EP0012942B1 - Electrolytic process for producing benzaldehydes - Google Patents

Electrolytic process for producing benzaldehydes Download PDF

Info

Publication number
EP0012942B1
EP0012942B1 EP79105128A EP79105128A EP0012942B1 EP 0012942 B1 EP0012942 B1 EP 0012942B1 EP 79105128 A EP79105128 A EP 79105128A EP 79105128 A EP79105128 A EP 79105128A EP 0012942 B1 EP0012942 B1 EP 0012942B1
Authority
EP
European Patent Office
Prior art keywords
tert
electrolysis
formula
acetate
butylbenzyl
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP79105128A
Other languages
German (de)
French (fr)
Other versions
EP0012942A3 (en
EP0012942A2 (en
Inventor
Dieter Dr. Dipl.-Chem. Degner
Hardo Dr. Dipl.-Chem. Siegel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF SE
Original Assignee
BASF SE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BASF SE filed Critical BASF SE
Publication of EP0012942A2 publication Critical patent/EP0012942A2/en
Publication of EP0012942A3 publication Critical patent/EP0012942A3/en
Application granted granted Critical
Publication of EP0012942B1 publication Critical patent/EP0012942B1/en
Expired legal-status Critical Current

Links

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.

Description

Die Erfindung betrifft ein Verfahren zur elektrochemischen Herstellung von Benzaldehyden.The invention relates to a method for the electrochemical production of benzaldehydes.

Die Elektrosynthese von in 4-Stellung substituierten Benzaldehyden durch anodische Oxidation der entsprechenden Alkylbenzole wird z. B. in Helv. Chem. Acta 9, 1097 (1926) beschrieben. Bei diesem bekannten Verfahren, bei dem man die Alkylbenzole in schwefelsaurer Lösung elektrolysiert, werden die Benzaldehyde nur in geringer Ausbeute erhalten. Außerdem bereitet die Isolierung der Aldehyde aus dem bei der Elektrolyse entstehenden Vielkomponentengemisch so große Schwierigkeiten, daß sich diese Synthese in der Technik nicht realisieren ließ.The electrosynthesis of benzaldehydes substituted in the 4-position by anodic oxidation of the corresponding alkylbenzenes is, for. B. in Helv. Chem. Acta 9, 1097 (1926). In this known process, in which the alkylbenzenes are electrolyzed in sulfuric acid solution, the benzaldehydes are obtained only in low yield. In addition, the isolation of the aldehydes from the multicomponent mixture resulting from the electrolysis is so difficult that this synthesis could not be achieved in industry.

In Trans. Am. Elektrochem. Soc. 47 (1925) 101-115 wird ein Verfahren zur Herstellung von Benzaldehyd durch Elektrooxidation von Toluol in einem Salpetersäure enthaltenden Elektrolyten beschrieben. Hierbei wird der Benzaldehyd unter den günstigsten Verfahrensbedingungen in nur 19%iger Ausbeute erhalten.In Trans. Am. Electrochem. Soc. 47 (1925) 101-115 describes a process for the preparation of benzaldehyde by electrooxidation of toluene in an electrolyte containing nitric acid. The benzaldehyde is obtained in only 19% yield under the most favorable process conditions.

Es wurde nun gefunden, daß man Benzaldehyde der allgemeinen Formel

Figure imgb0001
in der R1 ein Wasserstoffatom, ein Alkylrest oder ein Arylrest bedeutet, in hohen Material- und Stromausbeuten erhält, wenn man eine Verbindung der Formel
Figure imgb0002
in der X für ein Wasserstoffatom, eine Hydroxylgruppe oder eine R2-COO-Gruppe steht, und R2 ein Wasserstoffatom oder eine Alkylgruppe mit 1 bis 6 C-Atomen bedeutet, in Gegenwart von Wasser und einer Alkansäure der Formel
R'COOH (III) in der R3 ein Wasserstoffatom oder eine Alkylgruppe mit 1 bis 6 C-Atomen bedeutet, elektrochemisch oxidiert.It has now been found that benzaldehydes of the general formula
Figure imgb0001
 in which R 1 represents a hydrogen atom, an alkyl radical or an aryl radical, is obtained in high material and current yields if a compound of the formula
Figure imgb0002
 in which X represents a hydrogen atom, a hydroxyl group or an R 2 -COO group, and R 2 represents a hydrogen atom or an alkyl group having 1 to 6 C atoms, in the presence of water and an alkanoic acid of the formula
R'COOH (III) in which R 3 represents a hydrogen atom or an alkyl group having 1 to 6 C atoms, oxidized electrochemically.

