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
  • C25B3/25—Reduction

Definitions

• the addition of the halogen causes an increase in the boiling point, so that impurities can be removed by distillation.
• the halogen must be split off from the compounds of the formula (II) after the purification. This is generally done with the help of zinc or other metals, but this is associated with the inevitable occurrence of zinc or other metal salts.
• the method according to the invention is carried out in divided or undivided cells.
• the usual diaphragms made of polymers, preferably perfluorinated polymers, or other organic or inorganic materials, such as glass or ceramic, are used to divide the cells into anode and cathode spaces.
• Ion exchange membranes, in particular cation exchange membranes made of polymers, preferably perfluorinated polymers with carboxyl and / or sulfonic acid groups, are preferably used.
• the use of stable anion exchange membranes is also possible.
• the electrolysis can be carried out in all customary electrolysis cells, such as, for example, in beaker or plate and frame cells or cells with fixed bed or fluidized bed electrodes. Both the monopolar and the bipolar circuit of the electrodes can be used.
• the electrolysis can be carried out on all cathodes stable in the electrolyte.
• Materials with a medium to high quality are particularly suitable Hydrogen overvoltage, such as carbon, Pb, Cd, Zn, Cu, Sn, Zr, Hg and alloys of the metals mentioned, such as the amalgams of copper or lead, but also alloys such as lead-tin or zinc-cadmium.
• the use of carbon cathodes is preferred, in particular for the electrolysis in acid electrolytes.
• all possible carbon electrode materials come into question as carbon cathodes, such as electrode graphites, impregnated graphite materials, carbon felts and also glassy carbon.
• All materials on which the corresponding anode reactions take place can be used as anode material.
• lead, lead dioxide on lead or other carriers, platinum, titanium dioxide doped with noble metal oxides (such as platinum oxide) on titanium are suitable for the development of oxygen from dilute sulfuric acid.
• Platinum, titanium dioxide doped with noble metal oxides are suitable, for example, for the development of chlorine from aqueous alkali metal chloride or aqueous or alcoholic hydrogen chloride solutions.
• Preferred anolyte liquids are aqueous mineral acids or solutions of their salts, such as, for example, dilute sulfuric acid, concentrated hydrochloric acid, sodium sulfate or sodium chloride solutions or solutions of hydrogen chloride in alcohol.
• the electrolyte in the undivided or the catholyte in the divided cell contains the compound of formula (II) used and one or more organic solvents and can additionally contain water.
• suitable organic solvents are short-chain aliphatic alcohols such as methanol, ethanol, Propanol or butanol; Diols such as ethylene glycol, propanediol, but also polyethylene glycols and their ethers; Ethers such as tetrahydrofuran, dioxane; Amides such as N, N-dimethylformamide, hexamethylphosphoric triamide, N-methyl-2-pyrrolidone; Nitriles such as acetonitrile, propionitrile; Ketones such as acetone; and sulfolane.
• organic acids such as acetic acid, is also possible.
• the electrolyte can also consist of water or water and a water-insoluble organic solvent such as t-butyl methyl ether or methylene chloride in combination with a phase transfer catalyst.
• a water-insoluble organic solvent such as t-butyl methyl ether or methylene chloride
• salts of metals with a hydrogen overvoltage of at least 0.25 V (based on a current density of 300 mA / cm2) and / or dehalogenating properties are added to the electrolyte in the undivided cell or the catholyte in the divided cell.
• Possible salts of this type are mainly the soluble salts of Cu, Ag, Au, Zn, Cd, Hg, Sn, Pb, Tl, Ti, Zr, Bi, V, Ta, Cr, Ce, Co or Ni, preferably the soluble salts of Pb, Sn, Ag, Zn, Cd and Cr.
• the preferred anions of these salts are Cl ⁇ , SO ⁇ , NO , and CH3COO ⁇ .
• the salts can be added directly or also, e.g. by adding oxides, carbonates - in some cases also the metals themselves (if soluble) - in the solution.
