ii) is performed, the catalyst is generated in situ.

[0032] Optionally, at least one additional substance may be present in step (ii). For example, this at least one additional substance may promote the synthesis of HCSI. According to one embodiment, the at least one additional substance may be added in step (ii). Alternatively or simultaneously, the at least one additional substance is mixed with one or more starting materials, preferably with the CSI and / or CSA provided in step (ii).

[0033] The amount of the at least one additional substance is not limited. Preferably, the amount of the at least one additional substance is calculated based on the reaction conditions and the selected one or more starting materials.

[0034] According to a preferred embodiment, the at least one additional substance is water. The water may be present in trace amounts in the reactor and / or in one or more starting materials, in particular in chlorosulfonic acid (CSA).

[0035] Preferably, the weight ratio of water to composition (H) is from 0.0001:1 to 0.001:1.

[0036] Without being bound by any theory, the applicants believe that the presence of water in the reactor produces sulfuric acid, optionally in the presence of other by-products, which in turn acts as a catalyst.

[0037] Preferably, step (ii) is carried out by heating at a temperature of at least 40° C. and at most 150° C., preferably at least 60° C. and more preferably at least 80° C. More preferably, the heating is carried out at a temperature of 115° C. to 145° C. and even more preferably 120° C. to 140° C.

[0038] The heating time in step (ii) is not limited. Advantageously, the heating time is determined by monitoring the conversion of chlorosulfonyl isocyanate according to methods known in the art.

[0039] According to a preferred embodiment, the method for preparing bis(chlorosulfonyl)imide (HCSI) according to the present invention comprises the following steps after step (ii):

[0040] (iii) treating the mixture (M1) to recover an amount of HCSI (HCSI-3) and a composition (C2) comprising an amount of chlorosulfonyl isocyanate (CSI-4), an amount of chlorosulfonic acid (CSA-4) and an amount of HCSI (HCSI-4) of up to 20 wt.%, based on the total weight of the composition (C2), wherein the HCSI-3 is higher than the HCSI-4.

[0041] It will be appreciated that at the end of step (iii), the sum of the amount of HCSI-3 and the amount of HCSI-4 is equal to the amount of HCSI-2 at the end of step (ii) ± 1 wt. % or less.

[0042] Preferably, step (ii) and step (iii) are performed simultaneously. Alternatively, step (ii) and step (iii) are performed sequentially. For example, the heating in step (ii) is stopped before starting step (iii).

[0043] In step (iii), the method of recovering the composition (C2) and optionally HCSI from the mixture (M1) obtained in step (ii) is not particularly limited.

[0044] A preferred method may be distillation.

[0045] Optimal distillation conditions (eg, pressure and temperature) and equipment may be appropriately selected to recover a composition (C2) comprising CSI-4 and CSA-4 mixed with up to 20 wt.% of HCSI.

[0046] If the situation requires, two or more distillation steps may be carried out to recover composition (C2) and optionally HCSI.

[0047] Good results have been obtained, for example, by carrying out at least one distillation under reduced pressure to recover composition (C2).

[0048] More preferably, said at least one distillation is performed at a pressure between 40 and 5 mbar absolute (4000 Pa and 500 Pa). More preferably, said at least one distillation is performed by maintaining the distillation apparatus at a temperature between 30°C and 140°C.

[0049] For example, two or more distillation steps are carried out in step (iii).

[0050] According to this example, the first distillation is carried out at a pressure between 40 and 20 mbar absolute (4000 Pa and 2000 Pa).

[0051] Preferably, the further distillation is carried out at a pressure between 30 and 5 mbar absolute (3000 Pa and 500 Pa).

[0052] Preferably, the first distillation is performed by maintaining the distillation apparatus at a temperature between 30°C and 130°C.

[0053] Preferably, the further distillation is performed by maintaining the distillation apparatus at a temperature between 40°C and 160°C.

[0054] Optimal distillation conditions (eg, pressure and temperature) and equipment may be appropriately selected to recover HCSI.

[0055] For example, good results have been obtained by carrying out at least one reduced pressure distillation to recover HCSI. Preferably, the at least one distillation is carried out at a pressure between 1 and 10 mbar absolute (100 Pa and 1000 Pa). Preferably, the at least one distillation is carried out by keeping the distillation apparatus at a temperature between 100° C. and 160° C.

