Electrochemical transformations

Abstract

Electrochemical Transformations A process for synthesising a compound according to Formula (I), wherein the process comprises subjecting a reaction solution comprising a compound according to Formula (II) to a potential difference applied across two or more electrodes, wherein for the compounds according to Formulae (I) and (II): each X is independently selected from the group consisting of O, S, NRY and PRY, each of R1 to R6 and RY is a group selected from the list consisting of hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C6-C12 aryl, and C3-C12 heterocyclyl, and each of R1 to R6 and RY optionally contains one or more heteroatom containing groups, Formulae (I) and (II) include tautomeric and stereochemically isomeric forms thereof, and the reaction solution is separated from the anode by an ion exchange membrane.

Description

[0001] ELECTROCHEMICAL TRANSFORMATIONS

[0002] Field of the Invention

[0003] The present invention relates to a process for the synthesis of compounds of Formula (I), such as solketal. Such compounds can be used as a solvent, a fuel additive, a pharmaceutical intermediate, and / or in applications such as air care, fragrances, paints and varnishes, printing inks, household and institutional cleaners, and / or leather treatments. The present invention also relates to compounds of Formula (I) obtainable by the process, products containing such compounds, uses of such compounds, and compositions comprising such compounds.

[0004] Background

[0005] There is an industry-wide desire to move away from traditional fossil fuel-based products. New technologies that switch away from a fossil fuel-based economy are of significant value.

[0006] A few specific product lines exist as replacements for fossil fuel-based products. For example, BASF recently switched to biomass feedstocks for some products (e.g. Styropor®).

[0007] Solketal is another bio-based replacement for fossil fuel-based chemicals and is marketed by Solvay under the brand name Augeo®.

[0008] Solketal is conventionally synthesised from the condensation of glycerol and acetone. Owing to this, solketal can be made from non-animal-based materials and has a low carbon footprint. Glycerol is a waste product from factories and therefore its use in the synthesis of solketal can be considered to be environmentally benign.

[0009] Solketal can be used as an organic solvent, a fuel additive, a pharmaceutical intermediate, and in applications such as air care, fragrances, paints and varnishes, printing inks, household and institutional cleaners, and leather treatments. The global market for solketal is projected to reach USD 100 billion by 2030. Solketal also has the benefit that it is not toxic to humans or the environment. Summary of the Invention

[0010] According to a first aspect, the present invention provides a process for synthesising a compound according to according to Formula (I): wherein the process comprises subjecting a reaction solution comprising a compound according to Formula (II):

[0011] Formula (II) to a potential difference applied across two or more electrodes, wherein, for the compounds according to Formulae (I) and (II): each X is independently selected from the group consisting of O, S, NRYand PRY, each of R1to R6and RYis a group selected from the list consisting of hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, Ce- C12 aryl, and C3-C12 heterocyclyl, each of R1to R6and RYoptionally contains one or more heteroatom containing groups, wherein Formulae (I) and (II) include tautomeric and stereochemically isomeric forms thereof, and wherein the reaction solution is separated from the anode by an ion exchange membrane.

[0012] In some embodiments, the reaction solution is both separated from the anode by an ion exchange membrane and comprises a transition metal salt. As discussed above, solketal finds applications in a variety of fields, usually as a solvent. Thus, processes to synthesise compounds of Formula (I), such as solketal, are particularly desirable.

[0013] The present inventors have surprisingly determined that compounds according to Formula (I), such as solketal, can be synthesised using the process of the first aspect in improved yields over known processes and from highly impure sources of compounds of Formula (II).

[0014] The provision of the ion permeable membrane allows the reaction to be performed in a continuous flow reactor. The benefits of performing a reaction in flow are well established, and include improved throughput of a reaction, reduced downtime, improved safety and facile scalability and provision of gaseous reagents. In some embodiments the ion permeable membrane is a cation exchange membrane, for example a perfluorinated cation-exchange membrane.

[0015] The provision of a transition metal salt, such as a copper(II) salt, in the reaction solution of the process has been shown to improve the yield of compounds of formula (I). In some embodiments, the anions of the transition metal salt are halogens, triflates, sulfates, sulfites, phosphates, phosphite, hydroxides or combinations thereof.

[0016] In some embodiments the transition metal salt is selected from vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, silver or gold salts or combinations thereof. For example, the transition metal salt may be selected from cobalt, nickel, copper, silver or gold salts or combinations thereof, and preferably the transition metal salt is a copper salt or a nickel salt. In some embodiments, the transition metal salt is selected from the group consisting of CuX2, NiX2, Cu(OSO2CF3)2, NiSC , NiX2, FeXs or a combination thereof, optionally CuX2, Cu(OSO2CF3)2 or combinations thereof, wherein X is selected from fluoride, chloride, bromide or iodide.

[0017] In one embodiment the reaction solution is contacted with carbon dioxide. This provides a use for carbon dioxide, which is a fossil fuel by-product. The usage and storage of carbon dioxide is estimated to contribute GBP 5-9bn to the UK economy by 2030 and 30 bn by 2050. Without being bound by theory it is thought that the carbon dioxide can dissolve into the solution to provide carbonate ions, which may assist the process. The process synthesises the compound of Formula (I) from a compound according to Formula (II). The present process is capable of converting crude and impure sources of Formula (II) to Formula (I) in high yield. The compound according to Formula (II) may therefore be provided in a crude mixture having a concentration of the compound 0.01% or greater by weight of the crude mixture. However, the source material for the compound according to Formula (II) may be reaction grade, therefore in other embodiments, the compound according to Formula (II) is provided in an aqueous solution comprising 90% or more of the compound by weight of the aqueous solution, such as 98% by weight of the aqueous solution, or the compound according to Formula (II) may be provided in as an essentially pure compound.

[0018] Preferably the compound according to Formula (II) is glycerol (CAS 56-81-5, also known as glycerine or propane-1, 2, 3-triol):

[0019] Glycerol

[0020] Glycerol is particularly preferred as it is a by-product of biodiesel production. Using such glycerol as the compound of Formula (II) can therefore make use of this waste byproduct.

[0021] The reaction solution of the process may include a carbonyl group-containing molecule, such as acetone. This has been shown to provide beneficial yields of compounds of Formula (I), such as solketal. Without being limited by theory, it is believed that the presence of a carbonyl group-containing molecule, such as acetone, in the reaction solution reduces the proportion of compounds of Formula (I) that are re-converted back to compounds of Formula (II) by controlling the equilibrium between these compounds.

[0022] Compared to many methods of the prior art that condense a compound of Formula (II) with a carbonyl group-containing molecule to form a compound of Formula (I), the present invention has been found to successfully and efficiently operate with significantly lower amounts of the carbonyl group-containing molecule relative to the compound of Formula (II). For instance, the amount of the carbonyl group-containing molecule may be 1000 mol% or less relative to the amount of the compound of Formula (II).

[0023] It has been found that the process of the invention is able to produce compounds of Formula (I) at rates of 100g per hour or higher, which exemplifies the commercial potential of this process.

[0024] The process of the invention is able to provide surprisingly high yields even in the presence of water. Processes of the prior art that condense a compound of Formula (II) with a carbonyl group-containing molecule to form a compound of Formula (I) tend to continuously remove water from the reaction solution by distillation, requiring high temperatures and / or low pressures, and therefore requiring large amounts of energy. However, being able to achieve high yields even in the presence of water means that continuous distillation of water can be avoided and the process can be more energy efficient than processes of the prior art.

[0025] In some embodiments, the reaction solution is homogenised, optionally by stirring at 15000 to 30000 rpm.

[0026] The process of the first aspect provides a compound according to Formula (I), such as solketal. According to a second aspect, the present invention provides a compound according to Formula (I), wherein the compound is obtainable by (e.g. obtained by) the method of the first aspect.

[0027] The compound of Formula (I) may be contained in a composition. Thus, according to a third aspect, the present invention provides a composition comprising a compound of Formula (I). The composition is obtainable by (e.g. obtained by) the method of the first aspect and / or comprises a by-product characteristic of the method of the first process, such as a compound having the molecular formula C7H12O2 (e.g. ethyl cyclopentanolone) and / or formic acid.

