Electrochemical fluorination with hexafluorosilicate as fluorinating agent

Abstract

The present invention relates to a method for electrochemical fluorination with a hexafluorosilicate as fluorinating agent, and to the use of a hexafluorosilicate as fluorinating agent in electrochemical fluorination reactions.

Description

[0001] TITLE OF THE INVENTION

[0002] ELECTROCHEMICAL FLUORINATION

[0003] WITH HEXAFLUOROSILICATE AS FLUORINATING AGENT

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to a method for electrochemical fluorination with a hexafluorosilicate as fluorinating agent, and to the use of a hexafluorosilicate as fluorinating agent in electrochemical fluorination reactions.

[0006] BACKGROUND OF THE INVENTION

[0007] Fluorinated organic compounds are very important in pharmaceutical and agrochemical industry, as the introduction of fluorine atoms into organic molecules leads to improved properties such as enhanced bioavailabihty, metabolic stability, and binding affinity.

[0008] Due to the importance of fluorination, a very wide range of reagents to accomplish this transformation have been studied. Unfortunately, the most atom economic and cost-efficient fluorine sources are scarcely used. Elemental fluorine (F2), for example, is highly reactive, and fluorinations of complex molecules with this reagent are usually difficult to control. Furthermore, F2 poses significant safety concerns due to its corrosive nature and toxicity. Hydrogen fluoride (HF) is also relatively affordable, but it is a highly corrosive material, which requires careful handling due to its toxicity and ability to cause severe burns. Several reagent alternatives for the fluorination of organic compounds, easier to handle than F2 and HF, have been developed and used over the past years. Complexes of HF with amines such as EtsN 5HF or HF pyridine can be handled in an anhydrous form with relative ease, although they still are very harmful compounds. Organofluorine compounds such as NFSI, Selectfluor™, Fluolead™ or DAST, are versatile and efficient fluorinating agents, although relatively expensive and poorly atom economic. The SF4 related fluorinating agents are more specialized reagents, offering high atom economy but may be less cost- effective and require careful handling due to their toxicity and potential hazards. Electrochemical synthetic methods have also been employed to perform fluorinations of organic compounds. Indeed, a classical electrochemical transformation is the Simons process, developed in the 1930s. This process involves the electrolysis of a solution of the organic substrate in anhydrous hydrogen fluoride, which acts both as the solvent and the fluorine source. The Simons process operates under relatively mild conditions and can produce perfluorinated compounds with high efficiency. It has been instrumental in the large-scale production of fluorocarbons and various fluorinated intermediates essential in the manufacturing of refrigerants, polymers, and pharmaceuticals. More recently, additional electrochemical procedures for the introduction of single fluorine atoms into organic compounds have been described. For example, decarboxylative fluorinations, which use readily available aliphatic carboxylic acids as starting materials, have been reported. Xiang et al., Nature 2019, 573, 398-402, discloses the use of KF combined with 18-crown-6 as the fluoride source in the presence of AgClCh. Anodic decarboxylative fluorinations have also been demonstrated by M. Berger et al., Chem. Sci., 2020, 11, 6053-6057, using EtsN 5HF as the fluorine source, by M. C. Leech et al., Org. Lett. 2023, 25, 1353-1358, using collidinium tetrafluoroborate salt as the fluorine salt.

[0009] Hexafluorosilicic acid, H2SiFe, is produced in large quantities (> 2 million tons per year) as a byproduct of HF and phosphate fertilizers production. It is most commonly used for the preparation of AIF3 in aluminium metal production and as an additive for drinking water fluorination. It is one of the cheapest (< 1 USD / kg in bulk quantities) and most widely available fluorine sources. However, surprisingly, there are not reports of the use of this acid or its anion, i.e. its salts, for fluorination reactions in organic synthesis. Indeed, due to the large production volumes and lack of suitable applications, the substance is often dumped at sea after neutralization.

[0010] There was a need for a fluorinating agents, which is cheap, readily available in large quantities, toxicologically less hazardous then the commonlby known fluorinating agents such as F2, HF or SF4 and their derivatives, and allows for electrochemical oxidative decarboxylation of carboxylic acids. No metal catalyst should be required in the method, such as for example silver. It was found that hexafluorosilicate is a suitable fluorinating agent in electrochemical fluorination reactions.

[0011] It was further found that hexafluorosilicate is a suitable fluorinating agent for electrochemical oxidative decarboxylation fluorination of carboxylic acids.

[0012] It was further found that hexafluorosilicate is a suitable fluorinating agent for electrochemical benzylic fluorination.

[0013] The desired electrochemical fluorination, such as the oxidative decarboxylation fluorination, can be applied to a wide range of aliphatic carboxylic acids. The reaction shows good scalability and applicability to flow mode.

[0014] SUMMARY OF THE INVENTION

[0015] Subject of the invention is a method for the preparation of a fluorinated organic product by an electrochemical fluorination reaction of an organic substrate, wherein the fluorinating agent is a salt of hexafluorosilicic acid.

[0016] BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 shows the experimental set up for examples which were done in batch mode.

[0018] Figure 2 shows the experimental set up for examples which were done in circular flow mode.

[0019] Figure 3 shows the Mylar® foil with the reaction channel

[0020] DETAILED DESCRIPTION OF THE INVENTION

[0021] The electrochemical fluorination reaction is shortly called "reaction" or "electrolysis" herein.

[0022] The organic product is an organic compound, it can also be called organic product compound.

[0023] The organic substrate is an organic compound, it can also be called organic substrate compound. The salt of hexafluorosilicic acid, the fluorinating agent, can be present in the reaction in various embodiments, so the fluorinating agent can be selected from the list of: a hexafluorosilicate salt, a hexafluorosilicate anion, a [SiFs]2anion, a salt of hexafluorosilicic acid with an organic, nitrogen containing compound, preferably wherein the hexafluorosilicic acid has protonated the nitrogen of the organic, nitrogen containing compound, a salt of hexafluorosilicic acid with an organic compound containing pyridine, preferably wherein the hexafluorosilicic acid has protonated the endocyclic nitrogen of the pyridine of the organic compound containing pyridine, a pyridinium salt of hexafluorosilicic acid,

[0024] (MepH)2SiFe, with Mep being 5-ethyb2- methylpyridine, and MepH being protonated 5-ethyl-2-methylpyridine, and combinations thereof.

[0025] (MepH)2SiFe can be called bis(5-ethyl-2-methylpyridin-l-ium) hexafluorosilicate(lV).

[0026] (MepH)2SiFe is the salt of 2 molar equiv of Mep with 1 molar equiv of FhSiFe.

[0027] (MepH)2SiFe is the compound of formula (100).

[0028] The reaction can be done neat or in a solvent. Preferably, the reaction is done in a solvent. So preferably, the reaction mixture at the beginning of the reaction comprises the substrate, the fluorinating agent and a solvent. Preferably, the solvent is selected from the group consisting of dichloro methane (DCM), propylene carbonate (PC), acetonitrile (MeCN), nitromethane, 1, 1,1, 3,3,3- Hexafluoroisopropanol (HFIP), and mixtures thereof; more preferably, the solvent is DCM or 1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) or a mixture thereof; even more preferably the solvent is DCM or a mixture of DCM with HFIP.

[0029] For the reaction a power supply and two electrodes, an anode and a cathode, are provided. The electrodes may be provided as parts which are separate from a reservoir, which can also be called a container, wherein the reaction takes place, in this case the electrodes fit into the reservoir; or the electrodes may be provided as parts of a reservoir wherein the reaction takes place. The electrodes are immersed into the reaction mixture. The electrodes are connected to a power source. One of the electrodes is connected to the (+) side of the power source and serves as the anode. The other electrode is connected to the (-) side of the power source and serves as the cathode. An electric potential is applied by the power source between the electrodes. The reaction is done with the two electrodes by applying to the reaction mixture an electrical current flowing through the reaction mixture between the electrodes. The electric current is caused to flow by the electric potential that is applied between the electrodes by the power supply. The electrical current is also simply called current herein for ease of reading. The current flows from the cathode through the reaction mixture to the anode.

[0030] The reaction can be done in batch mode, which can also be called batch reaction mode, or in flow mode, which can also be called flow reaction mode. Flow mode may for example be circular flow mode or single pass flow mode. In one embodiment, the reaction is done in batch mode. In another embodiment, the reaction is done in circular flow mode. In another embodiment, the reaction is done in single pass flow mode.

[0031] In batch mode the reaction mixture is contained in a reservoir, such as a flask or a reaction vessel, depending on the volume of reaction mixture. The electrodes are immersed in the reaction mixture. Circular flow mode means that the reaction mixture is contained in a reservoir, which can for example be a flask or a reaction vessel, depending on the volume of reaction mixture, and the reaction mixture is continuously pumped from the reservoir through a flow electrolysis cell and back into the reservoir. The flow electrolysis cell contains the electrodes. The reaction mixture passes between the electrodes when being pumped through the flow electrolysis cell.

[0032] Single pass flow mode means that the reaction mixture is contained in a first reservoir, which can for example be a flask or a reaction vessel, depending on the volume of reaction mixture, and the reaction mixture is continuously pumped from this first reservoir through a flow electrolysis cell into a second reservoir. The flow electrolysis cell contains the electrodes. The reaction mixture passes between the electrodes when being pumped through the flow electrolysis cell.

[0033] The anode, also called electrode (+), is the electrode into which electrons flow from the reaction mixture and at which an oxidation takes place. Preferably, the anode is a carbon electrode.

[0034] A carbon electrode is preferably an impervious graphite electrode.

[0035] In a particular embodiment, the anode is an impervious graphite electrode.

[0036] In a particular embodiment, the anode is made of impervious graphite.

[0037] The cathode, also called electrode (-), is the electrode from which electrons flow into the reaction mixture and at which a reduction takes place.

[0038] Preferably, the cathode is is a carbon electrode.

[0039] A carbon electrode is preferably an impervious graphite electrode.

[0040] In a particular embodiment, the cathode is an impervious graphite electrode.

[0041] In a particular embodiment, the cathode is made of impervious graphite.

[0042] So preferably, the electrochemical fluorination reaction is done with an anode which is a carbon electrode, more preferably an impervious graphite electrode! and / or the electrochemical fluorination reaction is done with a cathode which is a carbon electrode, more preferably an impervious graphite electrode. Preferably, the anode material and the cathode material is the same, and / or preferably the electrode polarity is alternated during the electrolysis! and / or preferably, the anode material and the cathode material is the same and the electrode polarity is alternated during the electrolysis.

