Process for the preparation of acetals of alpha-chloro- or alpha-bromo-aldehydes

Abstract

The present invention relates to a process for the production of acetals of aliphatic or cycloaliphatic α-chloro- or α-bromoaldehydes, comprising the electrolysis of a liquid reaction mixture containing i) a halogen acceptor selected from - primary aliphatic or cycloaliphatic alcohols, - mono-1-alkyenyl ethers of aliphatic diols and - mixtures comprising a mono-1-alkyenyl ether of an aliphatic, cycloaliphatic or aromatic alcohol and at least one aliphatic or cycloaliphatic alcohol, ii) at least one halogen source containing chlorine or bromine, iii) at least one solvent and iv) at least one conducting salt in an undivided electrolysis cell.

Description

[0001] The present invention relates to a process for the preparation of acetals of aliphatic or cycloaliphatic aldehydes which carry a bromine or chlorine atom in the α-position to the acetal group and which are also referred to below as acetals of α-chloro- or α-bromoaldehydes.

[0002] α-Chloroaldehydes and α-bromoaldehydes, as well as their acetals, are of great commercial interest as they are synthetic building blocks for the production of a wide variety of organic compounds, particularly heterocycles. However, the known production routes are complex and require the use of elemental, highly corrosive bromine or iodine and / or the use of chloroacetaldehyde, which is difficult to handle and toxicologically hazardous.

[0003] The production of acetals of α-chloroaldehydes, e.g. B. of acetals of chloroacetaldehyde, starts from chloroacetaldehyde itself (see K. Natterer, Monatshefte für Chemie und verwandte Teile andere Wissenschaften 1884, 5, 491; DE 102015204901; Z. Wu et al., The Journal of Organic Chemistry 1999, 64, 8386; Li, F. Shi et al., The Journal of Organic Chemistry 2004, 69, 3582L. Shao et al., Applied Catalysis A: General 2012, 443, 133G. Xing, Monatshefte für Chemie-Chemical Monthly 2013, 144, 1369; S. Zhong et al, Journal of the Chilean Chemical Society 2015, 60, 3005; N. Fu et al., J. Am. Chem. Soc. 2017, 139, 15548) or a precursor such as vinyl chloride (US2803668A), 1,2-dichloroethyl acetate (see e.g. US 2330570, US 2411826, US 4532338A), 1-ethoxy-1,2-dichloroethane (A. Lieben, Justus Liebigs Annalen der Chemie 1868, 146, 180) or 1-(2-chloroethoxy)-1,2-dichloroethane (MJ Astle et al., The Journal of Organic Chemistry 1955, 20, 178).These are acetalized by reaction with an alkanol such as ethanol, ethylene glycol, butylene glycol, or with an alkoxide. The starting materials are typically prepared by chlorination with elemental chlorine. Simple acetals of α-chloroaldehydes, e.g., the acetals of chloroacetaldehyde, can also be prepared by chlorination of ethanol with elemental chlorine (P. Fritsch, Justus Liebigs Annalen der Chemie 1894, 279, 288) or by chlorination of ethyl vinyl ether with tert-butyl hypochloride (K. Weissermel et al., Chemische Berichte 1963, 96, 77) or with sulfuryl chloride (J.E. McCormick, R.S. McElhinney, Journal of the Chemical Society, Perkin Transactions 1 1972, 1335). The transacetalization of 1,1-dimethoxy-2-chloroethane has also been described several times (US3940259, US4532338, Diaz-Ortiz et al, Synthetic communications 1993, 23, 1935. Z. Wu et al., The Journal of Organic Chemistry 1999, 64, 8386).

[0004] All synthetic routes are limited to comparatively simple acetals and generally require multi-step syntheses or the use of the toxicologically problematic chloroacetaldehyde. In all cases, the halogen is introduced by reaction with elemental chlorine or bromine or highly corrosive chlorinating agents such as sulfuryl chloride or organohypochlorides.

[0005] The invention is therefore based on the object of providing a simple process for the preparation of acetals of α-chloro- or α-bromoaldehydes, which avoids the disadvantages of the prior art and which is particularly suitable in a general manner for the preparation of a large number of acetals of α-chloro- or α-bromoaldehydes, without the need for toxicologically harmful or corrosive starting materials.

[0006] It has surprisingly been found that the electrolysis of a primary aliphatic or cycloaliphatic alcohol as well as the electrolysis of a mixture comprising a mono-1-alkyenyl ether, in particular a monovinyl ether, of an aliphatic or cycloaliphatic alcohol and at least one aliphatic, cycloaliphatic or aromatic alcohol, with a halogen source containing chlorine or bromine, in a solvent and in the presence of at least one conducting salt in an undivided electrolysis cell leads to a selective formation of acetals of aliphatic or cycloaliphatic aldehydes which carry a bromine or chlorine atom in the α-position to the acetal group.

[0007] Accordingly, the present invention relates to a process for the preparation of acetals of aliphatic or cycloaliphatic α-chloro- or α-bromoaldehydes, comprising the electrolysis of a liquid reaction mixture containing i) a halogen acceptor selected from primary aliphatic or cycloaliphatic alcohols, mono-1-alkyenyl ethers of aliphatic diols and mixtures comprising a mono-1-alkyenyl ether of an aliphatic, cycloaliphatic or aromatic alcohol and at least one aliphatic or cycloaliphatic alcohol, ii) at least one halogen source containing chlorine or bromine, iii) at least one solvent and iv) at least one conducting salt in an undivided electrolysis cell.

[0008] The process according to the invention is associated with a number of advantages. The process according to the invention allows the selective production of a large number of different acetals of aliphatic or cycloaliphatic α-chloro- or α-bromoaldehydes, in particular the production of the acetals of α-chloro- or α-bromoacetaldehyde, in a one-step process, without the need to use toxicologically problematic α-chloro- or α-bromoaldehydes or the need to first prepare halogen-containing precursors such as dichloroethyl acetate, 1-ethoxy-1,2-dichloroethane, and 1-(2-chloroethoxy)-1,2-dichloroethane. Furthermore, the process allows the use of organic chlorine compounds or organic bromine compounds as halogen sources, which would otherwise require complex disposal.Furthermore, the process according to the invention allows the use of electricity as a safe and cost-effective oxidizing and reducing agent, making it an inherently safe process that also generates no significant reagent waste. Furthermore, it allows the convergent use of both electrode reactions.

[0009] Here and in the following, the prefix C n -C m indicates the number of carbon atoms that the compound or organic residue designated by it can have.

[0010] Here and below, "aliphatic" refers to a molecule composed of saturated, non-cyclic organic groups, e.g., alkyl groups, where the alkyl groups are optionally substituted and where one or more, e.g., 1, 2, 3, or 4, non-adjacent C atoms in the alkyl groups may be replaced by O or S. Optionally substituted means that the alkyl group(s) may have one or more substituents selected, for example, from fluorine, chlorine, bromine, CN, OH, alkyl, cycloalkyl, ether groups, carbonyl groups, carboxylic acid groups, carboxylic acid ester groups, and amino groups.

[0011] Here and below, "cycloaliphatic" refers to a molecule consisting of saturated, cyclic organic groups, e.g., cycloalkyl, and given saturated acyclic groups, e.g., alkyl, where cycloalkyl and any alkyl groups present are optionally substituted and where one or more, e.g., 1, 2, 3, or 4, non-adjacent C atoms in cycloalkyl and any alkyl present may be replaced by O or S. Optionally substituted means that cycloalkyl and any alkyl present may have one or more substituents selected, for example, from fluorine, chlorine, bromine, CN, OH, alkyl, cycloalkyl, ether groups, carbonyl groups, carboxylic acid groups, carboxylic acid ester groups, and amino groups.

[0012] Here and below, "aromatic" refers to a molecule composed of aromatically unsaturated organic groups, e.g., aryl and / or hetaryl, and optionally additionally of saturated acyclic groups, e.g., alkyl, or saturated cyclic groups, e.g., cycloalkyl, where aryl and hetaryl and any alkyl and cycloalkyl groups present are optionally substituted, and where one or more, e.g., 1, 2, 3, or 4, non-adjacent C atoms of the cycloalkyl and alkyl groups present may be replaced by O or S. Optionally substituted means that the aryl groups and any cycloalkyl and alkyl groups present may have one or more substituents selected, for example, from fluorine, chlorine, bromine, CN, OH, alkyl, cycloalkyl, ether groups, carbonyl groups, carboxylic acid groups, carboxylic acid ester groups, and amino groups.

[0013] Here and in the following, "alkyl" means a linear or branched, saturated aliphatic hydrocarbon group which preferably has 1 to 10 (C 1 -C 10 alkyl) and in particular 1 to 6 C atoms, e.g. B. for methyl, ethyl, 1-propyl, 2-propyl (= isopropyl), 1-butyl, 2-butyl, 2-methyl-1-propyl, 2-methyl-2-propyl (= tert-butyl), 1-pentyl, 2-pentyl, 3-pentyl, 2-methyl-1-butyl, 3-methyl-1-butyl, 2-Methyl-2-butyl, 3-Methyl-2-butyl, 1-Hexyl, 2-Hexyl, 3-Hexyl, 2-Methyl-1-pentyl, 2-Methyl-2-pentyl, 2-Methyl-3-pentyl, 3-Methyl-1-pentyl, 3-Methyl-2-pentyl, 3-Methyl-3-pentyl, 1,1-Dimethyl-1-butyl, 2,2-Dimethyl-1-butyl, 2,3-Dimethyl-1-butyl, 1-heptyl, 2-heptyl, 1-octyl, 2-octyl, 2,2-4-trimethyl-1-pentyl, 1-nonyl, 2-nonyl, 8-methyl-1-nonyl, 1-decyl or 2-decyl.The alkyl group is unsubstituted or can carry 1, 2, 3, 4, 5 or 6 substituents R Al< which are selected from C 1 -C 4 -alkoxy, hydroxy-C 1 -C 4 -alkoxy, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxy, carboxyl, C 1 -C 4 -alkoxycarbonyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N< 2 , where RN< is H, C 1 -C 4 -alkyl, hydroxy-C 1 -C 4 -alkyl or C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl.

[0014] Here and in the following, "alkenyl" refers to a linear or branched aliphatic hydrocarbon group which is mono- or polyunsaturated and which generally has 2 to 10, in particular 2 to 6 or especially 2 to 4 carbon atoms, e.g. ethenyl, 1-propenyl, 2-propenyl, 1-buten-1-yl, 2-buten-1-yl, 3-buten-1-yl, 1-buten-2-yl, 2-methyl-1-propen-1-yl, 2-methyl-2-propen-1-yl, etc. The alkenyl group is unsubstituted or can carry 1, 2, 3, 4, 5 or 6 substituents R Al< which are selected from C 1 -C 4 -alkoxy, hydroxy-C 1 -C 4 -alkoxy, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxy, carboxyl, C 1 -C 4 -alkoxycarbonyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N< 2 , where RN< is H, C 1 -C 4 -alkyl, hydroxy-C 1 -C 4 -alkyl or C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl stands.

[0015] Here and in the following, "alkylene" refers to a branched or unbranched, saturated, divalent aliphatic hydrocarbon group which generally has 2 to 20, in particular 3 to 10 and especially 3 to 6 carbon atoms, e.g. ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, 1-methylethane-1,2-diyl, 1,1-dimethylethane-1,2-diyl, 1-methylpropane-1,3-diyl, 1,1-dimethylpropane-1,3-diyl, 2,2-dimethylpropane-1,3-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, Dodecane-1,12-diyl, etc.

