Magnetic electroactive anion

Abstract

The invention relates to an anion of formula (I). Such an electroactive anion is, in particular, of particular interest for energy storage applications in electrochemical systems and / or in ionic liquids.

Description

MAGNETIC ELECTROACTIVE ANION FIELD OF INVENTION

[0001] The invention relates to electroactive anions, which find applications particularly in the fields of electrochemistry and energy storage. More specifically, the invention relates to a magnetic electroactive anion, derived from bistriflimidide, of particular interest in the field of electrochemistry and even more so in the field of ionic liquids. STATE OF THE ART

[0002] Environmental concerns and increasing energy demand are making the need for energy storage solutions increasingly urgent. Similarly, wireless systems and new technologies related to connected devices are contributing to this growing need for human activity. This need is further reinforced by the increasing share of renewable electricity (wind, solar, and even hydroelectric) in electricity consumption, the production of which is inherently unpredictable and inconsistent.

[0003] Ionic liquids are salts with a low melting point, below 100°C, even below room temperature. They thus form liquids composed solely of organic cations and organic or inorganic anions.

[0004] They have the advantages of being non-volatile, non-flammable, thermally and chemically stable, depending on the anion being hydrophilic or hydrophobic, being good conductors and having an electrochemical stability window of up to 6 V. These properties make them safer compounds for the environment and their handler, versatile in terms of their physicochemical characteristics by the simple change of the cation-anion pair, with a significant solvent power and presenting the possibility of infinite recycling without loss of activity.

[0005] Ionic liquids thus find very diverse applications in catalysis, extraction, electrochemistry, as organic solvents.

[0006] Electroactive ionic liquids are considered a specific class of ionic liquids. These liquids possess not only redox activity but also ionic conductivity and fluidity around room temperature. Consequently, no additional reagents, such as a solvent and supporting electrolyte, are required for electrochemical reactions.

[0007] Due to their properties and the diversity of their applications, there is a constant need for discoveries developing new ionic liquids, or precursor anions that can constitute them.

[0008] Among these, bistriflimidide (or TFSI) is particularly stable and relatively non-toxic; it is also a catalyst used in numerous reactions. TFSI also has applications in lithium-metal batteries.

[0009] A method for synthesizing TFSI is presented in patent application CN101456832. Anion of the invention

[0010] The inventors have developed a simple and relatively safe synthesis process for a new anion comprising the TFSI anion, with formula I:

[0011]

[0012] I

[0013] This anion is multifunctional: it is a precursor anion of ionic liquids, an electron donor, soluble in aqueous or polar organic media, and is magnetic, which multiplies its potential applications. Brief summary of the invention

[0014] Thus, a first object of the invention relates to an electroactive magnetic anion comprising a group of the radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO radical), according to the following formula I:

[0015]

[0016] (I)

[0017] According to other optional characteristics of the electroactive magnetic anion according to the invention, it may be included in: a composition comprising at least one cation selected from H + , N / A + K + , Li + ,and / or a composition comprising at least one organic cation precursor of ionic liquids selected from the following groups: imidazolium, quaternary ammonium, phosphonium, pyridinium, pyrrolidinium, their derivatives or mixtures thereof.

[0018] According to a second object, the invention relates to an electrochemical system comprising at least one electroactive magnetic anion according to the invention. Indeed, the electrochemical properties of this anion make it, in particular but not exclusively, a tool of choice in such systems.

[0019] According to a third object, the invention relates to an ionic liquid comprising as an anion, the electroactive magnetic anion of formula I.

[0020] According to other optional features of the ionic liquid according to the third object of the invention, the latter may comprise one or more of the following features, alone or in combination: an organic cation precursor of ionic liquids selected from imidazolium, quaternary ammonium, phosphonium, pyridinium or pyrrolidinium, their derivatives or mixtures thereof; an organic cation precursor of ionic liquids selected from:

[0021] ,

[0022] ,

[0023] ,

[0024] ,

[0025] ,

[0026] or their mixtures and in which R 1, R 2, R 3, R4s are, independently of each other, an alkyl in (C 3-C11), R5étant sélectionné parmi un atome d’hydrogène et un méthyle ;un cation comprenant un groupe ammonium quaternaire, imidazolium, ou pyridinium, ledit cation étant sélectionné parmi :

[0027] ,

[0028] ,

[0029] ,

[0030] ,

[0031] ,

[0032] ,

[0033]

[0034] ,

[0035] ,

[0036] ,

[0037] ,

[0038] ,

[0039] ,

[0040] ,

[0041] ;

[0042] ,

[0043] ,

[0044] with, when present, :R=H or a C1-C alkyl 5, 0≤m≤5,1≤n≤5,1≤o≤4.

[0045] According to a fourth object, the invention relates to an electrochemical system comprising an ionic liquid as described above.

[0046] A fifth object of the invention relates to the use of the electroactive magnetic anion of formula I in a catalytic system, in an electrochromic device, in an energy storage device such as a supercapacitor, an organic battery, a redox flow battery, a thermal battery, in a contrast agent for magnetic or paramagnetic imaging.