Als Alkylreste R1, R2 und R3 kommen solche mit 1 bis 6, vorzugsweise 1 bis 4 C-Atomen in Betracht. Als Arylreste R1 seien Phenylreste, die durch Alkyl-, Halogen-, Alkoxy- und/oder Acyloxygruppen substituiert sein können, genannt. Ausgangsstoffe der Formel 11 sind somit Methylbenzole, Benzylalkohole oder die Alkansäureester der Benzylalkohole, die in 4-Stellung nicht substituiert sind oder den genannten Rest R1 enthalten, wie Toluol, p-Xylol, p-tert.-Butyltoluol, p-Phenyltoluol, Benzylalkohol, p-Methylbenzylalkohol, p-tert.-Butylbenzylalkohol, Benzylacetat, p-Methylbenzylacetat und p-tert.-Butylbenzylacetat. Von diesen Ausgangsstoffen sind p-Xylol, p-tert.-Butyltoluol, p-Methylbenzylalkohol, p-tert.-Butylbenzylalkohol, p-Methylbenzylacetat und p-tert.-Butylbenzylace- tat von besonderem technischem Interesse.Suitable alkyl radicals R 1 , R 2 and R 3 are those having 1 to 6, preferably 1 to 4, carbon atoms. As 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. Of these starting materials, p-xylene, p-tert-butyltoluene, p-methylbenzyl alcohol, p-tert-butylbenzyl alcohol, p-methylbenzyl acetate and p-tert-butylbenzylate- tate are of particular technical interest.

Als Alkansäuren der Formel 111 sind Ameisensäure, Essigsäure und Propionsäure bevorzugt.Preferred alkanoic acids of formula 111 are formic acid, acetic acid and propionic acid.

Als Elektrolyt wird ein Gemisch aus dem Benzolderivat der Formel II, Wasser und der Alkansäure der Formel 111 verwendet, das zur Verbesserung der Leitfähigkeit zusätzlich ein Leitsalz enthalten kann. Als Leitsalze können dabei die in der organischen Elektrochemie üblichen Salze eingesetzt werden, die in der zu elektrolysierenden Lösung löslich und unter den Versuchsbedingungen weitgehend stabil sind. Besonders vorteilhaft als Leitsalze sind Fluoride wie NaF und KF, Tetrafluoroborate wie NaBF4 und Et4NBF4, Perchlorate wie NaC104 und Et4ClO4 und Sulfate wie Et4NS04Et. Die Zusammensetzung des Elektrolyten kann in weiten Grenzen gewählt werden. Die in die Elektrolyse eingesetzten Lösungen haben beispielsweise folgende Zusammensetzung:

Figure imgb0003
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:
Figure imgb0003

Als Elektrodenmaterialien wird man bei dem erfindungsgemäßen Verfahren solche wählen, die unter den Bedingungen der Elektrolyse stabil sind. Geeignete Anodenmaterialien sind z. B. Graphit, Edelmetalle wie Platin und edelmetallbeschichtete Titanelektroden. Als Kathoden werden beispielsweise Graphit-, Eisen-, Stahl-, Blei- oder Edelmetallelektroden eingesetzt. Stromdichte und Umsatz können ebenfalls in weiten Grenzen gewählt werden. Die Stromdichte beträgt beispielsweise 1 bis 10A/dm2. Die Elektrolyse selbst wird z. B. mit 2 bis 12, vorzugsweise 4 bis 12 F/Mol Ausgangsverbindung und bei Temperaturen unter 100°C, vorteilhaft zwischen 10 und 90°C durchgeführt. Das erfindungsgemäße Verfahren kann sowohl in geteilten als auch in ungeteilten Elektrolysezellen durchgeführt werden.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. For example, 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.