[0016] Here and in the following, "alkenylene" refers to a branched or unbranched, monosaturated, divalent aliphatic hydrocarbon group which generally has 2 to 20, in particular 3 to 10 and especially 3 to 6 carbon atoms, e.g. 1,2-ethenediyl, propene-1,3-diyl, 2-butene-1,4-diyl, 1-methylethene-1,2-diyl, 1-methyl-1-propene-1,3-diyl, 2-methyl-1-propene-1,3-diyl, 1-pentene-1,5-diyl, 2-pentene-1,5-diyl, 1-hexene-1,6-diyl, 2-hexene-1,6-diyl, 3-hexene-1,6-diyl, 1-heptene-1,7-diyl, 2-Hepten-1,7-diyl, 3-Hepten-1,7-diyl, etc.

[0017] Here and below, "alkoxy" refers to a branched or unbranched, saturated alkyl group as defined above, which is linked to the rest of the molecule via an oxygen atom. The term "C 1 -C 10 alkoxy" refers below to an alkyl radical as defined above having 1 to 10 carbon atoms. The term "C 1 -C 4 alkoxy" refers below to an alkyl radical as defined above having 1 to 4 carbon atoms, e.g., methoxy, ethoxy, propyloxy, isopropyloxy, n-butyloxy, 2-butyloxy, sec-butyloxy, tert-butyloxy.-Butyloxy, n-Pentyloxy, 2-Pentyloxy, 2-Methylbutyloxy, 3-Methylbutyloxy, 1,2-Dimethylpropyloxy, 1,1-Dimethylpropyloxy, 2,2-Dimethylpropyloxy, 1-Ethylpropyloxy, n-Hexyloxy, 2-Hexyloxy, 2-Methylpentyloxy, 3-Methylpentyloxy, 4-Methylpentyloxy, 1,2-Dimethylbutyloxy, 1,3-Dimethylbutyloxy, 2,3-Dimethylbutyloxy, 1,1-Dimethylbutyloxy, 2,2-Dimethylbutyloxy, 3,3-Dimethylbutyloxy, 1,1,2-Trimethylpropyloxy, 1,2,2-Trimethylpropyloxy, 1-Ethylbutyloxy, 2-Ethylbutyloxy, 1-Ethyl- 2-methylpropyloxy, n-Heptyloxy, 2-Heptyloxy, 3-Heptyloxy, 2-Ethylpentyloxy, 1-Propylbutyloxy, n-Octyloxy, 2-Ethylhexyloxy, 2-Propylheptyloxy, Nonyl, Decyloxy.

[0018] Hier und im Folgenden bezeichnet "Hydroxyalkyl" eine Alkylgruppe, wie vorstehend definiert, die eine Hydroxyl-Gruppe als Substituenten trägt. Beispiele sind Hydroxymethyl, 2-Hydroxyethyl, 2-Hydroxpropyl und 3-Hydroxypropyl.

[0019] Here and below, "hydroxyalkoxy" refers to an alkoxy group, as defined above, bearing a hydroxyl group as a substituent. Examples are 2-hydroxyethoxy, 2-hydroxypropoxy, and 3-hydroxypropoxy.

[0020] Here and below, "alkoxyalkyl" refers to an alkyl group, as defined above, bearing an alkoxy group, as defined above, as a substituent. Examples are methoxymethyl, ethoxymethyl, 2-methoxyethyl, and 2-ethoxyethyl.

[0021] Here and below, "alkoxyalkoxy" refers to an alkoxy group, as defined above, bearing an alkoxy group, as defined above, as a substituent. Examples are 2-methoxyethoxy and 2-ethoxyethethoxy.

[0022] Here and in the following, "C 3 -C 10 -cycloalkyl" denotes a saturated, mono-, bi-, tri- or tetracyclic hydrocarbon group which generally contains 3 to 20 carbon atoms, e.g. cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, bicyclo[2.2.1]heptyl, bicyclo[3.3.0]octyl, bicyclo[3.2.1]octyl, bicyclo[2.2.2]octyl, adamantyl etc.. C 3 -C 20 -cycloalkyl is unsubstituted, but can also contain 1 or more, e.g. B. have 1, 2, 3, or 4 substituents R Cyc< which are selected from C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, hydroxy-C 1 -C 4 -alkyl, hydroxy-C 1 -C 4 -alkoxy, C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxy, carboxyl, C 1 -C 4 -alkoxycarbonyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N< 2 , C 1 -C 4 -alkyl-NR N< 2 , where RN< is H, C 1 -C 4 -alkyl, hydroxy-C 1 -C 4 -alkyl or C 1 -C 4 -Alkoxy-C 1 -C 4 -alkyl.

[0023] Here and below, "aryl" refers to an aromatic or semi-aromatic hydrocarbon group that is mono- or polycyclic and usually has 6, 9, 10, 13, or 14 carbon atoms and is preferably phenyl, naphthyl, tetrahydronaphthyl, indenyl, indanyl, fluorenyl, anthracenyl, phenanthrenyl, or naphthacenyl, particularly preferably phenyl or naphthyl. Aryl is unsubstituted but can also contain one or more, e.g., phenyl, naphthyl, phenyl, or naphthyl groups. B. carry 1, 2, 3, 4 or 5 substituents R Ar< which are selected from C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, hydroxy-C 1 -C 4 -alkyl, hydroxy-C 1 -C 4 -alkoxy, C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxy, carboxyl, C 1 -C 4 -alkoxycarbonyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N< 2 , C 1 -C 4 -alkyl-NR N< 2 , where RN< is H, C 1 -C 4 -alkyl, hydroxy-C 1 -C 4 -alkyl or C 1 -C 4 -Alkoxy-C 1 -C 4 -alkyl.

[0024] Here and below, "hetaryl" refers to an aromatic or semi-aromatic heterocyclic group that is mono- or polycyclic and usually has 5 to 14 ring members, which, in addition to carbon, have at least one heteroatom as a ring atom selected from N, O, and S, e.g., 1 to 4 N atoms or 1 atom selected from O and S and optionally 1, 2, or 3 further N atoms, and which preferably contains the groups pyridyl, quinolinyl, acridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, tetrazinyl, pyrrolyl, pyrazolyl, isoxazolyl, imidazolyl, oxazolyl, thiazolyl, thienyl, or furyl. Hetaryl is unsubstituted, but can also contain 1 or more, e.g.,1, 2, 3, 4 or 5 substituents R Ar< which are selected from C 1 -C 4 alkyl, C 1 -C 4 alkoxy, hydroxy-C 1 -C 4 alkyl, hydroxy-C 1 -C 4 alkoxy, C 1 -C 4 alkoxy-C 1 -C 4 alkyl, C 1 -C 4 alkoxy-C 1 -C 4 alkoxy, carboxyl, C 1 -C 4 alkoxycarbonyl, C 1 -C 4 alkoxy-C 1 -C 4 alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N< 2 , C 1 -C 4 alkyl-NR N< 2 , where RN< is H, C 1 -C 4 alkyl, hydroxy-C 1 -C 4 alkyl or C 1 -C 4 alkoxy-C 1-C4-alkyl.

[0025] Here and below, "5- to 8-membered carbocycle" refers to a saturated or unsaturated, mono- or polycyclic hydrocarbon group containing 5 to 8 carbon atoms as ring members. The carbocycle is unsubstituted, but may also have one or more, e.g., 1, 2, 3, 4, or 5, substituents R Cyc<, where R Cyc< is as defined above.

[0026] Here and below, "5- to 8-membered heterocycle" refers to a saturated or unsaturated, mono- or polycyclic heterocyclic group having 5 to 8 ring atoms, wherein the ring atoms, in addition to carbon, have at least one heteroatom, which is preferably selected from nitrogen, sulfur and oxygen, e.g. pyrrolidinyl, piperidinyl, morpholinyl, thiomorpholinyl, piperazinyl, hexahydroazepinyl, etc. The heterocycle is unsubstituted, but can also have 1 or more, e.g. 1, 2, 3, 4 or 5, substituents R Cyc<, where R Cyc< is as defined above.

[0027] The invention relates in particular to the following embodiments 1 to 23. Here, embodiment 1 refers to the following process: Process for the preparation of acetals of aliphatic or cycloaliphatic α-chloro- or α - Bromaldehydes, comprising the electrolysis of a liquid reaction mixture containing i) a halogen acceptor selected from primary aliphatic or cycloaliphatic alcohols, mono-1-alkyenyl ethers of aliphatic diols, and mixtures comprising a mono-1-alkyenyl ether of an aliphatic, cycloaliphatic or aromatic alcohol and at least one aliphatic or cycloaliphatic alcohol, ii) at least one halogen source containing chlorine or bromine, iii) at least one solvent and iv) at least one conducting salt in an undivided electrolysis cell.

[0028] According to the invention, a halogen source containing chlorine or bromine is used. In principle, mixtures of different halogen sources can be used. In these cases, the different halogen sources preferably either have the same halogen or, in the case of halogen sources with different halogens, have different reactivities. The halogen sources preferably have either bromine or chlorine as the halogen. Suitable halogen sources include elemental chlorine and elemental bromine, inorganic or organic salts with chloride or bromide as the anion, and in particular organic chlorine and bromine compounds in which the bromine or chlorine atom is bonded to a nitrogen atom or a carbon atom, which is preferably not part of a C=C double bond.Examples of suitable chlorine sources are Cl 2 (also in the form of chloride chains), hypochlorite, hydrogen chloride, N-chlorosuccinimide, vicinal chlorohydrocarbons such as hexachlorocyclohexane, polyvinyl chloride, iodobenzene dichloride, chloride salts such as sodium chloride, or conducting salts with chloride anions. Examples of suitable bromine sources are Br 2 (also in the form of bromide chains), hypobromide, hydrogen bromide, N-bromosuccinimide, vicinal bromohydrocarbons such as HBCD, iodobenzene tribromide, bromide salts such as sodium bromide, or conducting salts with bromide anions.

[0029] According to a preferred embodiment 2 of the process according to the invention of embodiment 1, the halogen source comprises an organic chlorine compound and / or an organic bromine compound. The organic chlorine compounds and bromine compounds generally carry at least 1, in particular at least 2, e.g., 2, 3, 4, 5, or 6 bromine or chlorine atoms per molecule. The bromine or chlorine atoms are preferably bonded to a C atom that is not part of a C=C double bond. In particular, the main source of the halogen required in the electrolysis is the organic chlorine compound or the organic bromine compound.

[0030] According to a particularly preferred embodiment of embodiment 2 of the process according to the invention according to embodiment 1, the organic bromine compound has at least 2 vicinally bonded chlorine atoms or at least 2 vicinally bonded bromine atoms, i.e. the chlorine or bromine atoms are bonded to 2 adjacent C atoms, which are preferably not part of a C=C double bond. In particular, the halogen source of this embodiment comprises one of the two following compounds: 1,2,3,4,5,6-hexachlorocyclohexane or 1,2,5,6,9,10-hexabromocyclododecane. In particular, the halogen source is one of the two following compounds: 1,2,3,4,5,6-hexachlorocyclohexane or 1,2,5,6,9,10-hexabromocyclododecane.