[0043] More preferably, the electrochemical fluorination reaction is done with a cathode which is an impervious graphite electrode and with an anode which is an impervious graphite electrode! and / or the electrode polarity is alternated during the electrolysis.

[0044] An alternation of the electrode polarity during the electrolysis serves for example the purpose of reducing electrode fouling and corrosion.

[0045] Preferably, an alternation of the electrode polarity during the electrolysis is done at least once, more preferably more than once, even more preferably constantly with a predetermined frequency during the reaction. The frequency of alternation of the electrode polarity can be adjusted and optimized as required to give optimum results! preferably, a frequency of alternation of the electrode polarity is from 1 sec to 10 min, more preferably from 30 sec to 5 min! a typical value is 2 min.

[0046] The anode and the cathode face each other when immersed in the reaction mixture! the size of the area of the surface of the anode and of the cathode that face each other is one of the factors that determines the size of the current that flows between the electrodes through the reaction mixture. Between the anode and the cathode there is a gap. In a particular embodiment, the cathode and the anode each have a flat surface facing each other and running parallel to each other. Preferably each flat surface of the cathode and of the anode that face each other has the same size, that means the areas of the surfaces facing each other is the same. Preferably, the size of the gap, also called gap size, that is the distance between the two electrodes, is constant over the flat areas of the electrodes facing each other and running parallel to each other. Preferably, the gap size is of from 0.01 to 20 mm, preferably from 0.01 to 15 mm, more preferably from 0.01 to 10 mm, even more preferably from 0.05 to 7.5 mm, especially from 0.05 to 6 mm! other embodiments of the gap size, for example for flow mode, within these ranges are from 0.01 to 1 mm, preferably from 0.05 to 1 mm, more preferably from 0.05 to 0.75 mm, even more preferably from 0.05 to 0.5 mm, especially from 0.05 to 0.4 mm, more especially from 0.075 to 0.4 mm, a specific value may be about 0.3 mm; yet other embodiments of the gap size, for example for batch mode, within these ranges are from 0.01 mm to 10 mm, preferably from 0.1 to 7.5 mm, more preferably from 0.5 to 7.5 mm, even more preferably from 1 to 7.5 mm, especially from 2 to 7.5 mm; a specific value may be about 5 mm.

[0047] When the reaction is done in a solvent, the concentration of the substrate in the reaction mixture depends on the solubility of the substrate and of the product in the reaction mixture.

[0048] In particular the concentration of the substrate in the reaction mixture is chosen to be such that both the substrate and product remain in solution during the reaction.

[0049] Preferably, the concentration of the substrate in the solvent at the beginning of the reaction is from 0.001 to 1 M, more preferably from 0.005 to 1 M, even more preferably from 0.005 to 1 M, especially from 0.0075 to 1 M, more especially from 0.0075 to 0.75 M, even more especially from 0.0075 to 0.5 M.

[0050] Particular values of the concentration of the substrate in the solvent mixture at the beginning of the reaction are about 0.066 M.

[0051] Preferably, the amount of the fluorinating agent in the reaction mixture at the beginning of the reaction is from 1 to 10 equiv, more preferably from 1 to 7.5 equiv, even more preferably from 1 to 5 equiv, the equiv being based on the amount of organic substrate.

[0052] The reaction can be done in the presence of Mep. So in an embodiment the reaction mixture at the beginning of the reaction comprises the substrate, the fluorinating agent and Mep; preferably, the reaction mixture at the beginning of the reaction comprises the substrate, the fluorinating agent, a solvent and Mep Preferably, the amount of Mep in the reaction mixture at the beginning of the reaction is from 1 to 10 equiv, more preferably from 1 to 7.5 equiv, even more preferably from 1 to 5 equiv, the equiv being based on the amount of organic substrate.

[0053] The reaction is preferably done under anhydrous conditions. For the purpose of minimizing the amount of any residual water in the reaction mixture, the reaction can be done in the presence of a molecular sieve (MS). The molecular sieve can be any type of molecular sieve that is inert under reaction conditions and capable of removing any residual traces of water in the reaction mixture. Preferably, the amount of a molecular sieve in the reaction mixture is of from 0.1 to 50 wt%, more preferably of from 1 to 25 wt%, the wt% being based in the weight of solvent.

[0054] The surface of the electrodes, which is in contact with the reaction mixture, has a predetermined size; preferably said surface of the anode has the same size as said size of the cathode.

[0055] Preferably, the current density during the reaction is from 0.01 to 100 mA / cm2, more preferably from 0.01 to 50 mA / cm2, even more preferably from 0.01 to 25 mA / cm2, especially from 0.05 to 20 mA / cm2.

[0056] In batch reaction mode the current density during the reaction is preferably from 0.1 to 100 mA / cm2, more preferably from 0.1 to 50 mA / cm2, even more preferably from 0.5 to 25 mA / cm2, especially from 0.75 to 20 mA / cm2, more especially from 1 to 15 mA / cm2. Particularly, the current density for batch reaction mode is about 5 mA / cm2, about 6.7 mA / cm2or about 13.3 mA / cm2.

[0057] In flow mode the current density during the reaction is preferably from 0.01 to 100 mA / cm2, more preferably from 0.01 to 50 mA / cm2, even more preferably from 0.05 to 25 mA / cm2, especially from 0.1 to 20 mA / cm2. Particularly, the current density for circular flow mode is about 6.25 mA / cm2, 9.4 mA / cm2, about 12.5 mA / cm2, or about 15.6 mA / cm2. Preferably, the reaction is done until a current of from 2 F equiv to 20 F equiv, more preferably of from 2 F equiv to 17.5 F equiv, has passed through the reaction mixture, wherein F equiv means an amount of charge equivalent to the molar amount of organic substrate has passed through the reaction mixture. Especially when the reaction becomes slower which may happen with decreasing concentration of the substrate and / or increasing molecular weight and / or increasing size of substrate, the reaction time needs to be prolonged in order to attain as much conversion is possible; increase of reaction time essentially means increase of the total current based on the molecular equivalents of the substrate that has passed through the reaction mixture.

[0058] Preferably, the reaction is done at a temperature of from 0 to 50 °C, more preferably of from 10 to 50 °C, even more preferably of from 15 to 50 °C.

[0059] In flow mode, preferably the flow rate is from 0.001 to 50 ml / min, more preferably from 0.0025 to 25 ml / min, even more preferably from 0.005 to 20 ml / min.

[0060] In an embodiment, the electrochemical fluorination reaction is an electrochemical oxidative decarboxylation reaction, preferably as disclosed herein, also with all its embodiments.

[0061] Preferably, the method is a method for the preparation of an organic product containing a fluoro residue bonded to a non -aromatic C atom by an electrochemical oxidative decarboxylation reaction of an organic substrate containing a carboxylic acid residue bonded to a non -aromatic C atom; wherein the carboxylic acid residue bonded to a non -aromatic C atom is exchanged against a fluorine atom from a fluorinating agent; and the fluorinating agent is a salt of hexafluorosilicic acid; with the salt of hexafluorosilicic acid as defined herein, also with all its embodiments. The organic substrate containing a carboxylic acid residue bonded to a non- aromatic C atom is the substrate of the electrochemical oxidative decarboxylation reaction.

[0062] The organic product containing a fluoro residue bonded to a non -aromatic C atom is the product of the electrochemical oxidative decarboxylation reaction.

[0063] The electrochemical oxidative decarboxylation reaction of the substrate is an electrolysis reaction! for ease of reading the electrochemical oxidative decarboxylation reaction is shortly called "reaction" or "electrolysis" herein. The reaction oxidizes the carboxylic acid residue of the substrate, CO2 is thereby formed.

[0064] The reaction is a fluorination reaction wherein the carboxylic acid residue bonded to a non-aromatic C atom of the substrate is exchanged against a fluorine atom! so the reaction can also be called an electrochemical oxidative decarboxylation fluorination reaction.

[0065] Preferably, the organic substrate containing a carboxylic acid residue bonded to a non-aromatic C atom, that is the substrate, is a compound of formula (I), and the organic product containing a fluoro residue bonded to a non-aromatic C atom, that is the product, is a compound of formula (II);

[0066] (I) (ID wherein

[0067] Rl, R2 and R3 are identical or different and independently from each other selected from the group consisting of

[0068] H, Ci-30 alkyl, C230 alkenyl, F, Cl, Br, I, CN,

[0069] O-Ci-10 alkyl, O-C240 alkenyl,

[0070] C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,

[0071] O-R5, N(H)R5, a ring RINGALIPH, (Yl) -RINGALIPH, aryl, and (Yl)-aryl; or

[0072] R1 and R2 together with the connecting C atom form a ring RINGALIPH; or

[0073] R1 and R2 together with the connecting C atom form a first ring RINGALIPH and R3 and R1 together with the connecting C atom form a second, identical or different ring RINGALIPH; and wherein any RINGALIPH is, independently from any other RINGALIPH,

[0074] • a 4, 5 or 6 membered saturated or unsaturated, non -aromatic carbocyclic or heterocyclic residue, the heterocyclic residue containing 1 or 2 identical or different endocyclic heteroatoms Y2,

[0075] • a bicyclic spiro residue, each ring of the bicyclic spiro residue is independently from the other ring a 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic ring, in case of a 4 membered ring of the bicyclic spiro residue the ring contains 0 or 1 endocyclic heteroatom Y2, in case of a 5 or 6 membered ring of the bicyclic spiro residue the ring contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, or

[0076] • a bicyclic non-spiro residue, wherein a first 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic residue is fused with a second 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic residue, wherein a first and a second heterocycle of the bicyclic non-spiro residue, independently from each other, contain, in case of a 4 membered ring, 1, in case of a 5 or 6 membered ring, 1 or 2, identical or different endocyclic heteroatoms Y2, and RINGALIPH is unsubstituted or substituted by one or more substituents independently from each other selected from the group consisting of oxo, Ci-30 alkyl, C230 alkenyl, F, Cl, Br, I, CN, O-Ci-10 alkyl, O-C240 alkenyl,

[0077] C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,

[0078] O-R5, N(H)R5, aryl, and (Yl)-aryl; any aryl in formula (I) and (II) is, independently from any other aryl in formula (I) and (II),