[0056] For example, good results have been obtained in the present invention when at least one distillation step is carried out to recover composition (C2) and at least one distillation step is carried out to recover HCSI.

[0057] Preferably, in step (ii), the composition (H) is heated in the presence of chlorosulfonyl isocyanate and chlorosulfonic acid. It will be understood that chlorosulfonyl isocyanate and chlorosulfonic acid are newly added in the process of the present invention and add up to an amount equal to the amount of chlorosulfonyl isocyanate and chlorosulfonic acid already present in the reactor.

[0058] According to this embodiment, step (ii) comprises feeding into the reactor (CSI-2) amount of chlorosulfonyl isocyanate and (CSA-2) amount of chlorosulfonic acid.

[0059] According to this embodiment, before heating, the weight ratio of composition (H) to the sum of the amount of chlorosulfonyl isocyanate (CSI-2) and the amount of chlorosulfonic acid (CSA-2) is at least 0.001:1.

[0060] Preferably, before heating, the weight ratio of composition (H) to the sum of the amount of chlorosulfonyl isocyanate (CSI-2) and the amount of chlorosulfonic acid (CSA-2) is at least 0.005:1, preferably at least 0.01:1 and more preferably at least 0.035:1.

[0061] Preferably, before heating, the weight ratio of composition (H) to the sum of the amount of chlorosulfonyl isocyanate (CSI-2) and the amount of chlorosulfonic acid (CSA-2) is at most 1:1, preferably at most 0.75:1, preferably at most 0.50:1 and more preferably 0.35:1.

[0062] Advantageously, before heating, the weight ratio of composition (H) to the sum of the amount of chlorosulfonyl isocyanate (CSI-2) and the amount of chlorosulfonic acid (CSA-2) is in the range of 0.02:1 to 0.4:1, preferably 0.05:1 to 0.25:1.

[0063] Preferably, the molar ratio of the amount of chlorosulfonyl isocyanate (CSI-2) to the amount of chlorosulfonic acid (CSA-2) is 1:1 to 1:20, preferably 1:1 to 1:10, more preferably 1:1 to 1:5, even more preferably 1:1 to 1:2 and most preferably 1:1 to 1:1.1.

[0064] When chlorosulfonyl isocyanate and chlorosulfonic acid are present in step (ii), the process according to the invention preferably comprises the following steps:

[0065] (ii-a) adding (CSA-2) amount of chlorosulfonic acid to composition (H) to provide a mixture (M*) and

[0066] (ii-b) (CSI-2) amount of chlorosulfonyl isocyanate is added to the mixture (M*).

[0067] Preferably, the mixture (M*) is heated prior to step (ii-b).

[0068] Preferably, the heating is performed at a temperature of 100°C to 120°C.

[0069] Preferably, in step (ii-b), the temperature is maintained at 100°C to 120°C.

[0070] Step (ii-a) can be performed by adding chlorosulfonic acid all at once (also called "batch mode") or gradually (also called "fed batch mode").

[0071] Step (ii-b) can be carried out by adding chlorosulfonyl isocyanate all at once or gradually.

[0072] The methods of the present disclosure can be adapted for use in batch, fed-batch or continuous modes.

[0073] Some steps or preferably all steps of the method according to the invention are advantageously carried out in a reactor capable of withstanding the corrosion of the reaction medium. For this purpose, the parts of the reactor in contact with the reaction medium are selected from corrosion-resistant materials.

[0074] Preferably, the corrosion resistant material is selected from alloys based on molybdenum, chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum, carbon and tungsten, which are marketed under the trade name As especially C276 is commercially available; an alloy of nickel, chromium, iron, and manganese with additions of copper and / or molybdenum, sold under the trade name or Monel TM , such as especially 600, 625 or 718 are commercially available.

[0075] The corrosion resistant material may be selected from stainless steels, such as austenitic steels and more particularly 304, 304L, 316 or 316L stainless steels. Preferably, a steel having a nickel content of up to 22 wt.%, preferably between 6 wt.% and 20 wt.% and more preferably between 8 wt.% and 14 wt.% is used. 304 and 304L steels have a nickel content varying between 8 wt.% and 12 wt.%, and 316 and 316L steels have a nickel content varying between 10 wt.% and 14 wt.%. More preferably, 316L steel is selected.