[0031] According to one embodiment 3 of the process according to the invention of embodiments 1 and 2, a primary aliphatic or cycloaliphatic alcohol having a hydrogen atom in the 2-position, relative to the carbon atom bearing the OH group, is used as the halogen acceptor compound. Such alcohols generally have 2 to 20 carbon atoms and can bear one or more, e.g., 1, 2, 3, or 4, substituents, which are selected in particular from the groups R Al< and R Cyc< defined above.

[0032] It is assumed that halogenation of the two carbon atoms in the 1- and 2-positions relative to the OH group initially occurs, forming an alcohol chlorinated or brominated in the 1- or 2-position, respectively. This alcohol then reacts with two further alcohol molecules, possibly via the intermediate α-chlorine or α-bromoaldehyde, to form the acetal of the α-chlorine or α-bromoaldehyde, respectively. It is also possible that the primary alcohol is initially oxidized to the aldehyde, followed by halogenation of the α-position, followed by acetalization by two further alcohol molecules.

[0033] Preferred primary aliphatic or cycloaliphatic alcohols can be described by the formula (Ia): R 1< -CH(R 11< )CH 2 -OH (Ia) wherein R 1< represents hydrogen, a monovalent aliphatic group having 1 to 18 C atoms or a cycloaliphatic group having 3 to 18 C atoms, R 11< represents hydrogen, a monovalent aliphatic group having 1 to 10 C atoms or a cycloaliphatic group having 3 to 10 C atoms, wherein the aliphatic groups in R 1< , R 11< are unsubstituted or have 1, 2, 3 or 4 substituents R Al<, wherein the aliphatic groups in R 1< , R 11< are unsubstituted or have 1, 2, 3 or 4 substituents R Cyc<, and wherein 1, 2, 3 or 4 non-adjacent C atoms of the aliphatic or cycloaliphatic groups can be replaced by O or S.

[0034] In particular, R 1< and R 11< in formula (Ia) independently of one another and preferably in combination have the following meanings: R 1< represents hydrogen, C 1 -C 10 alkyl which is optionally substituted by 1, 2, 3 or 4 radicals R Al<, or C 1 -C 10 cycloalkyl which is optionally substituted by 1, 2, 3 or 4 radicals R Cyc<; R 11< represents hydrogen or C 1 -C 4 alkyl which is optionally substituted by 1, 2, 3 or 4 radicals R Al<.

[0035] Particularly preferably, R 1< and R 11< in formula (Ia) independently of one another and preferably in combination have the following meanings: R 1< represents hydrogen or C 1 -C 10 alkyl which is optionally substituted by 1, 2 or 3 radicals R Al<; R 11< represents hydrogen.

[0036] Specifically, R 1< and R 11< in formula (Ia) have the following meanings, R 1< stands for hydrogen or C 1 -C 6 alkyl; R 11< stands for hydrogen.

[0037] Examples of alcohols of the general formula (Ia) are ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, 2-methoxyethanol, 2-ethoxyethanol, 3-ethoxypropanol, etc.

[0038] According to one embodiment 4 of the process according to the invention of embodiments 1 and 2, a mono-1-alkyenyl ether, in particular a mono-1-(C 2 -C 6 -alkyenyl) ether and especially a monovinyl ether of an aliphatic diol, is used as the halogen acceptor. The main reaction product obtained is not the expected 1,2-dichloro- or 1,2-dibromoalkyl ether compound, but rather a cyclic acetal of a 2-chloro- or 2-bromoaldehyde. Presumably, dihalogenation initially occurs to give the corresponding 1,2-dichloro- or 1,2-dibromoalkyl ether, which then reacts intramolecularly with the carbon atom in the 1-position to the ether oxygen, with substitution of the halogen atom, to form the cyclic acetal.

[0039] Preferred monovinyl ethers of an aliphatic diol can be described by the formula (Ib): HO-R 2< -O-CH=C(R 3< ,R 4< ) (Ib) wherein R 2< represents a divalent aliphatic group having 2 to 20 C atoms, in particular 2 to 10 C atoms, in particular C 2 -C 10 alkylene, in which 1, 2, 3 or 4, in particular 1 or 2 non-adjacent C atoms of the aliphatic or cycloaliphatic groups can be replaced by O or S, in particular by O, and in which the aliphatic group, in particular C 2 -C 10 alkylene, is unsubstituted or carries 1, 2, 3 or 4 substituents R Al<. R 3< represents hydrogen, a monovalent aliphatic group having 1 to 10 C atoms or a monovalent cycloaliphatic group having 3 to 10 C atoms and is particularly hydrogen, R 4< represents hydrogen, a monovalent aliphatic group having 1 to 10 C atoms or a monovalent cycloaliphatic group having 3 to 10 C atoms and is particularly hydrogen,

[0040] In particular, R 2< , R 3< and R 4< in formula (Ic) independently of one another and preferably in combination have the following meanings: R 2< C 2 -C 10 -alkylene, wherein 1, 2 or 3 non-adjacent C atoms may be replaced by O and wherein C 2 -C 10 -alkylene is unsubstituted or may carry 1, 2, 3 or 4, in particular 1 or 2, substituents R Al<, R 3< hydrogen, methyl or ethyl, R 4< hydrogen, methyl or ethyl.

[0041] Particularly preferably, R 2a< , R 3< and R 4< in formula (Ic) independently of one another and preferably in combination have the following meanings: R 2< C 2 -C 8 -alkylene, wherein 1, 2 or 3 non-adjacent C atoms may be replaced by O and wherein C 2 -C 8 -alkylene is unsubstituted or may carry 1 or 2 substituents R Al<, R 3< hydrogen, methyl or ethyl, R 4< hydrogen.

[0042] Specifically, R 2a< , R 3< and R 4< in formula (Ic) independently of one another and preferably in combination have the following meanings: R 2< C 2 -C 6 -alkylene, wherein 1 or 2 non-adjacent C atoms may be replaced by O and wherein C 2 -C 6 -alkylene is unsubstituted or may carry 1 or 2 substituents R Al<, R 3< hydrogen, R 4< hydrogen.

[0043] Examples of 1-alkenyl ethers of the formula (Ib) are 2-hydroxyethyl vinyl ether (= ethylene glycol vinyl ether or ethylene glycol monovinyl ether), 1,2-propanediol monovinyl ether, 1,3-propanediol monovinyl ether, 1,4-butanediol monovinyl ether (= tetramethylene glycol monovinyl ether), 1,5-pentanediol monovinyl ether and 2-hydroxyethoxyvinyl ether (= 2-[2-(ethenyloxy)ethoxy]ethanol).

[0044] According to one embodiment 5 of the process according to the invention of embodiments 1 and 2, a mixture comprising a mono-1-alkyenyl ether, in particular a mono-1-(C 2 -C 6 -alkyenyl) ether and especially a monovinyl ether of an aliphatic, cycloaliphatic or aromatic alcohol, and at least one aliphatic or cycloaliphatic alcohol is used as the halogen acceptor compound. The main reaction product obtained is not the expected 1,2-dichloro- or 1,2-dibromoalkyl ether compound, but rather an acetal of a 2-chloro- or 2-bromoaldehyde. Presumably, dihalogenation initially occurs to give the corresponding 1,2-dichloro- or 1,2-dibromoalkyl ether, which subsequently reacts with the alcohol at the carbon atom in the 1-position to the ether oxygen, with substitution of the halogen atom to form the acetal.

[0045] The mono-1-alkyenyl ether of the aliphatic, cycloaliphatic or aromatic alcohol is described in particular by the formula (Ic) and the aliphatic or cycloaliphatic alcohol is described in particular by the formula (Id): R 2a< -O-CH=C(R 3< ,R 4< ) (Ic) R 5< -OH (Id) R 2a< represents a monovalent aliphatic group having 1 to 20 C atoms, a monovalent cycloaliphatic group having 3 to 20 C atoms or a monovalent aromatic group having 3 to 20 C atoms, R 3< represents hydrogen, a monovalent aliphatic group having 1 to 10 C atoms or a monovalent cycloaliphatic group having 3 to 10 C atoms and is in particular hydrogen, R 4< represents hydrogen, a monovalent aliphatic group having 1 to 10 C atoms or a monovalent cycloaliphatic group having 3 to 10 C atoms and is in particular hydrogen, R 5< represents a monovalent aliphatic group having 1 to 20 C atoms or a monovalent cycloaliphatic group having 3 to 20 C atoms, wherein the aliphatic groups in R 2a< , R 3< , R 4< , R 5< are unsubstituted or have 1, 2, 3 or 4 substituents R Al<, wherein the cycloaliphatic groups in R 2a< , R 3< , R 4< , R 5< are unsubstituted or have 1, 2, 3 or 4 substituents R Cyc<, wherein the aromatic groups in R 2a< are unsubstituted or have 1, 2, 3 or 4 substituents R Ar<, and wherein 1, 2, 3 or 4 non-adjacent C atoms of the aliphatic or cycloaliphatic groups in R 2a< , R 3< , R 4< , R 5< can be replaced by O or S.

[0046] In particular, R 2a< , R 3< and R 4< in formula (Ic) independently of one another and preferably in combination have the following meanings: R 2a< C 1 -C 10 alkyl, in which 1, 2 or 3 non-adjacent C atoms may be replaced by O and in which C 1 -C 10 alkyl is unsubstituted or may carry 1, 2, 3 or 4, in particular 1 or 2, substituents R Al<, or C 3 -C 10 cycloalkyl, which is unsubstituted or may carry 1, 2, 3 or 4 substituents R cyc<, R 3< hydrogen, methyl or ethyl, R 4< hydrogen, methyl or ethyl.

[0047] Particularly preferably, R 2a< , R 3< and R 4< in formula (Ic) independently of one another and preferably in combination have the following meanings: R 2a< C 1 -C 8 -alkyl, wherein 1, 2 or 3 non-adjacent C atoms may be replaced by O and wherein C 1 -C 8 -alkyl is unsubstituted or may carry 1 or 2 substituents R Al<, R 3< hydrogen, methyl or ethyl, R 4< hydrogen.

[0048] Specifically, R 2a< , R 3< and R 4< in formula (Ic) independently of one another and preferably in combination have the following meanings: R 2a< C 1 -C 8 -alkyl, wherein 1 or 2 non-adjacent C atoms may be replaced by O and wherein C 2 -C 8 -alkyl is unsubstituted or may carry 1 or 2 substituents R Al<, R 3< hydrogen, R 4< hydrogen.

[0049] Examples of 1-alkenyl ethers of the general formula (Ic) are methyl vinyl ether, ethyl vinyl ether, 2-chloroethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, 2-butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, benzyl vinyl ether and phenol vinyl ether.

[0050] In the alcohol of formula (Id), R 5< has in particular the following meanings: C 1 -C 10 alkyl, in which 1, 2 or 3 non-adjacent C atoms may be replaced by O and in which C 1 -C 10 alkyl is unsubstituted or may carry 1, 2, 3 or 4, in particular 1 or 2, substituents R Al<, or C 3 -C 10 cycloalkyl, which is unsubstituted or may carry 1, 2, 3 or 4 substituents R cyc<.