Die Elektrolyseausträge werden in der Regel destillativ aufgearbeitet. Alkansäure, Wasser und evtl. noch vorhandene Ausgangsmaterialien werden von den Benzaldehyden durch Destillation abgetrennt und können zur Elektrolyse zurückgeführt werden. Die verwendeten Leitsalze lassen sich dann von den Aldehyden beispielsweise durch Filtration abtrennen und können ebenfalls wieder in die Elektrolyse eingesetzt werden. Die Benzaldehyde lassen sich z. B. durch Rektifikation weiter reinigen. Die bei dem erfindungsgemäßen Verfahren als Nebenprodukte anfallenden Carbonsäureester der entsprechenden Benzylalkohole können in die Elektrolyse zurückgeführt werden. Man kann sie aber auch vor dieser Rückführung isolieren und nach an sich bekannten Verfahren, z. B. durch saure Umesterung mit CH30H/H2S04, zu den entsprechenden Benzylalkoholen verseifen.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.

Die nach dem erfindungsgemäßen Verfahren erhältlichen Benzaldehyde sind wertvolle Zwischenprodukte für Wirkstoffe und Riechstoffe. So findet 4-tert.-Butylbenzaldehyd z. B. Verwendung als Vorprodukt für Fungizide und dient als Ausgangsmaterial für den Riechstoff Lilial.The benzaldehydes obtainable by the process according to the invention are valuable intermediates for active substances and fragrances. For example, 4-tert-butylbenzaldehyde takes place e.g. B. Use as a precursor for fungicides and serves as a starting material for the fragrance Lilial.

Das erfindungsgemäße Verfahren wird an folgenden Beispielen weiter verdeutlicht.The process according to the invention is further illustrated in the following examples.

Beispiel 1example 1 Anodische Oxidation von p-tert.-ButyltoluolAnodic oxidation of p-tert-butyltoluene

Figure imgb0004
Figure imgb0004

Der Elektrolyt wird während der Elektrolyse über einen Wärmeaustauscher umgepumpt.The electrolyte is pumped through a heat exchanger during the electrolysis.

AufarbeitungRefurbishment

Nach Beendigung der Elektrolyse werden Essigsäure und Wasser bei Normaldruck abdestilliert, NaBF4 (57 g) abfiltriert und der Rückstand bei 20 bis 2 Torr und 30 bis 100°C fraktioniert destilliert. Hierbei erhält man neben 6,2 g unumgesetztem p-tert.-Butyltoluol 133,5 g p-tert.-Butylbenzaldehyd und 141,1 g p-tert.-Butylbenzylacetat. Dies entspricht einer Materialausbeute von 77% und einer Stromausbeute von 58,4%. Zur Isolierung des p-tert.-Butylbenzaldehyds wird das Gemisch bei 20 bis 30 Torr und einer Sumpftemperatur von 150 bis 170°C rektifiziert. Das dabei als Sumpfprodukt anfallende p-tert.-Butylbenzylacetat kann erneut der Elektrolyse zugeführt werden.After the electrolysis has ended, acetic acid and water are distilled off at atmospheric pressure, NaBF 4 (57 g) is filtered off and the residue is fractionally distilled at 20 to 2 torr and 30 to 100 ° C. In addition to 6.2 g of unreacted p-tert-butyltoluene, 133.5 g of p-tert-butylbenzaldehyde and 141.1 g of p-tert-butylbenzyl acetate are obtained. This corresponds to a material yield of 77% and an electricity yield of 58.4%. To isolate the p-tert-butylbenzaldehyde, the mixture is rectified at 20 to 30 torr and a bottom temperature of 150 to 170 ° C. The p-tert-butylbenzyl acetate obtained as the bottom product can be returned to the electrolysis.