[0047] According to a sixth object, the invention relates to a process for synthesizing the electroactive magnetic anion of formula I according to the invention, comprising the following steps: adding dropwise, over a period of 120 to 180 minutes, one molar equivalent of chlorosulfonic acid to a suspension of 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl in anhydrous diethyl ether maintained between 0°C and 5°C; stirring the mixture at room temperature for at least 24 hours, preferably at least 40 hours; cooling the reaction mixture to between 0°C and 5°C; then adding two molar equivalents of phosphorus trichloride and stirring the mixture for at least 1 hour, preferably at least 2 hours, between 0°C and 5°C; followed by stirring at room temperature for at least 12 hours, preferably at least 24 hours. ambient, evaporation of the solvent under reduced solvent pressure, the residual solid being (2,2,6,6-tetramethylpiperidine-N-oxyl)chlorosulfate, (2,2,6,6-tetramethylpiperidine-N-oxyl)chlorosulfate, is placed in acetonitrile, then 1 molar equivalent of trifluoromethanesulfonamide and 1 molar equivalent of the metallic carbonate salts are added, then the mixture is maintained at 70°C under stirring for at least 24 hours, the acetonitrile is evaporated, the crude product is dissolved in absolute ethanol, the resulting mixture is filtered to remove the carbonate, the liquid phase is evaporated under reduced pressure to give the electroactive magnetic anion according to the invention, associated with a metallic cation.

[0048] This process may further include the following steps of replacement by metathesis of the metallic cation by a second precursor cation of the ionic liquids:

[0049] (viii) heating to at least 60°C for at least 12 hours in the presence of a second precursor cation of ionic liquids,

[0050] (ix) purification of the ionic liquid.

[0051] These steps vii and ix make it possible to obtain an ionic liquid comprising the electroactive magnetic anion according to the invention. Brief descriptions of the drawings

[0052] Characterization by cyclic voltammetry of the electroactive magnetic anion according to the invention. A- representation of the current resulting from the applied potential variation, the sweep speeds in mV / s are indicated by the arrows; B- cyclic voltammetry responses of the electroactive magnetic anion at pH = 7 in Na2SO4.

[0053] : an embodiment of the process for synthesizing the electroactive magnetic anion according to the invention. RT: ambient temperature, ACN: Acetonitrile.

[0054] : Characterization by cyclic voltammetry of ionic liquids L1, L2 and L3 comprising the electrochemical anion according to the invention (1mM of ionic liquid, in a 0.1M KCl solution at a scan rate of 100 mV / s). Detailed description of the invention Definitions

[0055] The terms "(C1-C5) alkyl" or "C1-C5 alkyl" used in the present invention refer to a saturated, linear or branched hydrocarbon chain comprising 1 to 5 carbon atoms, including, but not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and n-pentyl. Preferably, the terms "(C1-C5) alkyl" or "C1-C5 alkyl" are used. 1-C5)» ou « alkyle en C1-C5» utilisés dans la présente invention désignent une chaîne d’hydrocarbures saturée linéaire (c’est-à-dire non branchée). De la même manière, « alkyle en (C3-C11) » ou « alkyle en C3-C11» désignent une chaîne d’hydrocarbure saturée, linéaire ou branchée, comprenant de 3 à 11 atomes de carbone. De préférence, « alkyle en (C3-C11) » ou « alkyle en C3-C11» désigne une chaine saturée linéaire comprenant de 3 à 11 atomes de carbone.

[0056] Bistriflimidide (or TFSI), or, in English, bistriflimid, refers to the anion 1,1,1-trifluoro-N-(trifluoromethylsulfonyl)-methanesulfonimidate (IUPAC name) with the formula:

[0057]

[0058] “TEMPO” or “TEMPO radical” or “TEMPO group” refers to the (2,2,6,6-tetramethylpiperidin-1-yl)oxy or 1-λ group 1 -oxidanyl-2,2,6,6-tetramethylpiperidine (IUPAC name) with the formula:

[0059]

[0060] For the purposes of the invention, imidazolium, quaternary ammonium, phosphonium, pyridinium or pyrrolidinium derivatives refer to a compound comprising at least one of these positively charged groups.

[0061] Unless otherwise stated, the intervals mentioned include the bounds. Thus, unless otherwise specified, a value that is said to be between the values ​​x and y can be equal to x or y, and of course to any intermediate value.

[0062] The inventors have developed a method for synthesizing a multifunctional anion comprising a TEMPO radical and a TFSI group. This magnetic and electroactive anion has numerous potential applications, notably, but not exclusively, in the fields of electrochemistry and energy storage. Indeed, its mixed ionic and electronic conductivity allows for a broad range of potential applications, such as the development of fully organic materials that conduct electricity. This anion can be coupled with an electron acceptor, thus opening up the field of applications for ionic liquids. Another advantage of the anion according to the invention is its magnetic properties, which allow for its easy recovery and reuse. Electroactive magnetic anion

[0063] Thus, a first object of the invention is the electroactive magnetic anion comprising, preferably composed of, a group of the radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO radical), according to the following formula I:

[0064]

[0065] (I)

[0066] This anion, whose nomenclature might include (2,2,6,6-tetramethylpiperidine-N oxyl)chlorosulfonyl(trifluoromethylsulfonyl)imide, can be associated with various cations depending on its application. For example, these cations can be metallic cations such as Na + K + or Li + Also, in an aqueous environment, it can be H + Advantageously, these cations can be directly associated with the anion of the invention at the end of their synthesis by using, for example, the corresponding carbonate salt during step 2 of the synthesis process of the invention described below.