[0051] In the alcohol of formula (Id), R 5< particularly preferably has the following meanings: C 1 -C 8 -alkyl, in which 1, 2 or 3 non-adjacent C atoms may be replaced by O and in which C 1 -C 8 -alkyl is unsubstituted or may carry 1 or 2 substituents R Al<.

[0052] In the alcohol of formula (Id), R 5< has specifically the following meanings: C 1 -C 6 -alkyl, wherein 1 or 2 non-adjacent C atoms may be replaced by O and wherein C 2 -C 6 -alkyl is unsubstituted or may carry 1 substituent R Al<.

[0053] Examples of suitable alcohols of the general formula (Id) are C 1 -C 6 -alkanols, which may optionally be substituted by C 1 -C 4 -alkoxy, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, 1-pentanol, 2-pentanol, 1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, 3-ethoxypropanol and C 3 -C 6 -cycloalkanols, such as cyclopropanol, cyclobutanol, cyclopentanol or cyclohexanol.

[0054] In embodiments 3, 4 and 5, the substituents R Al< , R Cyc< or R Ar< independently of one another have the meanings given below: R Al< can be the same or different and are selected from C 1 -C 4 -alkoxy, hydroxy-C 1 -C 4 -alkoxy, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxy, carboxyl, C 1 -C 4 -alkoxycarbonyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N< 2 , where RN< is H, C 1 -C 4 -alkyl, hydroxy-C 1 -C 4 -alkyl or C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl, and are in particular selected from C 1 -C 4 -alkoxy such as methoxy or ethoxy, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxy such as 2-methoxyethoxy or 2-ethoxyethoxy; R Cyc< can be the same or different and are selected from C 1 -C 4 alkyl, C 1 -C 4 alkoxy, hydroxy-C 1 -C 4 alkyl, hydroxy-C 1 -C 4 alkoxy, C 1 -C 4 alkoxy-C 1 -C 4 alkyl, C 1 -C 4 alkoxy-C 1 -C 4 alkoxy, carboxyl, C 1 -C 4 alkoxycarbonyl, C 1 -C 4 alkoxy-C 1 -C 4 alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N< 2 , C 1 -C 4 alkyl-NR N< 2 , where RN< is H, C 1 -C 4 alkyl, hydroxy-C 1 -C 4 alkyl or C 1 -C 4 alkoxy-C 1 -C 4 alkyl,and are in particular selected from C 1 -C 4 alkyl such as methyl or ethyl, C 1 -C 4 alkoxy such as methoxy or ethoxy, C 1 -C 4 alkoxy-C 1 -C 4 alkyl such as methoxymethyl, ethoxymethyl, 2-methoxyethyl or 2-ethoxyethyl or C 1 -C 4 alkoxy-C 1 -C 4 alkoxy such as 2-methoxyethoxy or 2-ethoxyethoxy. R Ar< can be the same or different and are selected from C 1 -C 4 alkyl, C 1 -C 4 alkoxy, hydroxy-C 1 -C 4 alkyl, hydroxy-C 1 -C 4 alkoxy, C 1 -C 4 alkoxy-C 1 -C 4 alkyl, C 1 -C 4 alkoxy-C 1 -C 4 alkoxy, carboxyl, C 1 -C 4 -alkoxycarbonyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N< 2 , C 1 -C 4 -alkyl-NR N< 2 , where RN< is H, C 1 -C 4 -alkyl, hydroxy-C 1 -C 4 -alkyl or C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl, and are in particular selected from fluorine, chlorine, bromine, C 1 -C 4 -alkyl such as methyl or ethyl, C 1 -C 4 -alkoxy such as methoxy or ethoxy, C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl such as methoxymethyl, ethoxymethyl,2-Methoxyethyl or 2-ethoxyethethyl, C 1 -C 4 alkoxy-C 1 -C 4 alkoxy such as 2-methoxyethoxy or 2-ethoxyethoxy or C 1 -C 4 alkoxycarbonyl such as methoxycarbonyl or ethoxycarbonyl. ,

[0055] According to a preferred embodiment 6 of the process according to the invention of embodiments 1 to 3, the concentration of the primary aliphatic or cycloaliphatic alcohol in the liquid reaction mixture is in the range of 5 to 200 g / L, in particular in the range of 5 to 100 g / L. The primary aliphatic or cycloaliphatic alcohol can also be the solvent. In this case, its concentration in the liquid reaction mixture can also be above 200 g / L.

[0056] According to a preferred embodiment 7 of the process according to the invention of embodiments 1 to 2 or 4, the concentration of the mono-1-alkenyl ether of the aliphatic diol in the liquid reaction mixture is in the range from 5 to 100 g / L, in particular in the range from 5 to 50 g / L.

[0057] According to a preferred embodiment 8 of the process according to the invention of embodiments 1 to 2 or 5, the concentration of the mono-1-alkenyl ether of the aliphatic, cycloaliphatic or aromatic alcohol in the liquid reaction mixture is in the range from 5 to 100 g / L, in particular in the range from 5 to 50 g / L, and the concentration of the aliphatic or cycloaliphatic alcohol in the liquid reaction mixture is in the range from 5 to 100 g / L, in particular in the range from 5 to 50 g / L.

[0058] According to a further embodiment 9 of the process according to any one of embodiments 1 to 8, a reaction mixture is used in which the concentration of the halogen source in the liquid reaction mixture is in the range from 5 to 300 g / L and in particular in the range from 5 to 150 g / L, in each case based on the total volume of the reaction mixture before the start of the electrolysis.

[0059] According to the invention, the electrolysis solution used contains at least one conducting salt. Suitable conducting salts are, in principle, all inorganic and organic salts that are sufficiently soluble in the reaction mixture and inert under the electrolysis conditions. Suitable conducting salts are well known to those skilled in the art of electrolysis. Conducting salts containing an organic cation are preferred.

[0060] According to a preferred embodiment 10 of the process according to any one of embodiments 1 to 9, the supporting salt is selected from quaternary ammonium salts, pyridinium salts, imidazolium salts, quaternary phosphonium salts, and mixtures thereof. Particularly preferred supporting salts are tetra(C 1 -C 6 -alkyl)ammonium salts, tri(C 2 -C 6 -alkyl)methylammonium salts, and tri(C 2 -C 6 -alkyl)benzylammonium salts. Examples thereof are tetramethylammonium salts, tetraethylammonium salts, tetra-n-butylammonium salts, triethylmethylammonium salts, trimethylbenzylammonium salts, and triethylbenzylammonium salts. Also particularly suitable are pyridinium salts and imidazolium salts, in particular those bearing 1 or 2 C 1 -C 8 -alkyl groups as substituents.

[0061] Suitable counterions for the aforementioned salts are, in principle, all anions that are inert under electrolysis conditions. These are well known to those skilled in the art of electrolysis.

[0062] According to a preferred embodiment 11 of the process according to any one of embodiments 1 to 9 and in particular according to embodiment 10, the anions of the conducting salt are selected from chloride, bromide, tetrafluoroborate, trifluoromethanesulfonate, tosylate, sulfate, C 1 -C 4 alkyl sulfate, perchlorate, acetate, hexafluorophosphate, bis(trifluoromethylsulfonyl)imide, nitrate, carbonate and bromate and in particular from chloride and bromide.

[0063] According to a preferred embodiment 12 of the process according to any one of embodiments 1 to 9 and in particular according to embodiments 10 and 11, the conducting salt is used in an amount such that its concentration in the reaction mixture is in the range from 0.01 to 0.2 mol / L and in particular in the range from 0.02 to 0.1 mol / L.

[0064] According to a preferred embodiment 13 of the process according to the invention of embodiments 1 to 12, the solvent is selected from water, C 1 -C 4 -alkanols, C 1 -C 4 -fluoroalkanols, C 1 -C 4 -alkylnitriles, di-C 1 -C 4 -alkyl carbonates, C 2 -C 4 -alkylene carbonates, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, NC 1 -C 4 -alkylpyrrolidone, C 1 -C 4 -alkyl esters of C 2 -C 4 -alkanoic acids, C 1 -C 4 -alkyl esters of C 2 -C 4 -hydroxyalkanoic acids, C 1 -C 4 -chloroalkanes, dihydrolevoglucosenone and mixtures thereof.

[0065] Preferred solvents of embodiment 13 are selected from C 1 -C 4 -fluoroalkanols, such as 1,1,2,2-tetrafluoroethanol, pentafluoroethanol, hexafluoroisopropanol and perfluoro-n-propanol; C 1 -C 4 -alkylnitriles, such as acetonitrile, propionitrile and butyronitrile, di-C 1 -C 4 -alkyl carbonates, such as diethyl carbonate, C 2 -C 4 -alkylene carbonates, such as ethylene carbonate, which is also called 2-oxo-1,3-dioxolane, and propylene carbonate, which is also called 4-methyl-2-oxo-1,3-dioxolane, C 1 -C 4 -alkyl esters of C 2 -C 4 -alkanoic acids, such as methyl acetate, ethyl acetate, propyl acetate, methyl propionate and ethyl propionate, C 1 -C 4 -chloroalkanes, such as dichloromethane, dichloroethane, trichloromethane, isomers of dichloroethane, dichlorobutane or dichloropentane etc., where the above-mentioned isomers do not include isomers in which the two Chlorine atoms are bonded to vicinal carbon atoms, and their mixtures.

[0066] According to a preferred embodiment 14 of the process according to the invention of embodiments 1 to 13, the solvent comprises at least one organic solvent selected from the group consisting of C 1 -C 4 alkyl nitriles, di-C 1 -C 4 alkyl carbonates, and C 2 -C 4 alkylene carbonates. In this embodiment, the solvent from the group consisting of C 1 -C 4 alkyl nitriles, di-C 1 -C 4 alkyl carbonates, and C 2 -C 4 alkylene carbonates accounts for at least 50% by weight, in particular at least 70% by weight, and especially 100% by weight, based on the total amount of solvent present in the liquid reaction mixture.

[0067] According to a particularly preferred embodiment of embodiment 14 of the process according to the invention, the solvent comprises at least one organic solvent selected from the group of C 2 -C 4 alkylene carbonates. In this embodiment, the solvent from the group of C 2 -C 4 alkylene carbonates accounts for at least 50 wt.%, in particular at least 70 wt.%, and especially 100 wt.%, based on the total amount of solvent present in the liquid reaction mixture.

[0068] According to another particularly preferred embodiment of embodiment 14 of the process according to the invention, the solvent comprises at least one organic solvent selected from a mixture of at least one C 2 -C 4 alkylene carbonate and mixtures thereof with one or more C 1 -C 4 alkylnitriles. In this embodiment, the mixture constitutes at least 50 wt.%, in particular at least 70 wt.%, and especially 100 wt.%, based on the total amount of solvent present in the liquid reaction mixture.

[0069] According to a preferred embodiment 15 of the process according to the invention of embodiment 14, the organic solvent makes up at least 50 wt.%, in particular at least 70 wt.% or at least 95 wt.% or 100 wt.% of the total amount of solvents in the liquid reaction mixture.

[0070] According to a preferred embodiment 16 of the process according to any one of embodiments 1 to 15, the liquid reaction mixture contains a mediator. Mediators are understood to be compounds that enable indirect electrochemical oxidation. These are compounds that can exist in different oxidation states. The mediator is electrochemically converted to the higher oxidation state, then acts as an oxidizing agent, and subsequently regenerates itself through electrochemical oxidation. This is therefore an indirect electrochemical oxidation of the organic compound, since the mediator is the oxidizing agent. The oxidation of the organic compound with the mediator in the oxidized form can be carried out in the electrolysis cell in which the mediator was converted to the oxidized form, or in one or more separate reactors ("ex-cell process").

