PROCESS FOR PREPARING AN IMID SALT CONTAINING A GROUP

FLUOROSULFONYL

FIELD OF THE INVENTION

The present invention relates to a process for preparing imide salts containing a fluorosulfonyl group.

TECHNICAL BACKGROUND

Sulfonylimide type anions, due to their very low basicity, are increasingly used in the field of energy storage in the form of inorganic salts in batteries, or organic salts in supercapacitors or in the field of liquids. ionic. As the battery market is booming and the reduction of battery manufacturing costs is becoming a major issue, a large-scale, low-cost synthesis process for this type of anions is necessary.

In the specific field of Li-ion batteries, the salt currently most used is LiPF 6 but this salt shows many disadvantages such as limited thermal stability, sensitivity to hydrolysis and therefore lower battery safety. . Recently, new salts possessing the FS0 2 group have been studied and have demonstrated many advantages such as better ionic conductivity and resistance to hydrolysis. One of these salts, LiFSI (LiN (FS0 2 ) 2 ) has shown very interesting properties which make it a good candidate to replace LiPF 6 .

WO 2015/158979 describes in particular the preparation of LiFSI via a step of chlorination of sulfamic acid, with thionyl chloride and sulfuric acid, at atmospheric pressure (examples). However, after 24 hours at reflux of the thionyl chloride, the conversion of the sulfamic acid is not complete.

There is therefore a need for a process for preparing an imide salt comprising a fluorosulfonyl group which does not have the aforementioned drawbacks. In particular, there is a need for a process allowing (almost) total conversion of the sulfonamide reagent in a short time.

DESCRIPTION OF THE INVENTION

The present invention relates to a process for preparing a compound of the following formula (IV):

R 2 - (S0 2 ) -NLi- (S0 2 ) -F (IV)

in which R 2 represents one of the following radicals: F, CF 3 , CHF 2 , CH 2 F, C 2 HF 4 , C 2 H 2 F 3 ,

C 2 H 3 F 2 , C 2 F 5 , C 3 F 7 , C 3 H 4 F 3 , C 3 HF 6 , C 4 Fg, C 4 H 2 F 7 , C 4 H 4 F 5 , C 5 F 11 , CeF I 3 , C 7 F 15 , C 8 F 17 OR C 9 F 19 , preferably R2 representing F;

said process comprising a step a) of reacting a sulfonamide of the following formula (A):

R O - (S0 2 ) -NH 2 (A)

in which R 0 represents one of the following radicals: OH, Cl, F, CF 3 , CHF 2 , CH 2 F, C 2 HF 4 ,

C 2 H 2 F 3 , C 2 H 3 F 2J C 2 F 5 , C 3 F 7J C 3 H 4 F 3J C 3 HF 6 , C 4 Fg, C 4 H 2 F 7 , C 4 H 4 F 5 , C 5 F 11 , CeF I 3 , C 7 F 15 , C 8 F 17

OR C 9 F 19 ;

with at least one sulfur acid and at least one chlorinating agent, said step a) being carried out:

- at a temperature between 90 0 C and 130 0 C, preferably between 100 0 C and 130 0 C; and

- at a pressure strictly greater than 7 bars abs.

Step a) advantageously leads to a compound of formula (I):

R I - (S0 2 ) -NH- (S0 2 ) -CI (I)

in which Ri represents one of the following radicals: Cl, F, CF 3 , CHF 2 , CH 2 F, C 2 HF 4 ,

C 2 H 2 F 3 , C 2 H 3 F 2J C 2 F 5 , C 3 F 7J C 3 H 4 F 3J C 3 HF 6 , C 4 Fg, C 4 H 2 F 7 , C 4 H 4 F 5 , C 5 F 11 , C S F 13 , C 7 F 15 , C 8 F17 or C 9 F 19, Ri preferably representing Cl.

Preferably, the compound (A) is that in which R 0 represents OH.

According to the invention, the sulfur-containing agent can be chosen from the group consisting of chlorosulfonic acid (CIS0 3 H), sulfuric acid, oleum, and mixtures thereof.

Preferably, the sulfur-containing agent is sulfuric acid or oleum, preferably sulfuric acid.

According to the invention, the chlorinating agent can be chosen from the group consisting of thionyl chloride (SOCI 2 ), oxalyl chloride (COCI 2 ), phosphorus pentachloride (PCI 5 ), phosphonyl trichloride (PCI 3 ), phosphoryl trichloride (POCI 3 ), and mixtures thereof.

Preferably, the chlorinating agent is thionyl chloride.

Step a) can be carried out in the presence of a catalyst, such as, for example, chosen from a tertiary amine (such as trimethylamine, triethylamine, or diethylmethylamine); pyridine; and 2,6-lutidine.

Preferably, the reaction is carried out in the absence of catalyst.

The molar ratio between the sulfur acid and the compound (A) (in particular in which R 0 = OH) can be between 0.7 and 5, preferably between 0.9 and 5.

The molar ratio between the chlorinating agent and the compound (A) (in particular in which Ro = OH), can be between 2 and 10, preferably between 2 and 5.

In particular, when the sulfur-containing agent is chlorosulfonic acid, the molar ratio between the latter and the compound (A) (in particular in which R 0 = OH) is between 0.9 and 5, and / or the molar ratio between the chlorinating agent and the compound (A), in particular with R 0 = OH, is between 2 and 5.

In particular, when the sulfur-containing agent is sulfuric acid (or oleum), the molar ratio between sulfuric acid (or oleum) and compound (A) (in particular in which R 0 = OH) , is between 0.7 and 5.