[0079] • a 5 or 6 membered monocyclic aryl residue,

[0080] • a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or

[0081] • an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the aryl in formula (I) and (II) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the aryl in formula (I) and (II) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2, and aryl in formula (I) and (II) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of C1 10 alkyl, C2 10 alkenyl, F, Cl, Br, I, CN,

[0082] O-Ci-10 alkyl, O’Cs-io alkenyl,

[0083] C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,

[0084] O-R5, N(H)R5, a terminal aryl, and (Yl)-aryl which is a terminal aryl; terminal aryl in formula (I) and (II) is, independently from any other terminal aryl in formula (I) and (II),

[0085] • a 5 or 6 membered monocyclic aryl residue, • a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or

[0086] • an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the terminal aryl in formula (I) and (II) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the terminal aryl in formula (I) and (II) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; and terminal aryl in formula (I) and (II) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of Ci io alkyl, C2 10 alkenyl, F, Cl, Br, I, CN,

[0087] O-Ci-10 alkyl, O’Cs-io alkenyl,

[0088] C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,

[0089] O-R5, N(H)R5; any heteroatom Y2 is, independently from any other Y2, selected from the group consisting of O and N, said N is unsubstituted or substituted by R5; any Y1 is, independently from any other Yl, a connecting group selected from the group consisting of

[0090] O, N(R5), C1-6 alkylene, O-Ci-6 alkylene, C1-6 alkylene-O,

[0091] C(O)-O-Ci-6alkylene-O-C(O), and

[0092] O-C(O)-Ci-6alkylene-C(O)-O; any C1-30 alkyl and any C2 30 alkenyl is, independently from any other C 1-30 alkyl and C230 alkenyl respectively, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical of different substituents selected from the group consisting of

[0093] F, Cl, Br, I, CN,

[0094] O-Ci-10 alkyl, O-C240 alkenyl,

[0095] C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,

[0096] O-R5, N(H)R5, aryl, and (Yl)-aryl; any Ci-io alkyl and any C2 10 alkenyl is, independently from any other C1-10 alkyl and C2 10 alkenyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical or different substituents selected from a group consisting of

[0097] F, Cl, Br, I, CN,

[0098] O-Ci-9 alkyl, O-C2-9 alkenyl,

[0099] C(O)-O-Ci-9alkyl, C(O)-O-C2-9 alkenyl,

[0100] O-R5, and N(H)R5; any R5 is, independently from any other R5, a protecting group for protecting OH NH or NH2.

[0101] In a preferred embodiment,

[0102] Rl, R2 and R3 are identical or different and independently from each other selected from the group consisting of

[0103] H, Ci-3o alkyl, F, Cl, Br, I, CN,

[0104] O-Ci-10 alkyl,

[0105] C(0)-0-Ci io alkyl,

[0106] O-R5, N(H)R5, a ring RINGALIPH,

[0107] (Yl) -RINGALIPH, aryl, and

[0108] (Yl)-aryl; or

[0109] Rl and R2 together with the connecting C atom form a ring RINGALIPH, or

[0110] Rl and R2 together with the connecting C atom form a first ring RINGALIPH and R3 and Rl together with the connecting C atom form a second, identical or different ring RINGALIPH; and wherein any RINGALIPH is, independently from any other RINGALIPH, • a 4, 5 or 6 membered saturated or unsaturated, non -aromatic carbocyclic or heterocyclic residue, the heterocyclic residue containing 1 or 2 identical or different endocyclic heteroatoms Y2,

[0111] • a bicyclic spiro residue, each ring of the bicyclic spiro residue is independently from the other ring a 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic ring, in case of a 4 membered ring of the bicyclic spiro residue the ring contains 0 or 1 endocyclic heteroatom Y2, in case of a 5 or 6 membered ring of the bicyclic spiro residue the ring contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, or

[0112] • a bicyclic non-spiro residue, wherein a first 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic residue is fused with a second 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic residue, wherein a first and a second heterocycle of the bicyclic non-spiro residue, independently from each other, contain, in case of a 4 membered ring, 1, in case of a 5 or 6 membered ring, 1 or 2, identical or different endocyclic heteroatoms Y2, and

[0113] RINGALIPH is unsubstituted or substituted by one or more substituents independently from each other selected from the group consisting of oxo, Ci-30 alkyl, F, Cl, Br, I, CN,

[0114] O-Ci-io alkyl,

[0115] C(0)-0-Ci io alkyl,

[0116] O-R5, N(H)R5, aryl, and (Yl)-aryl; any aryl in formula (I) and (II) is, independently from any other aryl in formula (I) and (II),

[0117] • a 5 or 6 membered monocyclic aryl residue, • a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or

[0118] • an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the aryl in formula (I) and (II) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the aryl in formula (I) and (II) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2, and aryl in formula (I) and (II) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of Ci io alkyl, F, Cl, Br, I, CN, O-Ci-io alkyl, C(0)-0-Ci io alkyl, O-R5, N(H)R5, a terminal aryl, and (Yl)-aryl which is a terminal aryl; terminal aryl in formula (I) and (II) is, independently from any other terminal aryl in formula (I) and (II),

[0119] • a 5 or 6 membered monocyclic aryl residue,

[0120] • a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or

[0121] • an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the terminal aryl in formula (I and (II) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the terminal aryl in formula (I) and (II) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; and terminal aryl in formula (I) and (II) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of Ci io alkyl, F, Cl, Br, I, CN, O-Ci-io alkyl, C(0)-0-Ci io alkyl, O-R5, N(H)R5; any heteroatom Y2 is, independently from any other Y2, selected from the group consisting of O and N, said N is unsubstituted or substituted by R5; any Y1 is, independently from any other Yl, a connecting group selected from the group consisting of

[0122] O, N(R5), CI-6 alkylene, O-Ci-6 alkylene, Ci-6 alkylene-O,

[0123] C(O)-O-Ci-6alkylene-O-C(O), and

[0124] O-C(O)-Ci-6alkylene-C(O)-O; any C1-30 alkyl is, independently from any other C1-30 alkyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical of different substituents selected from the group consisting of

[0125] F, Cl, Br, I, CN,

[0126] O-Ci-10 alkyl,

[0127] C(0)-0-Ci io alkyl,

[0128] O-R5, N(H)R5, aryl, and

[0129] (Yl)-aryl; any C1-10 alkyl is, independently from any other C1-10 alkyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical or different substituents selected from a group consisting of

[0130] F, Cl, Br, I, CN,

[0131] O-Ci-9 alkyl,

[0132] C(O)-O-Ci-9alkyl,

[0133] O-R5, and N(H)R5; any R5 is, independently from any other R5, a protecting group for protecting OH NH or NH2. In a preferred embodiment, the substrate of an electrochemical fluorination reaction of an organic substrate, wherein the fluorine source is a salt of hexafluorosilicic acid, preferably (MepH^SiFe, is an organic substrate containing a carboxylic acid residue bonded to a non -aromatic C atom; wherein the carboxylic acid residue bonded to the non -aromatic C atom is exchanged against a fluorine atom from the fluorinating agent; preferably the substrate is a compound of formula (I); with the compound of formula (I) as described herein, also with all its embodiments; with the electrochemical fluorination reaction as described herein, also with all its embodiments.

[0134] When the electrochemical fluorination reaction is an electrochemical oxidative decarboxylation reaction, then preferably the reaction is done in the presence of Mep, with the presence of Mep as described herein, also with all its embodiments..

[0135] In an embodiment, the electrochemical fluorination reaction is an electrochemical benzylic fluorination reaction, preferably as disclosed herein, also with all its embodiments.

[0136] Preferably, the method is a method for the preparation of an organic product containing a fluoro residue bonded to a benzylic non -aromatic C atom by an electrochemical benzylic fluorination reaction of an organic substrate containing a benzylic H atom bonded to a benzylic non -aromatic C atom; wherein the benzylic H atom bonded to the benzylic non -aromatic C atom is exchanged against a fluorine atom from a fluorinating agent; and the fluorinating agent is a salt of hexafluorosilicic acid; with the salt of hexafluorosilicic acid as defined herein, also with all its embodiments. The organic substrate containing a benzylic H atom bonded to a benzylic nonaromatic C atom is the substrate of the electrochemical benzylic fluorination reaction.

[0137] The organic product containing a fluoro residue bonded to a benzylic non- aromatic C atom is the product of the electrochemical benzylic fluorination reaction.

[0138] The electrochemical benzylic fluorination reaction of the substrate is an electrolysis reaction; for ease of reading the electrochemical benzylic fluorination reaction is shortly called "reaction" or "electrolysis" herein.

[0139] Preferably, the organic substrate containing a benzylic H atom bonded to a benzylic non-aromatic C atom, that is the substrate, is a compound of formula (III), and the organic product containing a fluoro residue bonded to a benzylic non-aromatic C atom, that is the product, is a compound of formula (IV);

[0140] (III) (IV) wherein

[0141] RIO and Rll are identical or different and are H or Ci -30 alkyl;

[0142] ARYLBENZ is

[0143] • a 5 or 6 membered monocyclic aryl residue,

[0144] • a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or

[0145] • an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, the aryl residue being connected with the 5 or 6 membered aromatic ring to the C atom of formula (III), to which RIO, Rll and the H are bonded, any 5 membered ring in the ARYLBENZ contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the ARYLBENZ contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; and

[0146] ARYLBENZ is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of

[0147] Ci io alkyl, C2 10 alkenyl, F, Cl, Br, I, CN,

[0148] O-Ci-10 alkyl, O’Cs-io alkenyl,

[0149] C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,

[0150] O-R5, N(H)R5, a terminal aryl, and (Yl)-aryl which is a terminal aryl; terminal aryl in formula (III) and (IV) is, independently from any other terminal aryl in formula (III) and (IV),

[0151] • a 5 or 6 membered monocyclic aryl residue,

[0152] • a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or

[0153] • an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the terminal aryl in formula (III) and (IV) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the terminal aryl in formula (III) and (IV) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; and terminal aryl in formula (III) and (IV) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of C1 10 alkyl, C2 10 alkenyl, F, Cl, Br, I, CN, O-Ci-10 alkyl, O’Cs-io alkenyl,

[0154] C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl, O-R5, N(H)R5; any heteroatom Y2 is, independently from any other Y2, selected from the group consisting of O and N, said N is unsubstituted or substituted by R5; any Y1 is, independently from any other Yl, a connecting group selected from the group consisting of

[0155] O, N(R5), CI-6 alkylene, O-Ci-6 alkylene, Ci-6 alkylene-O,

[0156] C(O)-O-Ci-6alkylene-O-C(O), and

[0157] O-C(O)-Ci-6alkylene-C(O)-O; any C1-30 alkyl is, independently from any other C1-30 alkyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical of different substituents selected from the group consisting of

[0158] F, Cl, Br, I, CN,

[0159] O-Ci-10 alkyl, O-C240 alkenyl,

[0160] C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,

[0161] O-R5, N(H)R5, aryl, and

[0162] (Yl)-aryl; any C1-10 alkyl and any C2 10 alkenyl is, independently from any other C 1-10 alkyl and C2 10 alkenyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical or different substituents selected from a group consisting of

[0163] F, Cl, Br, I, CN,

[0164] O-Ci-9 alkyl, O-C2-9 alkenyl,

[0165] C(O)-O-Ci-9alkyl, C(O)-O-C2-9alkenyl,

[0166] O-R5, and N(H)R5; any R5 is, independently from any other R5, a protecting group for protecting OH NH or NH2.

