Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B3/00—Electrolytic production of organic compounds
  • C25B3/01—Products
  • C25B3/07—Oxygen containing compounds
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
  • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
  • C25B11/042—Electrodes formed of a single material
  • C25B11/043—Carbon, e.g. diamond or graphene
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B3/00—Electrolytic production of organic compounds
  • C25B3/01—Products
  • C25B3/11—Halogen containing compounds
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B3/00—Electrolytic production of organic compounds
  • C25B3/20—Processes
  • C25B3/27—Halogenation
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B3/00—Electrolytic production of organic compounds
  • C25B3/20—Processes
  • C25B3/29—Coupling reactions

Definitions

• 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 ⁇ -position to the acetal group and which are also referred to below as acetals of ⁇ -chloro- or ⁇ -bromoaldehydes.
• ⁇ -Chloroaldehydes and ⁇ -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.
• 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.
• the invention is therefore based on the object of providing a simple process for the preparation of acetals of ⁇ -chloro- or ⁇ -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 ⁇ -chloro- or ⁇ -bromoaldehydes, without the need for toxicologically harmful or corrosive starting materials.
• 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 ⁇ -chloro- or ⁇ -bromoaldehydes, in particular the production of the acetals of ⁇ -chloro- or ⁇ -bromoacetaldehyde, in a single-step process, without the need to use toxicologically problematic ⁇ -chloro- or ⁇ -bromoaldehydes or the need to first prepare complex halogen-containing precursors such as dichloroethyl acetate, 1-ethoxy-1,2-dichloroethane, and 1-(2-chloroethoxy)-1,2-dichloroethane.
• 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.
• C n -C m indicates the number of carbon atoms that the compound or organic residue designated by it can have.
• 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.
• Optionally substituted means that cycloalkyl and the optionally present alkyl 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.
• 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.
• 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.
• alkenyl means 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 R N is H, C 1 -C 4 -alkyl, hydroxy-C 1 -C 4 -alkyl or C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl.
• 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, Do
• 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.
• 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.
• C 1 -C 10 alkoxy refers hereinafter to an alkyl radical as defined above, which has 1 to 10 carbon atoms.
• C 1 -C 4 alkoxy hereinafter refers to an alkyl radical as defined above, which has 1 to 4 carbon atoms, for example methoxy, ethoxy, propyloxy, isopropyloxy, n-butyloxy, 2-butyloxy, sec-butyloxy, tert-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-Dimethylbutyl
• hydroxyalkyl refers to an alkyl group, as defined above, bearing a hydroxyl group as a substituent. Examples are hydroxymethyl, 2-hydroxyethyl, 2-hydroxypropyl, and 3-hydroxypropyl.
• 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.
• 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.
• 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.
• 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 R N is H, C 1 -C 4 -alkyl,
• 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.
• 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 R N is H, C 1 -C 4 -alkyl, Hydroxy-C 1 -C 4 alkyl or C 1 -C 4 alkoxy-C 1 -C 4 -alkyl.
• heteroaryl refers to an aromatic or partially aromatic heterocyclic group which 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 which is selected from N, O and S, e.g.
• Hetaryl is unsubstituted, but can also contain 1 or more, e.g. B.
• 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 R N is H, C 1 -C 4 -alkyl, Hydroxy-C 1 -C 4 alkyl or C 1 -C 4 alkoxy-C 1 -C 4 -alkyl.
• 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.
• 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.
• a halogen source containing chlorine or bromine is used.
• mixtures of different halogen sources can be used.
• 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.
• chlorine sources are Cl2 (also in the form of chloride chains), hypochlorite, hydrogen chloride, N-chlorosuccinimide, vicinal chlorinated hydrocarbons such as hexachlorocyclohexane, polyvinyl chloride, iodobenzene dichloride, chloride salts such as sodium chloride, or conducting salts with chloride anions.
• suitable bromine sources are Br 2 (also in the form of bromide chains), hypobromide, hydrogen bromide, N-bromosuccinimide, vicinal bromocarbons such as HBCD, iodobenzene tribromide, bromide salts such as sodium bromide or conducting salts with bromide anions.
• 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 main source of the halogen required in the electrolysis is the organic chlorine compound or the organic bromine compound.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• dihalogenation initially takes place to give the corresponding 1,2-dichloro- or 1,2-dibromoalkyl ether, which is then Reaction with the alcohol at the carbon atom in 1-position to the ether oxygen with substitution of the halogen atom to form the acetal.
• 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.
• 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 .
• 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 .
• 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 .
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• tetramethylammonium salts examples thereof are tetramethylammonium salts, tetraethylammonium salts, tetra-n-butylammonium salts, triethylmethylammonium salts, trimethylbenzylammonium salts, and triethylbenzylammonium salts.