In particular, when the sulfur-containing agent is sulfuric acid (or oleum), the molar ratio between sulfuric acid (or oleum) and compound (A) (in particular in which R 0 = OH) is between 0.9 and 5, and / or the molar ratio between the chlorinating agent and the compound (A), (in particular in which R 0 = OH) is between 2 and 10.

According to one embodiment, step a) is carried out at a temperature greater than or equal to 90 ° C, preferably greater than or equal to 100 ° C, preferably greater than or equal to 105 ° C, advantageously greater than or equal to 1 10 ° C, even more advantageously greater than or equal to 115 ° C, and in particular greater than or equal to 120 ° C.

According to one embodiment, step a) is carried out at a temperature between 105 ° C and 130 ° C, preferably between 105 ° C and 125 ° C, preferably between 1 10 ° C and 125 ° C, advantageously between 1 15 ° C and 125 ° C, and ink more preferably between 118 ° C and 122 ° C, and in particular at 120 ° C.

According to one embodiment, step a) is carried out at a pressure greater than or equal to 7.5 bar abs, preferably greater than or equal to 8 bar abs, more preferably greater than or equal to 9 bar abs, preferably greater or equal to 10 bar abs, advantageously greater than or equal to 1 1 bar abs, even more advantageously greater than or equal to 12 bar abs, preferably greater than or equal to 13 bar abs, for example greater than or equal to 15 bar abs.

Chlorination step a) can be carried out batchwise or semi-continuously.

Step a) can be carried out in a reactor made of a corrosion resistant material.

Step a) can be carried out in a reactor comprising heating means.

The reactor of step a) can be heated by means of a double jacket surrounding the reactor in which a heating fluid can circulate, for example steam, hot water, or a mixture of benzyltoluene and dibenzyltoluene ( eg Jarrytherm BT06).

According to one embodiment, the pressure of the reactor is regulated by a pressure regulating valve. The use of a pressure regulating valve advantageously makes it possible to evacuate the gases formed and to maintain the pressure of the reactor at a given pressure.

The pressure adjustment is advantageously independent of the temperature adjustment.

Step a) advantageously makes it possible to provide the compound of formula (I) with a (quasi) -total conversion into sulfonamide reagent (A) in a reduced time, preferably in less than 48 hours, advantageously in less than 24 hours, and preferably in less than 22 hours.

Step a) also makes it possible to reduce the molar ratio between the volatile reactants and the compound (A), and in particular the molar ratio between the chlorinating agent and the compound (A). In fact, when the pressure is carried out at atmospheric pressure in an open medium, the release of gas from the reaction products causes a loss of the volatile reactants during the reaction. Step a) advantageously makes it possible to limit this loss of reagents, and therefore to reduce said molar ratio in the reaction.

The process according to the invention advantageously makes it possible to prepare the compound of formula (IV) in a shorter time, and to reduce the molar ratio between the volatile reactants and the compound (A).

If thionyl chloride is used, step a) leads in particular to gas evolution comprising HCl and S0 2 . The method according to the invention may comprise a step of treating said gas evolution, for example by distillation or by means of a membrane, preferably by distillation, for example with a view to upgrading HCl and / or S0 2 .

The process according to the invention advantageously makes it possible to facilitate the treatment of said evolution of gas by distillation. Indeed, the fact of carrying out step a) under the reaction conditions indicated above (temperature and pressure), advantageously makes it possible to condense HCl at a temperature higher than at atmospheric pressure in the condenser of the column of distillation.

The method according to the invention can comprise a step b), subsequent to step a), said step b) comprising the reaction of the compound of formula (I) obtained in the preceding step, with at least one fluorinating agent, optionally in the presence of at least one SOI organic solvent.

Step b) advantageously allows the fluorination of the compound of formula (I) into a compound of formula (II):

R 2 - (S0 2 ) -NH- (S0 2 ) -F

in which R 2 represents one of the following radicals: F, CF 3 , CHF 2 , CH 2 F, C 2 HF 4 , C 2 H 2 F 3 ,

C 2 H 3 F 2 , C 2 F 5 , C 3 F 7 , C 3 H 4 F 3 , C 3 HF 6 , C 4 Fg, C 4 H 2 F 7 , C 4 H 4 F 5 , C5F1 1, C 3 F I 3 , C 7 F 15, C 8 F 1 7 OR C9F19.

Preferably, in formula (II) above, R 2 represents F, CF 3 , CHF 2 , or CH 2 F. It is particularly preferred that R 2 represents F.

According to one embodiment, the fluorinating agent is chosen from the group consisting of HF (preferably anhydrous HF), KF, AsF 3 , BiF 3 , ZnF 2 , SnF 2 , PbF 2 , CuF 2 , and their mixtures , the fluorinating agent preferably being HF, and even more preferably anhydrous HF.

In the context of the invention, by “anhydrous HF” is meant THF containing less than 500 ppm of water, preferably less than 300 ppm of water, preferably less than 200 ppm of water.

Step b) of the process is preferably carried out in at least one SOI organic solvent. The SOI organic solvent preferably has a donor number between 1 and 70 and advantageously between 5 and 65. The donor index of a solvent represents the value -DH, DH being the enthalpy of the interaction between the solvent and antimony pentachloride (according to the method described in Journal of Solution Chemistry, vol. 13, no. 9, 1984). As SOI organic solvent, mention may in particular be made of esters, nitriles, dinitriles, ethers, diethers, amines, phosphines, and mixtures thereof.