[0167] Preferably,

[0168] ARYLBENZ is

[0169] • a 5 or 6 membered monocyclic aryl residue, • a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or

[0170] • an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, the aryl residue being connected with said 5 or 6 membered aromatic ring to the C atom of formula (III), to which RIO, Rll and the H are bonded, any 5 membered ring in the ARYLBENZ contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the ARYLBENZ contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; and

[0171] ARYLBENZ is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of

[0172] Ci io alkyl, F, Cl, Br, I, CN,

[0173] O-Ci-io alkyl,

[0174] C(0)-0-Ci io alkyl,

[0175] O-R5, N(H)R5, a terminal aryl and,

[0176] (Yl)-aryl which is a terminal aryl; terminal aryl in formula (III) and (IV) is, independently from any other terminal aryl in formula (III) and (IV),

[0177] • a 5 or 6 membered monocyclic aryl residue,

[0178] • a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or

[0179] • an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the terminal aryl in formula (III) and (IV) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the terminal aryl in formula (III) and (IV) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; and terminal aryl in formula (III) and (IV) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of Ci io alkyl, F, Cl, Br, I, CN, O-Ci-io alkyl, C(0)-0-Ci io alkyl, O-R5, N(H)R5; any heteroatom Y2 is, independently from any other Y2, selected from the group consisting of O and N, said N is unsubstituted or substituted by R5; any Y1 is, independently from any other Yl, a connecting group selected from the group consisting of

[0180] O, N(R5), CI-6 alkylene, O-Ci-6 alkylene, Ci-6 alkylene-O, C(O)-O-Ci-6alkylene-O-C(O), and O-C(O)-Ci-6alkylene-C(O)-O; any C1-30 alkyl is, independently from any other C1-30 alkyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical of different substituents selected from the group consisting of

[0181] F, Cl, Br, I, CN,

[0182] O-Ci-10 alkyl,

[0183] C(0)-0-Ci io alkyl,

[0184] O-R5, N(H)R5, aryl, and (Yl)-aryl; any C1-10 alkyl is, independently from any other C1-10 alkyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical or different substituents selected from a group consisting of

[0185] F, Cl, Br, I, CN,

[0186] O-Ci-9 alkyl, C(O)-O-Ci-9alkyl, O-R5, and N(H)R5; any R5 is, independently from any other R5, a protecting group for protecting OH NH or NH2.

[0187] In a preferred embodiment, the substrate of the electrochemical fluorination reaction of an organic substrate, wherein the fluorine source is a salt of hexafluorosilicic acid, preferably (MepH)2SiFe, is an organic substrate containing a benzylic H atom bonded to a benzylic non -aromatic C atom; wherein the benzylic H atom bonded to the benzylic non -aromatic C atom is exchanged against a fluorine atom from the fluorinating agent; preferably the substrate is a compound of formula (III); with the compound of formula (III) as described herein, also with all its embodiments; with the electrochemical fluorination reaction as described herein, also with all its embodiments.

[0188] Any R5 mentioned herein is, independently from any other R5, a protecting group for protecting OH, NH or NH2, which is stable under reaction conditions, such groups are known to the skilled person.

[0189] Preferably,

[0190] • if OH is to be protected then R5 is Fmoc, Boc, benzoyl, Cbz, C(0)-Ci io alkyl, Bn (Benzyl), or tBu (tert'Butyl), preferably Fmoc, Boc, benzoyl, Cbz, C(O)-Ci-6 alkyl, or Bn (Benzyl);

[0191] • if NH or NH2is to be protected then R5 is Fmoc, Boc, benzoyl, Cbz, C(0)-Ci io alkyl, or Bn (Benzyl).

[0192] Preferably, any spiro residue mentioned herein is non -aromatic.

[0193] More preferably, any RINGALIPH mentioned herein is non -aromatic.

[0194] The term "terminal aryl" within the meaning of the invention denotes an aryl which is not substituted by any further aryl and / or any further (Yl)-aryl. When any heteroatom Y2 herein is N, said N may be unsubstituted or substituted by R5, and said N may be saturated or unsaturated; the term “saturated N” is to be understood as referring to a nitrogen atom as part of a non-aromatic or aromatic ring system as an endocyclic heteroatom being connected to the other ring atom members each via a single bond; the term “unsaturated N” is to be understood as referring to a nitrogen atom as part of a non-aromatic or aromatic ring system as an endocyclic heteroatom being connected to one of the other ring atom members via a double bond; preferably, when any heteroatom Y2 herein is a saturated N, then said N is substituted by R5.

[0195] A further subject of the invention is the compound (MepH^SiFe, with Mep being 5 ■ ethyl ■ 2 - methyip y ridine .

[0196] (MepH)2SiFe can be prepared from the readily available FLSiFe and Mep. Mep is a cost efficient, sustainable (it can be readily manufactured form paraldehyde and ammonia) and widely available pyridine derivative.

[0197] The salt (MepHLSiFc is bench stable at room temperature, an easyto-handle crystalline solid, and can be prepared on large quantities by simply adding a slight excess of Mep to the commercial solution of FhSiFe and stripping the solvent.

[0198] A further subject of the invention is a method for the preparation of (MepH^SiFe, with Mep being 5-ethyl-2-methylpyridine; wherein FLSiFe and Mep are brought into contact with each other.

[0199] The contacting of JHFSiFr; and Mep with each other can be done by any known method, preferably, FLSiFe and Mep are mixed; and / or preferably, FLSiFe is an aqueous solution of FhSiFe; and / or preferably, an aqueous solution of JHFSiFr; and Mep are mixed; and / or preferably, Mep is added to an aqueous solution of FhSiFe and the obtained mixture is mixed. Preferably, H2S1F6 and Mep are brought into contact with each other in equimolar or near equimolar amounts! more preferably with a slight molar excess of Mep over FbSiFe, even more preferably the molar ratio of Mep to FbSiFe is from 1 to 1.5 equiv, more preferably from 1 to 1.4 equiv, even more preferably from 1 to 1.3 equiv, especially from 1 to 1.2 equiv, more especially from 1 to 1.1 equiv.

[0200] The contacting of JHFSiFr; with Mep can be done at room temperature. The contacting of JHFSiFr; with Mep can be done under ambient pressure. The time of the contacting of JHFSiFr; with Mep can be from 1 sec to 24 h.

[0201] The isolation of (MepH^SiFe from an aqueous mixture can be done by removal of water from the aqueous mixture, preferably by vacuum distillation, providing dried (MepH^SiFe. Any residual trace amounts of water still contained in dried (MepH)2SiFe can be removed by mixing dried (MepH^SiFe with DCM and removing DCM and any residual trace amounts of water by ensuing distillation, preferably vacuum distillation; this removal of residual trace amounts of water can be repeated once or more than once.

[0202] Further subject of the invention is the use a of a salt of hexafluorosihcic acid as fluorinating agent in an electrochemical fluorination reaction! with the salt of hexafluorosilicic acid as defined herein, also with all its embodiments.

[0203] Further subject of the invention is the fluorinated organic product obtainable by the method for the preparation of a fluorinated organic product by an electrochemical fluorination reaction of an organic substrate, with the method as defined herein, also with all its embodiment.

[0204] Further subject of the invention is the fluorinated organic product obtained by the method for the preparation of a fluorinated organic product by an electrochemical fluorination reaction of an organic substrate, with the method as defined herein, also with all its embodiment.

[0205] Abbreviations, Definitions, Materials, Sources used and disclosed in this specification

[0206] Electrodes

[0207] Electrode area For batch reaction mode, the reaction mixture was exposed to two flat plate-like electrodes, each with a submerged electrode area of 3 cm2.

[0208] With a submerged electrode area of 3 cm2particular current densities were:

[0209] 15 mA: 5 mA / cm2

[0210] 40 mA: 13.3 mA / cm2

[0211] For circular flow mode, the reaction mixture was exposed to two flat plate-like electrodes, each with an electrode area of 6.4 cm2. With an electrode area of 6.4 cm2particular current densities were:

[0212] 40 mA: 6.25 mA / cm2

[0213] 100 mA: 15.6 mA / cm2

[0214] IG electrode Impervious graphite electrode, also called only IG herein: Graphite-resin impervious bipolar plates of FC'GR grade by Graphtek LLC, IL 60089, USA were sourced from graphitestore.com, Northbrook, IL 60062, USA. The impervious graphite (IG) plates were molded and of resin-filled grade that combines best properties of graphite such as high electrical conductivity, high thermal conductivity, chemical resistance and easy machining with low permeability of molded composites. For batch reaction mode, these graphite -resin impervious bipolar plates were cut to the size similar to the size of standard IKA electrodes for the IKA-ElectraSyn™ device (IKA®-Werke GmbH & CO. KG, 79219 Staufen, DE).

[0215] Gap size was 5 mm.

[0216] Submerged area of the electrodes was 1 cm x 3 cm = 3 cm2

[0217] For circular flow mode or single pass flow mode, these graphiteresin impervious bipolar plates were cut to a plate of the size of 50 x 50 x 6 mm.

[0218] Impervious graphite electrodes were polished with a 3000 grit whetstone before each experiment.