[0071] According to a preferred embodiment 17 of the process according to embodiment 16, the reaction mixture contains as mediator at least one transition metal salt selected from the transition metals of groups 5-10 of the Periodic Table of the Elements, according to IUPAC.

[0072] According to a preferred embodiment 18 of the process according to embodiment 17, salts of manganese, copper, cobalt, nickel, chromium, vanadium, iron, ruthenium, rhodium, iridium or palladium are used as mediators in the process according to the invention.

[0073] According to a preferred embodiment 19 of the process according to embodiment 18, transition metal salts selected from Mn(II) salts, Cu(I) salts, Cu(II) salts, Co(II) salts, Ni(II) salts, Cr(II) salts, Cr(III) salts, V(III) salts, Fe(II) salts, Fe(III) salts, Ru(III) salts, Rh(III) salts, Ir(III) salts, Pd(II) salts and combinations thereof are used as mediators in the process according to the invention.

[0074] The anions of the transition metal salts are of minor importance. According to a preferred embodiment 20 of the process according to embodiments 17 to 19, the anions of the transition metal salts are selected from chloride, bromide, tetrafluoroborate, trifluoromethanesulfonate, tosylate, sulfate, C 1 -C 4 alkyl sulfate, such as methyl sulfate or ethyl sulfate, perchlorate, acetate, hexafluorophosphate, bis(trifluoromethylsulfonyl)imide, nitrate, carbonate, and bromate. Preferred transition metal salts are the bromides and chlorides of the aforementioned transition metals.

[0075] According to a preferred embodiment 21 of the process according to embodiments 17 to 20, the mediator is used in an amount such that its concentration is up to 20 mol%, based on the amount of halogen source used, and in particular in the range from 0.1 to 20 mol%, based on the amount of halogen source used.

[0076] According to the invention, the electrolysis is carried out in an undivided electrolysis cell. In contrast to a divided electrolysis cell, an undivided electrolysis cell is an electrolysis cell in which the anode compartment is not separated from the cathode compartment, so that the electrolyte has essentially the same composition throughout the electrolysis cell, apart from transport-related concentration differences in the region of the electrodes.

[0077] The electrolysis cell naturally has at least one anode and at least one cathode.

[0078] According to a preferred embodiment 22 of the method according to embodiments 1 to 21, the anode material of the electrolysis cell is selected from graphite, including isostatic graphite, graphite foils, graphite fibers, and metal-doped graphite, glassy carbon (GC), platinum, boron-doped diamond (BDD), and mixed metal oxides comprising at least one metal oxide from the group consisting of ruthenium oxide, iridium oxide, and tantalum oxide, preferably in combination with a titanium support. A particularly preferred electrode material for the anode is graphite, in particular isostatic graphite.

[0079] In principle, any electrode material can be used as the electrode material for the cathode. According to a preferred embodiment 23 of the process according to embodiments 1 to 22, the cathode material of the electrolysis cell is selected from graphite, including isostatic graphite, graphite foils, graphite fibers, and metal-doped graphite, glassy carbon, platinum, boron-doped diamond, platinum, molybdenum, vanadium, tungsten, niobium, lead (which can be used either in elemental form or in the form of lead bronzes such as CuSn7Pb15), tantalum, nickel, silver, titanium, and zirconium.

[0080] Particularly preferred combinations of electrode materials are summarized in the following table anode cathode Graphite, isostatic Graphite, isostatic Graphite, isostatic Boron-doped diamond Boron-doped diamond Boron-doped diamond glassy carbon glassy carbon glassy carbon graphite RuO x / Ti 1)< graphite Graphite, isostatic Graphite fibers Graphite foil graphite Graphite, isostatic Graphite foil Graphite foil Graphite foil Graphite, isostatic Silver Graphite, isostatic CuSn7Pb15 Graphite, isostatic molybdenum Graphite, isostatic niobium Graphite, isostatic nickel Graphite, isostatic Lead Graphite, isostatic Tantal Graphite, isostatic titanium Graphite, isostatic Vanadium Graphite, isostatic tungsten Graphite, isostatic zirconium 1) Ruthenium oxide on titanium support

[0081] In principle, any electrode shape known to those skilled in the art can be used as the anode. This can consist entirely of the respective electrode material or be a carrier electrode comprising an electrically conductive carrier coated with the electrode material. Electrodes made of the respective electrode material are preferred. The electrodes used as the anode can be, for example, electrodes in the form of expanded metal, mesh, or sheet metal.

[0082] Any undivided electrolysis cell known to those skilled in the art can be used for the electrolysis, such as undivided pot cells, undivided flow cells, capillary gap cells, stacked-plate cells or staggered pot cells, and bipolar pot cells, i.e., cells with a bipolar electrode arrangement. Particular preference is given to undivided flow cells, e.g., a flow cell with forced electrolyte flow, i.e., the electrolyte is continuously guided past the electrodes, with the electrolyte flow being configured as a circulation or continuous flow. Staggered pot cells, preferably with mixing, are also preferred. Staggered pot cells can also be configured as flow cells.

[0083] The arrangement of the anode and cathode in the electrolysis cell is not limited and includes, for example, arrangements of planar grids and / or plates, which can also be arranged in the form of several alternatingly polarized stacks, and cylindrical arrangements of cylindrically shaped meshes, grids, or tubes, which can also be arranged in the form of several alternatingly polarized cylinders. Bipolar-connected electrode arrangements can also be used.

[0084] Various electrode geometries are known to those skilled in the art to achieve optimal space-time yields. Suitable examples include parallel arrangements of electrode sheets, bipolar arrangements of multiple electrodes, an arrangement in which a rod-shaped anode is surrounded by a cylindrical cathode, or an arrangement in which both the cathode and the anode consist of a wire mesh, which are placed on top of each other and rolled into a cylindrical shape. The electrode spacing is typically in the range of 1 to 10 mm, and in flow cells, in the range of 0.25 to 10 mm.

[0085] The process can be carried out successfully both batchwise and continuously. The process according to the invention can also be carried out on an industrial scale. Appropriate electrolysis cells are known to those skilled in the art. All embodiments of this invention relate to both laboratory and industrial scales.

[0086] In a preferred embodiment of the invention, the contents of the electrolysis cell are thoroughly mixed. Any mechanical stirrer known to those skilled in the art can be used for this mixing of the cell contents.

[0087] By applying the electrolysis voltage to the anodes and cathodes, an electric current is passed through the electrolyte. To avoid side reactions such as overoxidation, a current density of 500 mA / cm 2 , in particular 100 mA / cm 2 , is generally not exceeded. The current densities at which the process is carried out are generally 1 to 500 mA / cm 2 , preferably 1 to 100 mA / cm 2 . The process according to the invention is particularly preferably carried out at current densities between 1 and 50 mA / cm 2 .

[0088] The total duration of electrolysis naturally depends on the electrolysis cell, the electrodes used, and the current density. The optimal duration can be determined by a specialist through routine experiments, e.g., by taking samples during electrolysis.

[0089] Typically, the amount of current required to achieve quantitative conversion is in the range of 2 to 12 coulombs / mole based on the amount of electrons transferred per 1 mole of starting material.

[0090] To prevent deposits on the electrodes, the polarity can be reversed at short intervals. The polarity reversal can occur at intervals of 30 seconds to 10 minutes, but preferably at intervals of 30 seconds to 2 minutes. For this purpose, it is advisable for the anode and cathode to be made of the same material.

[0091] According to the process according to the invention, the electrolysis is generally carried out at a temperature in a range from 0 to 100 °C, preferably 10 to 90 °C, in particular 15 to 90 °C.

[0092] In the process according to the invention, the electrolysis is generally carried out at a pressure below 2000 kPa, preferably below 1000 kPa, in particular below 150 kPa, e.g., in the range from 50 to 1000 kPa, in particular 80 to 150 kPa. It is particularly preferred to carry out the process according to the invention at a pressure in the range of atmospheric pressure (101 ± 20 kPa).

[0093] The halogenation product obtained by the process according to the invention can be recovered from electrolytes by methods known to those skilled in the art. For example, the halogenation product formed during electrolysis can be removed or depleted from the electrolyte by distillation or extraction.

[0094] Distillation processes known to the person skilled in the art are suitable as distillation methods, such as vacuum distillation, distillation under a protective gas atmosphere, rotary evaporators, Kugelrohr distillation and the use of various columns such as Vigreux, packed and rotating band columns.

[0095] For extraction, the electrolyte can be mixed with an organic solvent that is immiscible or only partially miscible with the solvent used, for example, to separate the resulting halogenation product (liquid-liquid extraction). Suitable organic solvents include hydrocarbons with 5 to 12 carbon atoms, such as pentane, hexane, cyclohexane, heptane, or octane.

[0096] The resulting halogenation product can also be removed from the electrolyte by solid-phase extraction. For this purpose, a solid-phase extraction agent is added to the electrolyte. The halogenation product adsorbed onto the extraction agent can then be eluted from the solid phase using organic solvents known to those skilled in the art. This yields a concentrated crude product, which can then be more easily purified and isolated by distillation. I.1 Materials and equipment

[0097] Chemicals of analytical quality were purchased and used from common suppliers such as Carl Roth TCI, Sigma Aldrich and Acros.

[0098] Unless otherwise stated, the hexachlorocyclohexane used is a stereoisomer mixture of 1,2,3,4,5,6-hexachlorocyclohexane.

[0099] Unless otherwise stated, the hexabromocyclododecane used is a stereoisomer mixture of 1,2,5,6,9,10-hexabromocyclododecane.

[0100] As Electrode material Isostatic graphite, glassy carbon (SIGRADUR ®< G, from HTW Hochtemperatur Werkstoffe GmbH, Thierhaupten, Germany), Sigraflex foil, boron-doped diamond (BDD), lead, copper-tin-lead (CuSn7Pb15), molybdenum, nickel, niobium, silver, tantalum, titanium, vanadium, tungsten, zirconium, and ruthenium oxide DSA were used.

[0101] The used Electrolysis cells were supplied by IKA. 5 mL glass vials were used for the batch experiments and Teflon cells for the flow experiments.

[0102] The used Galvanostat It is an HMP4040 from Rohde&Schwarz (Rohde & Schwarz GmbH & Co. KG, Munich, Germany).

[0103] Gas chromatographywas carried out on a GC-2010 from Shimadzu (Shimadzu, Japan) using an HP-5MS column (Agilent, USA; length: 30 m, inner diameter: 0.25 mm, film thickness: 0.25 µm, carrier gas: helium (pressure: 26.7 kPa, total flow rate: 22.8 mL◆min -1< , column flow: 0.68 mL◆min -1< , linear velocity: 30.0 cm◆sec -1< , purge flow: 5.0 mL◆min -1< , split ratio: 25.0)). Injector temperature: 250 °C; Program: "Medium" method: 50 °C start temperature for 1 min, heating rate: 17.5 °C min -1< to 300 °C, 300 °C final temperature for 4.72 min.