Beispiel 2Example 2

Man verfährt, wie in Beispiel 1 beschrieben, wobei man die Elektrolyse von p-tert.-Butyltoluol jedoch mit 6,5 F/Mol ausführt. Es werden hierbei neben 22 g p-tert.-Butylbenzylacetat 198 g p-tert.-Butylbenzaldehyd erhalten. Dies entspricht einer Ausbeute von 66,5%.The procedure is as described in Example 1, but the electrolysis of p-tert-butyltoluene is carried out at 6.5 F / mol. In addition to 22 g of p-tert-butylbenzyl acetate, 198 g of p-tert-butylbenzaldehyde are obtained. This corresponds to a yield of 66.5%.

Beispiel 3Example 3 Anodische Oxidation von p-tert.-ButyltoluolAnodic oxidation of p-tert-butyltoluene

Figure imgb0005
Figure imgb0006
Elektrolyse mit 4,25 F/Mol p-tert.-Butyltoluol
Figure imgb0005
Figure imgb0006
 Electrolysis with 4.25 F / mol p-tert-butyltoluene

Der Elektrolyt wird während der Elektrolvse über einen Wärmeaustauscher umgepumpt.The electrolyte is pumped through a heat exchanger during the electrolysis.

AufarbeitungRefurbishment

Arbeitet man den Elektrolyseaustrag analog Beispiel 1 auf, so erhält man neben 13,2 g unumgesetztem p-tert.-Butyltoluol 120,3 g p-tert.-Butylbenzaldehyd und 144,1 g p-tert.-Butylbenzyl- acetat. Dies entspricht einer Materialausbeute von 75,5% und einer Stromausbeute von 51,4%.If the electrolysis discharge is worked up as in Example 1, 120.3 g of p-tert-butylbenzaldehyde and 144.1 g of p-tert-butylbenzyl acetate are obtained in addition to 13.2 g of unreacted p-tert-butyltoluene. This corresponds to a material yield of 75.5% and a current yield of 51.4%.

Beispiel 4Example 4 Anodische Oxidation von p-tert.-ButyltoluolAnodic oxidation of p-tert-butyltoluene

Figure imgb0007
Elektrolyse mit 4,25 F/Mol p-tert.-Butyltoluol
Figure imgb0007
 Electrolysis with 4.25 F / mol p-tert-butyltoluene

Der Elektrolyt wird während der Elektrolyse über einen Wärmeaustauscher umgepumpt.The electrolyte is pumped through a heat exchanger during the electrolysis.

AufarbeitungRefurbishment

Arbeitet man den Elektrolyseaustrag analog Beispiel 1 auf, so erhält man neben 25,2 g unumgesetztem p-tert.-Butyltoluol 284,8 g p-tert.-Butylbenzaldehyd und 295,3 g p-tert.-Butylbenzyl- acetat. Dies entspricht einer Materialausbeute von 83,3% und einer Stromausbeute von 58,2%. Man trennt den p-tert.-Butylbenzaldehyd wie in Beispiel 1 beschrieben vom p-tert.-Butylbenzylacetat ab.If the electrolysis discharge is worked up analogously to Example 1, 284.8 g of p-tert-butylbenzaldehyde and 295.3 g of p-tert-butylbenzyl acetate are obtained in addition to 25.2 g of unreacted p-tert-butyltoluene. This corresponds to a material yield of 83.3% and an electricity yield of 58.2%. The p-tert-butylbenzaldehyde is separated from the p-tert-butylbenzyl acetate as described in Example 1.