[0219] GF electrode graphite felt electrode; AvCarb G280A Soft Graphite Battery Felt, Brand: AvCarb Material Solutions, Product Code: 18070069

[0220] GC electrode glassy carbon electrode; IKA®-Werke GmbH & CO. KG, 79219

[0221] Staufen, DE, Ident-Nr.: 0040002842

[0222] Abbreviations

[0223] Ac acetyl about the term “about” used in connection with a numerical value indicates that the actual value can be within a range of ± 20% of the specified numerical value, preferably within a range of ± 10% of the specified numerical value, more preferably within a range of ± 5% of the specified numerical value. The term “about” encompasses all values within a range of ± 20%, preferably ± 10%, more preferably ± 5%, of the specified numerical value. amino acid the term amino acid refers to organic amino acids, that is to organic compounds having an amino group and a carboxylic acid group alpha amino acids refers to such organic amino acids wherein the amino group and the carboxylic acid group are covalently bonded to the same C atom as, that is to the alpha C atom according to the common nomenclature of organic chemistry Boc tert'Butyloxycarbonyl protecting group i-Bu iso-butyl n-Bu n-butyl tert-Bu tert-butyl

[0224] CEx Comparative Example current density the size of the current divided by the size of the area of the surface of each of the electrodes facing each other in the reaction mixture

[0225] DCM dichloro methane

[0226] HPLC high performance liquid chromatography equiv molar equivalent

[0227] Et ethyl

[0228] Ex Example

[0229] F Faraday constant:

[0230] F = elementary charge e x Avogadro constant NA

[0231] = 1.602176634X10-19C x 6.02214076xl023mol’1

[0232] = 9.64853321233100184X104C-moF1

[0233] The amount of charge, that passes through a reaction mixture, divided by the Faraday constant equals the molar amount of substrate that has been electrolyzed.

[0234] F equiv is used herein to denote the amount of charge equivalent to the molar amount of substrate, that has passed through the reaction mixture, so for example 1 F equiv, 2 F equiv or 4 F equiv means that the 1-fold, 2 -fold or 4-fold amount of charge equivalent to the molar amount of the substrate has passed through the reaction mixture.

[0235] For a reduction reaction involving two electrons per molecule of substrate 2 F equiv are the stoichiometric charge equivalent to the molar amount of substrate.

[0236] Fc ferrocene

[0237] HFIP 1, 1, 1,3,3,3-Hexafluoroisopropanol

[0238] MeCN acetonitrile

[0239] Me methyl Mep 5-ethyl-2-methylpyridine

[0240] MS3 molecular sieve with a pore size of 3 A (3 A beads) in form of a powder; supplier Acros Organics, Cat No 21479, CAS 308080- 99-1 AlNaOeSi2, "Molekularsieb 3A (0.3 nm, 3 A), Pulver <50 pm"

[0241] Mylar® foil Polyethylenterephthalat (PET) Foil, particularly biaxially- oriented polyethylene terephthalate (BoPET), of DuPont Teijin Films

[0242] PC propylene carbonate i-Pr iso-propyl n-Pr n-propyl rpm rounds per minute

[0243] RT room temperature vs versus

[0244] Benzyloxycarbonyl, also abbreviated with Cbz

[0245] Materials

[0246] All chemicals were bought from vendors listed in Table 1 and used without further purification if not stated otherwise. Source and purity of the substrates are shown in Table 1.

[0247] EXAMPLES

[0248] Methods

[0249] Experimental set up for Batch Mode and for Flow Mode

[0250] Examples in batch reaction mode were conducted with an experimental set up as shown in Figure 1.

[0251] Examples in circular flow mode were conducted with an experimental set up as shown in Figure 2.

[0252] Analytical Methods

[0253] NMR Analysis

[0254] 'H NMR spectra were recorded on a 300 MHz instrument.13C NMR at 75 MHz.19F NMR at 282 MHz. Chemical shifts (5) are expressed in ppm downfield from TMS as internal standard. The letters s, d, t, q, and m are used to indicate singlet, doublet, triplet, quadruplet, and multiplet, respectively.

[0255] Sample Preparation

[0256] After the electrochemical reaction, 0.33 mmol (55.5 mg, 1 equiv.) of 1,3,5- trimethoxybenzene as internal standard was added to the reaction mixture and the workup described in the "General Procedure - Batch Mode" below was applied. The resulting product containing the internal standard was dissolved in CDC13 and submitted to 1H NMR.

[0257] HPLC-UV / Vis Analysis

[0258] Analytical HPLC analysis was carried out on a C 18 reversed-phase (RP) analytical column (150 x 4.6 mm, particle size 5 mm) at 37 °C by using mobile phases A [water / acetonitrile 90: 10 (v / v) + 0.1% TFA] and B (acetonitrile + 0.1% TFA) at a flow rate of 1.5 mL / min. The following gradient was applied: linear increase from solution 30% B to 100% B within 10 min.

[0259] Sample Preparation

[0260] 10 jxL of the crude reaction mixture was added to a HPLC vial containing 1 mL Acetonitrile. The vial was capped and the content of the vial was then directly analyzed by HPLC-UV / Vis. Peak area integration was carried out at 194 nm. GC-MS / GC-FID Analysis

[0261] GOFID analysis was performed on a Shimadzu GC FID 230 with a flame ionization detector (FID), using an RTX-5MS Cap. column (30 m x 0.25 mm ID x 0.25 pm) and helium as carrier gas (40 cm / secl linear velocity). The injector temperature was set to 280 °C. After 1 min at 50 °C, the temperature was increased by 25 °C / min to 300 °C and kept constant at 300 °C for 4 min. FID was used for detection, and the detector gases used for flame ionization were hydrogen and synthetic air (5.0 quality).

[0262] Sample Preparation

[0263] 50 jxL of the crude reaction mixture was added to a 1 mL Diethyl ether and filtered through a MgSO plug to exclude any precipitate into a GC vial and capped. The content of the vial was then directly analyzed via GC-MS / GC-FID.

[0264] GC-MS analysis

[0265] GC-MS analysis was performed using a Shimadzu GCMS-QP2010 SE, using an RTX-5MS column (30 m x 0.25 mm x 0.25 pm) and helium as carrier gas (40 cm / sec linear velocity). The injector temperature was set to 280 °C. After 1 min at 50 °C, the oven temperature was increased by 25 °C / min to 300 °C and then kept at 300 °C for 3 min. The mass detector was a quadrupole with pre -rods and electron impact ionization. The following settings were used in the detector: ion source temperature 200 °C, interface temperature 310 °C, solvent cut time 2 min 30 sec, acquisition mode scan, mass range m / z = 50 till m / z = 400.

[0266] Synthesis of substrate lp, 2-(3,5-di-tert-butylphenoxy)acetic add Ip was synthesized according to M. Berger et al., Chem. Sci., 2020, 11, 6053- 6057:

[0267] A solution of 2.1 g (10 mmol) 3,5-di-tert-butylphenol, 1.33 ml ethyl bromoacetate (12 mmol, 1.2 equiv.) and 2.76 g potassium carbonate (20 mmol, 2 equiv) in 50 ml acetonitrile: acetone 5:1 was heated under reflux over night (12 h). The solvents were stripped in vacuo. The residue was dissolved with 0.96 g (24 mmol, 2.4 equiv.) sodium hydroxide in 20 ml water Acetone 1:1. The reaction mixture was stirred at 50 °C for 2 h. Acetone was stripped in vacuo and the pH was adjusted to 2 with aqueous HC1 (6M), the precipitate that had formed was filtered off and recrystallized from cyclohexane. 'H NMR (300 MHz, Chloroform -d) 5 7.06 (t, J = 1.5 Hz, 1H), 6.76 (d, J = 1.7 Hz, 2H), 4.58 (s, 2H), 1.27 (s, 17H).13C NMR (75 MHz, CDC13) 5 157.01, 152.51, 116.33, 109.25, 34.99, 31.37, 26.92.

[0268] Synthesis of substrate Is, 3-((4-(tert-butyl)benzyl)oxy)-2,2-dimethylpropanoic add

[0269] Ip was synthesized according to M. Berger et al., Chem. Sci., 2020, 11, 6053- 6057:

[0270] A 3-necked round bottom flask, dried over night at 105, was charged with 10 ml dry THF and 1.24 g NaH (31 mmol, 60 wt% dispersion in mineral oil) and cooled to 0 °C. 1.27 ml (10 mmol) methyl 3-hydroxy-2,2-dimethylpropanoate was added and the reaction mixture was stirred for 20 min at room temperature. Then, 2.27 g 4-tert.-butyl-benzylbromide (10 mmol) was added at 0 °C, the mixture was stirred at room temperature for 20 minutes and then heated to reflux until complete as verified by Thin Layer Chromatography (TLC), which was after ca. 2.5 h. After cooling the mixture was quenched by slow addition of water until no gas evolution from the sodium hydride occurred anymore indicating that the sodium hydride was fully quenched, and the mixture was transferred into a separatory funnel. The mixture was extracted 3 times with 50 ml EtOAc, and the combined extracts were washed 1 time with 30 ml brine. The organic phase was dried over MgSCh , filtered and the solvent was stripped in vacuo to afford an orange oil. The crude was then added to 4.2 g LiOH*H2O (100 mmol) and dissolved in 33.3 ml THF:MeOH:H2O 2-2-1 and stirred at room temperature overnight. The pH was adjusted to 2 by addition of aqueous H2SO4 (2M). A solution was obtained which was concentrated in vacuo to remove THF and the residue was washed with 10 ml H2O. The residue was extracted 3 times with 10 ml EtOAc and the organic phase was dried over MgSO and the solvent was stripped in vacuo. The crude product was purified by flash chromatography (Hexane :EtO Ac, 19: 1) to afford the carboxylic acid Is as a colorless oil. 'H NMR (300 MHz, Chloroform-d) 5 7.41 - 7.34 (m, 1H), 7.25 (dd, J = 7.6, 1.0 Hz, 1H), 4.55 (s, 1H), 3.48 (s, 1H), 1.32 (s, 5H), 1.24 (s, 3H).13C NMR (75 MHz, CDC13) 5 181.01, 150.74, 134.70, 127.39, 125.35, 73.37, 43.28, 34.56, 31.36, 22.44.

