EP0129795A2 - Process for manufacturing benzaldehyde dialkylacetals - Google Patents

Process for manufacturing benzaldehyde dialkylacetals Download PDF

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EP0129795A2
EP0129795A2 EP84106858A EP84106858A EP0129795A2 EP 0129795 A2 EP0129795 A2 EP 0129795A2 EP 84106858 A EP84106858 A EP 84106858A EP 84106858 A EP84106858 A EP 84106858A EP 0129795 A2 EP0129795 A2 EP 0129795A2
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acid
tert
weight
electrooxidation
alkanol
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EP0129795A3 (en
EP0129795B1 (en
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Dieter Dr. Degner
Heinz Hannebaum
Hardo Dr. Siegel
Walter Dr Gramlich
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BASF SE
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    • 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
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    • C25B3/23—Oxidation

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  • This invention relates to a new process for the preparation of alkyl substituted benzaldehyde dialkyl acetals by electrooxidation of alkyl toluenes.
  • EP-PS 12 240 describes a process for the preparation of benzaldehyde dialkyl acetals, in which the electrooxidation of the toluenes is carried out in alcoholic solution and in the presence of tetraalkylammonium sulfonates and phosphates as conductive salts.
  • collidine for example, is added as an auxiliary base to the electrolyte.
  • electro-oxidation of p-xylene and 4-tert-butyl toluene yields of only 64 and '55% are erreitht by this method.
  • FR-PS 2 351 932 describes a process in which toluenes are anodically oxidized on Pt electrodes.
  • electrolytes consist of toluene, an inert organic solvent such as methylene chloride, methanol and an acid containing H 3 S groups consist.
  • the electrooxidation of p-xylene gives this method drive a mixture that contains 4-methylbenzaldehyde but no 4-methylbenzaldehyde dimethyl acetal in addition to ether and ester compounds.
  • the benzaldehyde dialkyl acetals are obtained by avoiding the disadvantages described in a particularly economical manner and in good yields by the process according to the invention.
  • Alkyl radicals with I to 8 carbon atoms are, for example, methyl, ethyl, isopropyl, n-, iso- and tert-butyl groups.
  • Preferred alkyltoluenes are xylenes and butyltoluenes, such as p-xylene and 4-tert-butyltoluene. Of the two alkanols, methanol is of particular technical interest.
  • Suitable acids containing H 3 S groups are, for example, acids of the formula R 3 SO 3 H , in which R 3 represents an alkyl, aryl, hydroxyl or alkoxy group.
  • Preferred acids are methanesulfonic acid, benzenesulfonic acid and methylsulfuric acid, especially sulfuric acid.
  • the method according to the invention does not require a special electrolysis cell; it is preferably carried out in undivided electrolysis cells.
  • Preferred electrolytes are those which have an alkanol content of 70 to 90% by weight, alkyltoluene of 8.5 to 30% by weight and acids of 0.05 to 1.5% by weight.
  • All anode materials which are customary per se and are stable under the electrolysis conditions can be used as anodes, graphite anodes are preferably used.
  • steel, nickel, precious metals or graphite can be used as cathode materials.
  • the current densities are, for example, 2 to 20 A / dm 2
  • electrolysis is preferably carried out at current densities of 2 to 12 A / dm 2 .
  • the electrolysis temperature is limited by the boiling point of the alkanol. When using methanol, electrolysis is carried out, for example, at temperatures up to 60 ° C., preferably at 20 to 60 ° C.
  • the process according to the invention offers the possibility of largely converting the alkyltoluenes and the alkylbenzylalkyl ethers which have passed through as intermediates without the selectivities of the electrooxidation being significantly impaired.
  • the electrolysis is carried out with 2.8 to 7, preferably 4 to 6.5 F per mole of alkyl toluene.
  • the process can be carried out batchwise or continuously.
  • the electrolysis discharges can be worked up in a very simple manner. One proceeds e.g. so that the small amount of acid is neutralized with an equivalent amount of an alkali. So you give e.g. when using sulfuric acids sodium hydroxide or sodium methylate.
  • the alkanol and any alkyltoluenes and alkylbenzylalkyl ethers which may still be present are then distilled off and, if appropriate, returned to the electrolysis.
  • the alkylbenzaldehyde dialkyl acetals can then be further purified by vacuum distillation.
  • the benzaldehyde dialkyl acetals obtainable by the new process are valuable precursors for fragrances and fungicides.
  • the electrolyte is pumped through a heat exchanger at 200 l / h during the electrolysis.
  • Example 2 It is electrolyzed and worked up as indicated in Example 1. This gives 51.6 g of p-xylene, 34.4 g of 4-methylbenzyl ether and 366.9 g of 4-methylbenzaldehyde dimethyl acetal. This corresponds to a yield of 67.6%.
  • the electrolyte is pumped through a heat exchanger at 200 l / h during the electrolysis.
  • Example 4 It is electrolyzed and worked up as described in Example 4. There are 11.8 g of 4-tert-butylbenzyl methyl ether and 353.6 g of 4-tert-butylbenzaldehyde dimethyl acetal. This corresponds to a yield of 74.3%.