[0067] The Li cation+ is particularly preferred in the context of, for example, the use of the anion according to the invention in lithium-ion accumulators or batteries and lithium-metal accumulators or batteries.

[0068] The Na cation + is also preferred in the context of, for example, the use of the anion according to the invention in sodium-ion accumulators or batteries and sodium-metal accumulators or batteries.

[0069] Advantageously, the anion according to the invention can be combined with precursor cations of ionic liquids such as, for example, imidazolium, quaternary ammonium, phosphonium, pyridinium or pyrrolidinium and their derivatives.

[0070] Some of these cations may be, for example, redox active cations such as those mentioned in patent EP3453038, such as:

[0071] ,

[0072] ,

[0073] ,

[0074] ,

[0075] ,

[0076] ,

[0077] ,

[0078] ;

[0079] ,

[0080] .

[0081] Redox active cations can also be selected from the following redox active cations:

[0082] ,

[0083] ,

[0084] ,

[0085] ,

[0086] ,

[0087] ,

[0088] ,

[0089] and their mixtures, with, when present:

[0090] - R=H or a C1-C5,

[0091] - 0≤m≤5.

[0092] - 1≤n≤5, and

[0093] - 1≤o≤4.

[0094] The presence of the Tempo radical in the electroactive magnetic anion of formula I allows us to consider its particular use in contrast agents, useful, for example but not exclusively, in medicine, in techniques such as MRI, Electron Paramagnetic Resonance Imaging (EPR) or IRMO techniques (MRI by Overhauser effect). For example, the application of the TEMPO radical in MRI is described by Lumata et al. (2024) (Lumata JL, Hagge LM, Gaspar MA, Trashi I, Ehrman RN, Koirala S, Chiev AC, Wijesundara YH, Darwin CB, Pena S, Wen as a magnetic resonance imaging contrast agent for detection of superoxide production in the inflamed liver. J Mater Chem B. 2024 Mar 27;12(13):3273-3281.).Furthermore, and without wishing to be bound by any theory, having a negatively charged contrast agent such as the anion of the invention may be of interest in the diagnosis of pathologies, such as cancer, in which a disturbance of the net surface charge of cells is observed. Electrochemical system

[0095] Another object of the invention is the use of the anion according to the invention in an electrochemical system. The presence of the TFSI group combined with the electrochemical performance illustrated in the experimental part makes the use of this anion particularly relevant in electrochemical systems, such as electrochemical energy storage systems (supercapacitors, batteries including organic batteries, solid-state batteries, redox flow batteries), lithium-ion, sodium-metal, and sodium-ion accumulators or batteries.

[0096] These systems may include ionic liquids comprising, as a precursor anion, the electroactive magnetic anion according to the invention of formula I:

[0097]

[0098] (I) Ionic liquid

[0099] An ionic liquid, as defined in this invention, is understood to be a salt having a melting point below 100°C, or even below ambient temperature. In the present invention, ionic liquids therefore contain, as an anion, the electroactive magnetic anion of formula I ((2,2,6,6-tetramethylpiperidine-N oxyl)chlorosulfonyl(trifluoromethylsulfonyl)imide) and a cation suitable for forming an ionic liquid. Those skilled in the art know which cations are precursors of ionic liquids.

[0100] Advantageously, the anion according to the invention can be associated with precursor cations of ionic liquids; such an ionic liquid constitutes another object of the present invention. Precursor cations of ionic liquids are such as, for example, imidazolium, quaternary ammonium, phosphonium, pyridinium or pyrrolidinium and their derivatives.

[0101] In one embodiment, said organic cation precursor of ionic liquids is selected from:

[0102] ,

[0103] ,

[0104] ,

[0105] ,

[0106] ,

[0107] or their mixtures and in which R 1, R 2, R 3, R 4, , are, independently of each other, an alkyl in (C 3-C11), R5 étant sélectionné parmi un hydrogène et un méthyle.

[0108] Some of the precursor cations of ionic liquids may be redox-active cations such as those described in patent EP3453038, or mixtures thereof, and in particular redox-active cations selected from:

[0109] ,

[0110] ,

[0111] ,

[0112] ,

[0113] ,

[0114] ,

[0115] ,

[0116]

[0117] ,

[0118] ,

[0119] or mixtures thereof.

[0120] The synthesis processes for these cations are known to those skilled in the art.

[0121] Some of the precursor cations of ionic liquids can advantageously be the active cations selected from:

[0122]

[0123] with 1≤n≤5.

[0124] A possible synthesis process for this cation is as follows: step A)

[0125]

[0126] 4-OH-Tempo (Sigma-Aldrich, France) is dissolved in distilled DCM. The (C1-C5) acyl chloride solution (Sigma-Aldrich) is added dropwise under argon. Pyridine is added to the flask under argon, and the mixture is stirred at 0–5°C for 4 hours and then left at room temperature for 18 hours.