[0271] Synthesis of (MepHESiFc

[0272] 12.8 ml (41 mmol, aqueous, 35 wt%) Hexafluorosilicic acid were added to a 50 ml round bottom flask and cooled to 0 °C. Under strong stirring, 12 ml (42 mmol) of 5-ethyl-2-methylpyridine were slowly added and the solution was stirred for 1 h at room temperature. Water was stripped from the reaction mixture in vacuo at 20 mbar for 1 h. 10 ml dry DCM were added to the reaction mixture and stripped in vacuo. This process of removing water was repeated 3 times. The formed slightly yellow oil was then seeded with a crystal from a first such experiment and left to crystalize in a desiccator with CaCE attached to a Schlenk line at ca. 1 mbar for at least 3 h. The crystallized product was then crushed into a fine powder and stored over CaCE in a desiccator. Isolated Yield: 12,8 g (85 %). 'H NMR (300 MHz, Chloroform-d) 5 8.77 (d, J = 2.2 Hz, 1H), 8.13 (dd, J = 8.2, 2.2 Hz, 1H), 7.68 (d, J = 8.2 Hz, 1H), 2.78 (s, 3H), 2.72 (q, J = 7.6 Hz, 2H), 1.22 (t, J = 7.6 Hz, 3H).13C NMR (75 MHz, CDC13) 5 151.32, 145.25, 141.40, 140.54, 127.20, 25.44, 19.34, 14.44.19F NMR (282 MHz, CDC13) 5 -130.35. General Procedure - Batch Mode

[0273] Reaction Scheme 1

[0274] (1) (2)

[0275] Substrate Product

[0276] Reaction Scheme 1 shows the general reaction scheme.

[0277] The electrochemical decarboxylative fluorination using (MepHVSiFc as the fluorine source was evaluated using the aliphatic carboxylic acid la as model substrate (Table 2). All reactions were carried out in undivided cells under constant current with Impervious Graphite as anode (+) and Impervious Graphite as Cathode (-) ( (+)!G / (-)lG ). A small amount of 3 A molecular sieves powder (MS3) was added to the reaction mixture to ensure that no water was present during the reactions. The reaction was done with 0.33 mmol of substrate, with 3 cm2submerged electrode area, at RT, with electrode polarity inversion every 2 min. The reaction mixture contained the substrate and 2.5 equiv (MepH)2SiFe, 3 equiv Mep, 5 mL DOM and 75 mg MS3. Different solvents (Examples 1 to 3) revealed formation of the fluorinated product 2a. Variation of the current are shown in Examples 4 and 5. It was preferred that the anode and the cathode materials was the same in all reactions to enable alternation of the electrode polarity, thereby electrode fouling and corrosion was reduced. The amount of charge (F / mol) passed through the reaction was gradually increased (example 6 to 8) to 12 F / mol to maximize the reaction conversion.

[0278] Workup of the reaction mixture of example 8 consisted of adding diethyl ether under vigorous stirring to crystalize any remaining salts, which were filtered off using a silica plug, and washing the filtrate, an organic solution, with IM aqueous HOI. Fluorinated product 2a was isolated in a pure form with 61% yield. In particular:

[0279] Batch electrochemical reactions were carried out in IKA ElectraSyn 2.0 5 ml vials utilizing standard Electrasyn electrodes. Figure 1 shows the experimental set up for examples which were done in batch mode.

[0280] Impervious graphite electrodes were cleaned by grinding on a whetstone and sonication in acetone before left for drying in a 150 °C drying oven. The IKA 5 ml vial and magnetic stir bar were also dried with the same conditions prior to use.

[0281] The 5 ml IKA vial was charged with 0.33 mmol substrate and 300 mg (0.825 mmol, 2.5 equiv) powdered (MepH^SiFe. The powder was dissolved in 5 ml dry DCM (stored under N2 atmosphere with additional MS3) and after dissolving, 130.8 ul (0.99 mmol, 3 equiv) 5-ethyl-2-methylpyridine was added into the reaction mixture. After that 75 mg of MS 3 was added to the reaction mixture and the electrodes are connected to the vial. The reaction was pre -stirred for 10 minutes before the electricity was turned on. The reaction mixture was then electrolyzed at the specified current (e.g. of 20 mA) for a desired total charge (e.g. 12F / mol). For determining the yield via NMR, 0.33 mmol (55.5 mg) of 1,3,5- trimethoxybenzene was dissolved in the reaction mixture. After electrolysis the reaction mixture was slowly added to a beaker with 30 ml diethyl ether under strong stirring until most of the dark brown oil separated and the remaining solution was yellow. After filtration through a ca. 3 cm silica plug, the slightly yellow solution was added to a separatory funnel with 20 ml aqueous HC1 (1M) and extracted one time. The organic layer was dried with MgSO4 and the solvent was carefully stripped in vacuo. The product was dissolved in 0.5 ml CDC13 and 'H NMR,13C NMR and19F NMR was recorded.

[0282] Examples 1 to 10 - Batch Mode

[0283] Examples 1 to 10 were done according to the General Procedure - Batch Mode with the details given in Table 2.

[0284] Reaction Scheme A shows the reaction. Reaction Scheme A

[0285] (b) Determined by HPLC-UV / VIS area percentage at 194 nm (c) Current density = current value divided by the submerged area of 3 cm2

[0286] (d) Isolated yield in brackets

[0287] Comparative Example CExl and CEx2

[0288] Example 3 was repeated with the sole difference that different anode and cathode were used:

[0289] Example CExl graphite felt (GF) anode and cathode: (+)GF / (-)GF

[0290] Example CEx2 glassy carbon (GO) anode and cathode: (+)GC / (-)GC The results were:

[0291] Electrodes Conv (b) [%] Sei (b) [%]

[0292] CExl (+)GF / (-)GF 46 <1

[0293] CEx2 (+)GC / (-)GC 6 <1

[0294] (b) Determined by HPLC-UV / VIS area percentage at 194 nm

[0295] Example 20 to 33 - Substrate Scope - Batch Mode

[0296] With the conditions of example 8, various aliphatic carboxylic acids, the substrates 1 of general formula 1 were converted into the corresponding fluorinated derivative, the products 2 of general formula 2 according to Reaction Scheme 1.

[0297] Table 3 shows the data for various residues ResA of products 2-ResA a primary benzylic fluoride.

[0298] 2-ResA

[0299] Table 4 shows the data for various products 2, secondary benzylic fluorides.

[0300] Table 5 shows the data for various product 2, aryloxymethylfluorides.

[0301] Table 6 shows the data for various products 2. Table 7 shows the data for various products, tertiary fluorides.

[0302] The yields in Tables 3 to 7 were the following type of yields:

[0303] (a) Yield determined via quantitative 1H NMR with 1,3, 5 -trimethoxybenzene as internal standard. (b) Isolated Yield.

[0304] (c) Calibrated GC-FID yield

[0305] Notably, fluorinated furanose 2q could also be synthetized using the electrochemical protocol. N-boc-protected amino acids were transformed into 2u to 2w in synthetically useful yields, despite being substrates that are sensitive to oxidation of the amine (via Shono oxidation).

[0306] Examples 41 to 47 - Flow Mode

[0307] To demonstrate the scalability of the electrochemical fluorination process using hexafluorosilicate as the fluorine source and substrate la providing a reaction according to Reaction Scheme A, the experimental conditions were transferred to a undivided flow electrolysis cell. In particular, a parallel plate-type reactor was utilized. The electrodes were separated by a Mylar® foil featuring a reaction channel (i.e., a so-called extended channel reactor), which is shown in Figure 3. The channel allowed for an electrode surface area of 6.4 cm2and its thickness for an interelectrode gap of 0.3 mm and a volume of 190 pL. The reaction conditions of Example 8, were used in the flow reactor, except for

[0308] • the scale was doubled, i.e. was 0.66 mmol of substrate

[0309] • the current and current density was adapted,

[0310] Then, using a recirculation approach, the current density and pump flow rate were varied, Table 8 gives the details. To avoid clogging of the flow reactor with the molecular sieves powder, a filter frit was installed on the inlet tubing of the pump. The current density could be increased to 15.6 mA / cm2in the flow reactor (100 mA in total) without any detrimental effect on the reaction conversion or selectivity. Under these conditions, a 10 mL reaction mixture was processed and, upon application of the same workup procedure as in batch, 61 mg of fluorinated product 2a (yield: 62% (c) I 62% (d)) were isolated.

[0311] In particular:

[0312] Impervious graphite electrodes were cleaned by grinding on a whetstone and sonication in acetone before left for drying in a 150 °C drying oven. A IKA 10 ml vial and magnetic stir bar were also dried with the same conditions prior to use. The 10 ml IKA vial was charged with 0.66 mmol substrate and 600 mg (1.65 mmol, 2.5 equiv) (MepH^SiFe. The powder was dissolved in 10 ml dry DCM (stored under N2 atmosphere with additional MS 3) and after dissolving, 261.6 ul (1.98 mmol, 3 equiv) 5-ethyl-2-methylpyridine was added into the reaction mixture. After that 150 mg of MS3 were added to the reaction mixture. The reaction was recirculated for 10 minutes at e.g. 10 ml / min before the electricity was turned on. The reaction mixture was then electrolyzed at a current of e.g. 100 mA for 12 F / mol. For determining the yield via NMR, 0.33 mmol (55.5 mg) of 1,3,5'trimethoxybenzene was dissolved in the reaction mixture. After electrolysis the reaction mixture was slowly added to a beaker with 60 ml diethyl ether under strong stirring until most of the dark brown oil separated and the remaining solution was yellow. After filtration through a ca. 3 cm silica plug, the slightly yellow solution was added to a separatory funnel with 40 ml aqueous HC1 (1M) and extracted one time. The organic layer was dried with MgSO4 and the solvent was carefully stripped in vacuo. The Product was dissolved in 0.5 ml CDCI3 and 'H NMR,13C NMR and19F NMR was recorded.

[0313] (a) 0.66 mmol scale, 6.4 cm2electrode surface area, RT, electrode polarity inversion every 2 min, 12 F / mol of charge passed in all cases

[0314] (b) Determined by HPLC-UV / VIS area percentage at 194 nm

[0315] (c) 'H NMR yield using 1,3,5'trimethoxybenzene as internal standard

[0316] (d) Isolated yield

[0317] Using the flow reactor, the reaction scale could be readily increased to prepare larger amounts of material without any changes in the reaction conditions. In particular, an additional reaction mixture with a 50 mL volume (10 times with respect to batch) was electrolyzed under exactly the same conditions as Example 47 in Table 2. To achieve 12 F / mol charge under the same current, the electrolysis time was increased proportionally to the increase in amount of material. Under these conditions, 310 mg of product 2a were isolated (62% isolated yield). The isolated yield in batch (5 mL scale) and the two flow experiments (10 mL and 50 mL scale) provided identical yields. Example 50

[0318] The electrochemical decarboxylative fluorination using (MepHKSiFc as the fluorine source for a benzylic fluorination was evaluated in an undivided cell under constant current with Impervious Graphite as anode (+) and Impervious Graphite as Cathode (-) ( (+)!G / (-)lG ).