[0028] In a fourth aspect there is provided a compound of the second aspect or a composition of the third aspect, wherein the product is a solvent, a fuel, a pharmaceutical intermediate, a pharmaceutical carrier, an air care product, a paint or varnish, ink, cleaning agent; and / or a leather treatment agent. Detailed Description

[0029] Compounds of Formula (I)

[0030] The first aspect defines a process for synthesising a compound according to Formula (I):

[0031] Formula (I) includes tautomeric and stereochemically isomeric forms thereof.

[0032] Each X is independently selected from the list consisting of O, S, NRYand PRY. The X groups may be the different, but preferably they are the same. Each X group may be selected from the list consisting of O, NRYand S, preferably the group consisting of O and NRY. Preferably both X groups are selected from the list consisting of O, NRYand S, preferably the list consisting of O and NRY. Preferably at least one X is O. Preferably both X groups are O, such that the compound of Formula (I) can be termed an acetal. N and O are more preferable, and O is most preferable, because of a reduced susceptibility to oxidation compared to S and P.

[0033] Each of R1to R6and RYis a group selected from the list consisting of hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, Ce-C 12 aryl and C3-C12 heterocyclyl.

[0034] The prefix “Cx y” (where x and y are integers) as used herein refers to the number of carbon atoms in a given group. For example, a C1-6 alkyl group contains from 1 to 6 carbon atoms, and a C3-6 alkyl group contains from 3 to 6 carbon atoms.

[0035] The term “alkyl” may refer to a linear, branched and / or cyclic (“cycloalkyl”) hydrocarbon group that is saturated. Examples of alkyl groups include methyl, ethyl, n- propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl or hexyl and the like. The term “cycloalkyl” refers to cyclic hydrocarbon groups. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.

[0036] The term “alkenyl” may refer to a linear, cyclic (“cycloalkenyl”) and / or branched hydrocarbon group containing one or more carbon-carbon double bond. Examples of such groups include vinyl, allyl, prenyl, isoprenyl.

[0037] The term ‘alkynyl’ may refer to a linear, cyclic and / or branched hydrocarbon group containing one or more carbon-carbon triple bond.

[0038] The term “aryl” as used herein refers to carbocyclic aromatic groups including phenyl, benzyl, naphthyl, anthracenyl, pyrenyl, chrysenyl, benz[a]anthracenyl, fluoranthene, indenyl, and tetrahydronaphthyl groups.

[0039] The term "heterocyclyl" shall, unless the context indicates otherwise, include both aromatic (i.e. heteroaryl) and non-aromatic (i.e. heterocycloalkyl / heterocycloalkenyl) ring systems. Thus, for example, the term "heterocyclyl group" includes within its scope aromatic, non-aromatic, unsaturated, partially saturated and fully saturated heterocyclyl ring systems. Heterocyclyl groups may include heteroatoms selected from the list consistingof oxygen, nitrogen and sulfur. In general, unless the context indicates otherwise, such groups may be monocyclic or bicyclic and may contain, for example, 4 to 10 ring members, more usually 5 to 10 ring members.

[0040] Examples of monocyclic groups are groups containing 4, 5, 6, 7 and 8 ring members, more usually 4 to 7, and preferably 5, 6 or 7 ring members, more preferably 5 or 6 ring members. Examples of bicyclic groups are those containing 8, 9 and 10 ring members. Non-aromatic heterocyclic groups may include oxiranes, aziridines, axetidines, oxetanes, dihydrofurans, tetrahydrofurans, pyrrolidines, piperidines, piperazines, dioxanes, decahydroisoquinolines and morpholines.

[0041] The heterocyclyl groups can be heteroaryl groups having from 5 to 10 ring members. The term "heteroaryl" is used herein to denote an aromatic heterocyclyl group. The term "heteroaryl" embraces polycyclic (e.g. bicyclic) ring systems wherein one or more rings are non-aromatic, provided that at least one ring is aromatic. In such polycyclic systems, the group may be attached by an aromatic ring, or by a non-aromatic ring. Examples of such polycyclic systems include l,4,5,6-tetrahydrocyclopenta[6]pyrrole, indoline, tetrahydroquinoline, tetrahydroisoquinoline, 1,2-dihydroquinoline, 1,2- dihydroisoquinoline, 2 / / -bcnzo| e ] [ 1 ,3 ]oxazine, 2 / / -bcnzo| / ) | | l .4 |-oxazinc. 2H- benzo[e] [ 1,2] oxazine, / / / -isochromcnc and 22 -chromene. The heteroaryl group may be a five membered or six membered monocyclic ring or a bicyclic structure formed from fused five and six membered rings or two fused six membered rings. Each ring may contain up to five heteroatoms typically selected from nitrogen, sulphur and oxygen. The heteroaryl group may contain one or two or more ring nitrogen atoms. Typically the heteroaryl ring will contain up to 4 heteroatoms, more typically up to 3 heteroatoms, more usually up to 2, for example a single heteroatom. In one embodiment, the heteroaryl ring contains at least one ring nitrogen atom. Examples of heteroaryl groups include pyrrole, furan, thiophene, imidazole, furazan, oxazole, oxadiazole, oxatriazole, isoxazole, thiazole, thiadiazole, isothiazole, pyrazole, triazole, tetrazole, pyridine, pyrazine, pyridazine, pyrimidine, triazine, / / / -indole. 22 -isoindole, benzimidazole, 4- azaindole, 5-azaindole, 6-azaindole, 7-azaindole, benzofuran, isobenzofuran, benzo[c]thiophene, benzo[6]thiophene, benzo[<7]isoxazole, benzo[<7]thiazole, quinolone, isoquinoline, quinoxaline, phthalazine, quinazoline, cinnoline and 1,8- naphthyridine.

[0042] It will be understood that the alkyl, alkenyl, alkynyl, aryl and heterocyclyl groups are not mutually exclusive and can be intermixed between these groups within the claim scope, for example to form a group containing an alkyl and an aryl group. However, the overall limit of the number of carbons should be adhered to, for example where an aryl group is present there must be from 6 to 12 carbon atoms present in that overall R group, including any alkyl moieties.

[0043] Each of R1to R6and RYmay be a group selected from the list consisting of hydrogen, Ci-Cs alkyl, C2-C8 alkenyl, C2-C8 alkynyl, Ce-Cs aryl, and C4-C8 heterocyclyl. Each of R1to R6and RYmay be a group selected from the list consisting of hydrogen and Ci-Cs alkyl. Preferably each of R1to R6and RYmay be a group selected from the list consisting of hydrogen and C1-C4 alkyl; such as hydrogen, Ci alkyl and C2 alkyl. Each of R1to R6and RYmay be limited to such groups independently of the other R groups. Preferably R1is hydrogen. Preferably R2is hydrogen. Preferably R3is -CH2OH. Preferably R4is hydrogen. Preferably R5is hydrogen. Preferably R6is methyl. Where R6is a hydrocarbon group (e.g. C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C6-C12 aryl, or C4-C12 heterocyclyl group, such as a methyl group) the compound of Formula (I) can be termed a ketal, which is preferable.

[0044] In one embodiment the compound of Formula (I) has 80 carbon atoms or fewer, such as 60 carbon atoms or fewer, or 40 carbon atoms or fewer, preferably 30 carbon atoms or fewer, such as 20 carbon atoms or fewer, for example 10 carbon atoms or fewer, more preferably 8 carbon atoms or fewer. For example, the compound of Formula (I) may have from 4 to 80 carbon atoms, or from 4 to 60 carbon atoms, such as from 5 to 20 carbon atoms, or from 6 to 8 carbon atoms.