Preferably, the SOI organic solvent is chosen from the group consisting of methyl acetate, ethyl acetate, butyl acetate, acetonitrile, propionitrile, isobutyronitrile, glutaronitrile , dioxane, tetrahydrofuran, triethylamine, tripropylamine, diethylisopropylamine, pyridine, trimethylphosphine, triethylphosphine, diethylisopropylphosphine, and mixtures thereof. In particular, the SOI organic solvent is dioxane.

Step b) can be carried out at a temperature between 0 ° C. and the boiling point of the SOI organic solvent (or of the mixture of SOI organic solvents). Preferably, step b) is carried out at a temperature between 5 ° C and the boiling point of the SOI organic solvent (or of the mixture of SOI organic solvents), preferably between 20 ° C and the boiling point of the SOI. SOI organic solvent (or mixture of SOI organic solvents).

Step b), preferably with anhydrous hydrofluoric acid, can be carried out at a pressure P, preferably between 0 and 16 bar abs.

This step b) is preferably carried out by dissolving the compound of formula (I) in the SOI organic solvent, or the mixture of SOI organic solvents, prior to the step of reaction with the fluorinating agent, preferably with GI-IF anhydrous.

The mass ratio between the compound of formula (I) and the SOI organic solvent, or the mixture of SOI organic solvents, is preferably between 0.001 and 10, and advantageously between 0.005 and 5.

According to one embodiment, anhydrous GI-IF is introduced into the reaction medium, preferably in gaseous form.

The molar ratio x between the fluorinating agent, preferably the anhydrous FIF, and the compound of formula (I) used is preferably between 1 and 10, and advantageously between 1 and 5.

The reaction step with the fluorinating agent, preferably anhydrous HF, can be carried out in a closed environment or in an open environment, preferably step b) is carried out in an open environment with in particular release of HCl in the form gas.

The fluorination reaction typically leads to the formation of HCl, the majority of which can be degassed from the reaction medium (just like the excess HF if the fluorinating agent is HF), for example by stripping with a neutral gas (such as nitrogen, helium or argon).

However, residual HF and / or HCl can be dissolved in the reaction medium. In the case of HCl, the amounts are very low because at the working pressure and temperature, the HCl is mainly in gas form.

The composition obtained at the end of step b) can be stored in an HF resistant container.

The composition obtained in step b) can comprise HF (it is in particular unreacted HF), the compound of formula (II) above, the SOI solvent (such as, for example, dioxane), and optionally HCl, and / or optionally heavy compounds.

The process according to the invention can optionally comprise a stage of distillation of the composition obtained in stage b).

The process according to the invention can comprise a step c), subsequent to step b), of reacting the compound of formula (II) obtained in the preceding step (step b)), with a composition comprising at least one salt of alkali or alkaline earth metal.

This step c) advantageously makes it possible to form a compound of the following formula (III):

R 2 - (S0 2 ) -NM- (S0 2 ) -F (III)

in which R 2 is as defined above, and M represents a monovalent or divalent cation of an alkali or alkaline earth metal.

The alkali or alkaline earth metal salt may be an alkali or alkaline earth metal carbonate, or an alkali or alkaline earth metal hydroxide, or an alkali or alkaline earth metal chloride, or an alkali metal fluoride or alkaline earth.

In particular, the alkali or alkaline earth metal is chosen from: lithium, potassium, sodium, magnesium and calcium, the alkali metal preferably being potassium or lithium, and advantageously potassium.

According to one embodiment, the alkali or alkaline earth metal salt is chosen from the group consisting of: LiOH, U0H, H 2 0, LiHCOs, U 2 C0 3 , LiCl, LiF, KOH, K0H, H 2 0, KHCO3, K 2 C0 3 , KOI, Ca (OH) 2 , Ca (0H) 2 , H 2 0, Ca (HC0 3 ) 2 , CaC0 3 , CaCl 2 , CaF 2 , Mg (OH) 2 , Mg (0H ) 2 , H 2 0, Mg (HC0 3 ) 2 , MgC0 3 , MgCl 2 , MgF2 and their mixtures. Preferably, the alkali or alkaline earth metal salt is K 2 C0 3

When the alkali or alkaline earth metal salt is a lithium salt, the compound of formula (III) is a compound of the above-mentioned formula (IV).

The composition comprising at least one alkali or alkaline earth metal salt can be an aqueous composition.

The composition comprising at least one alkali or alkaline earth metal salt can consist of a solid alkali or alkaline earth metal salt.

Step c) can comprise the addition of the composition obtained in the preceding step in the composition comprising at least one alkali or alkaline earth metal salt, or the reverse, namely the addition of the composition comprising at least an alkali or alkaline earth metal salt in the composition obtained in the preceding step.

To determine the amount of alkali or alkaline earth salt to be introduced, it is typically possible to carry out an analysis of the total acidity of the mixture to be neutralized.

According to one embodiment, step c) is such that:

- the molar ratio of the alkali or alkaline earth salt divided by the number of basicities of said salt relative to the compound of formula (II) is greater than or equal to 1, preferably less than 5, preferably less than 3, preferably between 1 and 2; and or

the mass ratio of the alkali or alkaline earth salt to the mass of water in the aqueous composition is between 0.1 and 2, preferably between 0.2 and 1, preferably between 0.3 and 0.7.

For example, the K 2 CO 3 salt has a number of basicities equal to 2.