[0319] The batch electrochemical reaction was carried out in IKA ElectraSyn 2.0 5 ml vial utilizing standard Electrasyn electrodes.

[0320] Figure 1 shows the experimental set up for examples which were done in batch mode.

[0321] The reaction was done with 3 cm2submerged electrode area, at RT, with electrode polarity inversion every 2 min, thereby electrode fouling and corrosion was reduced.

[0322] The impervious graphite electrodes were cleaned by grinding on a whetstone and sonication in acetone before left for drying in a 150 °C drying oven. The IKA 5 ml vial and magnetic stir bar were also dried with the same conditions prior to use.

[0323] Reaction Scheme B shows the reaction.

[0324] Reaction Scheme B

[0325] 3a 4a

[0326] A 5 ml IKA vial was charged with 3a (0.33 mmol) and powdered (MepH^SiFe (300 mg, 0.825 mmol, 2.5 equiv). The powder was dissolved in 4 ml dry DOM (stored under N2 atmosphere with additional MS3) and 1 ml 1, 1,1, 3,3,3- Hexafluoroisopropanol (HFIP). 75 mg of MS3 were added to the reaction mixture and the electrodes were connected to the vial The reaction was pre-stirred for 10 minutes and simultaneously degassed with argon before the electricity was turned on. The reaction mixture was electrolyzed at a current of 20 mA for 2.5 F / mol (6.7 mA / cm2). The reaction mixture was then poured into 15 ml Et20 under strong stirring and filtered through a 2 cm silica plug. The solvent was removed in vacuo on a schlenk line. Trifluorotoluene (0.11 mmol, 0.33 equiv) was added to the residue and the resulting mixture was dissolved in 0.5 ml DMSO'de. Yield of 4a was determined via19F NMR on a Magritek Benchtop NMR (Spinsolve Ultra 43 MHz) immediately after the workup, the yield was 42%.

Claims

CLAIMS1. A method for the preparation of a fluorinated organic product by an electrochemical fluorination reaction of an organic substrate, wherein the fluorinating agent is a salt of hexafluorosilicic acid.

2. The method according to claim 1, wherein the fluorinating agent is selected from the list of a hexafluorosilicate salt, a hexafluorosilicate anion, a [SiFs]2anion, a salt of hexafluorosilicic acid with an organic, nitrogen containing compound, preferably wherein the hexafluorosilicic acid has protonated the nitrogen of the organic, nitrogen containing compound, a salt of hexafluorosilicic acid with an organic compound containing pyridine, preferably wherein the hexafluorosilicic acid has protonated the endocyclic nitrogen of the pyridine of the organic compound containing pyridine, a pyridinium salt of hexafluorosilicic acid,(MepH)2SiFe, with Mep being 5-ethyb2- methylpyridine, and MepH being protonated 5-ethyl-2-methylpyridine, and combinations thereof.

3. The method according to claim 1 or 2, wherein the reaction is done in a solvent; preferably, the solvent is selected from the group consisting of dichloro methane (DCM), propylene carbonate (PC), acetonitrile (MeCN), nitromethane, 1, 1,1, 3,3,3- Hexafluoroisopropanol (HFIP), and mixtures thereof; more preferably, the solvent is DCM or 1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) or a mixture thereof; even more preferably the solvent is DCM or a mixture of DCM with HFIP.

4. The method according to one or more of claims 1 to 3, wherein the reaction is done with an anode which is a carbon electrode, preferably an impervious graphite electrode! and / or the reaction is done with a cathode which is a carbon electrode, preferably an impervious graphite electrode.

5. The method according to one or more of claims 1 to 4, wherein the amount of the fluorinating agent in the reaction mixture at the beginning of the reaction is from 1 to 10 equiv, preferably from 1 to 7.5 equiv, more preferably from 1 to 5 equiv, the equiv being based on the amount of organic substrate.

6. The method according to one or more of claims 1 to 5, wherein the reaction is done in the presence of Mep! preferably, the amount of Mep in the reaction mixture at the beginning of the reaction is from 1 to 10 equiv, more preferably from 1 to 7.5 equiv, even more preferably from 1 to 5 equiv, the equiv being based on the amount of organic substrate.

7. The method according to one or more of claims 1 to 6, wherein the current density during the reaction is from 0.01 to 100 mA / cm2, preferably from 0.01 to 50 mA / cm2, more preferably from 0.01 to 25 mA / cm2, even more preferably from 0.05 to 20 mA / cm2.

8. The method according to one or more of claims 1 to 7, wherein the reaction is done until a current of from 2 F equiv to 20 F equiv, more preferably of from 2 F equiv to 17.5 F equiv, has passed through the reaction mixture, wherein F equiv means an amount of charge equivalent to the molar amount of organic substrate has passed through the reaction mixture.

9. The method according to one or more of claims 1 to 8, wherein the electrochemical fluorination reaction is an electrochemical oxidative decarboxylation reaction.

10. The method according to claim 9, wherein the method is a method for the preparation of an organic product containing a fluoro residue bonded to a non-aromatic C atom by an electrochemical oxidative decarboxylation reaction of an organic substrate containing a carboxylic acid residue bonded to a non-aromatic C atom; wherein the carboxylic acid residue bonded to a non-aromatic C atom is exchanged against a fluorine atom from a fluorinating agent; and the fluorinating agent is a salt of hexafluorosilicic acid.

11. The method according to claim 10, wherein the organic substrate containing a carboxylic acid residue bonded to a non- aromatic C atom is a compound of formula (I), and the organic product containing a fluoro residue bonded to a non -aromatic C atom is a compound of formula (II)(I) (ID whereinRl, R2 and R3 are identical or different and independently from each other selected from the group consisting ofH, Ci-30 alkyl, C230 alkenyl, F, Cl, Br, I, CN,O-Ci-10 alkyl, O-C240 alkenyl,C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,O-R5, N(H)R5, a ring RINGALIPH,(Yl) -RINGALIPH, aryl, and(Yl)-aryl; orR1 and R2 together with the connecting C atom form a ring RINGALIPH, orR1 and R2 together with the connecting C atom form a first ring RINGALIPH and R3 and R1 together with the connecting C atom form a second, identical or different ring RINGALIPH; and wherein any RINGALIPH is, independently from any other RINGALIPH,• a 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic residue, the heterocyclic residue containing 1 or 2 identical or different endocyclic heteroatoms Y2,• a bicyclic spiro residue, each ring of the bicyclic spiro residue is independently from the other ring a 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic ring, in case of a 4 membered ring of the bicyclic spiro residue the ring contains 0 or 1 endocyclic heteroatom Y2, in case of a 5 or 6 membered ring of the bicyclic spiro residue the ring contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, or• a bicyclic non-spiro residue, wherein a first 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic residue is fused with a second 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic residue, wherein a first and a second heterocycle of the bicyclic non-spiro residue, independently from each other, contain, in case of a 4 membered ring, 1, in case of a 5 or 6 membered ring, 1 or 2, identical or different endocyclic heteroatoms Y2, andRINGALIPH is unsubstituted or substituted by one or more substituents independently from each other selected from the group consisting of oxo, Ci-30 alkyl, 62-30 alkenyl, F, Cl, Br, I, CN,O-Ci-10 alkyl, O-C2-10 alkenyl,C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,O-R5, N(H)R5, aryl, and (Yl)-aryl; any aryl in formula (I) and (II) is, independently from any other aryl in formula (I) and (II),• a 5 or 6 membered monocyclic aryl residue,• a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or• an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the aryl in formula (I) and (II) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the aryl in formula (I) and (II) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2, and aryl in formula (I) and (II) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of Ci io alkyl, C2 10 alkenyl, F, Cl, Br, I, CN,O-Ci-10 alkyl, O’Cs-io alkenyl,C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,O-R5, N(H)R5, a terminal aryl, and(Yl)-aryl which is a terminal aryl; terminal aryl in formula (I) and (II) is, independently from any other terminal aryl in formula (I) and (II),• a 5 or 6 membered monocyclic aryl residue,• a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or• an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring,any 5 membered ring in the terminal aryl in formula (I) and (II) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the terminal aryl in formula (I) and (II) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; and terminal aryl in formula (I) and (II) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of Ci io alkyl, C2 10 alkenyl, F, Cl, Br, I, CN,O-Ci-10 alkyl, O’Cs-io alkenyl,C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,O-R5, N(H)R5; any heteroatom Y2 is, independently from any other Y2, selected from the group consisting of O and N, said N is unsubstituted or substituted by R5; any Y1 is, independently from any other Yl, a connecting group selected from the group consisting ofO, N(R5), C1-6 alkylene, O-Ci-6 alkylene, C1-6 alkylene-O,C(O)-O-Ci-6alkylene-O-C(O), andO-C(O)-Ci-6alkylene-C(O)-O; any C1-30 alkyl and any C230 alkenyl is, independently from any other C1-30 alkyl and C230 alkenyl respectively, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical of different substituents selected from the group consisting ofF, Cl, Br, I, CN,O-Ci-10 alkyl, O-C240 alkenyl,C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,O-R5, N(H)R5, aryl, and (Yl)-aryl;any Ci-io alkyl and any C2 10 alkenyl is, independently from any other C 1-10 alkyl and C2 10 alkenyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical or different substituents selected from a group consisting ofF, Cl, Br, I, CN,O-Ci-9 alkyl, O-C2-9 alkenyl,C(O)-O-Ci-9alkyl, C(O)-O-C2-9 alkenyl,O-R5, and N(H)R5; any R5 is, independently from any other R5, a protecting group for protecting OH NH or NH2.