[0076] The corrosion-resistant material may be a polymer compound resistant to corrosion by the reaction medium, which provides a coating on the part of the reactor in contact with the reaction medium. For example, PTFE (polytetrafluoroethylene or Teflon) or PFA (perfluoroalkyl resin) may be mentioned.

[0077] Alternatively and more preferably, the corrosion resistant material is selected from glass, glass lining and porcelain lining equipment.

[0078] Preferably, before step (i), the following steps are performed:

[0079] 0-a) contacting chlorosulfonyl isocyanate with chlorosulfonic acid to obtain a mixture (M) comprising HCSI, chlorosulfonyl isocyanate and chlorosulfonic acid;

[0080] 00-a) treating said mixture (M) so as to obtain HCSI and a composition (H) as defined above.

[0081] In this step 0-a), chlorosulfonyl isocyanate and chlorosulfonic acid are preferably contacted under heating.

[0082] Preferably, the heating is performed at a temperature of 100°C to 160°C.

[0083] Step 0-a) and step 00-a) may be performed at the same temperature.

[0084] Alternatively, step 0-a) is performed at a temperature between 110 and 130° C. and step 00-a) is performed at a temperature between 120 and 160° C. According to an embodiment, the temperature is increased, for example between 120 and 160° C., before starting step 00-a).

[0085] Preferably, step 00-a) is performed by maintaining the temperature between 100°C and 160°C.

[0086] Preferably, step 00-a) is performed by distillation.

[0087] According to an embodiment, the composition (C2) obtained in step (iii) can be recovered and fed to the reactor in step (i) or step (ii), so that the composition (C2) is recycled. It will be understood that in the process of the present invention, this composition (C2) is used as composition (H).

[0088] According to this embodiment, the method according to the present invention comprises the following steps after step (iii):

[0089] (iv) feeding the composition (C2) into a reactor;

[0090] (v) heating the composition (C2) to obtain a mixture (M2) comprising HCSI in an amount of (HCSI-5), chlorosulfonyl isocyanate in an amount of (CSI-5), and chlorosulfonic acid in an amount of (CSA-5), wherein HCSI-5 is higher than HCSI-4, CSI-5 is lower than CSI-4, and CSA-5 is lower than CSA-4;

[0091] (vi) treating the mixture (M2) to recover a composition (C3) comprising chlorosulfonyl isocyanate in an amount (CSI-7), chlorosulfonic acid in an amount (CSA-7) and up to 20 wt.% of HCSI in an amount (HCSI-7), and optionally HCSI in an amount (HCSI-6), based on the total weight of the composition (C3), wherein HCSI-7 is lower than HCSI-5;

[0092] (vii) optionally, repeating steps (iv), (v) and (vi) at least once by feeding a composition (C3) comprising chlorosulfonyl isocyanate in an amount (CSI-x), chlorosulfonic acid in an amount (CSA-x) and HCSI in an amount (HCSI-x) of up to 20 wt.% based on the total weight of the composition (Cx) into a reactor, heating and recovering a composition (Cx) and optionally HCSI;

[0093] Provided that HCSI is recovered in at least one of steps (vi) or (vii),

[0094] wherein "x" in (Cx), (CSI-x) and (CSA-x) represents the different amount of each compound obtained each time steps (iv) to (vi) are repeated.

[0095] It will be appreciated that at the end of step (vi) the sum of the amount of HCSI-6 and the amount of HCSI-7 is equal to the amount of HCSI-5 at the end of step (v) ± 1 wt. % or less.

[0096] Each of step (ii), step (v) and step (vii) can be independently carried out in the presence of chlorosulfonyl isocyanate and chlorosulfonic acid.

[0097] Preferably, the heating in step (v) is carried out in the presence of (CSI-6) amount of chlorosulfonyl isocyanate and (CSA-6) amount of chlorosulfonic acid.

[0098] Preferably, before heating, the weight ratio of composition (C2) to the sum of the amount of chlorosulfonyl isocyanate (CSI-6) and the amount of chlorosulfonic acid (CSA-6) is at least 0.001:1.

[0099] According to an alternative embodiment, the composition (C2) obtained in step (iii) is recovered and fed to a suitable container. According to this embodiment, different compositions (in particular composition (H), composition (C2), composition (C3), and any composition (Cx) recovered from different reactions or reaction mixtures of the isocyanate route) are fed to the same container or to different containers. Such compositions can then be combined together and fed as composition (H) to step (i) of the process of the invention.