Step c) of the process according to the invention can be carried out at a temperature less than or equal to 40 ° C, preferably less than or equal to 30 ° C, preferably less than or equal to 20 ° C, and in particular less than or equal to 15 ° C.

According to one embodiment, the method according to the invention comprises an additional step of filtering the composition obtained in step c), resulting in a filtrate F and a cake G.

The compound of formula (III) prepared can be contained in the filtrate F and / or in the cake G.

The filtrate F can be subjected to at least one extraction step with an organic solvent SO2 typically slightly soluble in water, in order to extract the compound of formula (III) mentioned above in an organic phase. The extraction step typically leads to the separation of an aqueous phase and an organic phase.

In the context of the invention, and unless otherwise stated, by “slightly soluble in water” is meant a solvent whose solubility in water is less than 5% by weight.

The above-mentioned organic solvent SO2 is in particular chosen from the following families: esters, nitriles, ethers, chlorinated solvents, aromatic solvents, and mixtures thereof. Preferably, the organic solvent SO 2 is chosen from dichloromethane, ethyl acetate, butyl acetate, tetrahydrofuran, diethyl ether, and mixtures thereof. In particular, the organic solvent SO2 is butyl acetate.

For each extraction, the mass quantity of organic solvent used can vary between 1/6 and 1 times the mass of the filtrate F. The number of extractions can be between 2 and 10.

Preferably, the organic phase, resulting from the extraction (s), has a content by mass of compound of formula (III) ranging from 5% to 40% by mass.

The separated organic phase (obtained at the end of the extraction) can then be concentrated to reach a concentration of compound of formula (III) of between 30% and 60%, preferably between 40% and 50% by mass, said concentration which can be achieved by any means of evaporation known to those skilled in the art.

The aforementioned cake G can be washed with an organic solvent SO 3 chosen from the following families: esters, nitriles, ethers, chlorinated solvents, aromatic solvents, and mixtures thereof. Preferably, the organic solvent SO3 is chosen from dichloromethane, ethyl acetate, butyl acetate, tetrahydrofuran, acetonitrile, diethyl ether, and mixtures thereof. In particular, the organic solvent SO3 is butyl acetate.

The quantity by mass of organic solvent S03 used can vary between 1 and 10 times the weight of the cake. The total amount of organic solvent S03 intended for washing can be

used all at once or in several times with the aim in particular of optimizing the dissolution of the compound of formula (III).

Preferably, the organic phase, resulting from the washing (s) of the cake G, has a content by weight of compound of formula (III) ranging from 5% to 20% by weight.

The separated organic phase resulting from the washing (s) of the cake G can then be concentrated to reach a concentration of compound of formula (III) of between 30% and 60%, preferably between 40% and 50% by mass , said concentration possibly being achieved by any means of evaporation known to those skilled in the art.

According to one embodiment, the organic phases resulting from the extraction (s) of the filtrate F and from the washing (s) of the cake G can be combined together, before the concentration step.

The method according to the invention can comprise an optional step d), subsequent to step c), of cation exchange between a compound of formula (III) obtained in the previous step (step c)), and at least one lithium salt.

In particular, the process according to the invention comprises this step d) when the salt obtained in step c) is not a lithium salt.

Step d) is in particular a cation exchange reaction making it possible to convert a compound of formula (III) above into a compound of formula (IV):

R 2 - (S0 2 ) -NLi- (S0 2 ) -F (IV)

in which R 2 represents one of the following radicals: F, CF 3 , CHF 2 , CH 2 F, C 2 HF 4 , C 2 H 2 F 3 ,

C 2 H 3 F 2 , C 2 F 5 , C 3 F 7 , C 3 H 4 F 3 , C 3 HF 6 , C 4 Fg, C 4 H 2 F 7 , C 4 H 4 F 5 , C5F1 1, C 3 F - | 3 , C 7 F 15, C 8 F 1 7 OR C9F19, preferably R 2 representing F.

According to one embodiment, the lithium salt is a salt of formula LiX, X representing a fluoride, a chloride, a carbonate, a tetrafluoroborate, a hydroxide, a sulfate, a chlorate, a perchlorate, a nitrile or a nitrate. Preferably LiX is LiCI.

The aforementioned lithium salt can be dissolved in a polar organic solvent, preferably chosen from the following families: alcohols, nitriles and carbonates. By way of example, mention may in particular be made of methanol, ethanol, acetonitrile, dimethylcarbonate, ethylmethylcarbonate, and their mixtures, and preferably methanol.

The molar ratio of the compound of formula (III) relative to the lithium salt can vary: it can be at least equal to 1 and less than 5. Preferably the molar ratio of the compound of formula (III) / lithium salt is between 1, 2 and 2.

The reaction medium can be left with stirring for between 1 to 24 hours, and / or at a temperature of, for example, between 0 ° C and 50 ° C.

At the end of the reaction, the reaction medium can be filtered and then optionally be concentrated. The concentration step can optionally be carried out by a thin-film evaporator, by an atomizer, by an evaporator, or by any other device allowing the evaporation of solvent.

The process according to the invention can also comprise a step of purification of the compound of formula (IV) mentioned above.

Step d) of purification of the compound of formula (IV) can be carried out by any known conventional method. It may be, for example, an extraction method, a washing method with solvents, a reprecipitation method, a recrystallization method, or a combination thereof.

At the end of step e) mentioned above, the compound of formula (IV) can be in the form of a solid, or of a composition comprising from 1% to 99.9% by weight of compound of formula (IV).

According to a first embodiment, step e) is a step of crystallization of the compound of formula (IV).