• pyridinium salts and imidazolium salts in particular those bearing 1 or 2 C 1 -C 8 -alkyl groups as substituents.
• 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.
• 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.
• the conducting salt is used in an amount such that its concentration in the reaction mixture is in the range of 0.01 to 0.2 mol/L and in particular in the range of 0.02 to 0.1 mol/L.
• 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.
• 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.
• 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.
• the solvent comprises at least one organic solvent selected from the group of C 2 -C 4 -alkylene carbonates.
• the solvent from the Group of C 2 -C 4 alkylene carbonates at least 50 wt.%, in particular at least 70 wt.% and especially 100 wt.%, based on the total amount of solvent contained in the liquid reaction mixture.
• 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.
• 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.
• 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.
• 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").
• 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.
• salts of manganese, copper, cobalt, nickel, chromium, Vanadium, iron, ruthenium, rhodium, iridium or palladium salts of manganese, copper, cobalt, nickel, chromium, Vanadium, iron, ruthenium, rhodium, iridium or palladium.
• 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.
• the anions of the transition metal salts are of minor importance.
• 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.
• 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.
• 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.
• the electrolysis cell naturally has at least one anode and at least one cathode.
• 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 ruthenium oxide, iridium oxide and tantalum oxide, preferably in combination with a titanium support.
• a particularly preferred electrode material for the anode is graphite, especially isostatic graphite.
• 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.
• 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.
• Electrode cathode Graphite isostatic Graphite, isostatic Graphite, isostatic Boron-doped diamond Boron-doped diamond Boron-doped diamond Boron-doped diamond 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
• any electrode shape known to the person skilled in the art can be used as the anode.
• This can be made entirely of the respective electrode material or 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 anodes can, for example, be electrodes in the form of expanded metal, mesh, or sheet metal.
• any undivided electrolysis cells 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.
• undivided flow cells e.g., a flow cell with forced electrolyte flow, i.e., the electrolyte is continuously passed past the electrodes, whereby the electrolyte flow can be 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.
• 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.
• Electrodes 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.
• 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.
• 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.
• an electric current is passed through the electrolyte.
• 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 .
• 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.
• 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.
• 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.
• 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.
• 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).
• the halogenation product obtained by the process according to the invention can be isolated from electrolytes by methods known to those skilled in the art.
• the halogenated product formed during electrolysis Halogenation product can be removed or depleted from the electrolyte by distillation or extraction.
• 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.
• 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).
• organic solvents include hydrocarbons with 5 to 12 carbon atoms, such as pentane, hexane, cyclohexane, heptane, or octane.
• the resulting halogenation product can also be removed from the electrolyte by solid-phase extraction.
• 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.
• hexachlorocyclohexane used is a stereoisomer mixture of 1,2,3,4,5,6-hexachlorocyclohexane.
• hexabromocyclododecane used is a stereoisomer mixture of 1,2,5,6,9,10-hexabromocyclododecane.
• the electrode materials used were 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.
• SIGRADUR ® G glassy carbon
• BDD boron-doped diamond
• CuSn7Pb15 copper-tin-lead
• molybdenum nickel, niobium, silver, tantalum, titanium, vanadium, tungsten, zirconium, and ruthenium oxide DSA.
• the electrolysis cells used were from IKA. 5 mL glass vials were used for the batch experiments and Teflon cells for the flow experiments.
• the galvanostat used is an HMP4040 from Rohde & Schwarz (Rohde & Schwarz GmbH & Co. KG, Kunststoff, Germany).
• 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).
• 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.
• 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.
• Temperature-controlled flow cells from the IKA® Screening System (IKA-Werke GmbH & Co. KG, Staufen, Germany) were used for the flow reactions.
• the electrode dimensions were 12 cm x 4 cm x 0.3 cm for the temperature-controlled cell with a 1 mm spacer.
• hexachlorocyclohexane 290.8 mg, 1.0 mmol, 1.0 eq.
• ethyl vinyl ether 219 mg, 290 ⁇ L, 3.0 mmol, 3.0 eq.
• Methanol 387 mg, 490 ⁇ L, 12.0 mmol, 12.0 eq.
• Tetraethylammonium chloride 41.4 mg, 0.25 mmol
• 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%)
• hexachlorocyclohexane 290.8 mg, 1.0 mmol, 1.0 eq.
• ethyl vinyl ether 219 mg, 290 ⁇ L, 3.0 mmol, 3.0 eq.
• methanol 387 mg, 490 ⁇ L, 12.0 mmol, 12.0 eq.
• Tetraethylammonium chloride 41.4 mg, 0.25 mmol was added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and with an 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. used. 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%)
• hexachlorocyclohexane 290.8 mg, 1.0 mmol, 1.0 eq.