90 g des als Nebenprodukt isolierten p-tert.-Butylbenzylacetats werden mit 96 g Methanol und 1 g konzentrierter Schwefelsäure gemischt und unter Rühren drei Stunden Rückfluß gekocht. Nach Abkühlen wird die Lösung mit NaOH neutralisiert. Methanol und Methylacetat werden bei Normaldruck abdestilliert und der Rückstand bei 0,1 Torr und 68 bis 70° C fraktioniert destilliert. Hierbei erhält man 65 g p-tert.-Butylbenzylakohol (entsprechend einer Ausbeute von 90,7%), die z. B. nach Beispiel 5 für die Herstellung von p-tert.-Butylbenzaldehyd herangezogen werden können.90 g of the p-tert-butylbenzyl acetate isolated as a by-product are mixed with 96 g of methanol and 1 g of concentrated sulfuric acid and refluxed for three hours with stirring. After cooling, the solution is neutralized with NaOH. Methanol and methyl acetate are distilled off under normal pressure and the residue is fractionally distilled at 0.1 Torr and 68 to 70 ° C. This gives 65 g of p-tert-butylbenzyl alcohol (corresponding to a yield of 90.7%), which, for. B. can be used according to Example 5 for the preparation of p-tert-butylbenzaldehyde.

Beispiel 5Example 5 Anodische Oxidation von p-tert.-ButylbenzylalkoholAnodic oxidation of p-tert-butylbenzyl alcohol

Figure imgb0008
Elektrolyse mit 2 F/Mol p-tert.-Butylbenzylalkohol
Figure imgb0008
 Electrolysis with 2 F / mol p-tert-butylbenzyl alcohol

Der Elektrolyt wird während der Elektrolyse über einen Wärmeaustauscher umgepumpt.The electrolyte is pumped through a heat exchanger during the electrolysis.

AufarbeitungRefurbishment

Nach Beendigung der Elektrolyse werden Essigsäure und Wasser bei Normaldruck abdestilliert, NaBF4 (55 g) abfiltriert und der Rückstand bei 2 bis 3 Torr und 77 bis 100°C fraktioniert destilliert. Hierbei erhält man 4,9 g p-tert.-Butylbenzylalkohol, 166,9 g p-tert.-Butylbenzaldehyd und 70,4 g p-tert.-Butylbenzylacetat. Dies entspricht einer Materialausbeute von 73,7% und einer Stromausbeute von 58,3%.After the electrolysis has ended, acetic acid and water are distilled off at atmospheric pressure, NaBF 4 (55 g) is filtered off and the residue is fractionally distilled at 2 to 3 torr and 77 to 100 ° C. This gives 4.9 g of p-tert-butylbenzyl alcohol, 166.9 g of p-tert-butylbenzaldehyde and 70.4 g of p-tert-butylbenzyl acetate. This corresponds to a material yield of 73.7% and an electricity yield of 58.3%.

Beispiel 6Example 6 Anodische Oxidation von p-tert.-ButylbenzylacetatAnodic oxidation of p-tert-butylbenzyl acetate

Figure imgb0009
Elektrolyse mit 2 F/Mol p-tert.-Butylbenzylacetat
Figure imgb0009
 Electrolysis with 2 F / mol p-tert-butylbenzyl acetate

Der Elektrolyt wird während der Elektrolyse über einen Wärmeaustauscher umgepumpt.The electrolyte is pumped through a heat exchanger during the electrolysis.

AufarbeitungRefurbishment

Nach Beendigung der Elektrolyse werden Essigsäure und Wasser bei Normaldruck abdestilliert, NaBF4 (55 g) abfiltriert und der Rückstand bei 1 bis 5 Torr und 35 bis 110°C fraktioniert destilliert. Hierbei erhält man neben 139,6 g unumgesetzten p-tert.-Butylbenzylacetat 105,7 g p-tert.-Butylbenzal- dehyd. Dies entspricht einer Materialausbeute von 79,4% und einer Stromausbeute von 43,5%.After the electrolysis has ended, acetic acid and water are distilled off at atmospheric pressure, NaBF 4 (55 g) is filtered off and the residue is fractionally distilled at 1 to 5 torr and 35 to 110 ° C. In addition to 139.6 g of unreacted p-tert-butylbenzyl acetate, 105.7 g of p-tert-butylbenzaldehyde are obtained. This corresponds to a material yield of 79.4% and an electricity yield of 43.5%.