[0100] The parameters of the process according to the invention may be appropriately selected and optimized based on, for example, the starting materials (particularly based on the amounts of one or more other compounds in the starting CSI and CSA, such as their purity), and the scale on which the process is carried out, e.g. whether the process is carried out on an industrial scale or a laboratory scale.

[0101] In a second aspect, the present invention relates to a process for recycling a composition comprising chlorosulfonyl isocyanate, chlorosulfonic acid and up to 20 wt.% of HCSI, the process comprising feeding the composition to a reactor and heating the composition at a temperature of at least 40°C and up to 150°C, optionally in the presence of chlorosulfonyl isocyanate and chlorosulfonic acid.

[0102] Preferably, the heating is carried out at a temperature of 115°C to 145°C and more preferably 120°C to 140°C.

[0103] Advantageously, the HCSI obtained at the end of the process according to the invention is suitable for use in a subsequent process for preparing bis(fluorosulfonyl)imide or a salt thereof, or a salt of bis(chlorosulfonyl)imide.

[0104] Preferably, the salt is an ammonium salt, or a salt with an alkali metal or an alkaline earth metal.

[0105] According to a preferred embodiment, the salt of bis(fluorosulfonyl imide) or the salt of bis(chlorosulfonyl) imide is selected from ammonium, sodium or lithium.

[0106] The present disclosure will now be described with reference to the following examples, which are intended to be illustrative only and are not intended to limit the scope of the invention.

[0107] Should the disclosure of any patents, patent applications, and publications incorporated herein by reference conflict with the description of the present application to the extent that it might render a term unclear, the present description shall take precedence.

[0108] Experimental Section

[0109] raw material

[0110] Chlorosulfonyl isocyanate (ClSO2NCO): CAS No. 1189-71-5, commercially available from Lonza Ltd. or synthesized according to known procedures.

[0111] Chlorosulfonic acid (ClSO3H): CAS No. 7790-94-5, commercially available from Sigma Aldrich.

[0112] Composition “Light fractions”: Synthesized in-house at Solvay.

[0113] Test Method

[0114] Differential Scanning Calorimetry (DSC): For the purity determination by DSC, ASTM E928-19 is followed and the measurement conditions are optimized. HCSI 20 sampling must be performed using a stainless steel or gold coated pressure-sealed crucible under a strict inert atmosphere. DSC is performed on samples in the range of 10 to 30 mg. The melting peaks obtained after at least two melting / crystallization cycles and possibly up to 4 cycles are integrated by DSC software. As an example, the DSC method used is defined as follows: a cycle (4 melting / 3 crystallizations) from -30 ° C to 150 ° C at 5 ° C / min under N2 25 gas flow 50 mL / min (duration of 4 hours and 12 minutes). As another example, a DSC device from Mettler Toledo is used for analytical research and development, wherein the software for commanding the device and performing data analysis is STARe software also from Mettler Toledo, version 11.00a (Build 4393). Other DSC devices can be similarly adopted. Crucibles and membranes for HCSI DSC analysis can be selected from over 30 references including the following from METTLER TOLEDO:

[0115] -HP steel crucible: 51140404

[0116] -HP gold coated crucible: 51140405

[0117] -Gold coated disposable membrane: 51140403.

[0118] Molar purity can be estimated by the "Purity" or "Purity+" function of the software applying the Van't Hoff law equation. The DSC purity determination can be considered as a supermelting point determination. The DSC purity determination is based on the fact that impurities will lower the melting point of a eutectic system.

[0119]

[0120] The simplified equation is:

[0121]

[0122] Among them, T f is the melting temperature (which is the same as the liquidus temperature during melting);

[0123] T0 is the melting point of the pure substance;

[0124] R is the gas constant;

[0125] ΔHf is the molar heat of fusion (calculated from the peak area);

[0126] x 2.0 is the concentration (molar fraction of the impurity to be determined);

[0127] T 熔化 It is the clear melting point of an impure substance;

[0128] F is the melting fraction, and ln is the natural logarithm.

[0129] In both cases, the inverse of the melting fraction (1 / F) is given by the following equation:

[0130]

[0131] Among them, A 部分 is the partial area of ​​the DSC peak;

[0132] A 总 is the total area of ​​the peak, and

[0133] c is the linearization factor.