[0127] The organic phase is extracted, washed, and the solvent is evaporated. (step B)

[0128]

[0129] 4,4'-Bipyridyl (Sigma-Aldrich, France) is dissolved in distilled ACN, then, under argon, 1,3-propane sulfone (Sigma-Aldrich, France) dissolved in distilled ACN is added dropwise. The mixture is kept under stirring at 80°C, the product (white powder) is filtered and washed. (Step C)

[0130]

[0131] The compound obtained in step A ([Chem24] ) is dissolved in distilled N,N-dimethylformamide in a reaction flask. A solution of the compound obtained in step B is dissolved in N,N-dimethylformamide and then added to the flask, and the mixture is stirred at 70°C. After the reaction, the solvent is evaporated. The crude product is washed. In the case illustrated here, the chloride anions are provided by the reaction intermediates. They can easily be exchanged by metathesis according to methods commonly used in the art.

[0132]

[0133] with 1≤n≤5.

[0134] A possible synthesis process for this cation is as follows: step A)

[0135]

[0136] 4-OH-Tempo (Sigma-Aldrich, France) is dissolved in distilled DCM. The acyl chloride (C1-C5) solution is added dropwise under argon. Pyridine is added to the flask under argon, and the mixture is stirred at 0-5°C for 4 hours and then left at room temperature for 18 hours.

[0137] The organic phase is extracted, washed, and the solvent is evaporated. (step B)

[0138]

[0139] In a flask containing one equivalent of 4,4-bipyridyl (Sigma-Aldrich, France) in 10 mL of acetonitrile solvent, one equivalent of 4-bromobutyric acid (Sigma-Aldrich, France) was added while stirring. The solution was refluxed for 18 hours at 80 °C. After the reaction, a yellow solid formed, which was then filtered and washed with acetonitrile. (step C)

[0140]

[0141] The compound obtained in step A ([Chem24] ) is dissolved in distilled N,N-dimethylformamide in a reaction flask. A solution of the compound obtained in step B is dissolved in N,N-dimethylformamide and then added to the flask, and the mixture is stirred at 70°C. After the reaction, the solvent is evaporated. The crude product is washed. In the case illustrated here, the chloride anions are provided by the reaction intermediates. They can easily be exchanged by metathesis according to methods commonly used in the art.

[0142] ,

[0143] with :

[0144] - 1≤n≤5, and

[0145] - 1≤o≤4.

[0146] A possible synthesis process for this cation is as follows: step A)

[0147]

[0148] 4-OH-Tempo (Sigma-Aldrich, France) is dissolved in distilled DCM. The acyl chloride (C1-C5) solution is added dropwise under argon. Pyridine is added to the flask under argon, and the mixture is stirred at 0-5°C for 4 hours, then left at room temperature for 18 hours.

[0149] The organic phase is extracted, washed, and the solvent is evaporated. The crude product is washed. (Step B)

[0150]

[0151] 4,4'-Bipyridyl is dissolved in DCM under vigorous stirring. Alkyl bromide (C1-C4) dissolved in DCM is added dropwise to the mixture, then held at 50°C under stirring. After the reaction, the solution is filtered. The solid is washed. The organic solvent is evaporated under reduced pressure, resulting in a solid as well. The crude product is recrystallized in a dichloromethane:hexane mixture (1:20). The product is dried under vacuum. (Step C)

[0152]

[0153] The compounds from the previous steps are mixed in a flask with distilled ACN. The reaction is maintained under stirring at 50°C. After the reaction, the crude product is recrystallized. In the case illustrated here, the chloride and bromide anions are introduced by the reaction intermediates. They can easily be exchanged by metathesis according to methods commonly used in the art.

[0154] ,

[0155] with :

[0156] - 0≤m≤5, and

[0157] - 1≤n≤5.

[0158] A possible synthesis process for this cation is as follows: step A)

[0159]

[0160] A 2-aminoalkyl anthraquinone (1 equivalent, Sigma-Aldrich) is dissolved in distilled DCM. Acyl chloride solution (C1-C5, 1.2 equivalents, Sigma-Aldrich) is added dropwise under argon. Pyridine (1.2-1.5 equivalents, Sigma-Aldrich) is added to the flask under argon, and the mixture is stirred at 0-5°C for 4 hours and then left at room temperature for 18 hours.

[0161] The organic phase is extracted, washed with 3M HCl solution, then with saturated NaCl aqueous solution. The organic phase is dried over anhydrous MgSO4. Next, 50 mL of petroleum ether was slowly added to the dichloromethane filtrate to obtain a brown powder. (step B)

[0162]

[0163] In a flask containing 1 equivalent of imidazole (Sigma-Aldrich) in tetrahydrofuran, NaH (1.25 equivalents, Sigma-Aldrich) is introduced into the reaction. Then, the product from step A (1 equivalent) is added to the flask. The mixture is stirred at 50°C for 18 hours. After the reaction, the solvent is evaporated to obtain a crude product, which is then dissolved in ethyl acetate. The organic phase is then washed with saturated NaCl solution and dried with anhydrous MgSO4. The solvent is evaporated using a rotary evaporator to obtain a brown solid product. (step C)

[0164]

[0165] with X - = Cl - , Br - , Yes - ,

[0166] In a flask containing 1 equivalent of the product obtained in step B in 30 mL of acetonitrile solvent, 1-3 equivalents of alkyl halide (C1-C5, Sigma-Aldrich) are added while stirring. The solution is refluxed for 18-24 hours at 80 °C. After the reaction, the solvent and excess alkyl halide are evaporated using a rotary evaporator.