[0104] Gas chromatography-coupled mass spectrometry was performed using a Shimadzu GCMS-QP2010 SE single quadrupole (Shimadzu, Japan) (mass range: m / z 1.5 to 1000, measurable FWHM: 0.5 to 2.0 u; EI scan S / N: 1 pg octafluoronaphthalene m / z 272 S / N ≥ 600 (helium gas); high-speed scan rate: 10000 u / sec). I.2 General working procedure (AAV1) for batch reactions in 5 mL glass vials

[0105] For the batch reactions, 5 mL glass vials of the IKA ® Screening System (IKA-Werke GmbH & Co. KG, Staufen, Germany) were used. These vials were heated during the reactions in a commercially available stainless steel block. The dimensions of the electrodes were 7 cm x 1 cm x 0.3 cm, and those of the isostatic graphite electrodes were 5 cm x 1 cm x 0.3 cm. The glass vials were sealed with a Teflon lid with precisely fitting holes for the electrodes.

[0106] For the reactions, 145.4 mg of hexachlorocyclohexane (HCH) (0.5 mmol) was dissolved with 0.5 mmol of conducting salt in 5 mL of the solvent used in a 5 mL glass vial. Then, 1.5 mmol (3.0 eq.) of the acceptor substrate, such as 297.5 mg of methyl 10-undecenoate (MUD), was added. The cell was sealed with the lid, which provided an electrode spacing of 1 cm. The electrode thus protruded 3.5 cm into the reaction solution. The experiments were carried out galvanostatically at a current density of 4 mA cm -2 and 50 °C. 9 F (434.2 Q) based on the HCH was applied in each case, and after the reaction, 70 µL of mesitylene was added as a GC standard.

[0107] Scale-up reactions were carried out in cells (pot cells) with a volume of 50 mL and 500 mL, as well as in stacked cells with a volume of 0.8 L and 1.5 L.

[0108] The dimensions of the electrodes were 10 cm x 2.3 cm x 0.3 cm for cells with a volume of 50 mL and 22.5 cm x 5.7 cm x 0.3 cm for cells with a volume of 500 mL. The electrode spacing was 5 mm in each case. The electrodes were preferably graphite electrodes.

[0109] The stacked cells preferably had isostatic graphite electrodes, which were alternately connected as cathode and anode. The electrode spacing was 5 mm. The dimensions of the electrodes were 16 cm x 6.4 cm x 0.3 cm (10x number) in cells with a volume of 0.8 L and 21 cm x 8 cm x 0.3 cm (12x number) in cells with a volume of 1.5 L. I.3 General working procedure (AAV2) for flow reactions in different cell types

[0110] Temperature-controlled flow cells from the IKA ® Screening System (IKA-Werke GmbH & Co. KG, Staufen, Germany) were used for the flow reactions. An IPC-N ISM936 peristaltic pump from Ismatec was used to control the flow rate. The electrode dimensions were 12 cm x 4 cm x 0.3 cm for the temperature-controlled cell with a 1 mm spacer.

[0111] For the reactions, analogous concentrations were chosen as in AAV1, only the volume of the mixtures was increased. The experiments were carried out galvanostatically at a current density of 4 to 20 mA cm -2 and 50 to 75°C. In each case, 9 to 15 F, based on the HCH, was applied, and after the reaction, 70 µL of mesitylene was added as a GC standard. Furthermore, flow rates of 0.5 to 10 mL min -1 were selected. II. Production of chloro- and bromomethyl acetals in pot electrode Example 1: Chloroacetaldehyde dimethyl acetal (= 2-chloro-1,1-dimethoxyethane)

[0112]

[0113] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with ethyl vinyl ether (219 mg, 290 µL, 3.0 mmol, 3.0 eq.) and methanol (387 mg, 490 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was also added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and at 8.5 F at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was detected by GC-MS. m / z: 124.0 (100.0%), 126.0 (32.5%), 125.0 (4.5%), 127.0 (1.5%) Example 1a: 2-chloro-1,1-dimethoxyethane

[0114] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with ethyl vinyl ether (219 mg, 290 µL, 3.0 mmol, 3.0 eq.) and methanol (387 mg, 490 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 25 °C under room atmosphere with 8.5 F The product was electrolyzed galvanostatically at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were used as the anode and cathode. The product was detected by GC-MS. Subsequently, the product was isolated from the electrolyte by distillation under reduced pressure. To determine the yield, the product was quantified by GC using external calibration (yield: 47%, 175 mg, 1.41 mmol). m / z: 124.0 (100.0%), 126.0 (32.5%), 125.0 (4.5%), 127.0 (1.5%) 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.51 (t, J = 5.4 Hz, 1H), 3.50 (d,J = 5.4 Hz, 2H), 3.40 (s, 6H). Example 2: Chloroacetaldehyde-ethylmethylacetal (= 2-chloro-1-ethoxyl-1-methoxyethane)

[0115]

[0116] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with ethyl vinyl ether (219 mg, 290 µL, 3.0 mmol, 3.0 eq.) and methanol (387 mg, 490 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and at 8.5 F at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. To determine the yield, the product was quantified by GC using external calibration (yield: 19%, 79 mg, 0.57 mmol). The product was detected by GC-MS. m / z: 138.0 (100.0%), 140.0 (32.4%), 139.0 (5.5%), 141.0 (1.8%). Example 3: Chloroacetaldehyde diethyl acetal (2-chloro-1,1-di(ethoxy)ethane)

[0117]

[0118] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with ethyl vinyl ether (219 mg, 290 µL, 3.0 mmol, 3.0 eq.) and ethanol (552 mg, 700 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and at 8.5 F at a current density of 15.0 mA cm-2. Isostatic graphite electrodes were preferably used as the anode and cathode. The product was detected by GC-MS. The product was then isolated from the electrolyte by distillation under reduced pressure. To determine the yield, the product was quantified by GC using external calibration (yield: 88%, 403 mg, 2.64 mmol). Example 18a:2-Chloro-1,1-di(ethoxy)ethane (chlorine source not according to the invention) Example 4: 2-Chloro-1,1-di(ethoxy)ethane with non-preferred chlorine source

[0119] According to the modified AAV1, concentrated hydrochloric acid (37%, 200 µL) was dissolved with ethyl vinyl ether (219 mg, 290 µL, 3.0 mmol, 3.0 eq.) and ethanol (552 mg, 700 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 25 °C under room atmosphere with 8.5 F The product was electrolyzed galvanostatically at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were used as the anode and cathode. The product was detected by GC-MS. The yield was determined by quantification using external calibration via GC (yield: 30%, 139 mg, 0.91 mmol). m / z: 152.1 (100.0%), 154.1 (32.6%), 153.1 (6.7%), 155.1 (2.2%) m / z: 152.1 (100.0%), 154.1 (32.6%), 153.1 (6.7%), 155.1 (2.2%) Example 5: Chloroacetaldehyde ethylisopropylacetal (= 2-(2-chloro-1-ethoxyethoxy)propane)

[0120]

[0121] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with ethyl vinyl ether (219 mg, 290 µL, 3.0 mmol, 3.0 eq.) and isopropanol (721 mg, 925 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was also added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and at 8.5 F at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was detected by GC-MS. m / z: 166.1 (100.0%), 168.1 (32.6%), 167.1 (7.8%), 169.1 (2.5%) Example 6:Chloroacetaldehyde diisopropylacetal (= 1-chloro-2,2-di(methylethyloxy)ethane)

[0122]

[0123] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with isopropyl vinyl ether (258 mg, 342 µL, 3.0 mmol, 3.0 eq.) and isopropanol (721 mg, 925 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was also added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and at 8.5 F at a current density of 15.0 mA cm-2. Isostatic graphite electrodes were preferably used as the anode and cathode. The product was detected by GC-MS. m / z: 180.1 (100.0%), 182.1 (32.7%), 181.1 (8.9%), 183.1 (2.9%) Example 7: 2-chloromethyl-1,3-dioxolane

[0124]

[0125] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with ethylene glycol vinyl ether (264 mg, 270 µL, 3.0 mmol, 3.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) and manganese(II) chloride tetrahydrate (19.8 mg, 0.1 mmol) were also added to the solution and electrolyzed galvanostatically at 57 °C under room atmosphere and at a current density of 10.0 mA cm -2 < at 7.4 F. Isostatic graphite electrodes were preferably used as the anode and cathode. The product was detected by GC-MS. m / z: 122.0 (100.0%), 124.0 (32.4%), 123.0 (4.5%), 125.0 (1.5%) Example 7a: 2-chloromethyl-1,3-dioxolane

[0126] According to the modified AAV1, hexachlorocyclohexane (218.1 mg, 0.75 mmol, 1.0 eq.) was dissolved with 2-hydroxyethyl vinyl ether (198 mg, 202 µL, 2.25 mmol, 3.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and electrolyzed at 57 °C under room atmosphere using 7.4 F galvanostatic current at a current density of 10.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was then removed from the electrolyte by distillation under reduced pressure and subsequently fractionally distilled (yield: 35%, 97 mg, 0.79 mmol). The product was detected by GC-MS. m / z: 122.0 (100.0%), 124.0 (32.4%), 123.0 (4.5%), 125.0 (1.5%) 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 5.14 (t, J = 4.0 Hz, 1H), 4.06-4.01 (m, 2H), 3.9-3.89 (m, 2H), 3.52 (d, J = 3.9 Hz, 2H). Example 8:2-Chlormethyl-1,3-dioxepan

[0127]

[0128] According to the modified AAV1, hexachlorocyclohexane (218.7 mg, 0.75 mmol, 1.0 eq.) was dissolved with tetramethylene glycol vinyl ether (= 4-hydroxybutyl vinyl ether) (261 mg, 276 µL, 3.0 mmol, 3.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) and manganese(II) chloride tetrahydrate (14.8 mg, 0.075 mmol) were also added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and at a current density of 10.0 mA cm -2 < at 7.0 F. Isostatic graphite electrodes were preferably used as the anode and cathode. The product was detected by GC-MS. The product was then removed from the electrolyte by distillation under reduced pressure and then fractionally distilled (yield: 79%, 276 mg, 1.78 mmol). To determine the yield, the product was also quantified by GC using external calibration. m / z: 150 (100.0%), 152 (32.6%), 151 (6.7%), 153 (2.2%) 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.84 (t, J = 5.3 Hz, 1H), 3.93 (min, J = 11.9, 3.4 Hz, 2H), 3.66 (dq, 2H), 3.46 (d, J = 5.3 Hz, 2H), 1.76–1.68 (m, 4H). Example 9: 2-Chlormethyl-1,3-dioxepan with HCl als nicht bevorzugter Chlorquelle

[0129] According to the modified AAV1, concentrated hydrochloric acid (37%, 100 µL) was dissolved with 4-hydroxybutyl vinyl ether (261 mg, 276 µL, 2.25 mmol, 3.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) and manganese(II) chloride tetrahydrate (14.8 mg, 0.075 mmol) were also added to the solution and electrolyzed at 25 °C under room atmosphere and with a current density of 10.0 mA cm -2 at 7.0 F. Isostatic graphite electrodes were preferably used as the anode and cathode. The product was detected by GC-MS. To determine the yield, the product was quantified by GC using external calibration (yield: 26%, 87 mg, 0.58 mmol). Example 10: 2-chloromethyl-1,3,6-trioxocane

[0130]