[0045] Each of R1to R6and RYoptionally contains one or more, such as one, two or three, heteroatom containing groups. Preferably each of R1to R6and RYcontains 0 or 1 heteroatom containing group. The optional heteroatom containing groups may be independently selected from the list consisting of cyano, halogen, boronic acid, boronate ester, ether, alcohol (i.e. hydroxyl), carbonyl, ester, carboxylic acid, amine, amide, urea, carbamate, sulfonate ester, sulfonamide, sulfone and sulfoxide. For example, the optional heteroatom containing groups may be independently selected from the list consisting of cyano, halogen, ether, alcohol, carbonyl, ester, carboxylic acid, amine, amide, urea and carbamate. Halogen may be selected from F, Cl, Br and I, for example F, Cl and Br, or preferably F and Cl. In particular, each RYmay be a protecting group for the N or P atom to which it is attached. The most preferable heteroatom containing group for R1to R6is alcohols. Preferably R3contains one heteroatom containing group, such as an alcohol. Preferably each of R1, R2, R4, R5and R6are, independently, unsubstituted, i.e. contain 0 heteroatom containing groups.

[0046] The compound according to Formula (I) may be defined by Formula (la): Formula (la) wherein:

[0047] • each X is independently selected from N and O; preferably both X groups are O,

[0048] • R1, R3, R4and R6may each independently be a group selected from the list consisting of hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C6-C12 aryl, and C3-C12 heterocyclyl; preferably R1, R3, R4and R6are each independently a group selected from the list consisting of hydrogen, Ci-Cs alkyl, C2-C8 alkenyl, C2-C8 alkynyl, Ce-Cs aryl, and C3-C8 heterocyclyl, and

[0049] • R1, R3, R4and R6may each independently contain one or more heteroatom containing groups; preferably one or two heteroatom groups, for example wherein the heteroatom groups are alcohol groups.

[0050] The compound according to Formula (I) may be defined by Formula (lb):

[0051] Formula (lb) wherein:

[0052] • each X is independently selected from N and O; preferably both X groups are O,

[0053] • R3and R6may each independently be a group selected from the list consisting of hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C6-C12 aryl, and C3-C12 heterocyclyl; preferably R3and R6are each independently a group selected from the list consisting of hydrogen, Ci-Cs alkyl, C2-C8 alkenyl, C2-C8 alkynyl, Ce-Cs aryl, and C3-C8 heterocyclyl, and

[0054] • R3and R6may each independently contain one or more heteroatom containing groups; preferably one or two heteroatom groups, for example wherein the heteroatom groups are alcohol groups.

[0055] It will be understood that the definitions of optional and preferable groups described in relation to Formula (I) apply equally to Formulae (la) and (lb) unless they are contradictory. Most preferably the compound according to Formula (I) is solketal:

[0056] Solketal corresponds to Formula (I) wherein both X groups are O, R1is hydrogen, R2is hydrogen, R3is -CH2OH, R4is hydrogen, R5is hydrogen, and R6is methyl.

[0057] The purity of the solketal produced by this method may be 20% or more, such as 40% or more, or 45% or more, preferably 50% or more, or 60% or more by moles, relative to glycerol. The purity may be 90% or lower, such as 80% or lower, or 75% or lower, such as 70% or lower. The purity may be from 20% to 90%, such as from 40% to 80%, or from 50% to 75%. A reaction product of the claimed process may include solketal in such a yield. In other words, the solketal produced by this electrochemical method may be purer than has previously been achieved by electrochemical means, for example due to fewer and / or a lower amount of by-products being produced.

[0058] Compounds of Formula (II)

[0059] The process synthesises the compound according to Formula (I) from a compound according to Formula (II):

[0060] Formula (II) includes tautomeric and stereochemically isomeric forms thereof.

[0061] The options described above for the X, R1to R3and RYgroups of Formula (I) apply equally to the groups in Formula (II) with the same designation (e.g. R1of Formula (I) corresponds with R1of Formula (II)). In one embodiment the compound of Formula (II) has 40 carbon atoms or fewer, such as 30 carbon atoms or fewer, or 20 carbon atoms or fewer, preferably 15 carbon atoms or fewer, such as 10 carbon atoms or fewer, for example 7 carbon atoms or fewer, more preferably 5 carbon atoms or fewer. For example, the compound of Formula (II) may have from 2 to 40 carbon atoms, or from 2 to 20 carbon atoms, such as from 3 to 10 carbon atoms, or from 3 to 5 carbon atoms.

[0062] Examples of compounds of Formula (II) include glycerol, ethylene glycol, 1,2-propane diol, and amino alcohols such as glycinol. Most preferably the compound according to Formula (II) is glycerol (also known as glycerine):

[0063] Glycerol

[0064] Glycerol corresponds to Formula (II) wherein both X groups are O, R1is hydrogen, R2is hydrogen, and R3is -CH2OH.

[0065] Glycerol is particularly preferred as it is a by-product of biodiesel production. Crude glycerol can be obtained from such processes at 30-90 wt% purity. Using such glycerol can make use of this waste by-product.

[0066] The process of the present invention is capable of converting crude and impure sources of Formula (II) to Formula (I) in high yield. The compound according to Formula (II) may therefore be provided to the reaction solution in a crude mixture having a concentration of the compound 0.01% of greater by weight of the crude mixture. For example, the compound according to Formula (II) may be provided in crude mixture containing 0.1% or greater, 1% or greater, 5% or greater, 1% or greater, 1% or greater of the compound, 10% or greater, 15% or greater, 20% or greater, 25% or greater, 30% or greater, 40% or greater, 45% or greater, 50% or greater, 55% or greater, 60% or greater, 65% or greater, 70% or greater, 75% or greater, 75% or greater by weight of the crude mixture. In some embodiments, the compound according to Formula (II) may be provided in crude mixture containing 85% or less of the compound, such as 80% or less, 75% or less, 65% or less, 60% or less, 55% or less or 50% or less of the compound according to Formula (II) by weight of the crude mixture. In some preferred embodiments, the compound of formula (II) may be provided in a crude mixture having a concentration of from 20% to 80% by weight of the crude mixture, most preferably 30% to 70% by weight of the crude mixture.

[0067] However, the presence of impurities in the source material for the compound according to Formula (II) are not essential and so the compound may provided in a reaction grade form. Therefore in other embodiments, the compound according to Formula (II) is provided in an aqueous solution comprising 90% or more of the compound by weight of the aqueous solution, such as 98% by weight of the aqueous solution, or the compound according to Formula (II) may be provided in as an essentially pure compound.

[0068] The compound according to Formula (II) may initially (i.e. before the potential difference is applied) be present in the reaction solution at a concentration of 0.1M or higher, such as 0.2M or higher, or 0.5M or higher, preferably 1.0M or higher, or 1.5M or higher, such as 1.8M or higher. The compound according to Formula (II) may be included in the reaction solution at a concentration of 10M or less, such as 5.0M or less, such as 4.0M or less, preferably 3.0M or less, or 2.5M or less. The compound according to Formula (II) may be included in the reaction solution at a concentration of from 0.1 to 10M, such as from 0.2 to 5.0M, or from 0.5 to 4.0M, preferably from 1.0 to 3.0M, or from 1 .5 to 2.5M.

[0069] Process

[0070] The claimed process for synthesising a compound according to Formula (I) requires subjecting a reaction solution comprising a compound according to Formula (II) to a potential difference, wherein the reaction solution is separated from the anode by an ion exchange membrane and / or the reaction solution further comprises a transition metal salt.

[0071] It will be appreciated that the potential difference can be provided using a battery or power supply. In one embodiment the potential difference is provided from a renewable energy source, such as solar, wind or hydroelectric energy, or a stored form thereof, for example in a battery. This further reduces the carbon footprint of the process. The skilled person will appreciate that the potential difference should be sufficiently high enough to perform the reaction. Thus, the potential difference may be 0.05V or higher, 1.0V or higher, or 1.2V or higher, preferably 1.5V or higher, such as 1.7V or higher, or 1.9V or higher, for example 2.0V or higher. Too high a potential difference may lead to excessive oxidation of the solvent, such as water. Thus, the potential difference may be 16.0V or lower, 15.5V or lower, 14.0V or lower, 12.0V or lower, 10.0V or lower, 8.0V or lower, 6.0V or lower, 5.0V or lower, or preferably 4V or lower, such as 3.5V or lower, 3.0V or lower, or 2.8V or lower, or 2.6V or lower, such as 2.5V or lower. The potential difference may be from 0.5V to 16V, 1.0V to 5.0V, or from 1.5V to 4.0V, such as from 2.0V to 3.5V or from 2.0V to 2.5V.