[0167] ,

[0168] with :

[0169] - 0≤m≤5, and

[0170] - 1≤n≤5.

[0171] A possible synthesis process for this cation is as follows: step A)

[0172]

[0173] A 2-aminoalkyl quinone (1 equivalent, Sigma-Aldrich) is dissolved in distilled DCM. Acyl chloride solution (C1-C5, 1.2 equivalents, Sigma-Aldrich) is added dropwise under argon. Pyridine (1.2-1.5 equivalents, Sigma-Aldrich) is added to the flask under argon, and the mixture is stirred at 0-5°C for 4 hours and then left at room temperature for 18 hours.

[0174] The organic phase is extracted, washed with 3M HCl solution, then with saturated NaCl aqueous solution. The organic phase is dried over anhydrous MgSO4. Next, 50 mL of petroleum ether was slowly added to the dichloromethane filtrate to obtain a brown powder. (step B)

[0175]

[0176] In a flask containing 1 equivalent of imidazole (Sigma-Aldrich) in tetrahydrofuran, NaH (1.25 equivalents, Sigma-Aldrich) is introduced into the reaction. Then, the product from step A (1 equivalent) is added to the flask. The mixture is stirred at 50°C for 18 hours. After the reaction, the solvent is evaporated to obtain a crude product, which is then dissolved in ethyl acetate. The organic phase is then washed with saturated NaCl solution and dried with anhydrous MgSO4. The solvent is evaporated using a rotary evaporator to obtain a brown solid product. (step C)

[0177]

[0178] with X = Cl - , I - or Br -

[0179] In a flask containing 1 equivalent of the product obtained in step B in 30 mL of acetonitrile solvent, 1–3 equivalents of alkyl halide (C1–C5, Sigma-Aldrich) are added while stirring. The solution is refluxed for 18–24 hours at 80 °C. After the reaction, the solvent and excess alkyl halide are evaporated using a rotary evaporator.

[0180] ,

[0181] with 0≤m≤5.

[0182] A possible synthesis process for this cation is as follows: step A)

[0183]

[0184] -with X - = Cl - , Br - Yes - ,

[0185] 4,4'-Bipyridyl (1 equivalent, Sigma-Aldrich) is dissolved in distilled dichloromethane, and then, under argon, alkyl halide (1 equivalent, Sigma-Aldrich) is added dropwise. The reaction is carried out under reflux for 18 to 24 hours. After the reaction, the product (in powder form) is filtered and washed with dichloromethane.

[0186] ,

[0187] with 0≤m≤5.

[0188] A possible synthesis process for this cation is as follows: step A)

[0189]

[0190] with X - = Cl - , Br - , I - .

[0191] 4,4'-Bipyridyl (1 equivalent, Sigma-Aldrich) is dissolved in distilled acetonitrile, and then, under argon, alkyl halide (2-3 equivalents, Sigma-Aldrich) is added dropwise. The reaction is carried out under reflux for 18 to 24 hours. After the reaction, the product (in powder form) is filtered and washed with acetonitrile.

[0192] Method for synthesizing the electroactive magnetic anion of the invention

[0193] The inventors have developed a process for the synthesis of the electroactive magnetic anion according to the invention (of formula I, or (2,2,6,6-tetramethylpiperidine-N oxyl)chlorosulfonyl(trifluoromethylsulfonyl)imide) which is safe, despite the use of highly reactive intermediates, such as chlorosulfonic acid, and of optimized yield, avoiding in particular the formation of undesired intermediate products.

[0194] The synthesis involves two steps: (i) synthesis of an intermediate from the sulfation of the initial reagent, then (ii) synthesis of the target molecule from the intermediate.

[0195] The first step in the synthesis uses chlorosulfonic acid, a highly reactive and corrosive substance. The main potential hazard arises from the clouds of hydrogen chloride and sulfuric acid produced whenever this chemical is exposed to moisture. It decomposes violently and sometimes explosively in the presence of water, releasing heat. Therefore, it is necessary to establish mild synthesis conditions not only to avoid the potential hazard but also to minimize the formation of byproducts resulting from a violent reaction of chlorosulfonic acid with the reactant.

[0196] The synthesis process includes the following steps:

[0197] 1. Synthesis of (2,2,6,6-tetramethylpiperidine-N-oxyl)chlorosulfate, comprising:

[0198] (i) the addition by drop-by-drop, over a period of between 120 and 180 minutes, of a molar equivalent of chlorosulfonic acid in a suspension of 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (called Hydroxy TEMPO or TEMPO-OH) in anhydrous diethyl ether maintained between 0°C and 5°C,

[0199] (ii) stirring the mixture for at least 24 hours at room temperature,

[0200] (iii) cooling the reaction mixture to between 0°C and 5°C, then adding 2 molar equivalents of phosphorus trichloride and stirring the mixture for at least 1 hour between 0°C and 5°C, followed by stirring at room temperature for at least 12 hours,

[0201] (iv) evaporation of the solvent under reduced solvent pressure, the residual solid being (2,2,6,6-tetramethylpiperidine-N-oxyl)chlorosulfate,

[0202] 2. Synthesis of (2,2,6,6-tetramethylpiperidine-N oxyl)chlorosulfonyl(trifluoromethylsulfonyl)imide, comprising:

[0203] (v) (2,2,6,6-tetramethylpiperidine-N-oxyl)chlorosulfate is placed in acetonitrile, then one molar equivalent of trifluoromethanesulfonamide (1 eq.) and then one molar equivalent of carbonate metal salts is added, and then the mixture is maintained at 70°C under stirring for at least 24 hours,

[0204] (vi) Acetonitrile is evaporated, the crude product is dissolved in absolute ethanol, the resulting mixture is filtered to remove the carbonate,

[0205] (vii) the liquid phase is evaporated under reduced pressure to give the electroactive magnetic anion according to the invention.