[0134] Examples

[0135] Example 1: Synthesis of HCSI via the isocyanate route (comparative)

[0136] Chlorosulfonic acid (CSA-145.70 g) was charged into a pre-inerted mechanically stirred double-jacketed 0.25 L glass stirred tank reactor at room temperature, which was equipped with baffles, a 4-blade stirring shaft, a double-jacketed distillation head connected to a double-jacketed fraction separator, two temperature probes, and the entire device was connected to a basic scrubber. The container was heated at 120°C (condenser at -10°C). Chlorosulfonyl isocyanate (CSI-167.50 g) was added within 4h15 using a syringe pump. The mixture was heated from 120°C to 140°C and maintained for 17 hours. The mixture was pre-distilled under reduced pressure (T 锅炉 =92°C to 117°C; P = 30-8.5 mbar absolute pressure = 3000-8500 Pa), to separate 18.10 g of a light fraction [composition (H)] (T 头 =25°C-72°C). The resulting mixture was further distilled to separate two HCSI fractions (T 锅炉 =120℃ to 145℃; T 头 =115°C to 118°C, P = about 2-4 mbar absolute pressure = 200-400 Pa).

[0137] The mass of HCSI isolated was 196.50 g (77.6%).

[0138] The remaining heavy fraction (17.13 g) was processed separately.

[0139] Example 2: Synthesis of HCSI via the isocyanate route with a composition (H) according to the invention doped with about 10%

[0140] The same protocol as found in Example 1 was repeated using chlorosulfonic acid (148 g), finished with 29.2 g of the light fraction [composition (H)] (obtained from the previous test). Chlorosulfonyl isocyanate (170.10 g) was added at 120° C. within 4 h, and the protocol was continued as described in Example 1. The resulting mixture was pre-distilled under reduced pressure (T 锅炉 =88°C to 118°C; P = 28-8 mbar absolute pressure = 2800-800 Pa), to separate 32.60 g of a light fraction (T 头 =35°C-70°C). The resulting mixture was further distilled to separate two HCSI fractions (T 锅炉 =110℃ to 129℃; T 头 =74°C to 106°C, P = 4 mbar absolute pressure = 400 Pa).

[0141] The mass of HCSI isolated was 212.20 g (82.7%).

[0142] The remaining heavy fraction (12.83 g) was processed separately.

[0143] Compared to Example 1, when 10% of the light fraction was doped, the yield of HCSI increased by 5.1% by weight, and the residual heavy fraction decreased by about 30% by weight.

[0144] like Figure 1 As shown, the quality of HSCI is acceptable.

[0145] Example 3: Synthesis of HCSI via the isocyanate route with a composition (H) according to the invention doped with about 20%

[0146] The same protocol as found in Example 1 was repeated using chlorosulfonic acid (143 g), finished with 62.80 g of the light fraction [composition (H)] (combined from 3 different previous experiments). Chlorosulfonyl isocyanate (165.40 g) was added at 120° C. within 4 h, and the protocol was continued as described in Example 1. The resulting mixture was pre-distilled under reduced pressure (T 锅炉 =83°C to 115°C; P = 29-7 mbar absolute pressure = 2900-700 Pa), to separate 41.00 g of light fraction (T 头 =31°C-78°C). The resulting mixture was further distilled to separate two HCSI fractions after about 5-6 hours (T 锅炉 =110℃ to 111℃; T 头 =91°C to 102°C, P = 3-5 mbar absolute pressure = 300-500 Pa).

[0147] The mass of HCSI isolated was 226.60 g (90.8%).

[0148] The remaining heavy fraction (16.90 g) was processed separately.

[0149] Compared to Example 1, when 10% of the light fraction was doped, the yield of HCSI increased by 13.2% by weight, and the residual heavy fraction decreased by about 6% by weight.

[0150] like Figure 1 As shown, the quality of HSCI is acceptable.