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Abstract

Verfahren zur Herstellung von Benzaldehyddialkylacetalen der Formel <IMAGE> in der R¹ und R² Alkylreste bedeuten, durch Elektrooxidation von Alkyltoluolen der Formel <IMAGE> bei der man einen Elektrolyten verwendet, der 60 bis 90 Gew.% an einem Alkanol der Formel R²OH, 8,5 bis 40 Gew.% an dem Alkytoluol und 0,01 bis 1,5 Gew.% an einer HO3S-Gruppen enthaltenden Säure enthält.Process for the preparation of benzaldehyde dialkyl acetals of the formula <IMAGE> in which R¹ and R² are alkyl radicals, by electrooxidation of alkyltoluenes of the formula <IMAGE>, in which an electrolyte is used which contains 60 to 90% by weight of an alkanol of the formula R²OH, 8, Contains 5 to 40% by weight of the alkytoluene and 0.01 to 1.5% by weight of an acid containing HO3S groups.

Description

Diese Erfindung betrifft ein neues Verfahren zur Herstellung von alkylsubstituierten Benzaldehyddialkylacetalen durch Elektrooxidation von Alkyltoluolen.This invention relates to a new process for the preparation of alkyl substituted benzaldehyde dialkyl acetals by electrooxidation of alkyl toluenes.

Aus J. Chem. Soc. Perkin I. 1978, 708 ist bekannt, daß man p-Methoxytoluol bzw. p-Xylol durch anodische Oxidation in Anisaldehyddimethylacetal bzw. 4-Methylbenzaldehyddimethylacetal überführen kann. Bei dieser Elektrooxidation, die in Methanol und in Gegenwart von Natriummethylat oder Lutidin durchgeführt wird, betragen die Ausbeuten nur 57 bis 66 %. Außerdem ist die Aufarbeitung des basischen Elektrolyten umständlich. In der EP-PS 12 240 wird ein Verfahren zur Herstellung von Benzaldehyddialkylacetalen beschrieben, bei dem man die Elektrooxidation der Toluole in alkoholischer Lösung und in Gegenwart von Tetraalkylammoniumsulfonaten und -phosphaten als Leitsalze durchführt. Um ein Absinken des pH-Wertes auf unter 7 zu verhindern, gibt man z.B. Collidin als Hilfsbase zum Elektrolyten. Bei der Elektrooxidation von p-Xylol und 4-tert.-Butyl- toluol werden nach dieser Methode nur Ausbeuten von 64 und'55 % erreitht. Bessere Ausbeuten werden nur erzielt, wenn man die niedersiedenden Nebenprodukte zunächst an Pd-Katalysatoren hydriert und dann zur Elektrolyse zurückführt. Führt man die Elektrooxidation nach dem in der DE-PS 28 48 397 beschriebenen Verfahren durch, bei dem man diese Nachteile durch Verwendung von Kaliumfluorid als Leitsalz vermeidet, so werden jedoch bei der Elektrooxidation von p-Xylol schlechtere Ausbeuten als bei der Elektrooxidation von p-Methoxitoluol erhalten.From J. Chem. Soc. Perkin I. 1978, 708 it is known that p-methoxytoluene or p-xylene can be converted into anisaldehyde dimethyl acetal or 4-methylbenzaldehyde dimethyl acetal by anodic oxidation. With this electrooxidation, which is carried out in methanol and in the presence of sodium methylate or lutidine, the yields are only 57 to 66%. The processing of the basic electrolyte is also cumbersome. EP-PS 12 240 describes a process for the preparation of benzaldehyde dialkyl acetals, in which the electrooxidation of the toluenes is carried out in alcoholic solution and in the presence of tetraalkylammonium sulfonates and phosphates as conductive salts. In order to prevent the pH value from dropping below 7, collidine, for example, is added as an auxiliary base to the electrolyte. In the electro-oxidation of p-xylene and 4-tert-butyl toluene yields of only 64 and '55% are erreitht by this method. Better yields can only be achieved if the low-boiling by-products are first hydrogenated on Pd catalysts and then returned to the electrolysis. If the electrooxidation is carried out according to the process described in DE-PS 28 48 397, in which these disadvantages are avoided by using potassium fluoride as the conductive salt, the yields in the electrooxidation of p-xylene are poorer than in the electrooxidation of p- Get methoxitoluol.