[0206] Following substeps iv and vii, the process of the invention may independently include at least one washing and / or recrystallization step. In one embodiment, following substep iv, the resulting solid is washed with boiling petroleum ether (for example, at 45-60°C) and then recrystallized in boiling petroleum ether. In another embodiment, following substep vii, the resulting solid is recrystallized in a tetrahydrofuran / hexane mixture.

[0207] In one embodiment, the amount of 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO-OH) is between 1 mmol and 50 mmol, preferably between 10 mmol and 40 mmol, or between 20 mmol and 35 mmol. In a particular embodiment, the amount of TEMPO-OH is 30 mmol.

[0208] In one embodiment, the metallic carbonate salts are selected from sodium carbonate, potassium carbonate, or lithium carbonate, or mixtures thereof. In one particular embodiment, the carbonate salt is lithium carbonate. In another particular embodiment, the carbonate salt is sodium carbonate.

[0209] In one embodiment, at step (i) of the process of the invention, the addition of chlorosulfonic acid by drop takes place over a period of 150 minutes.

[0210] In one embodiment, in step (ii) of the process of the invention, the agitation of the mixture at room temperature takes place for at least 40 hours, so as to ensure that the reaction is complete.

[0211] In one embodiment, in step (iii) of the process of the invention, the agitation of the mixture between 0°C and 5°C takes place for at least 2 hours.

[0212] In one embodiment, in step (iii) of the process of the invention, the agitation of the mixture at room temperature takes place for at least 24 hours, so as to ensure that the reaction is complete.

[0213] A synthesis process according to the invention is illustrated in Figure 1.

[0214] The process of the invention may include an additional step aimed at replacing the metallic cation by metathesis with a second cation, in particular but not exclusively, a precursor cation of ionic liquids such as those mentioned above:

[0215] 3. Synthesis of an ionic liquid, comprising

[0216] (viii) Heating to at least 60°C, for at least 12 hours, in the presence of a second cation, in particular a precursor cation of ionic liquids such as those listed above.

[0217] (ix) Purification of the ionic liquid.

[0218] In one embodiment, at step (viii) of the process of the invention, the heating takes place for at least 18 hours, so as to ensure that the reaction is complete.

[0219] In one embodiment, in step (viii) of the process the electroactive anion of the invention and the precursor cation of ionic liquid are dissolved in acetonitrile.

[0220] In one embodiment, in step (viii) of the process, the electroactive anion of the invention and the precursor cation of the ionic liquid are dissolved in distilled water. This environmentally friendly and inexpensive embodiment is of particular interest.

[0221] In one embodiment, the cation is supplied in the form of a salt of bromine, chlorine, iodine, or methanesulfonate (CH3SO3). - ), or monoethyl sulfate (C2H5SO4 - ).

[0222] In one embodiment, the precursor cation of the ionic liquid is a cation with the formula:

[0223] ,

[0224] in which R1et R2sontindépendamment l’un de l’autre sélectionnés parmi les alkyles en (C3-C11), R5étant sélectionné parmi un atome d’hydrogène et un méthyle.

[0225] The purification of the ionic liquid following metathesis can be carried out by any method known to the state of the art.

[0226] In one embodiment, the purification (ix) of the ionic liquid comprises the following steps: evaporation of excess acetonitrile in the reaction mixture, at least one rinse in ethyl acetate, evaporation of excess ethyl acetate, dissolution of the mixture in absolute ethanol, filtration of any solid particles, and then evaporation of the ethanol phase.

[0227] which result in obtaining a viscous brown liquid which is an ionic liquid comprising the anion according to the invention.

[0228] In one embodiment, when the metathesis takes place in water, the purification ix) of the ionic liquid comprises the following steps: evaporation of excess water in the reaction mixture, at least one rinse in ethyl acetate, evaporation of excess ethyl acetate, dissolution of the mixture in absolute ethanol, filtration of any solid particles, and then evaporation of the ethanol phase.

[0229] which result in obtaining a viscous brown liquid which is an ionic liquid comprising the anion according to the invention.

[0230] The metathesis is summarized below,

[0231]

[0232] Or,

[0233] - X + = Na + , Li + or K + ,

[0234] - HAS - = Cl - , Br - , I - , CH3SO3 - , or C2H5SO4 - And

[0235] - Z + = a precursor cation of ionic liquid. Examples

[0236] Abbreviations used: ACN: acetonitrile; Tempo-OH: 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl; RT: room temperature; THF: tetrahydrofuran; NMR: nuclear magnetic resonance; DMSO: dimethyl sulfoxide; p.b.: boiling point

[0237] 1. Synthesis of the electroactive magnetic anion of the invention

[0238] A. Synthesis of (2,2,6,6-tetramethylpiperidine-N-oxyl)chlorosulfate:

[0239] Starting from 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO-OH), the first step is to synthesize the intermediate compound (2,2,6,6-tetramethylpiperidine-N-oxyl)chlorosulfate.