[0072] The potential difference will cause an electrical current to flow through the reaction solution (and counter solution if present). The current may be 0.1mA or higher, such as 1.0mA or higher, or 2.0mA or higher, or 4.0mA or higher. The current may be 10A or lower, such as 1.0A or lower, such as 800mA or lower, or 500mA or lower, such as 400mA or lower, or 200mA or lower. For example, the current may be from 0.1mA to 1.0A, or from 2.0mA to 400mA. It will be understood that the current may depend upon factors such as the size of the electrodes, the distance between the electrodes, and the contents (and concentration thereof) of the solution.

[0073] The potential difference may be applied for any suitable period of time as the compound of Formula (I) will begin to be synthesised almost immediately. For example, the potential difference may be applied for a time of 1 minute or longer, or 15 minutes or longer, such as 30 minutes or longer, or 1 hour or longer. The time may be 24 hours or less, such as 12 hours or less, or 6 hours or less, for example 4 hours or less or 3 hours or less. The time may be from 1 minute to 24 hours, such as from 30 minutes to 6 hours.

[0074] The process may include terminating the potential difference, i.e. ceasing the subjection of the solution to the potential difference, for example when the compound according to Formula (I) has formed or after a particular time period has elapsed.

[0075] The potential difference may be applied across two or more electrodes, including a cathode and an anode. The two or more electrodes that are in contact with (e.g. submerged in) the reaction solution, or with at least one of the reaction solution and counter solution if a membrane is present. It will be understood that the electrodes should be electrically isolated from one another, other than via the solution or solutions and membrane. The electrodes may be made from any electrically conductive material. The skilled person will be aware of a variety of materials suitable for use as electrodes. For example, the electrodes may each be made of a material selected from the list consisting of graphite (e.g. coated graphite, such as SnC -coated graphite), glassy carbon (e.g. reticulated vitreous carbon), tin, cadmium, magnesium, stainless steel, zinc, copper, platinum, gold, rhodium, lead, copper, nickel (e.g. nickel foam or nickel mesh), palladium and / or silver. For example, the electrodes may each be made of a material selected from the list consisting of graphite, glassy carbon (e.g. reticulated vitreous carbon), magnesium, stainless steel, zinc, copper, platinum, gold, rhodium, lead, copper, nickel (e.g. nickel foam), palladium and / or silver. The electrodes may each be coated onto (i.e. supported on) a substrate such as ceramic, glass, alumina, plastic, or, preferably, graphite. The electrodes may each be gas diffusion electrodes. One or more plasma electrodes may be used. Plasma electrodes may be used independently of or in combination with one or more solid phase electrodes. Plasma electrodes are described by Bruggeman et al., 20 \ Plasma Sources Sci. Technol. 25 Q53QQ2 (DOI: 10.1088 / 0963-0252 / 25 / 5 / 053002). The electrodes may each be made of the same material or may be made of different materials.

[0076] Preferably at least one electrode (e.g. the anode) is made of a material selected from the list consisting of graphite, copper, copper-coated graphite, and zinc-coated graphite. Preferably at least one electrode (e.g. the anode) is made of a material selected from the list consisting of copper, copper-coated graphite, and zinc-coated graphite.

[0077] Preferably at least one electrode (e.g. the cathode) is made of a material selected from the list consisting of graphite and copper-coated graphite. More preferably one electrode (e.g. the anode) is copper and another electrode (e.g. the cathode) is graphite, or one electrode (e.g. the anode) is copper-coated graphite and another electrode (e.g. the cathode) is copper-coated graphite, or one electrode (e.g. the anode) is copper-coated graphite and another electrode (e.g. the cathode) is graphite, or one electrode (e.g. the anode) is zinc-coated graphite and another electrode (e.g. the cathode) is graphite. Preferably the anode is graphite, copper or stainless steel, and most preferably the anode is graphite. Preferably the cathode is graphite. Preferably the anode and the cathode are graphite. The process may include adding a carbonyl group-containing molecule, such as acetone, to the reaction solution, or the process may require that the reaction solution comprises a carbonyl group-containing molecule, before the potential difference is applied. The carbonyl group-containing molecule may not be a compound according to Formula (I) or (II).

[0078] The carbonyl group-containing molecule may be added (or contained) in an amount, relative to the compound of Formula (II), of lmol% or more, 2mol% or more, 5mol% or more, 10 mol% or more, or 20 mol% or more, or 50 mol% or more, or 75 mol% or more. The amount may be 5000 mol% or less, such as 2000 mol% or less, preferably 1000 mol% or less, more preferably 800 mol% or less, or 600 mol% or less, or 500 mol% or less, or 200 mol% or less, such as 150 mol% or less. For example, the carbonyl group-containing molecule may be added in an amount of from 1 mol% to 5000 mol%, or from 10 mol% to 1000 mol%, such as from 20 mol% to 500 mol%, or from 50 mol% to 200 mol%, or from 75 mol% to 150 mol% relative to the compound of Formula (II). It will be understood that an amount of 100 mol% would indicate that equimolar amounts of the carbonyl group-containing molecule and the compound of Formula (II) are present in the reaction solution. The option to include a carbonyl group-containing molecule in the reaction solution is most beneficial where both X groups in the compound of Formula (II) are not O, e.g. where one X group is O and the other X group is NRY, or where both X groups are NRY.

[0079] The carbonyl-group containing molecule may be a compound represented by Formula (HI):

[0080] Formula (III)

[0081] The options described above for the R4to R6groups of Formula (I) apply equally to the groups in Formula (III) with the same designation (e.g. R4of Formula (I) corresponds with R4of Formula (III)). In one embodiment the compound of Formula (III) has 40 carbon atoms or fewer, such as 30 carbon atoms or fewer, or 20 carbon atoms or fewer, preferably 15 carbon atoms or fewer, such as 10 carbon atoms or fewer, for example 7 carbon atoms or fewer, more preferably 5 carbon atoms or fewer. For example, the compound of Formula (III) may have from 2 to 40 carbon atoms, or from 2 to 20 carbon atoms, such as from 3 to 10 carbon atoms, or from 3 to 5 carbon atoms. For example, the carbonyl group-containing molecule may be acetone (CAS 67-64-1, propan-2-one). Acetone corresponds to Formula (III) wherein R4is hydrogen, R5is hydrogen, and R6is methyl. In preferred embodiments the carbonyl-group containing molecule is acetone and the acetone is bioderived and / or green acetone.

[0082] The amount of the carbonyl group-containing molecule, such as the compound of Formula (III) (e.g. acetone), in the reaction solution, relative to the total volume of the solution, may be 0.1 vol% or more, such as 0.5 vol% or more, preferably 1.0 vol% or more, such as 2.0 vol% or more, or 5.0 vol% or more, for example 8.0 vol% or more. The amount of the compound of Formula (III) (e.g. acetone) in the solution, relative to the total volume of the solution, may be 50 vol% or less, such as 40 vol% or less, or 30 vol% or less, preferably 20 vol% or less, such as 15 vol% or less, or 12 vol% or less. For instance, the amount may be from 0.1 to 50 vol%, or from 1.0 to 20 vol%.

[0083] However, while a carbonyl group-containing molecule, such as a compound of Formula (III), may be added to or comprised by the reaction solution, most preferably the reaction solution does not initially include such a molecule, and / or such a molecule is not added to the solution as this can be synthesised by the potential difference.

[0084] The reaction solution (initially) comprises a compound according to Formula (II) in a solvent. The reaction solution may comprise any suitable diluent, such as water, A,A-dimethylformamide, acetonitrile, tetrahydrofuran, dimethylsulfoxide, 1,2-dimethoxyethane, and / or dichloromethane.