[0151] Example 4: Synthesis of HCSI from 100% of the composition (H) according to the invention

[0152] 336.3 g of the combined light fractions (combined from 3 different previous runs) were heated in the same vessel as described in Example 1 following the same temperature ramp as in Example 1. The resulting mixture was pre-distilled under reduced pressure to isolate a first light fraction (143.4 g, T 100) after about 2 hours. 锅炉 =50℃-97℃, T 头 =31°C-78°C, P = 30 mbar absolute pressure = 3000 Pa) and the second light fraction (14.9 g, T 锅炉 =96℃-120℃, T 头 =40°C-50°C, P=7-20 mbar absolute pressure=700-2000 Pa). The resulting mixture was further distilled to separate the first HCSI fraction (12.3 g, T 锅炉 =113℃; T 头 =106°C, P = 4 mbar, absolute pressure = 400 Pa, and the second fraction (10.6 g, T 锅炉 =110℃-121℃; T 头 =96°C-104°C, P=4 mbar absolute pressure=400 Pa). The mass of HCSI separated was 118.3 g. The remaining heavy fraction (9.1 g) was treated separately.

[0153] If Figure 1 As shown, the quality of HSCI is acceptable and can therefore be directly used to synthesize NH4FSI, as shown in Example 5.

[0154] Example 5: Synthesis of NH4FSI from HCSI of Example 4

[0155] Under nitrogen flow, NH4F (76.9 g) and anhydrous EMC (303.1 g) are introduced into a pre-dried PTFE 0.5L mechanically stirred reactor, which is equipped with a 4-blade stirring shaft, 4 baffles, a PTFE condenser, an internal piping system based on PFA connected to a thermostat (for internal heating purposes), and an insulating outer layer. The resulting slurry is preheated at 60 ° C. The HCSI (101.5 g) obtained according to Example 4 is preheated at 60 ° C, and introduced in a molten form at a constant flow rate within 1 h. After addition, the mixture is maintained at 84 ° C for 3 hours and then cooled to room temperature. Under nitrogen flow, the suspension is transferred to a Büchner type filter equipped with a 0.22 μm PTFE membrane. The emptied reactor is washed with additional EMC (154.5 g), which is further used to wash the solid filter cake. The combined filtrate (472.1 g) showed a yield of 96.3% (88.9 g) of NH4FSI, as determined by 19 F NMR (Bruker Avance 400 NMR) was measured using trifluoromethoxybenzene as an internal standard.

Claims

1. A method for preparing bis(chlorosulfonyl)imide (HCSI), the method comprising the following steps: (i) providing a composition (H) into a reactor, which comprises (CSI-1) amount of chlorosulfonyl isocyanate, (CSA-1) amount of chlorosulfonic acid and (HCSI-1) amount of HCSI up to 20 wt.% based on the total weight of the composition (H), and (ii) heating the composition (H) to obtain a mixture (M1) comprising HCSI in an amount of (HCSI-2), wherein (HCSI-2) is higher than (HCSI-1).

2. The method according to claim 1, wherein: The composition (H) comprises the following (HCSI-1) amount of HCSI: - up to 15 wt.%, more preferably up to 12 wt.%, based on the total weight of composition (H); and / or - at least 0.01 wt.% and preferably at least 0.05 wt.% HCSI, based on the total weight of composition (H).

3. The method according to any one of claims 1 and 2, wherein: Step (ii) is carried out at a temperature between 40°C and 150°C.

4. A method according to any one of the preceding claims, wherein: The method comprises the following steps after step (ii): (iii) treating the mixture (M1) to recover an amount of HCSI (HCSI-3) and a composition (C2) comprising an amount of chlorosulfonyl isocyanate (CSI-4), an amount of chlorosulfonic acid (CSA-4) and an amount of HCSI (HCSI-4) of up to 20 wt.%, based on the total weight of the composition (C2), wherein the amount of (HCSI-3) is higher than the amount of (HCSI-4).

5. The method according to claim 4, wherein: In step (iii), at least one distillation under reduced pressure is performed to recover the composition (C2).

6. The method according to claim 5, wherein: The at least one distillation is carried out at a pressure between 40 and 5 mbar absolute (4000 Pa and 500 Pa), and / or by maintaining the distillation apparatus at a temperature between 30°C and 140°C.

7. The method according to claim 4, wherein: In step (iii), at least two distillation steps are carried out to recover composition (C2).

8. The method according to claim 7, wherein: - the first distillation is carried out at a pressure between 40 and 20 mbar absolute (4000 Pa and 2000 Pa) and / or by maintaining the distillation apparatus at a temperature between 30° C. and 130° C., and - at least the further distillation is carried out at a pressure between 30 and 5 mbar absolute (3000 Pa and 500 Pa), and / or by keeping the distillation apparatus at a temperature between 40°C and 160°C.