Beispiel 7Example 7 Anodische Oxidation von p-XylolAnodic oxidation of p-xylene

Figure imgb0010
Figure imgb0010

Der Elektrolyt wird während der Elektrolyse über einen Wärmeaustauscher umgepumpt.The electrolyte is pumped through a heat exchanger during the electrolysis.

AufarbeitungRefurbishment

Nach Beendigung der Elektrolyse werden Essigsäure, Wasser und unumgesetztes p-Xylol (24,8 g) bei Normaldruck abdestilliert, NaBF4 (54 g) abfiltriert und der Rückstand bei 30 bis 110°C und 0,7 bis 2 Torr fraktioniert destilliert. Hierbei erhält man 70,4 g p-Methylbenzaldehyd und 70,3 g p-Methylbenzylacetat. Dies entspricht einer Materialausbeute von 62,9%.After the electrolysis has ended, acetic acid, water and unreacted p-xylene (24.8 g) are distilled off at atmospheric pressure, NaBF 4 (54 g) is filtered off and the residue is fractionally distilled at 30 to 110 ° C. and 0.7 to 2 torr. This gives 70.4 g of p-methylbenzaldehyde and 70.3 g of p-methylbenzyl acetate. This corresponds to a material yield of 62.9%.

Beispiel 8Example 8 Anodische Oxidation von p-XylolAnodic oxidation of p-xylene

Figure imgb0011
Der Elektrolyt wird während der Elektrolyse über einen Wärmetauscher umgepumpt.
Figure imgb0011
 The electrolyte is pumped through a heat exchanger during the electrolysis.

AufarbeitungRefurbishment

Arbeitet man den Elektrolyseaustrag analog Beispiel 7 auf, so erhält man neben 136,2g unumgesetztem p-Xylol 30 g Methylbenzaldehyd und 40,3 g p-Methylbenzylacetat. Dies entspricht einer Materialausbeute von 69,4%.If the electrolysis discharge is worked up as in Example 7, 30 g of methylbenzaldehyde and 40.3 g of p-methylbenzyl acetate are obtained in addition to 136.2 g of unreacted p-xylene. This corresponds to a material yield of 69.4%.

Beispiel 9Example 9 Anodische Oxidation von ToluolAnodic oxidation of toluene

Figure imgb0012
Der Elektrolyt wird während der Elektrolyse über einen Wärmetauscher umgepumpt.
Figure imgb0012
 The electrolyte is pumped through a heat exchanger during the electrolysis.

AufarbeitungRefurbishment

Nach Beendigung der Elektrolye werden Wasser, Essigsäure und unumgesetztes Toluol (43 g) bei Normaldruck abdestilliert, NaBF4 (58 g) abfiltriert und der Rückstand bei 10 bis 30 Torr und 30 bis 100° C fraktioniert destilliert. Hierbei erhält man 81,6 g Benzaldehyd und 31,9 g Benzylacetat. Dies entspricht einer Materialausbeute von 64,6%.After the electrolysis has ended, water, acetic acid and unreacted toluene (43 g) are distilled off at atmospheric pressure, NaBF 4 (58 g) is filtered off and the residue is fractionally distilled at 10 to 30 torr and 30 to 100 ° C. This gives 81.6 g of benzaldehyde and 31.9 g of benzyl acetate. This corresponds to a material yield of 64.6%.

Claims (8)