[0085] The diluent may be a water miscible diluent, water miscible diluents include Ci to Cio alcohols including methanol, ethanol and isopropanol, glycols including ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether and 1 -methoxy - 2-propanol, CeCN, THF, DMSO, DMF, acetone, ethyl methyl ketone, butyl acetate, xylene, and l-methoxy-2-propanol. The diluent in some embodiments may comprise a compound represented by Formula (III), that is the compound represented by Formula (III) may serve as both a reagent and a diluent. The term "water-miscible organic solvent" denotes an organic solvent that forms a homogeneous liquid phase with water.

[0086] The diluent may be present in an amount of 1 vol% or more, such as 5 vol% or more, or 10 vol% or more, for example 20 vol% or more, or 40 vol% or more. The amount of diluent may be 70 vol% or less, such as 50 vol% or less, or 30 vol% or less, such as 20 vol% or less, or 10 vol% or less. For example, the amount of diluent may be from 1 to 70 vol%, such from 5 to 50 vol%, or from 10 to 40 vol%.

[0087] The reaction solution is preferably an aqueous solution, i.e. it preferably contains water. The solution may include water in an amount of 30 vol% or more, such as 50 vol% or more, or 70 vol% or more, preferably 90 vol% or more, such as 95 vol% or more. The solvent may contain water in an amount of from 50 to 99 vol%, such as from 50 to 98 vol%, or from 50 to 95 vol%, such as from 70 to 90 vol%.

[0088] Transition Metal Salt

[0089] The reaction solution may comprise a transition metal salt. The transition metal salt catalyses the reaction and improves the yield of compounds of Formula (I). The transition metal salt also allows lower purity sources of compounds of Formula (II) to be converted into compounds of Formula (I) in high yield.

[0090] The transition metal may have an oxidation state of (I), (II), or (III). The transition metal salt may be a metal halide salt, a metal triflate salt, a metal sulfate salt, a metal sulfite salt, a metal phosphate salt, a metal phosphite salt, a metal hydroxide salt, or a combination thereof. For example, the transition metal salt may be a copper or nickel halide salt, a copper or nickel triflate salt, a copper or nickel sulfate salt, a copper or nickel sulfite salt, a copper or nickel phosphate salt, a copper or nickel phosphite salt, a copper or nickel hydroxide salt, or a combination thereof. In a preferred embodiment the anion is a triflate ((OSO2CF 2 ) anion or a halide anion, most preferably a triflate anion.

[0091] The transition metal salt may be a vanadium salt, a chromium salt, a manganese salt, an iron salt, a cobalt salt, a nickel salt, a copper salt, a zinc salt, a silver salt, a gold salt or a combination thereof. Preferable, the transition metal salt is selected from cobalt salts, nickel salts, copper salts, silver salts or gold salts or a combination thereof. In a most preferred embodiment the transition metal salt is a copper salt, such as a copper (II) salt.

[0092] The transition metal salt may be selected from CuX2, NiX2, Cu(OSO2CF3)2, NiSC , NiX2, FeX3or a combination thereof, wherein X is a halide selected from fluoride, chloride, bromide or iodide. Preferably the transition metal salt comprises CuX2, NiX3, Cu(OSO2CF3)2, NiSC , NiX2, FeX3, or a combination thereof, and most preferably CuX2, CU(OSC>2CF3)2. In some embodiments, the reaction solution comprises a transition metal salt such as CuX3or Cu(OSC>2CF3)2 and an alkali metal salt such as KX or NaX.

[0093] Where an ion permeable membrane is also present the transition metal salt in the reaction solution is preferably a copper metal salt.

[0094] The transition metal salt may be present in the reaction solution in a concentration of 0.01 M or greater, such as 0.02 M or higher, or 0.05 M or higher, 0.1 M or higher, 0.2 M or higher, or 0.4 M or higher. The transition metal salt may be present in the reaction solution in a concentration of 5 M or less, such as 4 M or less, 3 M or less, 2 M or less, 1 M or less, 0.9 M or less, 0.8 M or less or 0.7 M or less. The transition metal salt may be present in a concentration of from 0.01 to 5 M, such as from 0.05 to 2M or from O. lM to IM. Therefore, in one embodiment the reaction solution comprises copper salt, such as a copper (II) salt, in an amount of from 0.05 to 2M.

[0095] In some embodiments the reaction solution further comprises an inorganic salt selected from the list consisting of a salt (e.g. halide) of a group 1 or group 2 metal, such as lithium, sodium, potassium, rubidium, beryllium, magnesium, calcium, strontium and / or barium at a concentration of from 0.01 to 10M, such as from 0.02 to 9 M, from 0.03 to 8 M, from 0.04 to 0.7M, from 0.05 to IM or from 0.2 to 0.8M. In a preferred embodiment, the counter solution is an aqueous solution comprising from 0.05 M to 0.2 M of a potassium halide salt.

[0096] Permeable Ion Membrane

[0097] The reaction solution may comprise a permeable ion membrane. The permeable ion membrane physically separates the anode form the reaction solution. The anode is therefore immersed in a counter solution. The permeable ion membrane allows ions, such as H+ions to pass between the two solutions. The cathode may be immersed in the reaction solution.

[0098] The permeable ion membrane may be a cation exchange membrane such as a proton exchange membrane. For example, the permeable ion membrane may be a perfluorinated cation-exchange membrane.

[0099] The counter solution may be an aqueous solution. The counter solution may comprise an inorganic salt (e.g. the inorganic salt may be added to the solution, preferably before the application of the potential difference to the solution). Preferably the inorganic salt is a salt of a group 1 or group 2 metal, such as lithium, sodium, potassium, rubidium, beryllium, magnesium, calcium, strontium and / or barium. Preferably the inorganic salt is a salt of a group 1 metal, such as lithium, sodium, potassium, and / or rubidium. More preferably the inorganic salt is a salt of sodium and / or potassium. The inorganic salt may be a metal halide salt, such as a group 1 or group 2 metal halide salt. The halide may be fluoride, chloride, bromide or iodide, preferably fluoride, chloride or bromide, more preferably chloride. In a preferred embodiment, the inorganic salt is a potassium halide, most preferably potassium chloride.

[0100] The inorganic salt may be included in the counter solution at a concentration of 0.0 IM or higher, such as 0.02M or higher, or 0.05M or higher, preferably 0.1M or higher, or 0.2M or higher, such as 0.4M or higher. The inorganic salt may be included in the solution at a concentration of 10M or lower, such as 5.0M or lower, such as 2.0M or lower, preferably 1 ,5M or lower, or 1 ,0M or lower, such as 0.8M or lower. The inorganic salt may be included in the solution at a concentration of from 0.01 to 10M, such as from 0.05 to 2.0M, or from 0.1 to 1.0M, preferably from 0.2 to 0.8M.

[0101] In some embodiments the counter solution contains an inorganic salt selected from the list consisting of a salt (e.g. halide) of a group 1 or group 2 metal, such as lithium, sodium, potassium, rubidium, beryllium, magnesium, calcium, strontium and / or barium at a concentration of from 0.01 to 10M, such as from 0.02 to 9 M, from 0.03 to 8 M, from 0.04 to 0.7M, from 0.05 to IM or from 0.2 to 0.8M. In a preferred embodiment, the counter solution is an aqueous solution comprising from 0.05 M to 0.2 of a potassium halide salt. The counter solution may comprise organic solvents, such as Ci-Cio alcohols. In some embodiments the organic solvent is methanol, ethanol, propanol or butanol.

[0102] In some embodiments, protons are generated in the counter solution by the application of the potential difference. Where the counter solution comprises water or is aqueous, this proton generation proceeds with the concomitant release of oxygen. The generated protons pass through the ion exchange membrane and participates in the conversion of compounds of Formula (II) to compounds of Formula (I) as exemplified in Schematic (I) showing the conversion of glycol to solketal.

[0103] Schematic (I)

[0104] Carbon Dioxide

[0105] Preferably the reaction solution comprises and / or is contacted with carbon dioxide. Without being bound by theory it is thought that the carbon dioxide dissolves to provide carbonate ions, which assist the process. This provides a use for this fossil fuel byproduct.