[0240] A suspension of Tempo-OH (30 mmol, 1 equiv.) in anhydrous diethyl ether (50 mL) is cooled in an ice bath. Chlorosulfonic acid (30 mmol, 1 equiv., 2.0 mL) is then added dropwise over 2.5 hours. The mixture is then stirred for 40 hours at room temperature. The reaction mixture is cooled in an ice bath before the addition of phosphorus trichloride (5.4 mL, 60 mmol, or 2 equiv.). After 2 hours of stirring at room temperature, the reaction mixture is stirred continuously for 24 hours at room temperature. The solvent is then evaporated under reduced pressure, and the residual solid is washed with boiling petroleum ether (bp 45–60°C) (100 mL) to obtain reddish-brown crystals. The crude product was then recrystallized in boiling petroleum ether (100 mL x 2 times). Red-orange crystals were obtained with a yield of 65%.

[0241] B.synthèse du (2,2,6,6-tetramethylpiperidine-N oxyl)chlorosulfonyl(trifluoromethylsulfonyl)imide de sodium:

[0242] In the second step, (2,2,6,6-tetramethylpiperidine-N-oxyl)chlorosulfate (34.8 mmol, 1.0 equiv.) is placed in a 100 mL flask containing 20 mL of acetonitrile, and trifluoromethanesulfonamide (36 mmol) is added. Sodium carbonate (72 mmol) is then added to the mixture, which has been stirred at 70°C for 24 hours. After the reaction, the acetonitrile evaporates, yielding an orange solid phase. The crude product is then dissolved in 20 mL of absolute ethanol. A heterogeneous mixture is obtained, from which the solid, sodium carbonate, is removed by filtration. The liquid phase is subsequently evaporated under reduced pressure, yielding a yellowish-brown solid. The crude product is recrystallized in the THF / hexane mixture. The final product is obtained as a brownish-yellow solid with a yield of 55%. The final product is soluble in water, acetonitrile, and ethanol.

[0243] NMR analyses confirm the final product:

[0244] 1H NMR (DMSO) δ: 3.70 (1H), 2.60 (4H), 1.39-1.70 (12H)

[0245] 19F NMR (DMSO) δ: 79 (3F)

[0246] 2. Electrochemical characterization of the electrochemical anion of the invention

[0247] The electrochemical responses in cyclic voltammetry of the anion of the invention show a rapid and reversible electron transfer in aqueous media for different pH values ​​(acidic, neutral, basic). These results indicate good stability of the anion. The characteristic responses are given in Figure 1.

[0248] The difference between the potentials of the peaks is stable and close to 60 mV, a value characteristic of a fast and reversible electronic transfer. 3. Synthesis of ionic liquids by metathesis.

[0249] The electrochemical anion according to the invention (2.4 mmol; 1.2 equivalents) is dissolved in a minimal volume of distilled water (2-5 mL). A precursor cation solution of the ionic liquid (2 mmol; 1 equivalent) in a minimal volume of distilled water (2-5 mL) is then slowly added dropwise to the electrochemical anion solution according to the invention. The combined solution is heated to 70 °C for 18 hours. Excess water is then carefully evaporated using a rotary evaporator, and the mixture is rinsed three times with 30 mL of distilled ethyl acetate. The excess ethyl acetate is evaporated using a rotary evaporator. The brown mixture is dissolved in 20 mL of absolute ethanol. The white solid particles that appear are filtered out. The ethanol phase is evaporated, yielding a highly viscous brown ionic liquid.

[0250] A first ionic liquid L1 with the following formula was synthesized:

[0251]

[0252] L1,

[0253] Following the protocol above, using a monoethylsulfate salt of the precursor ionic liquid cation, a yield of 65% was achieved. The resulting ionic liquid is a highly viscous brown liquid, very soluble in water and ethanol.

[0254] The NMR data are as follows:

[0255] 1 H NMR (DMSO): 1.0 (t, 3H,CH3), 1.1-1.2 (m, 12H,CH3), 1.4 (t, 3H,CH3CN), 3.37 (q, 2H,CH2N), 4.2 (q, 4H, CCH2), 5.6 (t,1H,CHC), 7.70 (d, 1H,CHN), 7.78 (d, 1H,CHN), 9.11 (s, 1H, NCHN)

[0256] 19 F NMR (DMSO): -78.72 (s, 3F).

[0257] A second ionic liquid L2 with the following formula was synthesized:

[0258] ,

[0259] L2

[0260] Following the protocol above, using a monoethylsulfate salt of the precursor ionic liquid cation, a yield of 75% was achieved. The resulting ionic liquid is a highly viscous brown liquid, very soluble in water and ethanol.