[0131] According to the modified AAV1, hexachlorocyclohexane (218.7 mg, 0.75 mmol, 1.0 eq.) was dissolved in 5 mL of propylene carbonate with 2-[2-(ethenyloxy)ethoxy]ethanol (368 mg, 382 µL, 3.0 mmol, 3.0 eq.). Tetraethylammonium chloride (41.4 mg, 0.25 mmol) and manganese(II) chloride tetrahydrate (14.8 mg, 0.075 mmol) were also added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and at 7.0 F at a current density of 10.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was detected by GC-MS. The product was subsequently sublimed from the electrolyte under reduced pressure. To determine the yield, the product was quantified by GC using external calibration (yield: 38%, 142 mg, 0.86 mmol). 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.77 (t, J = 5.4 Hz, 1H), 4.01-3.92 (m, 4H), 3.79-3.64 (m, 4H), 3.45 (d, J= 5.4 Hz, 2H). m / z: 166.0 (100.0%), 168.0 (32.8%), 167.0 (6.7%), 169.0 (2.2%) Example 11: 2-Brommethyl-1,3-dioxepan

[0132]

[0133] According to the modified AAV1, hexabromocyclododecane (481 mg, 0.75 mmol, 1.0 eq.) was dissolved with tetramethylene glycol vinyl ether (261 mg, 276 µL, 3.0 mmol, 3.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) and manganese(II) bromide tetrahydrate (21.4 mg, 0.075 mmol) were also added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and at 7.0 F at a current density of 10.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was detected by GC-MS. The product was then isolated from the electrolyte by distillation under reduced pressure. To determine the yield, the product was quantified by GC using external calibration (yield: 29%, 131 mg, 0.67 mmol). m / z: 194.0 (100.0%), 196.0 (97.9%), 195.0 (6.7%), 197.0 (6.5%) 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.89 (t, J = 5.3 Hz, 1H), 3.93 (dq, J = 11.9, 3.5 Hz, 2H), 3.69-3.64 (m, 2H), 3.32 (d, J = 5.4 Hz, 2H), 1.76-1.68 (m, 4H). Example 12: Chloroacetaldehyde dipropylacetal (1-chloro-2,2-di(propoxy)-ethane)

[0134]

[0135] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with propyl vinyl ether (258 mg, 340 µL, 3.0 mmol, 3.0 eq.) and propanol (721 mg, 900 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 25 °C under room atmosphere with 8.5 FThe product was electrolyzed galvanostatically at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were used as the anode and cathode. The product was also detected by GC-MS. The product was then isolated from the electrolyte by distillation under reduced pressure. To determine the yield, the product was quantified by GC using external calibration (yield: 42%, 233 mg, 1.29 mmol). m / z: 180.1 (100.0%), 182.1 (32.0%), 181.1 (8.9%), 183.1 (2.8%) 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.62 (t, J = 5.5 Hz, 1H), 3.60 (dt, J = 9.3, 6.7 Hz, 2H), 3.51 (d, J = 5.5 Hz, 2H), 3.46 (dt, J = 9.2, 6.7 Hz, 2H), 1.65-1.58 (h, 4H), 0.94 (t, J = 7.4 Hz, 6H). Example 13: Chloroacetaldehyde-dichloroethanolacetal (2-chloro-1,1-di(2-chloroethoxy)ethane)

[0136]

[0137] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with 2-chloroethyl vinyl ether (320 mg, 304 µL, 3.0 mmol, 3.0 eq.) and 2-chloroethanol (966 mg, 798 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 25 °C under room atmosphere with 8.5 F The reaction mixture was electrolyzed galvanostatically at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was also detected by GC-MS. The solvent was removed under reduced pressure. The product was then isolated from the residue by fractional distillation. To determine the yield, the product was quantified by GC using external calibration (yield: 46%, 306 mg, 1.38 mmol). m / z: 220.0 (100.0%), 222.0 (95.9%), 224.0 (31.0%), 221.0 (6.7%), 223.0 (6.3%), 226.0 (3.3%), 225.0 (2.1%) 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.80 (t, J = 5.6 Hz, 1H), 3.93 (dt, J = 11.2, 5.6 Hz, 2H), 3.84 (dt, J = 10.8, 5.6 Hz, 2H), 3.66 (t, J = 5.7 Hz, 4H), 3.57 (d, J = 5.5 Hz, 2H). Example 14: Chloracetaldehyd-dibutylacetal (2-Chlor-1,1-di(butoxy)ethan)

[0138]

[0139] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with butyl vinyl ether (300 mg, 390 µL, 3.0 mmol, 3.0 eq.) and butanol (889 mg, 1098 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was also added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and with the application of 8.5 F at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was also detected by GC-MS. The electrolyte was extracted with pentane. After removal of the solvent, the product was isolated from the residue by fractional distillation. To determine the yield, the product was quantified by GC using external calibration (yield: 49%, 307 mg, 1.47 mmol). m / z: 208.1 (100.0%), 210.1 (32.0%), 209.1 (11.1%), 211.1 (3.5%), 210.1 (1.0%) 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.60 (t, J = 5.4 Hz, 1H), 3.63 (dt, J = 9.2, 6.5 Hz, 2H), 3.53-3.47 (m, 4H), 1.57 (dq, J = 8.4, 6.6 Hz, 4H), 1.43-1.34 (m, 4H), 0.92 (t, J = 7.3 Hz, 6H). Example 15: 2-Chloro-1,1-di(butoxy)ethane (HCl as a non-preferred chlorine source)

[0140] According to the modified AAV1, concentrated hydrochloric acid (37%, 100 µL) was dissolved with butyl vinyl ether (300 mg, 390 µL, 3.0 mmol, 3.0 eq.) and butanol (889 mg, 1098 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. In addition, tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 25 °C under room atmosphere and application of 8.5 FThe reaction mixture was electrolyzed galvanostatically at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were used as the anode and cathode. The product was also detected by GC-MS. The yield was determined by quantifying the product by external calibration using GC (yield: 12%, 75 mg, 0.36 mmol). Example 16: Chloroacetaldehyde diisobutylacetal (2-chloro-1,1-di(2-methylpropoxy)ethane)

[0141]

[0142] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with 2-methylpropyl vinyl ether (300 mg, 390 µL, 3.0 mmol, 3.0 eq.) and 2-methylpropanol (889 mg, 1112 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 25 °C under room atmosphere with 8.5 FThe product was electrolyzed galvanostatically at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was also detected by GC-MS. The electrolyte was extracted with pentane. After removal of the solvent, the product was isolated from the residue by fractional distillation. To determine the yield, the product was quantified by GC using external calibration (yield: 56%, 351 mg, 1.68 mmol). Example 17: 2-Chloro-1,1-di(2-methylpropoxy)ethane (HCl as a non-preferred chlorine source)

[0143] According to the AAV1 modified as follows, concentrated hydrochloric acid (37%, 100 µL) was mixed with i< Butyl vinyl ether (300 mg, 390 µL, 3.0 mmol, 3.0 eq.) and i< Butanol (889 mg, 1112 µL, 12.0 mmol, 12.0 eq.) was dissolved in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was also added to the solution and incubated at 25 °C under room atmosphere with 8.5 F The reaction mixture was electrolyzed galvanostatically at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were used as the anode and cathode. The product yield was determined by quantifying it using external calibration via GC (yield: 17%, 104 mg, 0.50 mmol). m / z: 208.12 (100.0%), 210.12 (32.0%), 209.13 (11.1%), 211.12 (3.5%), 210.13 (1.0%) 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.60 (t, J = 5.5 Hz, 1H), 3.51 (d, J = 5.4 Hz, 2H), 3.40 (dd, J = 9.0, 6.6 Hz, 2H), 3.26 (dd, J = 9.0, 6.7 Hz, 2H), 1.86 (dp, J = 13.3, 6.7 Hz, 2H), 0.92 (d, J = 6.7 Hz, 12H). Example 18:Chloroacetaldehyde dibenzyl acetal (2-chloro-1,1-di(benzyloxy)-ethane)

[0144]

[0145] According to the modified AAV1, hexachlorocyclohexane (290.8 mg, 1.0 mmol, 1.0 eq.) was dissolved with benzyl vinyl ether (403 mg, 415 µL, 3.0 mmol, 3.0 eq.) and benzyl alcohol (1298 mg, 1248 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 25 °C under room atmosphere with 8.5 FThe reaction mixture was electrolyzed galvanostatically at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was also detected by GC-MS. The solvent was removed under reduced pressure. The product was then isolated from the residue by fractional distillation. To determine the yield, the product was quantified by GC using external calibration (yield: 31%, 260 mg, 0.93 mmol). m / z: 276.1 (100.0%), 278.1 (32.0%), 277.1 (17.6%), 279.1 (5.6%), 278.1 (1.9%) 1< H-NMR (400 MHz, CD 2 Cl 2 ) δ [ppm] = 7.41-7.29 (m, 10H), 4.88 (t, J = 5.4 Hz, 1H), 4.72 (d, J = 11.6 Hz, 2H), 4.63 (d, J = 11.6 Hz, 2H), 3.64 (d, J = 5.5 Hz, 2H). Example 19: 2-chloromethyl-1,3-dioxane

[0146]

[0147] According to the modified AAV1, hexachlorocyclohexane (218.1 mg, 0.75 mmol, 1.0 eq.) was dissolved with 3-hydroxypropyl vinyl ether (230 mg, 239 µL, 2.25 mmol, 3.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) and manganese(II) chloride tetrahydrate (14.8 mg, 0.075 mmol) were added to the solution and incubated at 25 °C under room atmosphere with 7.0 F The product was electrolyzed galvanostatically at a current density of 10.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was then removed from the electrolyte by distillation under reduced pressure. The product was detected by 1< H NMR in the distillation fraction and by GC-MS. Example 20: Bromoacetaldehyde dimethyl acetal (2-bromo-1,1-di(methoxy)-ethane)

[0148]

[0149] According to the modified AAV1, 1,2,5,6,9,10-hexabromocyclododecane (641.7 mg, 1.0 mmol, 1.0 eq.) was dissolved with ethyl vinyl ether (219 mg, 290 µL, 3.0 mmol, 3.0 eq.) and methanol (387 mg, 490 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 25 °C under room atmosphere with 8.5 F The product was electrolyzed galvanostatically at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was then isolated from the electrolyte by distillation under reduced pressure. The yield was determined by GC using external calibration (yield: 22%, 109 mg, 0.65 mmol). 1< H NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.55 (t, J = 5.4 Hz, 1H), 3.39 (s, 6H), 3.36 (d, J = 5.5 Hz, 2H). Example 21: Bromoacetaldehyde diethyl acetal (2-bromo-1,1-di(ethoxy)ethane)

[0150]

[0151] According to the modified AAV1, 1,2,5,6,9,10-hexabromocyclododecane (641.7 mg, 1.0 mmol, 1.0 eq.) was dissolved with ethyl vinyl ether (219 mg, 290 µL, 3.0 mmol, 3.0 eq.) and ethanol (552 mg, 700 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 25 °C under room atmosphere with 8.5 FThe product was electrolyzed galvanostatically at a current density of 15.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was then isolated from the electrolyte by distillation under reduced pressure. The yield was determined by quantification of the product by external calibration via GC (yield: 86%, 510 mg, 2.59 mmol). 1< H NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.66 (t, J = 5.5 Hz, 1H), 3.72-3.55 (m, 4H), 3.36 (d, J = 5.5 Hz, 2H), 1.23 (t, J = 7.1 Hz, 6H). Example 22: Bromoacetaldehyde dipropyl acetal (2-bromo-1,1-di(propoxy)-ethane)