[0106] The reaction solution may be substantially saturated (e.g. 90% saturated or more, or 95% saturated or more, or 99% saturated or more, by weight) with carbon dioxide prior to the solution being subjected to the potential difference. Carbon dioxide may be bubbled through the solution while it is being subjected to the potential difference. A stream of carbon dioxide may be passed through and / or over the solution. For example, the stream of carbon dioxide may include carbon dioxide at a concentration of 1 vol% or higher, such as 10 vol% or higher, or 50 vol% or higher, or 90 vol% or higher. It will be appreciated that the process does not require high pressures but that, nevertheless, high pressures may be used. The carbon dioxide may therefore be provided (e.g. whilst the potential difference is applied) at a pressure of 50kPa or higher, preferably 80kPa or higher, or 90kPa or higher, such as lOOkPa or higher, or at a pressure of 5MPa or less, such as 2MPa or less, or IMPa or less, for example 500kPa or less, or 300kPa or less, preferably 200kPa or less, such as 150kPa or less, or 120kPa or less. For example, the pressure may be from 50kPa to 5MPa, for example from 80kPa to IMPa, for example from 90kPa to 200kPa.

[0107] In some preferred embodiments a stream of carbon dioxide is continuously introduced to the reaction solution. This embodiment is particularly beneficial when the reaction is performed in a flow reactor. Therefore, in some particularly preferred embodiments an ion membrane is present physically separating the reaction solution from the anode and carbon dioxide is continuously introduced to the reaction mixture whilst reaction solution is subjected to the potential difference. The carbon dioxide may be continuously introduced to the reaction solution through a gas diffusion electrode.

[0108] Carbon dioxide may be continuously introduced to the reaction solution, for example during the application of the potential difference in an amount of .01 SCCM (standard cubic centimetres per minute) per mb of reaction volume (i.e. SCCM / mL) or more, such as 0.05 SCCM / mL or more, preferably 0.1 SCCM / mL or more, or 0.5 SCCM / mL or more, for example 1 SCCM / mL or more, or 1.5 SCCM / mL or more. The amount may be 100 SCCM / mL or less, such as 50 SCCM / mL or less, 30 SCCM / mL or less, 20 SCCM / mL or less or 10 SCCM / mL or less, for example 5 SCCM / mL or less, or 4 SCCM / mL or less, such as 3 SCCM / mL or less. The amount may be from 0.01 SCCM / mL to 100 SCCM / mL, such as from 0.1 SCCM / mL to 50 SCCM / mL.

[0109] As noted above, it has been observed that formic acid is generated under the reaction conditions, which may be generated by the electrochemical reduction of carbon dioxide.

[0110] The reaction solution and or the counter solution may comprise an oxidising agent, such as a peroxide, e.g. hydrogen peroxide. The oxidising agent, such as hydrogen peroxide, may facilitate the formation of an acidic agent such as formic acid from the carbon dioxide. Alternatively or additionally, the oxidising agent, such as hydrogen peroxide, may be reduced to provide a source of protons under the electrochemical conditions, which may catalyse the process (e.g. the condensation of the compound of Formula (I) with the compound of Formula (III)). The amount of oxidising agent, such as hydrogen peroxide, in the solution, relative to the total volume of the solution, may be 0.1 vol% or more, such as 0.5 vol% or more, preferably 1.0 vol% or more, such as 2.0 vol% or more, or 3.0 vol% or more, for example 4.0 vol% or more. The amount of the oxidising agent (e.g. hydrogen peroxide) in the solution, relative to the total volume of the solution, may be 50 vol% or less, such as 40 vol% or less, or 30 vol% or less, preferably 20 vol% or less, such as 15 vol% or less, or 12 vol% or less, e.g. 10 vol% or less, such as 8 vol% or less, or 5 vol% or less. For instance, the amount may be from 0.1 to 50 vol%, or from 1.0 to 20 vol%. The skilled person will be aware of other means to provide an acidic agent (such as formic acid) or protons to the solution, which may be used as an alternative to oxidising agents such as hydrogen peroxide.

[0111] Conditions

[0112] It will be appreciated that the process does not require high pressures but that, nevertheless, high pressures may be used. The pressure (of the reaction solution), whilst the potential difference is applied, may be 50kPa or higher, preferably 80kPa or higher, or 90kPa or higher, such as lOOkPa or higher, or of 5MPa or less, such as 2MPa or less, or IMPa or less, for example 500kPa or less, or 300kPa or less, preferably 200kPa or less, such as 150kPa or less, or 120kPa or less. For example, the pressure may be from 50kPa to 5MPa, for example from 80kPa to IMPa, for example from 90kPa to 200kPa.

[0113] Separation

[0114] The process may include isolating the product, for example by extraction (e.g. liquid / liquid extraction), filtration and / or distillation. For example, the product may be isolated from other components of the rection solution (e.g. unreacted compounds according to formula (II) and / or transition metal salts) following the application of the potential difference by liquid / liquid extraction, distillation and / or filtration.

[0115] In some embodiments, isolation of the product is achieved by flash separation (e.g. using a flash separator) where diluents such as acetone with trace water are vaporized and recovered and the Formula (I) (e.g. solketal) stream was collected.

[0116] In some embodiments, the non-product materials recovered from the reaction solution are reused in the claimed process. This is enabled by the tolerance of the process to impure / crude sources of compounds of Formula (II). In some embodiments, the isolation step is a flow isolation step.

[0117] Reactor

[0118] The process can be performed in one or more reactors, or modules thereof.

[0119] A batch reactor may be used to perform the process. Examples of batch reactors include test tubes, round bottomed flasks and large scale (e.g. 100L or more) reaction vessels.

[0120] A flow reactor may be used to perform the process. The reaction solution is continuously fed into a reaction chamber containing a cathode and separated from a counter chamber by a permeable ion membrane. The counter chamber contains an anode and a counter solution as defined above. A potential difference is passed through the reaction solution between the cathode and the anode. One the potential difference has been applied, the reaction solution exits the reaction chamber. The counter solution may also be continuously fed into the counter chamber during the process.

[0121] Applications

[0122] It will be appreciated that the compounds of Formula (I) obtainable by the process of the first aspect, as defined by the second aspect, and the compositions of the third aspect will find application in a variety of fields, and can be incorporated into a variety of products. The compound of Formula (I) may be part of a composition. For example, the compounds of Formula (I) may be contained in a product that is: a) a solvent; b) a fuel, for example a liquid petroleum fuel, such as gasoline (petrol), diesel and / or kerosene; c) a pharmaceutical intermediate; d) an air care product, for example a fragrance diluent, base or carrier, such as for an air freshener (e.g. a plug-in air freshener, a diffuser, or a spray) or a candle; e) a paint or varnish, such as an epoxy resin, for example for application to automobiles, metal and / or wood; f) an ink, such as a printing ink; g) a cleaning agent, such as a household or institutional cleaning agent, for example a surface cleaning agent and / or a degreaser; and / or h) a leather treatment agent, for example a penetrating agent, an adhesion promoter, a dye diluter, and / or a lacquer for paint.

[0123] It will be understood that the compounds of Formula (I) may be used in such products. The compound of Formula (I) may be present in the product in an amount of 1 wt% or more, such as 5 wt% or more, or 10 wt% or more, for example 20 wt% or more, or 50 wt% or more. The amount may be from 1 wt% to 100 wt%, such as from 2 wt% to 99 wt%, or from 5 wt% to 95 wt%, for example from 10 wt% to 90 wt%, or from 20 wt% to 80 wt%.

[0124] Brief Description of the Drawings

[0125] Figure 1 shows an example of a batch reactor that can be used to perform the process of the present invention;

[0126] Figure 2 illustrates a schematic of a suitable exemplary flow reactor;

[0127] Figure 3 illustrates a suitable exemplary flow reactor;

[0128] Figure 4 shows Gas Chromatography - Flame Ionisation Detection (GC-FID) traces following the conversion of glycerol to solketal. (A) shows identification of Standard Solketal and its isomer Acetal on GC-FID employing stabilwax column. (B) shows identification of Standard Glycerol on GC-FID employing stabilwax column. (C) shows post-reaction analysis on GC-FID employing stabilwax column;

[0129] Figure 5 illustrates the formation of solketal and the consumption of glycerol over time.