Preferably, during step e), the compound of formula (IV) is crystallized in the cold, in particular at a temperature less than or equal to 25 ° C.

Preferably, during step e), the crystallization of the compound of formula (IV) is carried out in an organic solvent (“crystallization solvent”) chosen from chlorinated solvents, such as for example dichloromethane, and aromatic solvents. , such as for example toluene, and alkanes such as pentane, hexane, cyclohexane, heptane, in particular at a temperature less than or equal to 25 ° C. Preferably, the compound of formula (IV) crystallized at the end of step (e) is recovered by filtration.

According to a second embodiment, step e) comprises the following steps: i) optionally dissolving the compound of formula (IV) in an organic solvent S'1;

ii) liquid-liquid extraction of the compound of formula (IV) with deionized water, and recovery of an aqueous solution of said compound of formula (IV);

iii) optional concentration of said aqueous solution of said compound of formula (IV);

iv) liquid-liquid extraction of the compound of formula (IV) from said aqueous solution with at least one organic solvent S'2; v) concentration of the compound of formula (IV) by evaporation of said organic solvent S'2;

vi) optionally crystallization of the compound of formula (IV).

Step e) may not include step i) above, if the compound of formula (IV) obtained in step d) already comprises an organic solvent (such as for example SO2 and / or SO3).

Step ii) above comprises in particular the addition of deionized water to the solution of the compound of formula (IV) in the above-mentioned organic solvent S'1, to allow the dissolution of said compound of formula (IV), and the extraction of said compound of formula (IV) in water (aqueous phase).

The extraction can be carried out by any known extraction means.

According to the invention, step ii) can be repeated at least once, for example three times. In a first extraction, an amount of deionized water corresponding to half the mass of the initial solution can be added, then an amount equal to approximately 1/3 of the mass of the initial solution during the second extraction, then a quantity equal to approximately 1/4 of the mass of the initial solution during the third extraction.

Preferably, step ii) is such that the mass of deionized water is greater than or equal to one third, preferably greater than or equal to half, of the mass of the initial solution of the compound of formula (III) in the organic solvent S'1 (in the case of a single extraction, or for the first extraction only if step ii) is repeated at least once).

In the event of multiple extractions (repetition of step ii)), the extracted aqueous phases are combined together to form a single aqueous solution.

At the end of step ii), an aqueous solution of compound of formula (IV) is in particular obtained.

According to one embodiment, the mass content of compound of formula (IV) in the aqueous solution is between 5% and 35%, preferably between 10% and 25%, relative to the total mass of the solution.

Preferably, step e) comprises a concentration step iii) between step ii) and step iv), preferably to obtain an aqueous solution of the compound of formula (IV)

comprising a mass content of compound of formula (IV) of between 20% and 80%, in particular between 25% and 80%, preferably between 25% and 70%, and advantageously between 30% and 65% relative to the mass total solution. The concentration step can be carried out by an evaporator under reduced pressure, at a pressure less than 50 mbar abs (preferably less than 30 mbar abs), and in particular at a temperature of between 25 ° C and 60 ° C, of preferably between 25 ° C and 50 ° C, preferably between 25 ° C and 40 ° C, for example at 40 ° C.

The compound of formula (IV), contained in the aqueous solution obtained at the end of step ii), and of a possible concentration step iii) or of a possible other intermediate step, can then be recovered by extraction. with an organic solvent S'2, said solvent S'2 (step iv). Step iv) leads in particular, after extraction, to an organic phase, saturated with water, containing the compound of formula (IV) (it is a solution of compound of formula (IV) in the organic solvent S'2, said solution being saturated with water).

Step iv) advantageously makes it possible to obtain an aqueous phase and an organic phase, which are separated.

Preferably, the organic solvent S'2 is chosen from the group consisting of esters, nitriles, ethers, chlorinated solvents, aromatic solvents, and mixtures thereof. Preferably, the solvent S'2 is chosen from ethers, esters, and mixtures thereof. For example, mention may be made of diethylcarbonate, methyl-t-butyl ether, cyclopentylmethyl ether, ethyl acetate, propyl acetate, butyl acetate, dichloromethane, tetrahydrofuran, acetonitrile, diethyl ether, and mixtures thereof. Preferably, the solvent S'2 is chosen from methyl-t-butyl ether, cyclopentylmethyl ether, ethyl acetate, propyl acetate, butyl acetate, and mixtures thereof. In particular, the organic solvent S'2 is butyl acetate.

The extraction step iv) is repeated at least once, preferably from one to ten times, and in particular four times. The organic phases can then be combined into one before step v). For each extraction, the quantity by mass of organic solvent S'2 used can vary between 1/6 and 1 time the mass of the aqueous phase. Preferably, the organic solvent S'2 / water mass ratio, during an extraction in step iv), varies from 1/6 to 1/1, the number of extractions varying in particular from 2 to 10.

Preferably, during extraction step iv), the organic solvent S'2 is added to the aqueous solution resulting from step ii) (and from optional step iii).

Step e) according to this embodiment can comprise a pre-concentration step between step iv) and step v), preferably to obtain a solution of the compound of formula (IV) in the organic solvent S'2 comprising a mass content of compound of formula (IV) of between 20% and 60%, and preferably between 30% and 50% by mass relative to the total mass of the solution. The pre-concentration step can be

carried out at a temperature ranging from 25 ° C to 60 ° C, preferably from 25 ° C to 45 ° C, optionally under reduced pressure, for example at a pressure below 50 mbar abs, in particular at a pressure below 30 mbar abs. The pre-concentration step is preferably carried out by an evaporator under reduced pressure, in particular at 40 ° C. and at a pressure less than 30 mbar abs.