9. The method according to claim 4, wherein: In step (iii), at least one reduced pressure distillation is performed to recover HCSI, preferably the at least one distillation is performed at a pressure between 1 and 10 mbar absolute (100 Pa and 1000 Pa), and / or by maintaining the distillation apparatus at a temperature between 100°C and 160°C.

10. A method according to any one of the preceding claims, wherein: Step (ii) is carried out by feeding (CSI-2) amount of chlorosulfonyl isocyanate and (CSA-2) amount of chlorosulfonic acid.

11. The method according to claim 10, wherein: Prior to heating, the weight ratio of composition (H) to the sum of the amount of chlorosulfonyl isocyanate (CSI-2) and the amount of chlorosulfonic acid (CSA-2) is at least 0.001:

1.

12. The method according to any one of claims 10 and 11, wherein: The weight ratio of composition (H) to the sum of the amount of chlorosulfonyl isocyanate (CSI-2) and the amount of chlorosulfonic acid (CSA-2) is - before heating, at least 0.005:1, preferably 0.01:1 and more preferably 0.035:1; and / or Before heating, at most 1:1, preferably 0.75:1, preferably 0.50:1 and more preferably 0.35:

1.

13. The method according to any one of claims 10 to 12, wherein: The molar ratio of the amount of chlorosulfonyl isocyanate (CSI-2) to the amount of chlorosulfonic acid (CSA-2) is 1:1 to 1:20, preferably 1:1 to 1:

10.

14. A method according to any one of the preceding claims, wherein: The method comprises the following steps before step i): 0-a) contacting chlorosulfonyl isocyanate with chlorosulfonic acid to obtain a mixture (M*); and 00-a) treating the mixture (M*) to obtain HCSI and a composition (H) comprising (CSI-1) amount of chlorosulfonyl isocyanate, (CSA-1) amount of chlorosulfonic acid and (HCSI-1) amount of HCSI up to 20 wt.% based on the total weight of the composition (H).

15. The method according to any one of claims 4 to 14, wherein: The method comprises the following steps after step (iii): (iv) feeding the composition (C2) into a reactor; (v) heating the composition (C2) to obtain a mixture (M2) comprising HCSI in an amount of (HCSI-5), chlorosulfonyl isocyanate in an amount of (CSI-5), and chlorosulfonic acid in an amount of (CSA-5), wherein HCSI-5 is higher than HCSI-4, CSI-5 is lower than CSI-4, and CSA-5 is lower than CSA-4; (vi) treating the mixture (M2) to recover a composition (C3) comprising chlorosulfonyl isocyanate in an amount (CSI-7), chlorosulfonic acid in an amount (CSA-7) and up to 20 wt.% of HCSI in an amount (HCSI-7), and optionally HCSI in an amount (HCSI-6), based on the total weight of the composition (C3), wherein HCSI-7 is lower than HCSI-5; (vii) optionally, repeating steps (iv), (v) and (vi) at least once by feeding a composition (C3) comprising chlorosulfonyl isocyanate in an amount (CSI-x), chlorosulfonic acid in an amount (CSA-x) and HCSI in an amount (HCSI-x) of up to 20 wt.% based on the total weight of the composition (Cx) into a reactor, heating and recovering a composition (Cx) and optionally HCSI; Provided that HCSI is recovered in at least one of steps (vi) or (vii), wherein "x" in (Cx), (CSI-x) and (CSA-x) represents the different amount of each compound obtained each time steps (iv) to (vi) are repeated.

16. The method according to claim 15, wherein: In step (v), the composition (C2) is heated in the presence of (CSI-6) amount of chlorosulfonyl isocyanate and (CSA-6) amount of chlorosulfonic acid, and before heating, the weight ratio of the composition (C2) to the sum of the (CSI-6) amount of chlorosulfonyl isocyanate and the (CSA-6) amount of chlorosulfonic acid is at least 0.001:

1.

17. A process for recycling a composition comprising chlorosulfonyl isocyanate, chlorosulfonic acid and up to 20 wt.% of HCSI, the process comprising feeding the composition to a reactor and heating the composition at a temperature between 40°C and 150°C, optionally in the presence of chlorosulfonyl isocyanate and chlorosulfonic acid.

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