1. An electrolytic process für the preparation of a benzaldehyde of the general formula
Figure imgb0016
where R1 is hydrogen, alkyl or aryl, characterized in that a compound of the formula
Figure imgb0017
where X is hydrogen, hydroxyl or R2-COO-, and R2 is hydrogen or alkyl of 1 to 6 carbon atoms, is oxidized electrochemically in the presence of water and an alkanoic acid of the formula
Figure imgb0018
where R3 is hydrogen or alkyl of 1 to 6 carbon atoms.
2. Aprocess as claimed in claim 1, characterized in that toluene, p-xylene, p-tert.-butyltoluene, benzyl alcohol, p-methylbenzyl alcohol, p-tert.-butylbenzyl alcohol, benzyl acetate, p-methylbenzyl acetate or p-tert.-butylbenzyl acetate is used as the starting compound of the formula II.
3. A process as claimed in claim 1, characterized in that formic acid, acetic acid or propionic acid is used as the alkanoic acid of the formula II.
4. A process as claimed in claim 1, characterized in that the electrolysis is carried out at a current density of from 1 to 10 A/dm2, and at below 100°C.
5. A process as claimed in claim 1, characterized in that the electrolysis is carried out with from 2 to 12 F per mole of compound of the formula II.
6. A process as claimed in claim 1, characterized in that a soultion is used for the electrolysis which contains from 5 to 50% by weight of the starting compound of the formula II, 3 to 25% by weight of water, 45 to 90% by weight of the alkanoic acid of the formula III, and 0,5 to 10% by weight of a conductive salt.
7. A process as claimed in claim 6, characterized in that a fluoride, tetrafluoroborate, perchlorate or sulfate is used as the conductive salt.
8. A process as claimed in claim 6, characterized in that a tetrafluoroborate is used as the conductive salt.
EP79105128A 1978-12-22 1979-12-13 Electrolytic process for producing benzaldehydes Expired EP0012942B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19782855508 DE2855508A1 (en) 1978-12-22 1978-12-22 METHOD FOR PRODUCING BENZALDEHYDES
DE2855508 1978-12-22

Publications (3)

Publication Number Publication Date
EP0012942A2 EP0012942A2 (en) 1980-07-09
EP0012942A3 EP0012942A3 (en) 1980-07-23
EP0012942B1 true EP0012942B1 (en) 1982-01-27

Family

ID=6058012

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79105128A Expired EP0012942B1 (en) 1978-12-22 1979-12-13 Electrolytic process for producing benzaldehydes

Country Status (5)

Country Link
US (1) US4235683A (en)
EP (1) EP0012942B1 (en)
JP (1) JPS5589487A (en)
DE (2) DE2855508A1 (en)
DK (1) DK149618C (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4164233A (en) * 1978-03-07 1979-08-14 Mcandrew James R Vehicle covering apparatus
DE3067628D1 (en) * 1979-11-16 1984-05-30 Hoffmann La Roche Process for the preparation of p-tert.-butylbenzaldehyde
DE2948455A1 (en) * 1979-12-01 1981-06-11 Basf Ag, 6700 Ludwigshafen METHOD FOR PRODUCING 4-TERT. BUTYLBENZALDEHYDE.
US4387007A (en) * 1980-11-17 1983-06-07 Hoffmann-La Roche Inc. Process for the manufacture of an aldehyde
DE3132726A1 (en) * 1981-08-19 1983-03-03 Basf Ag, 6700 Ludwigshafen PROCESS FOR PRODUCING ALKYL-SUBSTITUTED BENZALDEHYDES
GB8309571D0 (en) * 1983-04-08 1983-05-11 Albright & Wilson Accelerated sealing of anodised aluminium
AU6672286A (en) * 1986-01-06 1987-07-09 Dow Chemical Company, The Electrocatalytic method for producing quinone methides and dihydroxybenzophenones
DE3913166A1 (en) * 1989-04-21 1990-10-25 Basf Ag METHOD FOR PRODUCING BENZALDEHYDDIALKYLACETALS AND NEW BENZALDEHYDDIALKYLACETALS AND BENZYL ESTERS
KR102307579B1 (en) * 2019-09-18 2021-10-05 한국과학기술연구원 Method for preparing benzaldehyde

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS583035B2 (en) * 1976-04-12 1983-01-19 株式会社クラレ Method of oxidizing paraphenoxytoluene
US4148696A (en) * 1978-03-20 1979-04-10 Uop Inc. Electrochemical oxidation of activated alkyl aromatic compounds

Also Published As

Publication number Publication date
US4235683A (en) 1980-11-25
DK149618C (en) 1987-02-02
JPS5589487A (en) 1980-07-07
EP0012942A3 (en) 1980-07-23
DE2962005D1 (en) 1982-03-11
DK149618B (en) 1986-08-11
DE2855508A1 (en) 1980-07-10
DK543079A (en) 1980-06-23
EP0012942A2 (en) 1980-07-09
JPS6350434B2 (en) 1988-10-07