According to the invention, the concentration step v) can be carried out at a pressure between 10 -2 mbar abs and 5 mbar abs, preferably between 5.10 -2 mbar abs and 2 mbar abs, preferably between 5.10 1 and 2 mbar abs, even more preferably between 0.1 and 1 mbar abs, and in particular between 0.4 and 0.6 mbar abs. In particular, step v) is carried out at 0.5 mbar abs or at 0.1 mbar.

According to one embodiment, step v) is carried out at a temperature between 30 ° C and 95 ° C, preferably between 30 ° C and 90 ° C, preferably between 40 ° C and 85 ° C, and in particular between 50 ° C and 70 ° C.

According to one embodiment, step v) is carried out with a residence time less than or equal to 15 min, preferably less than 10 min and preferably less than or equal to 5 minutes and advantageously less than or equal to 3 minutes.

In the context of the invention, and unless otherwise specified, the term “residence time” is understood to mean the time which elapses between the entry of the solution of the compound of formula (III) (in particular obtained at the end of of step iv) above) in the evaporator and the outlet of the first drop of the solution.

According to a preferred embodiment, the temperature of the condenser of the short path thin film evaporator is between -55 ° C and 10 ° C, preferably between -50 ° C and 5 ° C, more preferably between -45 ° C and -10 ° C, and advantageously between -40 ° C and -15 ° C.

The aforementioned short path thin film evaporators are also known under the name "Wiped film short path" (WFSP). They are typically called so because the vapors generated during evaporation make a “short path” (short distance) before being condensed in the condenser.

Among the short path thin film evaporators, mention may in particular be made of the evaporators sold by the companies Buss SMS Ganzler ex Luwa AG, UIC Gmbh or VTA Process.

Typically, short path thin film evaporators may have a solvent vapor condenser placed inside the apparatus itself (especially in the center of the apparatus), unlike other types of film evaporators. thin (which are not short-path) in which the condenser is located on the outside of the device.

In this type of device, the formation of a thin film of product to be distilled on the internal hot wall of the evaporator can typically be ensured by continuous spreading on the evaporation surface using mechanical means. specified below.

The evaporator can in particular be provided at its center with an axial rotor on which the mechanical means which allow the formation of the film on the wall are mounted. They may be rotors equipped with fixed blades: lobed rotors with three or four blades made of flexible or rigid materials, distributed over the entire height of the rotor or else rotors equipped with mobile blades, vanes, wiper brushes, guided wipers. In this case, the rotor can be constituted by a succession of pivot-articulated vanes mounted on a shaft or axis by means of radial supports. Other rotors can be equipped with mobile rollers mounted on secondary axles and said rollers are pressed against the wall by centrifugation. The speed of rotation of the rotor which depends on the size of the device, can be readily determined by those skilled in the art. The different mobiles can be made of various materials, metallic for example steel, alloy steel (stainless steel), aluminum, or polymeric, for example polytetrafluroethylene PTFE or glass materials (enamel); metallic materials coated with polymeric materials.

Process

The process according to the present invention is particularly advantageous for manufacturing the following compounds of formula (IV): LiN (S0 2 F) 2 , UNSO 2 CF 3 SO 2 F, UNSO 2 C 2 F 5 SO 2 F, UNSO 2 CF 2 OCF 3 SO 2 F, UNSO 2 C 3 HF 6 SO 2 F, UNSO 2 C 4 F 9 SO 2 F, UNSO 2 C 5 F 11SO 2 F, L1NSO 2 C 6 F 13 SO 2 F, L1NSO 2 C 7 F 15 SO 2 F, L1NSO 2 C 8 F 17 SO 2 F and L1NSO 2 C 9 F 19 SO 2 F.

Preferably, the process according to the invention is a process for preparing LiN (S0 2 F) 2 (LiFSI).

In the context of the invention, the terms “lithium salt of bis (fluorosulfonyl) imide”, “lithium bis (sulfonyl) imide”, “LiFSI”, “LiN (S0 2 F) 2” , are used in an equivalent manner , "Lithium bis (sulfonyl) imide", or "lithium bis (fluorosulfonyl) imide".

In the context of the invention, by “between x and y”, or “ranging from x to y”, is meant an interval in which the limits x and y are included. For example, the temperature “between -20 and 80 ° C” notably includes the values ​​-20 ° C and 80 ° C.

All of the embodiments described above can be combined with each other. In particular, each embodiment of any step of the method of the invention can be combined with another particular embodiment.

The present invention is illustrated by the following example, to which it is however not limited.

EXAMPLES

Example 1 (comparative): reaction at atmospheric pressure

A one liter glass reactor equipped with stirring is charged with sulfamic acid (1 eq, 1, 24mol, 120g) and sulfuric acid 95% (1 eq, 1, 24mol, 127.5g ). Thionyl chloride (4 eq, 4.9mol, 583g) is gradually added to the reactor using a dropping funnel. The temperature of the reaction medium is maintained at 35 ° C for 2 hours then is gradually increased to 75 ° C. The readion is maintained at a temperature of 75 ° C. for 64 hours in order to obtain complete conversion to sulfamic acid. A condenser operating with cold water is placed on the vent line of the reactor so as to condense the vaporized thionyl chloride and to reflux it into the reaction medium. The gases generated by the reaction (HCl and S0 2) and not condensed by the condenser are directed to a bubbler containing water where they are absorbed.