[0261] The NMR data are as follows:

[0262] 1 H NMR (DMSO): 1.0 (t, 3H,CH3), 1.1-1.2 (m, 12H,CH3), 1.3 (t, 3H,CH3CN), 2.56 (s, 3H,CH3), 3.7 (q, 2H,CH2N), 4.1 (q, 4H, CCH2), 4.3 (t,1H,CHC), 7.6 (d, 1H,CHN), 7.65 (d, 1H,CHN)

[0263] 19 F NMR (DMSO): -78.67 (s, 3F).

[0264] A third ionic liquid with the following formula was synthesized:

[0265] ,

[0266] L3

[0267] Following the protocol above, and using a methanesulfonate salt of the precursor ionic liquid cation, a yield of 78% was achieved. The resulting ionic liquid is a viscous brown liquid, highly soluble in water and ethanol.

[0268] The NMR data are as follows:

[0269] 1 H NMR (DMSO): 0.91 (t, 3H,CH3), 1.1-1.2 (m, 12H,CH3), 1.25(m, 2H,CH2), 1.76 (m, 2H,CH2), 3.44 (q, 4H, 2CH2), 3.85 (s, 3H), 4.15 (t, 2H), 4.4 (t,1H,CHC), 7.77 (d, 1H,CHN), 7.79 (d, 1H,CHN), 9.13 (s, 1H, NCHN)

[0270] 19 F NMR (DMSO): -78.67 (s, 3F)

[0271] A similar yield (80%) is obtained using a bromine salt of the ionic liquid precursor cation.

[0272] 4. Electrochemical characterization of ionic liquids comprising the electrochemical anion according to the invention.

[0273] The electrochemical responses in cyclic voltammetry of ionic liquids comprising the electrochemical anion according to the invention are illustrated in Figure 1. The reference electrode used is a silver / silver chloride electrode; the measurements are performed at concentrations of 1 mM of the ionic liquid in 0.1 M KCl, at a scan rate of 100 mV / s. The data presented confirm the electrochemical properties of the ionic liquids comprising the anion according to the invention.

Claims

Electroactive magnetic anion composed of a group of the 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO radical), according to the following formula I: (I) Composition comprising the electroactive magnetic anion according to claim 1 and at least one cation selected from H + , N / A + K + , Li + . Composition comprising the electroactive magnetic anion according to claim 1 and at least one organic cation from among the following groups: imidazolium, quaternary ammonium, phosphonium, pyridinium, pyrrolidinium, their derivatives or mixtures thereof. electrochemical system comprising at least one electroactive magnetic anion according to claim 1. Ionic liquid comprising as an anion, the electroactive magnetic anion of formula I according to claim 1. The ionic liquid according to claim 5, comprising an organic cation precursor of ionic liquids selected from imidazolium, quaternary ammonium, phosphonium, pyridinium or pyrrolidinium, their derivatives or mixtures thereof. The ionic liquid according to any one of claims 5 or 6, comprising an organic cation precursor of ionic liquids selected from: , , , , , or their mixtures and in which R 1, R 2, R 3, R 4, are independently of each other an alkyl in (C 3-C11), R5étant sélectionné parmi un atome d’hydrogène et un méthyle. The ionic liquid according to any one of claims 5 or 6, comprising a cation comprising a quaternary ammonium group, imidazolium, or pyridinium, said cation being selected from: , , , , , , , , , , , , , ,with, when present, :R=H or a C1-C alkyl 5, 0≤m≤5,1≤n≤5,1≤o≤4. Electrochemical system comprising the ionic liquid according to any one of the preceding claims 5 to 8. Use of the electroactive magnetic anion of formula I according to claim 1 in a catalytic system, in an electrochromic device, in an energy storage device such as a supercapacitor, an organic battery, a redox flow battery, a thermal battery, in a contrast agent for electron magnetic or paramagnetic resonance imaging. A process for synthesizing the electroactive magnetic anion of formula I according to claim 1, comprising the following steps: adding dropwise, over a period of 120 to 180 minutes, one molar equivalent of chlorosulfonic acid to a suspension of 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl in anhydrous diethyl ether maintained between 0°C and 5°C; stirring the mixture at room temperature for at least 24 hours, preferably at least 40 hours; cooling the reaction mixture to between 0°C and 5°C; then adding two molar equivalents of phosphorus trichloride and stirring the mixture between 0°C and 5°C for at least 1 hour, preferably at least 2 hours, followed by stirring at room temperature for at least 12 hours, preferably at least 24 hours; and evaporating the solvent under pressure. reduced from the solvent, the residual solid being (2,2,6,6-tetramethylpiperidine-N-oxyl)chlorosulfate, the (2,2,6,6-Tetramethylpiperidine-N-oxyl)chlorosulfate is placed in acetonitrile, then 1 molar equivalent of trifluoromethanesulfonamide and 1 molar equivalent of the metallic carbonate salts are added, then the mixture is maintained at 70°C under stirring for at least 24 hours, the acetonitrile is evaporated, the crude product is dissolved in absolute ethanol, the resulting mixture is filtered to remove the carbonate, the liquid phase is evaporated under reduced pressure to give the electroactive magnetic anion according to the invention associated with a metallic cation. Synthesis process according to claim 11, further comprising the following steps of replacement by metathesis of the metal cation by a second precursor cation of the ionic liquids: (viii) heating at least 60°C, for at least 12 hours, in the presence of a second precursor cation of the ionic liquids, (ix) purification of the ionic liquid.

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