Similar Documents

Publication Publication Date Title
EP0011712B1 (en) Preparation of benzaldehyde dialkyl acetals substituted in the 4-position
DE2343054C2 (en) Process for the electrochemical production of pinacols
DE2460754C2 (en) Process for the preparation of p-benzoquinone diketals
EP0012942B1 (en) Electrolytic process for producing benzaldehydes
EP0072914B1 (en) Process for the production of alkyl-substituted benzaldehydes
EP0275489B1 (en) Benzaldehyde derivatives, their preparation and application
EP0129795B1 (en) Process for manufacturing benzaldehyde dialkylacetals
EP0902846B1 (en) Process for preparing phthalides
EP0287954A2 (en) Benzaldehyde dialkyl acetals, their preparation and use
EP0502372B1 (en) 4-tert-Alkyl-2-Methylbenzaldehydedialkylacetals
EP0078004B1 (en) Electrochemical process for the production of 2,5-dialcoxy-2,5-dihydrofurans
EP0393668B1 (en) Method of preparation of benzaldehyde dialkyl acetals and new benzaldehyde dialkyl acetals
EP0152801B1 (en) Process for manufacturing benzaldehyde dialkylacetals
EP0347690B1 (en) Process for manufacturing benzene derivatives, and benzene derivatives
EP0029995A1 (en) Process for the preparation of 4-tert.-butylbenzaldehyde
US3396093A (en) Electrochemical synthesis of ketones
EP0047947B1 (en) Omega-fluorosulphato-perfluoro-(2-methylalkane-3-ones) and process for the production of perfluoroisopropyl-keto-carboxylic-acid fluorides from the first mentioned compounds
DE2039991A1 (en) Process for the preparation of sebacic acid diesters of higher alcohols
DE2912058A1 (en) Substd. benzaldehyde di:alkyl acetal prodn. - by electrolysis of corresp. toluene dissolved in alcohol, with hydrogenation of by prod. before recycle
EP0292889B1 (en) Benzaldehyde derivatives, their preparation and use
EP0053261B1 (en) Process for the manufacture of a mixture of ketals of trimethyl-p-benzoquinone
DE2345461C3 (en) Process for the production of pinacol by the electrolytic hydrodimerization of acetone
DE2547464A1 (en) PROCESS FOR THE PRODUCTION OF HYDROQUINONDIMETHYLAETHERS
DE2758882A1 (en) Cis-7,8-epoxy-2-methyl-octadecane prodn. - by electrochemical condensn. of pelargonic acid and cis-4-octene-di:oic acid ester, useful as insect sex attractant
DE2851732A1 (en) Substd. benzaldehyde di:alkyl acetal cpds. prodn. - by electrochemical oxidn. of substd. toluene in alcohol contg. tetra:alkyl-ammonium aryl-sulphonate

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Designated state(s): CH DE FR GB IT SE

AK Designated contracting states

Designated state(s): CH DE FR GB IT SE

17P Request for examination filed
ITF It: translation for a ep patent filed

Owner name: ING. C. GREGORJ S.P.A.

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE PATENT HAS BEEN GRANTED

AK Designated contracting states

Designated state(s): CH DE FR GB IT SE

REF Corresponds to:

Ref document number: 2962005

Country of ref document: DE

Date of ref document: 19820311

ITTA It: last paid annual fee
EAL Se: european patent in force in sweden

Ref document number: 79105128.7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19981127

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19981130

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19981203

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: CH

Payment date: 19981208

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19981224

Year of fee payment: 20

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 19991212

Ref country code: CH

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 19991212

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY

Effective date: 19991230

REG Reference to a national code

Ref country code: GB

Ref legal event code: PE20

Effective date: 19991212

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

EUG Se: european patent has lapsed

Ref document number: 79105128.7

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261