[0152]

[0153] According to the modified AAV1 as follows, 1,2,5,6,9,10-hexabromocyclododecane (641.7 mg, 1.0 mmol, 1.0 eq.) was reacted with propyl vinyl ether (258 mg, 340 µL, 3.0 mmol, 3.0 eq.) and n< Propanol (721 mg, 900 µL, 12.0 mmol, 12.0 eq.) was dissolved in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was also added to the solution and incubated at 25 °C under room atmosphere with 8.5 F Galvanostatically electrolyzed at a current density of 15.0 mA◆cm -2. Isostatic graphite electrodes were preferably used as the anode and cathode. The electrolyte was extracted with pentane. After removal of the solvent, the product was isolated from the residue by fractional distillation. To determine the yield, the product was quantified by GC using external calibration (yield: 14%, 94 mg, 0.419 mmol). 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.66 (t, J = 5.5 Hz, 1H), 3.62-3.44 (m, 4H), 3.37 (d, J = 5.5 Hz, 2H), 1.66-1.58 (m, 4H), 0.94 (t, J = 7.5 Hz, 6H). Example 23: Bromoacetaldehyde diisobutylacetal (2-bromo-1,1-di(2-methylpropoxy)ethane)

[0154]

[0155] According to the modified AAV1, 1,2,5,6,9,10-hexabromocyclododecane (641.7 mg, 1.0 mmol, 1.0 eq.) was dissolved with 2-methylpropyl vinyl ether (300 mg, 390 µL, 3.0 mmol, 3.0 eq.) and 2-methylpropanol (889 mg, 1112 µL, 12.0 mmol, 12.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 25 °C under room atmosphere with 8.5 FGalvanostatically electrolyzed at a current density of 15.0 mA◆cm -2. Isostatic graphite electrodes were preferably used as the anode and cathode. The electrolyte was extracted with pentane. After removal of the solvent, the product was isolated from the residue by fractional distillation. To determine the yield, the product was quantified by GC using external calibration (yield: 36%, 273 mg, 1.08 mmol). 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 4.65 (t, J = 5.6 Hz, 1H), 3.42-3.37 (m, 4H), 3.25 (dd, J = 9.0, 6.6 Hz, 2H), 1.87 (dp, J = 13.3, 6.7 Hz, 2H), 0.93 (d, J = 6.7 Hz, 12H). Example 24: 2-Bromomethyl-1,3-dioxolane

[0156]

[0157] According to the modified AAV1, 1,2,5,6,9,10-hexabromocyclododecane (641.7 mg, 1.0 mmol, 1.0 eq.) was dissolved with 2-hydroxyethyl vinyl ether (264 mg, 270 µL, 3.0 mmol, 3.0 eq.) in 5 mL of propylene carbonate. Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and incubated at 57 °C under room atmosphere with 7.4 F The product was electrolyzed galvanostatically at a current density of 10.0 mA cm -2 . Isostatic graphite electrodes were preferably used as the anode and cathode. The product was then isolated from the electrolyte by distillation under reduced pressure. To determine the yield, the product was quantified by GC using external calibration (yield: 49%, 245 mg, 1.47 mmol).

[0158] 1< H-NMR (400 MHz, CDCl 3 ) δ [ppm] = 5.14 (t, J = 4.1 Hz, 1H), 4.07-3.93 (m, 4H), 3.39 (d, J = 4.2 Hz, 2H).

Claims

1. A process for the preparation of acetals of aliphatic or cycloaliphatic aldehydes which carry a bromine or chlorine atom in the a-position to the acetal group, comprising the electrolysis of a liquid reaction mixture containing i) a halogen acceptor selected from - primary aliphatic or cycloaliphatic alcohols, - mono-1-alkyenyl ethers of aliphatic diols and - mixtures comprising a mono-1-alkyenyl ether of an aliphatic, cycloaliphatic or aromatic alcohol and at least one aliphatic or cycloaliphatic alcohol, ii) at least one halogen source containing chlorine or bromine, iii) at least one solvent and iv) at least one conducting salt in an undivided electrolysis cell.

2. The process according to claim 1, wherein the halogen source comprises an organic chlorine compound and / or an organic bromine compound.

3. The process according to claim 2, wherein the organic chlorine compound or the organic bromine compound has at least two vicinally bonded chlorine atoms or at least two vicinally bonded bromine atoms.

4. The process according to claim 3, wherein the halogen source is selected from 1,2,3,4,5,6-hexachlorocyclohexane and 1,2,5,6,9,10-hexabromocyclododecane.

5. The process according to any one of the preceding claims, wherein the halogen acceptor compounds are selected from compounds of the formula (Ia), compounds of the formula (Ib) and mixtures of a compound of the formula (Ic) with a compound of the formula (Id) R 1 -CH(R 11 )CH2-OH (Ia) HO-R 2 -O-CH=C(R 3 ,R 4 ) (Ib) R 2a -O-CH=C(R 3 ,R 4 ) (Ic) R 5 -OH (Id) where R 1represents hydrogen or a monovalent aliphatic or cycloaliphatic group containing 1 to 18 carbon atoms, R 11 represents hydrogen or a monovalent aliphatic or cycloaliphatic group containing 1 to 10 C atoms, R 2 represents a divalent aliphatic group containing 2 to 20 C atoms, R 2a represents a monovalent aliphatic, cycloaliphatic or aromatic group having 1 to 20 C atoms, R 3 represents hydrogen or a monovalent aliphatic or cycloaliphatic group having 1 to 10 C atoms and in particular represents hydrogen, R 4 represents hydrogen or a monovalent aliphatic or cycloaliphatic group having 1 to 10 C atoms and in particular represents hydrogen, R 5 represents a monovalent aliphatic or cycloaliphatic group having 1 to 20 C atoms, where the aliphatic groups in R 1 , R 11 , R2 , R 2a , R 3 , R 4 and R 5 are unsubstituted or 1, 2, 3 or 4 substituents R Al where the cycloaliphatic radicals in R 1 , R 11 , R 2 , R 3 , R 4 and R 5 are unsubstituted or 1, 2, 3 or 4 substituents R Cyc where the aromatic groups in R 2 are unsubstituted or 1, 2, 3 or 4 substituents R Ar where R Al may be the same or different and are selected from C1-C4-alkoxy, hydroxy-C1-C4-alkoxy, C1-C4-alkoxy-C1-C4-alkoxy, carboxyl, C1-C4-alkoxycarbonyl, C1-C4-alkoxy-C1-C4-alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N 2, where R N represents H, C1-C4-alkyl, hydroxy-C1-C4-alkyl or C1-C4-alkoxy-C1-C4-alkyl, R Cycmay be the same or different and are selected from C1-C4-alkyl, C1-C4-alkoxy, hydroxy-C1-C4-alkyl, hydroxy-C1-C4-alkoxy, C1-C4-alkoxy-C1-C4-alkyl, C1-C4-alkoxy-C1-C4-alkoxy, carboxyl, C1-C4-alkoxycarbonyl, C1-C4-alkoxy-C1-C4-alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N 2, C1-C4-alkyl-NR N 2, where R N represents H, C1-C4-alkyl, hydroxy-C1-C4-alkyl or C1-C4-alkoxy-C1-C4-alkyl, R Ar may be the same or different and are selected from C1-C4-alkyl, C1-C4-alkoxy, hydroxy-C1-C4-alkyl, hydroxy-C1-C4-alkoxy, C1-C4-alkoxy-C1-C4-alkyl, C1-C4-alkoxy-C1-C4-alkoxy, carboxyl, C1-C4-alkoxycarbonyl, C1-C4-alkoxy-C1-C4-alkoxycarbonyl, fluorine, chlorine, bromine, CN, NR N 2, C1-C4-alkyl-NR N 2, where R N represents H, C1-C4-alkyl, hydroxy-C1-C4-alkyl or C1-C4-alkoxy-C1-C4-alkyl; wherein 1, 2, 3 or 4 non-adjacent C atoms of the aliphatic or cycloaliphatic groups may be replaced by O or S, 6. The process according to claim 5, wherein the halogen acceptor is selected from compounds of formula (Ia).

7. The process according to claim 5, wherein the halogen acceptor is selected from compounds of formula (Ib) and mixtures of a compound of formula (Ic) and a compound of formula (Id).

8. Process according to one of the preceding claims, wherein the concentration of the mono-1-alkenyl ether of the aliphatic, cycloaliphatic or aromatic alcohol or of the diol in the liquid reaction mixture is in the range of 5 to 100 g / L and / or the concentration of the primary aliphatic or cycloaliphatic alcohol in the liquid reaction mixture is in the range of 5 to 200 g / L and / or the concentration of the halogen source in the liquid reaction mixture is in the range of 5 to 300 g / L.

9. The method according to any one of the preceding claims, wherein the conducting salt is selected from quaternary ammonium salts, pyridinium salts, imidazolium salts, quaternary phosphonium salts and mixtures thereof, and wherein the anions of the conducting salt are selected in particular from chloride, bromide, tetrafluoroborate, trifluoromethanesulfonate, tosylate, sulfate, C1-C4 alkyl sulfate, perchlorate, acetate, hexafluorophosphate, bis(trifluoromethylsulfonyl)imide, nitrate, carbonate and bromate, and in particular from chloride and bromide.

10. The process according to claim 9, wherein the concentration of the conducting salt in the reaction mixture is in the range of 0.02 to 0.1 mol / L.

11. The process according to any one of the preceding claims, wherein the solvent is selected from water, C1-C4 alkanols, C1-C4 fluoroalkanols, C1-C4 alkylnitriles, di-C1-C4 alkyl carbonates, C2-C4 alkylene carbonates, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-C1-C4 alkylpyrrolidone, C1-C4 alkyl esters of C2-C4 alkanoic acids, C1-C4 alkyl esters of C2-C4 hydroxyalkanoic acids, C1-C4 chloroalkanes, dihydrolevoglucosenone and mixtures thereof.

12. The process according to any one of the preceding claims, wherein the solvent comprises at least one organic solvent selected from the group consisting of C1-C4 alkyl nitriles, di-C1-C4 alkyl carbonates and C2-C4 alkylene carbonates.

13. The process according to any one of the preceding claims, wherein the liquid reaction mixture contains at least one transition metal salt, which is in particular selected from Mn(II) salts, Cu(I) salts, Cu(II) salts, Co(II) salts, Ni(II) salts, Cr(II) salts, Cr(III) salts, V(III) salts, Fe(II) salts, Fe(III) salts, Ru(III) salts, Rh(III) salts, Ir(III) salts, Pd(II) salts and combinations thereof.

14. The process according to claim 13, wherein the liquid reaction mixture contains the transition metal salt in a concentration of up to 20 mol%, based on the amount of halogen source used.

15. The method according to any one of the preceding claims, wherein the anode material of the electrolysis cell is selected from graphite, glassy carbon, platinum, boron-doped diamond and mixed metal oxides comprising at least one metal oxide from the group consisting of ruthenium oxide, iridium oxide and tantalum oxide.

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