• ethyl vinyl ether 219 mg, 290 ⁇ L, 3.0 mmol, 3.0 eq.
• ethanol 552 mg, 700 ⁇ L, 12.0 mmol, 12.0 eq.
• 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.
• 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 (non-inventive chlorine source)
• hexachlorocyclohexane 290.8 mg, 1.0 mmol, 1.0 eq.
• ethyl vinyl ether 219 mg, 290 ⁇ L, 3.0 mmol, 3.0 eq.
• isopropanol 721 mg, 925 ⁇ L, 12.0 mmol, 12.0 eq.
• Tetraethylammonium chloride 41.4 mg, 0.25 mmol
• 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%)
• hexachlorocyclohexane 290.8 mg, 1.0 mmol, 1.0 eq.
• isopropyl vinyl ether (258 mg, 342 ⁇ L, 3.0 mmol, 3.0 eq.) and isopropanol (721 mg, 925 ⁇ L, 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. m/z: 180.1 (100.0%), 182.1 (32.7%), 181.1 (8.9%), 183.1 (2.9%)
• hexachlorocyclohexane 290.8 mg, 1.0 mmol, 1.0 eq.
• ethylene glycol vinyl ether 264 mg, 270 ⁇ L, 3.0 mmol, 3.0 eq.
• Tetraethylammonium chloride 41.4 mg, 0.25 mmol
• 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 , applying 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 12 Chloroacetaldehyde dipropyl acetal (1-chloro-2,2-di(propoxy)ethane)
• Example 13 Chloroacetaldehyde dichloroethanol acetal (2-chloro-1,1-di(2-chloroethoxy)ethane)
• hexachlorocyclohexane 290.8 mg, 1.0 mmol, 1.0 eq.
• 2-methylpropyl vinyl ether 300 mg, 390 ⁇ L, 3.0 mmol, 3.0 eq.
• 2-methylpropanol 889 mg, 1112 ⁇ L, 12.0 mmol, 12.0 eq.
• 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 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).
• hexachlorocyclohexane 218.1 mg, 0.75 mmol, 1.0 eq.
• 3-hydroxypropyl vinyl ether 230 mg, 239 ⁇ L, 2.25 mmol, 3.0 eq.
• Tetraethylammonium chloride 41.4 mg, 0.25 mmol
• 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 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.
• 1,2,5,6,9,10-hexabromocyclododecane 641.7 mg, 1.0 mmol, 1.0 eq.
• ethyl vinyl ether 219 mg, 290 ⁇ L, 3.0 mmol, 3.0 eq.
• methanol 387 mg, 490 ⁇ L, 12.0 mmol, 12.0 eq.
• 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 then isolated from the electrolyte by distillation under reduced pressure. To determine the yield, the product was quantified by GC using external calibration (yield: 22%, 109 mg, 0.65 mmol).
• 1,2,5,6,9,10-hexabromocyclododecane 641.7 mg, 1.0 mmol, 1.0 eq.
• ethyl vinyl ether 219 mg, 290 ⁇ L, 3.0 mmol, 3.0 eq.
• ethanol 552 mg, 700 ⁇ L, 12.0 mmol, 12.0 eq.
• Tetraethylammonium chloride (41.4 mg, 0.25 mmol) was added to the solution and electrolyzed galvanostatically at 25 °C under room atmosphere and with an 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 then isolated from the electrolyte by distillation under reduced pressure. To determine the yield, the product was quantified by GC using external calibration (yield: 86%, 510 mg, 2.59 mmol).
• 1,2,5,6,9,10-hexabromocyclododecane 641.7 mg, 1.0 mmol, 1.0 eq.
• propyl vinyl ether (258 mg, 340 ⁇ L, 3.0 mmol, 3.0 eq.) and n- propanol (721 mg, 900 ⁇ L, 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 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).
• 1,2,5,6,9,10-hexabromocyclododecane 641.7 mg, 1.0 mmol, 1.0 eq.
• 2-methylpropyl vinyl ether 300 mg, 390 ⁇ L, 3.0 mmol, 3.0 eq.
• 2-methylpropanol 889 mg, 1112 ⁇ L, 12.0 mmol, 12.0 eq.
• 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 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).
• 1,2,5,6,9,10-hexabromocyclododecane 641.7 mg, 1.0 mmol, 1.0 eq.
• 2-hydroxyethyl vinyl ether 264 mg, 270 ⁇ L, 3.0 mmol, 3.0 eq.
• Tetraethylammonium chloride 41.4 mg, 0.25 mmol
• Isostatic graphite electrodes were 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 via GC using external calibration (yield: 49%, 245 mg, 1.47 mmol).

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