321 5g of liquid are obtained containing bis (chlorosulfonyl) imide and residual thionyl chloride.

Example 2: reaction at 8 bars absolute

A glass reactor is charged with sulfamic acid (1 eq, 0.41 mole, 40 g) and thionyl chloride (3.25 eq, 1.34 mole, 159.3 g). 20% oleum (1 eq, 0.41 mol, 38.9 g) is gradually added to the reactor. The reaction medium is stirred and is heated until a temperature of 120 ° C. is obtained. The reactor pressure is regulated at 8 bars absolute by means of a regulator placed on the discharge of the reactor vent. Downstream of the overflow, this vent is directed towards a bubbler containing 1 kg of water allowing to absorb the gases. The reaction time is 20 hours to obtain complete conversion to sulfamic acid. The bis (chlorosulfonyl) imide obtained in the end has a light yellow appearance. At the end of the reaction, 136.4 g of liquid containing the bis (chlorosulfonyl) imide are recovered,2 solubilized.

Example 3 (comparative): reaction at atmospheric pressure

A one-liter glass reactor provided with stirring is charged with sulfamic acid (1 eq, 1.24 mol, 120 g) and sulfuric acid 95% (1 eq, 1.24 mol, 127.5 g). Thionyl chloride (4 eq, 4.9 mol, 583 g) is gradually added to the reactor using a dropping funnel. The temperature of the reaction medium is gradually increased to 90 ° C. The reaction is carried out at atmospheric pressure.

Total conversion to sulfamic acid is obtained after 52 hours. A condenser operating with cold water is placed on the vent line of the reactor so as to condense the vaporized thionyl chloride and to reflux it into the reaction medium. The gases generated by the reaction (HCl and SO2) and those not condensed by the condenser are directed to a bubbler containing water where they are absorbed.

319.5 g of liquid are obtained containing bis (chlorosulfonyl) imide and residual thionyl chloride.

Example 4: Reaction at 8 bar absolute

A one-liter glass reactor provided with stirring is charged with sulfamic acid (1 eq, 1.24 mol, 120 g) and sulfuric acid 95% (1 eq, 1.24 mol, 127.5 g). Thionyl chloride (4 eq, 4.9 mol, 583 g) is added gradually to the reactor using a dropping funnel. The temperature of the reaction medium is gradually increased to 90 ° C. The pressure of the reactor is regulated at 8 bars absolute by means of an overflow valve placed on the discharge of the reactor vent. Downstream of the overflow, this vent is directed to a bubbler containing water to absorb the gases.

Total conversion to sulfamic acid is achieved in less than 52 hours. 323 g of liquid are obtained containing bis (chlorosulfonyl) imide and residual thionyl chloride.

Example 5: Reaction at 8 bar absolute

A one-liter glass reactor provided with stirring is charged with sulfamic acid (1 eq, 1.24 mol, 120 g) and sulfuric acid 95% (1 eq, 1.24 mol, 127.5 g). Thionyl chloride (3.5 eq, 4.9 mol, 583 g) is added gradually to the reactor using a dropping funnel. The temperature of the reaction medium is gradually increased to 90 ° C. The reactor pressure is regulated at 8 bars absolute by means of a regulator placed on the discharge of the reactor vent. Downstream of the overflow, this vent is directed to a bubbler containing water to absorb the gases.

Total conversion to sulfamic acid is achieved in less than 52 hours. 320.5 g of liquid are obtained containing bis (chlorosulfonyl) imide and residual thionyl chloride.

The comparison of Example 3 and 4 shows that the implementation of the chlorination reaction under a pressure of 8 bars (Example 4) advantageously makes it possible to obtain the conversion

total sulfamic acid in a reduced time compared to the implementation at atmospheric pressure (Example 3).

In addition, the chlorination reaction carried out under a pressure of 8 bars advantageously makes it possible to reduce the time to obtain a total conversion into sulfamic acid while reducing the molar amount of thionyl chloride (example 5) compared to the reaction under atmospheric pressure. (example 3).

Example 6: preparation of LiFSI

LiFSI was prepared from each of the bis (chlorosulfonyl) imide obtained in Examples 1 to 5, according to the procedure described in Example 3 of WO2014 / 080120.

CLAIMS

1. Process for preparing a compound of the following formula (IV):

R 2 - (S0 2 ) -NU- (S0 2 ) -F (IV)

in which R 2 represents one of the following radicals: F, CF 3 , CHF 2 , CH 2 F, C 2 HF 4 ,

C 2 H 2 F 3 , C 2 H 3 F 2J C 2 F 5 , C 3 F 7 , C 3 H 4 F 3 , C 3 HF 6 , C 4 Fg, C 4 H 2 F 7 , C 4 H 4 F 5 , C 5 F 11 , C 3 F I3 , C 7 F 15 ,

C 8 FI 7 OR C 9 F 19 , preferably R 2 representing F;

said process comprising a step a) of reacting a sulfonamide of the following formula (A):

R 0 - (SO 2 ) -NH 2 (A)

in which R 0 represents one of the following radicals: OH, Cl, F, CF 3 , CHF 2 , CH 2 F,

C 2 HF, C 2 H 2 F 3 , C 2 H 3 F 2 , C 2 F 5 , C 3 F 7J C 3 H F 3 , C 3 HF 6 , C 4 Fg, C 4 H 2 F 7 , C 4 HF 5 , C 5 F 11 , C 3 F I3 , C 7 F 15 , C S FI 7OR C 9 F 19 ;

with at least one sulfur-containing acid and at least one chlorinating agent, said step a) being carried out:

- at a temperature between 90 ° C and 130 ° C, preferably between 100 ° C and 130 ° C, and

- at a pressure strictly greater than 7 bars abs.