• the salt concentration in the electrolyte of the undivided cell or in the catholyte of the divided cell is expediently from about 10 ⁇ 5 to 25% by weight, preferably from about 10 ⁇ 3 to 10% by weight, in each case based on the total amount of the electrolyte or catholyte , set.
• Electrolysis is carried out at a current density of 1 to 500 mA / cm2, preferably at 10 to 400 mA / cm2.
• the electrolysis temperature is in the range from -20 ° C to the boiling point of the electrolyte or catholyte, preferably 10 ° to 90 ° C, in particular 10 ° to 80 ° C.
• inorganic or organic acids can be added to the catholyte in the divided cell or to the electrolyte in the undivided cell, preferably Acids such as hydrochloric, boric, phosphoric, sulfuric or tetrafluoroboric acid or formic, acetic or citric acid or their salts.
• organic bases can also be useful for setting the pH value which is favorable for the electrolysis or can have a favorable influence on the course of the electrolysis.
• Suitable are primary, secondary or tertiary C2-C12 alkyl or cycloalkylamines, aromatic or aliphatic-aromatic amines or their salts, inorganic bases such as alkali or alkaline earth metal hydroxides such as Li, Na, K, Cs, Mg, Ca, Ba hydroxide, quaternary ammonium salts such as the fluorides, chlorides, bromides, iodides, acetates, sulfates, hydrogen sulfates, tetrafluoroborates, phosphates or hydroxides of C1-C12-tetraalkylammonium, C1-C12-trialkylarylammonium or C1-C12ammonium trialonyl also anionic or cationic emulsifiers, in amounts of 0.01 to 25 percent by weight
• compounds can be added to the electrolyte which are oxidized at a more negative potential than the released halogen ions in order to avoid the formation of the free halogen.
• the salts of oxalic acid, methoxyacetic acid, glyoxylic acid, formic acid and / or hydrochloric acid are suitable, for example.
• the electrolysis product is worked up in a known manner, e.g. by extracting or distilling off the solvent.
• the compounds added to the catholyte can thus be returned to the process.
• Electrodes were electrolyzed on a cathode made of electrode graphite at a current density of 166 mA / cm2, a terminal voltage of 32-16V, a temperature of 34-36 ° C, a current consumption of 12.66 Ah and a pH value of 7.85. Electrolysis result: 62.75 g (84%) after extraction with pentane and distillation of the pentane.
• Electrolysis was carried out on a cathode made of impregnated graphite at a current density of 83-42 mA / cm2, a terminal voltage of 20-8 V, a temperature of 30 ° and a current consumption of 3.15 Ah. Electrolysis result: 11.2 g (77%) after extraction with pentane and distillation of the pentane.
• the starting electrolyte contained 200 ml of methanol, 5 g of Na (OOCCH3), 0.5 g of AgNO3 and 20 g Electrolysis was carried out on a cathode made of impregnated graphite at a current density of 83.3 mA / cm2, a terminal voltage of 11-8.5 and a temperature of 30 °.
• the pH was 8.0 at the beginning; in the course of the electrolysis, the pH was kept in the range from 6.7 and 4.4 by adding 3 g of NaOCH3.
• the power consumption was 13.12 Ah.
• Electrolysis was carried out on a lead sheet cathode at a current density of 88 mA / cm2, a terminal voltage of 29-18 V, a temperature of 32 ° C. and a power consumption of 1.76 Ah. Electrolysis result: 8.84 g (64.1%) 1.81 g
• Electrolysis was carried out on a cathode made of impregnated graphite at a current density of 88 mA / cm2, a terminal voltage of 28-17 V, a temperature of 30 ° and a current consumption of 1.76 Ah. Electrolysis result: 1.8 g 11.7 g (87.6%)

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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)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1987
  • 1987-06-04 DE DE19873718726 patent/DE3718726A1/de not_active Withdrawn
• 1988
  • 1988-06-01 EP EP88108765A patent/EP0293856B1/fr not_active Expired - Lifetime
  • 1988-06-01 DE DE8888108765T patent/DE3869212D1/de not_active Expired - Fee Related
  • 1988-06-02 US US07/202,127 patent/US4908107A/en not_active Expired - Fee Related
  • 1988-06-03 JP JP63135730A patent/JP2680607B2/ja not_active Expired - Lifetime
  • 1988-06-03 CA CA000568655A patent/CA1327766C/fr not_active Expired - Fee Related

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