12. The method according to claim 11, whereinRl, R2 and R3 are identical or different and independently from each other selected from the group consisting ofH, Ci-3o alkyl, F, Cl, Br, I, CN,O-Ci-10 alkyl,C(0)-0-Ci io alkyl,O-R5, N(H)R5, a ring RINGALIPH,(Yl) -RINGALIPH, aryl, and(Yl)-aryl; orRl and R2 together with the connecting C atom form a ring RINGALIPH, orRl and R2 together with the connecting C atom form a first ring RINGALIPH and R3 and Rl together with the connecting C atom form a second, identical or different ring RINGALIPH; and wherein any RINGALIPH is, independently from any other RINGALIPH,• a 4, 5 or 6 membered saturated or unsaturated, non -aromatic carbocyclic or heterocyclic residue, the heterocyclic residue containing 1 or 2 identical or different endocyclic heteroatoms Y2,• a bicyclic spiro residue, each ring of the bicyclic spiro residue is independently from the other ring a 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic ring, in case of a 4 membered ring of the bicyclic spiro residue the ring contains 0 or 1 endocyclic heteroatom Y2, in case of a 5 or 6 membered ring of the bicyclic spiro residue the ring contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, or• a bicyclic non-spiro residue, wherein a first 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic residue is fused with a second 4, 5 or 6 membered saturated or unsaturated, non-aromatic carbocyclic or heterocyclic residue, wherein a first and a second heterocycle of the bicyclic non-spiro residue, independently from each other, contain, in case of a 4 membered ring, 1, in case of a 5 or 6 membered ring, 1 or 2, identical or different endocyclic heteroatoms Y2, andRINGALIPH is unsubstituted or substituted by one or more substituents independently from each other selected from the group consisting of oxo, Ci-30 alkyl, F, Cl, Br, I, CN,O-Ci-io alkyl,C(0)-0-Ci io alkyl,O-R5, N(H)R5, aryl, and (Yl)-aryl; any aryl in formula (I) and (II) is, independently from any other aryl in formula (I) and (II),• a 5 or 6 membered monocyclic aryl residue,• a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or• an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the aryl in formula (I) and (II) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the aryl in formula (I) and (II) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2, and aryl in formula (I) and (II) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of Ci io alkyl, F, Cl, Br, I, CN, O-Ci-io alkyl, C(0)-0-Ci io alkyl, O-R5, N(H)R5, a terminal aryl, and (Yl)-aryl which is a terminal aryl; terminal aryl in formula (I) and (II) is, independently from any other terminal aryl in formula (I) and (II),• a 5 or 6 membered monocyclic aryl residue,• a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or• an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the terminal aryl in formula (I and (II) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the terminal aryl in formula (I) and (II) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; and terminal aryl in formula (I) and (II) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of Ci io alkyl, F, Cl, Br, I, CN,O-Ci-io alkyl, C(0)-0-Ci io alkyl, O-R5, N(H)R5; any heteroatom Y2 is, independently from any other Y2, selected from the group consisting of O and N, said saturated N is or substituted by R5; any Y1 is, independently from any other Yl, a connecting group selected from the group consisting ofO, N(R5), CI-6 alkylene, O-Ci-6 alkylene, Ci-6 alkylene-O,C(O)-O-Ci-6alkylene-O-C(O), andO-C(O)-Ci-6alkylene-C(O)-O; any C1-30 alkyl is, independently from any other C1-30 alkyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical of different substituents selected from the group consisting ofF, Cl, Br, I, CN,O-Ci-10 alkyl,C(0)-0-Ci io alkyl,O-R5, N(H)R5, aryl, and(Yl)-aryl; any C1-10 alkyl is, independently from any other C1-10 alkyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical or different substituents selected from a group consisting ofF, Cl, Br, I, CN,O-Ci-9 alkyl,C(O)-O-Ci-9alkyl,O-R5, and N(H)R5; any R5 is, independently from any other R5, a protecting group for protecting OH NH or NH2.

13. The method according to one or more of claims 1 to 8, wherein the electrochemical fluorination reaction is an electrochemical benzylic fluorination reaction.

14. The method according to claim 13, wherein the method is a method for the preparation of an organic product containing a fluoro residue bonded to a benzylic non -aromatic C atom by an electrochemical benzylic fluorination reaction of an organic substrate containing a benzylic H atom bonded to a benzylic non -aromatic C atom; wherein the benzylic H atom bonded to the benzylic non -aromatic C atom is exchanged against a fluorine atom from a fluorinating agent; and the fluorinating agent is a salt of hexafluorosilicic acid; with the salt of hexafluorosilicic acid as defined herein, also with all its embodiments.

15. The method according to claim 14, wherein the organic substrate containing a benzylic H atom bonded to a benzylic nonaromatic C atom is a compound of formula (III), and the organic product containing a fluoro residue bonded to a benzylic non -aromatic C atom is a compound of formula (IV);H FJ R10 J .R10ARYL-BENZ Rll ARYL-BENZ^^Rll(III) (IV) whereinRIO and Rll are identical or different and are H or Ci -30 alkyl;ARYLBENZ is• a 5 or 6 membered monocyclic aryl residue,• a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or• an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, the aryl residue being connected with the 5 or 6 membered aromatic ring to the C atom of formula (III), to which RIO, Rll and the H are bonded, any 5 membered ring in the ARYLBENZ contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the ARYLBENZ contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; andARYLBENZ is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting ofCi io alkyl, C2 10 alkenyl, F, Cl, Br, I, CN,O-Ci-10 alkyl, O’Cs-io alkenyl,C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,O-R5, N(H)R5, a terminal aryl, and(Yl)-aryl which is a terminal aryl; terminal aryl in formula (III) and (IV) is, independently from any other terminal aryl in formula (III) and (IV),• a 5 or 6 membered monocyclic aryl residue,• a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or• an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the terminal aryl in formula (III) and (IV) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the terminal aryl in formula (III) and (IV) contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; andterminal aryl in formula (III) and (IV) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of Ci io alkyl, C2 10 alkenyl, F, Cl, Br, I, CN,O-Ci-10 alkyl, O’Cs-io alkenyl,C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,O-R5, N(H)R5; any heteroatom Y2 is, independently from any other Y2, selected from the group consisting of O and N, said N is unsubstituted or substituted by R5; any Y1 is, independently from any other Yl, a connecting group selected from the group consisting ofO, N(R5), C1-6 alkylene, O-Ci-6 alkylene, C1-6 alkylene-O,C(O)-O-Ci-6alkylene-O-C(O), andO-C(O)-Ci-6alkylene-C(O)-O; any C1-30 alkyl is, independently from any other C1-30 alkyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical of different substituents selected from the group consisting ofF, Cl, Br, I, CN,O-Ci-10 alkyl, O-C240 alkenyl,C(0)-0-Ci io alkyl, C(0)-0-C2-io alkenyl,O-R5, N(H)R5, aryl, and (Yl)-aryl; any C1-10 alkyl and any C2 10 alkenyl is, independently from any other C1-10 alkyl and C2 10 alkenyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical or different substituents selected from a group consisting ofF, Cl, Br, I, CN,O-Ci-9 alkyl, O-C2-9 alkenyl,C(O)-O-Ci-9alkyl, C(O)-O-C2-9alkenyl,O-R5, and N(H)R5;any R5 is, independently from any other R5, a protecting group for protecting OH NH or NH2.

16. The method according to claim 15, whereinARYLBENZ is• a 5 or 6 membered monocyclic aryl residue,• a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or• an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, the aryl residue being connected with the 5 or 6 membered aromatic ring to the C atom of formula (III), to which RIO, Rll and the H are bonded, any 5 membered ring in the ARYLBENZ contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the ARYLBENZ contains 0, 1, 2 or 3 identical or different endocyclic heteroatoms Y2; andARYLBENZ is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting ofCi io alkyl, F, Cl, Br, I, CN,O-Ci-io alkyl,C(0)-0-Ci io alkyl,O-R5, N(H)R5, a terminal aryl and,(Yl)-aryl which is a terminal aryl; terminal aryl in formula (III) and (IV) is, independently from any other terminal aryl in formula (III) and (IV),• a 5 or 6 membered monocyclic aryl residue,• a bicyclic aryl residue formed by a 5 or 6 membered aromatic ring fused with another 5 or 6 membered aromatic ring, or• an aryl residue wherein a 5 or 6 membered aromatic ring is fused with a 5 or 6 membered non- aromatic ring, any 5 membered ring in the terminal aryl in formula (III) and (IV) contains 0, 1 or 2 identical or different endocyclic heteroatoms Y2, any 6 membered ring in the terminal aryl in formula (III) and (IV) contains 0, 1,2 or 3 identical or different endocyclic heteroatoms Y2; and terminal aryl in formula (III) and (IV) is unsubstituted or substituted by one or more identical or different substituents selected from the group consisting of Ci io alkyl, F, Cl, Br, I, CN,O-Ci-io alkyl,C(0)-0-Ci io alkyl,O-R5, N(H)R5; any heteroatom Y2 is, independently from any other Y2, selected from the group consisting of O and N, said N is unsubstituted or substituted by R5; any Y1 is, independently from any other Yl, a connecting group selected from the group consisting ofO, N(R5), CI-6 alkylene, O-Ci-6 alkylene, Ci-6 alkylene-O,C(O)-O-Ci-6alkylene-O-C(O), andO-C(O)-Ci-6alkylene-C(O)-O; any C1-30 alkyl is, independently from any other C1-30 alkyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical of different substituents selected from the group consisting ofF, Cl, Br, I, CN,O-Ci-10 alkyl,C(0)-0-Ci io alkyl,O-R5, N(H)R5, aryl, and(Yl)-aryl;any Ci-io alkyl is, independently from any other Ci-io alkyl, unsubstituted or substituted by 1, 2, 3, 4, 5, or 6 identical or different substituents selected from a group consisting ofF, Cl, Br, I, CN,O-Ci-9 alkyl,C(O)-O-Ci-9alkyl,O-R5, and N(H)R5; any R5 is, independently from any other R5, a protecting group for protecting OH NH or NH2.

17. The compound (MepH)2SiFe, with Mep being 5-ethyl-2-methylpyridine.

18. A method for the preparation of (MepH)2SiFe, with Mep being 5-ethyl-2- methylpyridine; whereinH2SiFe and Mep are brought into contact with each other.

19. The use of a salt of hexafluorosilicic acid as fluorinating agent in an electrochemical fluorination reaction.

20. The fluorinated organic product obtainable by the method according to one or more of claims 1 to 16.

21. The fluorinated organic product obtained by the method according to one or more of claims 1 to 16.

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