2. The method of claim 1, wherein the compound (A) is that in which Ro represents OH.

3. Method according to any one of claims 1 or 2, wherein the sulfur agent is selected from the group consisting of chlorosulfonic acid (CIS0 3 H), sulfuric acid, oleum, and their mixtures, the sulfur-containing agent preferably being sulfuric acid or oleum, and preferably sulfuric acid.

4. Method according to any one of claims 1 to 3, wherein the chlorinating agent is selected from the group consisting of thionyl chloride (SOCI 2 ), oxalyl chloride (COCI 2 ), phosphorus pentachloride ( PCI 5 ), phosphonyl trichloride (PCI 3 ), phosphoryl trichloride (POCI 3 ), and mixtures thereof, the chlorinating agent preferably being thionyl chloride.

5. Method according to any one of claims 1 to 4, wherein:

o the molar ratio between the sulfur acid and the compound (A) (in particular in which R 0 = OH) is between 0.7 and 5, preferably between 0.9 and 5; and / or o the molar ratio between the chlorinating agent and the compound (A) (in particular in which R 0 = OH) is between 2 and 10, preferably between 2 and 5.

6. Method according to any one of claims 1 to 5, wherein step a) is carried out at a temperature greater than or equal to 90 ° C, preferably greater than or equal to 100 ° C, preferably greater than or equal to 105. ° C, advantageously greater than or equal to 1 10 ° C, even more advantageously greater than or equal to 1 15 ° C, and in particular greater than or equal to 1200.

7. Method according to any one of claims 1 to 6, wherein step a) is carried out at a temperature between 105 ° C and 130 ° C, preferably between 105 ° C and 125 ° C, preferably between 1 10 ° C and 125 ° C, advantageously between 115 ° C and 125 ° C, and even more preferably between 1118 ° C and 122 ° C, and in particular at 120 ° C.

8. Method according to any one of claims 1 to 7, wherein step a) is carried out at a pressure greater than or equal to 7.5 bar abs, preferably greater than or equal to 8 bar abs, more preferably. greater than or equal to 9 bar abs, preferably greater than or equal to 10 bar abs, advantageously greater than or equal to 1 1 bar abs, even more advantageously greater than or equal to 12 bar abs, preferably greater than or equal to 13 bar abs, for example greater than or equal to 15 bars abs.

9. Method according to any one of claims 1 to 8, comprising a step b) subsequent to step a), said step b) comprising the reaction of the compound of formula (I) obtained in the previous step:

R I - (S0 2 ) -NH- (S0 2 ) -CI (I)

in which Ri represents one of the following radicals: Cl, F, CF 3 , CHF 2 , CH 2 F, C 2 HF 4 ,

C 2 H 2 F 3 , C 2 H 3 F 2J C 2 F 5 , C 3 F 7 , C 3 H 4 F 3 , C 3 HF 6 , C 4 Fg, C 4 H 2 F 7 , C 4 H 4 F 5 , C 5 F 11 , CeF - | 3 , C 7 F 15 , C 8 FI 7OR C 9 F 19, Ri preferably representing Cl;

with at least one fluorinating agent, optionally in the presence of at least one SOI organic solvent.

10. The method of claim 9, wherein the fluorinating agent is selected from the group consisting of HF, KF, AsF 3 , BiF 3 , ZnF 2 , SnF 2 , PbF 2 , CuF 2 , and mixtures thereof, l the fluorinating agent being preferably HF, and even more preferably anhydrous HF.

1 1. A method according to any one of claims 9 or 10, comprising a step c), subsequent to step b), of reaction of the compound of formula (II) obtained in the previous step:

R 2 - (S0 2 ) -NH- (S0 2 ) -F

in which R 2 represents one of the following radicals: F, CF 3 , CHF 2 , CH 2 F, C 2 HF 4 ,

C 2 H 2 F 3 , C 2 H 3 F 2J C 2 F 5 , C 3 F 7 , C 3 H 4 F 3 , C 3 HF 6 , C 4 Fg, C 4 H 2 F 7 , C 4 H 4 F 5 , C 5 F 11 , C 3 F I3 , C 7 F 15 , CSFI 7OR C 9 F 19 ;

with a composition comprising at least one alkali metal or alkaline earth metal salt.

12. The method of claim 11, wherein the alkali or alkaline earth metal salt is an alkali metal or alkaline earth metal carbonate, or an alkali metal or alkaline earth metal hydroxide, or an alkali metal or alkaline chloride. -terreux, or an alkali metal or alkaline-earth metal fluoride, said salt advantageously being a potassium salt, and advantageously K 2 C0 3 .

13. Method according to any one of claims 1 1 or 12, comprising a step d), subsequent to step c), of cation exchange between a compound of formula (III) obtained in the previous step:

R 2 - (S0 2 ) -NM- (S0 2 ) -F (III)

wherein R 2 is as defined in claim 1, and M represents a monovalent or divalent cation of an alkali or alkaline earth metal;

and at least one lithium salt, said lithium salt preferably being a salt of formula LiX, X representing a fluoride, a chloride, a carbonate, a tetrafluoroborate, a hydroxide, a sulfate, a chlorate, a perchlorate, a nitrile or a nitrate.