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
  • C25B3/20—Processes
  • C25B3/23—Oxidation

Definitions

• DE-A-3000243 describes the methoxylation of ethers in electrolytic cells, that using glassy carbon or platinum as anode materials. With this Process, the regioselectivity is unsatisfactory and the current yield leaves a lot to be desired.
• EP-A-283807 describes the methoxylation of dimethoxyethane in Presence of triarylamine compounds known as a redox catalyst.
• a redox catalyst is required separation of the redox catalyst to be regarded as disadvantageous.
• Aliphatic or alicyclic are suitable as starting compounds
• Mono- or diether with preferably 3 to 6 carbon atoms with methine, methylene or methyl groups in the ⁇ -position stand for an ether oxygen atom (starting ether) as 1,2-dimethoxyethane, tetrahydrofuran, tetrahydropyran or 1,4-dioxane.
• start ether an ether oxygen atom
• H atom of these methine, methylene or methyl groups substituted by a methoxy group.
• the methoxylated ethers are preferred from the starting ethers prepared so that one is in the ⁇ -position to the ether oxygen located methine, methylene or methyl group only one only hydrogen atom substituted by a methoxy group.
• the methoxylates are particularly preferred from the starting ethers Ethers prepared so that you only one per molecule only hydrogen atom on a methylene or methyl group in ⁇ position to the ether oxygen substituted by a methoxy group.
• the method according to the invention is particularly suitable for production of 1,1,2-trimethoxyethane from 1,2-dimethoxyethane, of 2-methoxytetrahydrofuran from tetrahydrofuran, 2-methoxy-1,4-dioxane from 1,4-dioxane and methoxytetrahydropyran from tetrahydropyran.
• Electrolytic cells using a solid polymer electrolyte (SPE) work are generally known (see. “Ion exchange membranes in electrolysis and electro-organic synthesis ", Dr.-Ing. Jakob Jörissen, Progress Reports VDI Row 3 No. 442; Dusseldorf: VDI Verlag 1996, Chapter 4).
• Polymers are particularly suitable as cation exchange membranes such as polyethylene, polyacrylates, polysulfone and perfluorinated Polymers with negatively charged groups such as carboxylate and Sulfonate groups that are processed into films.
• the sulfonate groups can also be replaced by carboxylate groups to be replaced.
• Such films are commercially available and, for example, among the Trade names Nafion®, (E.I. Du Pont de Nemours and Company) and Gore Select® (W.L. Gore & Associates, Inc.).
• the solid electrolyte in the form of a gel swollen with an optionally N-alkylated C 1 -C 15 -carboxylic acid amide, which can be obtained by allowing the cation exchange membrane to swell in the carboxylic acid amide until the gel formed 1.2 to 10 times the weight of the cation exchange membrane used.
• the increase in weight can be determined by weighing the membrane before swelling, immediately after removal from the swelling medium by dabbing it with an absorbent fleece to remove the liquid wetting it and then immediately carrying out a differential weighing.
• the swelling with N, N-dimethylformamide is particularly advantageously carried out by.
• the swelling is expediently at a Temperature from 50 to 120 ° carried out.
• the solid electrolyte can be a single one Cation exchange membrane or around a layer of several, preferably act 2 to 10 membranes one above the other.
• the solid electrolyte conveniently has a thickness of 0.025 to 0.2 mm on.
• porous, electrically conductive materials especially graphite felt plates, Carbon felt sheets, or textile materials that are attached to the Contact surface to the solid electrolyte covered with carbon are considered.
• the electrolysis liquid preferably contains 50 to 99, especially preferably 70 to 97% by weight of methanol.
• the electrolysis liquid further contains 1 to 50, preferably 3 to 30% by weight of compounds selected from the group of Compounds consisting of aliphatic and alicyclic mono- or Diethern with preferably 3 to 6 carbon atoms Methine, methylene or methyl groups that are in the ⁇ -position to one Ether oxygen atom are (starting ether), and the corresponding Methoxylated ethers, the proportion of the starting ether Compounds in this group is at least 1 mol%.
• Inert organic solvents and water are suitable as solvents which are optionally present in the electrolysis liquid, preferably in amounts of 5 to 30% by weight.
• Organic solvents of this type which undergo virtually no reaction under the process conditions are, for example, N-alkylated C 3 -C 15 -carboxamides such as formamide, N-methylformamide, N, N-dimethylformamide, acetamides, N-methylpyrolidone, pyrrolidone and benzamide, N-alkylated ureas with 3 to 15 carbon atoms such as N, N, N ', N' tetramethyl urea, ether, acetonitrile, benzonitrile, sulfolane, and esters such as methyl acetate.
• the proportion of water in the electrolysis liquid is not more than 10, preferably 2 and very particularly preferably not more than 0.5% by weight.
• the electrolysis liquid essentially does not contain any of the others Lead electrolytes used in conventional cells such as acids, bases or electrolytes, i.e. that they are generally less than 10, particularly preferably less than 1, entirely particularly preferably less than 0.1% by weight of these lead electrolytes contains.
• the method according to the invention is expediently carried out in this way by making the electrolysis liquid parallel to the anode Solid electrolyte / anode interface preferably continuous flows through. Flow rates of the electrolysis liquid are suitable relative to the anode from 1 to 10 cm / s.
• the current density is generally 0.1 to 40, preferably 1 to 10 A / dm 2 .
• the voltages required to achieve these current densities are generally 2 to 20, preferably 3 to 10 volts. At higher voltages there is a risk of irreversible damage to the solid electrolyte.
• the cells in which the method can be carried out are known and for example in loc. cit, chapter 4.2 and in the DE-A-19533773.
• Suitable for practicing the process on an industrial scale especially those described in DE-A-19533773 serially switched plate stack cells.
• plate stack cells are made of layers aligned parallel to each other, where the layers from the porous, electrically conductive Alternate material and that from the solid electrolyte.
• the basic structure of plate stack cells is, for example from "Experiences with an Undivided Cell", Franz Wenisch et al. , AIChE Symposium Series No 185, Vol. 75, pages 14 to 18.
• the methoxylated ethers obtained by the process according to the invention are generally obtained as a mixture with the starting compounds, can by well known methods such as crystallization or distillation or separated chromatographically.
• the experimental setup corresponded to a capillary gap cell in the Batch operation in which alternately permeable graphite felt electrodes and ion exchange membranes are stacked.
• the size of the cell was a maximum of 5 membranes.
• the power yield was quasi quintupled, or Response times were reduced with the same current density.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

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• 1998
  • 1998-06-19 DE DE19827322A patent/DE19827322A1/de not_active Withdrawn
• 1999
  • 1999-06-10 EP EP99111280A patent/EP0965659A1/de not_active Withdrawn
  • 1999-06-21 JP JP11174688A patent/JP2000034590A/ja not_active Withdrawn

Non-Patent Citations (1)

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