[0130] Detailed Description of the Drawings

[0131] Figure 1 of the accompanying drawings shows an example of a batch reactor that can be used to perform the process of the present invention. This shows a carbon dioxidesaturated aqueous reaction solution of glycerol and copper (II) chloride 102, a magnetic stir bar (flea) 104 used to stir the reaction mixture, a copper-coated graphite electrode 106, and an uncoated graphite electrode 108, which is preferably a renewable energy power source. Figure 2 of the accompanying drawings illustrates a suitable exemplary flow reactor 200. The flow reaction includes cathode 202 and anode 204. Cathode 202 is present in reaction chamber 206 through which the reaction solution comprising glycerol 212 can flow. The flow reaction 200 further comprises counter chamber 208 comprising the counter solution. The counter chamber and the reaction chamber are separated by ion permeable membrane 210. The flow reaction further comprises power source 214. A potential difference is applied across the reaction and counter solutions between the cathode and the anode by power source 214.

[0132] Figure 3 of the accompanying drawings illustrates a suitable exemplary flow reactor 300. The reactor 300 comprises a gas chamber 302 through which CO2 can flow in through inlet 324 and tail gas can exit at outlet 326. Current collector 308 and cathode 310 are held between plates 322. The cathode is a permeable cathode through which CO2 can pass to the reaction chamber 304. Reaction chamber 304 comprises an inlet 328 through which reaction solution can pass into the reaction chamber and outlet 324 through which the reaction product can exit the reaction chamber. The interior of the reaction chamber is in fluid communication with the ion permeable membrane 316, which separates the reaction chamber from the 306, with which the ion permeable membrane 316 is also in fluid communication. The counter chamber may comprise the counter solution. Outlets 328 are provided to vent gases, for example oxygen, formed by the conversion of compounds according to Formula (II) to compounds according to Formula (I). The reaction further comprises reference electrode 312.

[0133] Figure 4 of the accompanying drawings shows Gas Chromatography - Flame Ionisation Detection traces following the conversion of glycerol to solketal. (A) shows identification of Standard Solketal and its isomer Acetal on GC-FID employing stabilwax column. (B) shows identification of Standard Glycerol on GC-FID employing stabilwax column. (C) shows post-reaction analysis on GC-FID employing stabilwax column. The presence of solketal following the application of a potential difference can be seen. 1,4 dioxane is used in all traces as an internal standard. The present disclosure comprises the subject-matter of the following clauses: l .A process for synthesising a compound according to Formula (I):

[0134] Formula (I) wherein the process comprises: subjecting a reaction solution comprising a compound according to Formula (II):

[0135] Formula (II) to a potential difference applied across two or more electrodes, wherein, for the compounds according to Formulae (I) and (II): each X is independently selected from the group consisting of O, S, NRYand PRY, each of R1to R6and RYis a group selected from the list consisting of hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, Ce- C12 aryl, and C3-C12 heterocyclyl, each of R1to R6and RYoptionally contains one or more heteroatom containing groups, and wherein Formulae (I) and (II) include tautomeric and stereochemically isomeric forms thereof. Wherein the reaction solution is separated from the anode by an ion exchange membrane and / or comprises a transition metal salt.

[0136] 2. The process of clause 1, wherein the transition metal salt has an oxidation state of (I), (II), or (III), and / or wherein the transition metal salt is selected from vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, silver or gold salts or combinations thereof.

[0137] 3. The process of any one of the preceding clauses, wherein the wherein the anions of the transition metal salt are halogens, triflates, sulfates, sulfites, phosphates, phosphite, hydroxides or combinations thereof. 4. The process of any one of the preceding clauses wherein the transition metal salt is selected from cobalt, nickel, copper, silver or gold salts or combinations thereof, optionally wherein the transition metal salt is selected from nickel salts, copper salts or a combination thereof.

[0138] 5. The process of any one of the preceding clauses wherein the transition metal salt is CuX2. NiX2, CU(OSO2CF3)2, NiSC , NiX2, FeXs, or a combination thereof, optionally CuX2, CU(OSO2CF3)2or a combination thereof, wherein X is selected from fluoride, chloride, bromide or iodide.

[0139] 6. The process of any one of the preceding clauses, wherein the transition metal salt is present in a concentration of from 0.01 to 5 M.

[0140] 7. The process of any one of the preceding clauses, wherein the reaction solution is separated from the anode by an ion exchange membrane and the ion exchange membrane is a cation exchange membrane, optionally a perfluorinated cation-exchange membrane.

[0141] 8. The process of clause 7, wherein the anode is immersed in a counter solution, and the counter solution is separated from the reaction solution by the ion exchange membrane, wherein optionally the counter solution is an aqueous solution.

[0142] 9. The process of clause 8, wherein the counter solution comprises a group 1 or group 2 metal halide, optionally potassium halide.

[0143] 10. The process of any one of the preceding clauses, wherein the reaction solution comprises a group 1 or group 2 metal halide, optionally potassium halide.

[0144] 11. The process of any one of the preceding clauses, wherein the reaction solution comprises and / or is contacted with carbon dioxide and / or wherein the pressure whilst the potential difference is applied is 5MPa or less.

[0145] 12. The process of any one of the preceding clauses wherein the potential difference is applied across two or more electrodes that are in electronic communication with the solution, and wherein the electrodes are made of a material selected from the list consisting of graphite, zinc, copper, platinum, aluminium, magnesium, niobium, tungsten, stainless steel, titanium, gold, rhodium, lead, copper, nickel, palladium, silver or alloys thereof or nickel foam, wherein optionally the material is coated onto a substrate.

[0146] 13. The process of any one or the preceding clauses, wherein each of R1to R6and RYis a group selected from the list consisting of hydrogen, Ci-Cs alkyl, C2-Cs alkenyl, C2Cx alkynyl, Ce-Cs aryl, and C4-C8 heterocyclyl.

[0147] 14. The process of clause 13, wherein each of R1to R6and RYis a group selected from the list consisting of hydrogen and C1-C4 alkyl. 15. The process of any one or the preceding clauses, wherein X is O.

[0148] 16. The process of any one of the preceding clauses, wherein the or each heteroatom containing group is an alcohol.

[0149] 17. The process of any one of clauses 13 to 16, wherein the compound according to Formula (I) is solketal:

[0150] 18. The process of any one of clauses 13 to 16, wherein the compound according to Formula (II) is glycerol:

[0151] 19. The process of any one of the preceding clauses, wherein the process comprises isolating the compound according to Formula (I), wherein optionally the compound according to Formula (I) is isolated by extraction, filtration and / or distillation.

[0152] 20. The process of any one of the preceding clauses, wherein unreacted starting materials are recovered and returned to the process and / or, wherein the reaction solution is homogenised, optionally by stirring at 15000 to 30000 rpm.

[0153] 21. The process of any one of the preceding clauses, wherein the compound of Formula (II) is provided to the reaction solution in a crude mixture comprising 0.01% or more of glycerol.

[0154] 22. The process of any one of the preceding clauses, wherein the reaction solution comprises diluent selected from water miscible solvents, optionally selected from Cl to CIO alcohols, glycols including ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether and l-methoxy-2-propanol, CeCN, THF, DMSO, DMF, acetone, ethyl methyl ketone, butyl acetate, xylene, and 1 -methoxylpropanol.

[0155] 23. A compound of Formula (I), as defined by any one of the preceding clauses, wherein the compound is obtainable by the process according to any preceding clause. 24. A composition comprising a compound of Formula (I), as defined by any one of clauses 1 and 13 to 17, wherein the composition: is obtainable by the method of any one of clauses 1 to 22; and / or comprises a by-product characteristic of the method of any one of clauses 1 to 30, wherein optionally the by-product product has the molecular formula C7H12O2 and / or is formic acid.

[0156] 25. A product comprising a compound of clause 23 or a composition of clause 24, wherein the product is: a) a solvent; b) a fuel; c) a pharmaceutical intermediate; d) a pharmaceutical carrier; e) an air care product; f) a paint or varnish; g) an ink; h) a cleaning agent; and / or i) a leather treatment agent.

