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

• the invention relates to a method for the electrochemical production of benzaldehydes.
• Suitable alkyl radicals R 1 , R 2 and R 3 are those having 1 to 6, preferably 1 to 4, carbon atoms.
• aryl radicals R 1 phenyl radicals which may be substituted by alkyl, halogen, alkoxy and / or acyloxy groups may be mentioned.
• Starting materials of formula 11 are thus methylbenzenes, benzyl alcohols or the alkanoic acid esters of benzyl alcohols which are not substituted in the 4-position or contain the radical R 1 mentioned , such as toluene, p-xylene, p-tert-butyltoluene, p-phenyltoluene, benzyl alcohol , p-methylbenzyl alcohol, p-tert-butylbenzyl alcohol, benzyl acetate, p-methylbenzyl acetate and p-tert-butylbenzyl acetate.
• Preferred alkanoic acids of formula 111 are formic acid, acetic acid and propionic acid.
• a mixture of the benzene derivative of the formula II, water and the alkanoic acid of the formula 111 is used as the electrolyte, which may additionally contain a conductive salt to improve the conductivity.
• the usual salts in organic electrochemistry can be used as the conductive salts, which are soluble in the solution to be electrolyzed and largely stable under the test conditions.
• Fluoride such as NaF and KF, tetrafluoroborate such as NaBF 4 and Et 4 NBF 4 , perchlorate such as NaC10 4 and Et 4 ClO 4 and sulfate such as Et 4 NS0 4 Et are particularly advantageous as conductive salts.
• the composition of the electrolyte can be chosen within wide limits.
• the solutions used in electrolysis have the following composition, for example:
• the electrode materials used in the process according to the invention will be those which are stable under the conditions of the electrolysis.
• Suitable anode materials are e.g. B. graphite, precious metals such as platinum and noble metal coated titanium electrodes.
• graphite, iron, steel, lead or noble metal electrodes are used as cathodes.
• Current density and turnover can also be selected within wide limits. The current density is, for example 1 to 10A / dm 2 .
• the electrolysis itself is e.g. B. with 2 to 12, preferably 4 to 12 F / mol of starting compound and at temperatures below 100 ° C, advantageously between 10 and 90 ° C.
• the method according to the invention can be carried out both in divided and in undivided electrolysis cells.
• the electrolysis discharges are generally worked up by distillation. Alkanoic acid, water and any starting materials still present are separated from the benzaldehydes by distillation and can be returned to the electrolysis.
• the conductive salts used can then be separated from the aldehydes, for example by filtration, and can also be used again in the electrolysis.
• the benzaldehydes can be e.g. B. further clean by rectification.
• the carboxylic acid esters of the corresponding benzyl alcohols obtained as by-products in the process according to the invention can be returned to the electrolysis. But you can also isolate them before this return and according to known methods, for. B. by acidic transesterification with CH 3 0H / H 2 S0 4 , to saponify the corresponding benzyl alcohols.
• benzaldehydes obtainable by the process according to the invention are valuable intermediates for active substances and fragrances.
• 4-tert-butylbenzaldehyde takes place e.g. B. Use as a precursor for fungicides and serves as a starting material for the fragrance Lilial.
• the electrolyte is pumped through a heat exchanger during the electrolysis.
• the electrolyte is pumped through a heat exchanger during the electrolysis.
• the electrolyte is pumped through a heat exchanger during the electrolysis.
• the electrolyte is pumped through a heat exchanger during the electrolysis.
• the electrolyte is pumped through a heat exchanger during the electrolysis.
• the electrolyte is pumped through a heat exchanger during the electrolysis.
• the electrolyte is pumped through a heat exchanger during the electrolysis.
• the electrolyte is pumped through a heat exchanger during the electrolysis.

Landscapes

• 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)

Applications Claiming Priority (2)

Publications (3)

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• 1978
  • 1978-12-22 DE DE19782855508 patent/DE2855508A1/de not_active Withdrawn
• 1979
  • 1979-12-05 US US06/100,654 patent/US4235683A/en not_active Expired - Lifetime
  • 1979-12-13 DE DE7979105128T patent/DE2962005D1/de not_active Expired
  • 1979-12-13 EP EP79105128A patent/EP0012942B1/de not_active Expired
  • 1979-12-19 DK DK543079A patent/DK149618C/da not_active IP Right Cessation
  • 1979-12-21 JP JP16580779A patent/JPS5589487A/ja active Granted

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