[0157] Examples

[0158] Example 1 Synthesis of solketal - Flow Protocol

[0159] In the cathode chamber of a divided electrochemical reactor, 10 m of a solution containing crude glycerol 1 (2.05 g, 72.6%), 2 Ethanol 99.97% (3.945 g, 5.0 mL),3 CuCh (100 mg, 0.743 mmol) was dissolved and completed to 10 m with acetone 99.8% (2.95 m ).

[0160] At the gas chamber compartment, a stream of CO2 (20 SCCM) was continuously introduced through 2.61 cm2, 250 microns thickness, 8 mQcm2carbono fiber paper PN- 1590034 obtained from BS Holdings Etd working as gas diffusion electrode (GDE), the GDE was attached on a stainless-steel thin metal sheet current collector.

[0161] At the anode chamber equipped with Titanium (Ti) mesh coated with Platinum (Pt) sheet current collector from GoodFellows, an aqueous solution of KC1 (0.1 mol / E) was continuously introduced with a flow of 0.217 mb / min.

[0162] An 8.42 cm2Fumapen F-1050 Cation Exchange membrane PN-5041733 from FuelCellStore was dividing anode (counter) and cathode (reaction) chamber. Current collector from anode and cathode was connected to a DC power supply at constant voltage. The potential difference applied was 3V.

[0163] At the end of the reaction, the separation was promoted by a flash separator, where acetone with trace water was vaporized and recovered and the solketal stream was collected. Example 2 - Synthesis of solketal for Reaction Tracking

[0164] In a single 10 mL electraSyn 2.0 Ident No. : 0020008980 vial equipped with 6.3 cm2Carbon electrode working as cathode and anode. A solution containing crude glycerol 1 (1.6 g, 72.6%), 2 EthanoL 99.97% (2.0 g, 2.5 mL),3 CuCl2(100 mg, 0.743 mmol) was dissolved and completed to 10 mL with acetone 99.8% (6.4 mL). A stream of CO2 (20 SCCM) was continuously introduced through the mixture until the end of reaction. 3.0 V direct current was applied to the system giving around 6 mA for 2 h.

[0165] At the end of the reaction, the separation was promoted by a flash separator, where acetone with trace water was vaporized and recovered and the solketal stream was collected.

[0166] Glycerol Acetone Solketal Acetal

[0167] Gas Chromatography was employed to monitor the experiments. An Agilent HP GC system 6890 series fitted with a Stabilwax-MS GC Column 30 m x 0.25 mm (L x I.D.), df 0.25 pm.

[0168] Programmed with an initial oven temperature of 40 °C for 1 min, oven program rate of 30 °C min-l up to 250 °C and hold for 3 min. Injection and detector temperature of 260 °C. The shift is given by retention time (min) and Voltage (V). Split liner was employed with ratio of 30: 1 .

[0169] Figure 4C shows the post reaction analysis on GC-FID employing stabilwax column. The formation of solketal along with the acetal by-product. Unreacted glycerol from the crude glycerol starting material can also be seen.

[0170] Example 3 - Synthesis of Solketal to Study Reaction Conditions

[0171] A series of reaction conditions were investigated. The experimental procedure was the same as for Example 2. The reaction conditions and outcomes are shown in Table 1 below. Example 4 - Synthesis of Solketal to Study Conversion

[0172] Reaction conditions: 10 mL of solution containing 1.6 g of crude glycerol (72.6%); 2 g

[0173] IPA; 6.4 g acetone; 46 mg Copper (II) triflate; 10 SCCM of CO2. 25 mA was applied giving 4.8 V at 500 rpm.

[0174] Set up: Electrasyn equipped with 6.3 cm2Carbon electrode working as cathode and anode. Figure 5 shows a reduction in the concentration of glycerol in the reaction solution, and the concomitant production of solketal, over the course of the reaction.

[0175] Table 1

Claims

CLAIMS1. A process for synthesising a compound according to Formula (I):Formula (I) wherein the process comprises subjecting a reaction solution comprising a compound according to Formula (II):Formula (II) to a potential difference applied across two or more electrodes, wherein: for the compounds according to Formulae (I) and (II):- each X is independently selected from the group consisting of O, S, NRYand PRY,- each of R1to R6and RYis a group selected from the list consisting of hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C6-C12 aryl, and C3-C12 heterocyclyl, and- each of R1to R6and RYoptionally contains one or more heteroatom containing groups,Formulae (I) and (II) include tautomeric and stereochemically isomeric forms thereof, and the reaction solution is separated from the anode by an ion exchange membrane.

2. The process of claim 1, wherein the reaction solution comprises a transition metal salt.

3. The process of claim 1 or claim 2, wherein the transition metal salt is a salt of a metal selected from the list consisting of vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, silver and gold.

4. The process of claim 3, wherein the transition metal salt is a nickel salt or a copper salt.

5. The process of any one of the preceding claims wherein the transition metal salt is a copper(II) salt.

6. The process of any one of the preceding claims, wherein the wherein the or each anion of the transition metal salt is selected from the list consisting of halogen, triflate, sulfate, sulfite, phosphate, phosphite and hydroxide.

7. The process of any one of the preceding claims, wherein the transition metal salt is present in a concentration of from 0.01 to 5 M.

8. The process of any one of the preceding claims, wherein the ion exchange membrane is a cation exchange membrane.

9. The process of any one of the preceding claims, wherein the reaction solution further comprises a carbonyl group-containing molecule.

10. The process of claim 9, wherein the carbonyl group-containing molecule is a compound represented by Formula (III):Formula (III), wherein R4-R6are as defined for Formula (I).

11. The process of claim 10, wherein the carbonyl group-containing molecule is acetone.

12. The process of any one of claims 9 to 1 1, wherein the reaction solution contains the carbonyl group-containing molecule in an amount, relative to the compound of Formula (II), of 1000 mol% or less.

13. The process of any preceding claim, wherein the anode is in contact with a counter solution that is separated from the reaction solution by the ion exchange membrane, and that comprises a group 1 or group 2 metal halide.

14. The process of any one of the preceding claims, wherein the reaction solution comprises and / or is contacted with carbon dioxide and / or wherein the pressure whilst the potential difference is applied is 5MPa or less.

15. The process of any one of the preceding claims wherein the potential difference is applied across two or more electrodes that are in electronic communication with the solution, and wherein the electrodes are made of a material selected from the list consisting of graphite, zinc, copper, platinum, aluminium, magnesium, niobium, tungsten, stainless steel, titanium, gold, rhodium, lead, copper, nickel, palladium, silver or alloys thereof or nickel foam.

16. The process of any one or the preceding claims, wherein each of R1to R6and RYis a group selected from the list consisting of hydrogen, Ci-Cs alkyl, C2-C8 alkenyl, C2 Cg alkynyl, Ce-Cg aryl, and C4-C8 heterocyclyl.

17. The process of claim 16, wherein each of R1to R6and RYis a group selected from the list consisting of hydrogen and C1-C4 alkyl.

18. The process of any one or the preceding claims, wherein X is O.

19. The process of claim 18, wherein the reaction solution further comprises:- a copper(II) salt; and- a carbonyl group-containing molecule represented by Formula (III), as defined by claim 10.

20. The process of any one of the preceding claims, wherein the or each heteroatom containing group is an alcohol.

21. The process of any one of claims 16 to 20, wherein the compound according to Formula (I) is solketal.

22. The process of any one of claims 16 to 21, wherein the compound according to Formula (II) is glycerol.

23. The process of claim 22, wherein:- the ion exchange membrane is a cation exchange membrane;- the compound according to Formula (I) is solketal; and- the reaction solution further comprises:- a copper(II) salt, and- acetone.

24. A composition comprising a compound of Formula (I) as defined by claim 1, wherein the composition:• is obtainable by the process of any preceding claim; and / or• comprises a by-product characteristic of the method of any preceding claim.

25. A product comprising a composition of claim 24, wherein the product is: a) a solvent; b) a fuel; c) a pharmaceutical intermediate; d) a pharmaceutical carrier; e) an air care product; f) a paint or varnish; g) an ink; h) a cleaning agent; and / or i) a leather treatment agent.

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