Aus der EP-PS 30 588 und der DE-OS 29 48 455 ist bekannt, daß man die Elektrooxidation von 4-tert.-Butyltoluol zu 4-tert.-Butylbenzaldehyd in Emulsionen durchführen kann, die H03S-Gruppen enthaltenden Säuren enthal- ten. Befriedigende Ausbeuten werden bei diesen Verfahren jedoch nur bei niedrigen 4-tert.-Butyltoluolumsätzen erreicht. Die Synthese erfordert eine technisch aufwendige, geteilte Zelle. Außerdem sind die verwendeten Bleidioxidanoden im Dauerversuch nicht stabil, so daß sich diese Verfahren nicht im technischen Maßstab haben realisieren lassen.From EP-PS 30 588 and DE-OS 29 48 455 it is known that the electrooxidation of 4-tert-butyltoluene to 4-tert-butylbenzaldehyde can be carried out in emulsions which contain acids containing H 3 S groups - t en. Satisfactory yields are only achieved with these processes at low 4-tert-butyltoluene conversions. The synthesis requires a technically complex, divided cell. In addition, the lead dioxide anodes used are not stable in the endurance test, so that these processes have not been able to be implemented on an industrial scale.

In der FR-PS 2 351 932 wird ein Verfahren beschrieben, bei dem man Toluole anodisch an Pt-Elektroden oxidiert. Bei diesem Verfahren, bei dem man Produktgemische aus Benzaldehyd und Anisaldehyd in sehr schlechten Ausbeuten (12 bis 20 X) erhält, verwendet man Elektrolyte, die aus dem Toluol, einem inerten organischen Lösungsmittel, wie Methylenchlorid, Methanol und einer H03S-Gruppen enthaltenden Säure bestehen. Bei der Elektrooxidation von p-Xylol (s. Beispiel 11) erhält man nach diesem Verfahren ein Gemisch, das neben Ether- und Esterverbindungen auch 4-Methylbenzaldehyd jedoch kein 4-Methylbenzaldehyddimethylacetal enthält.FR-PS 2 351 932 describes a process in which toluenes are anodically oxidized on Pt electrodes. In this process, in which product mixtures of benzaldehyde and anisaldehyde are obtained in very poor yields (12 to 20%), electrolytes are used which consist of toluene, an inert organic solvent such as methylene chloride, methanol and an acid containing H 3 S groups consist. The electrooxidation of p-xylene (see Example 11) gives this method drive a mixture that contains 4-methylbenzaldehyde but no 4-methylbenzaldehyde dimethyl acetal in addition to ether and ester compounds.

Es wurde nun gefunden, daß man Benzaldehyddialkylacetale der allgemeinen Formel

Figure imgb0001
in der R 1 einen Alkylrest mit 1 bis 8 C-Atomen und R2 Methyl oder Ethyl bedeuten, durch Elektrooxidation von Alkyltoluolen der allgemeinen Formel
Figure imgb0002
Ln einem Alkanol der Formel R20H und in Gegenwart einer die H03S-Gruppe enthaltenden Säure, besonders vorteilhaft herstellen kann, wenn man die Elektrooxidation mit einem Elektrolyten durchführt, dessen Gehalt an Alkanol 60 bis 90 Gew.%, an Alkyltoluol 8,5 bis 40 Gew.% und an Säure 0,01 bis 1,5 Gew.% beträgt.It has now been found that benzaldehyde dialkyl acetals of the general formula
Figure imgb0001
 in which R 1 is an alkyl radical having 1 to 8 carbon atoms and R 2 is methyl or ethyl, by electrooxidation of alkyltoluenes of the general formula
Figure imgb0002
 Ln an alkanol of the formula R 2 0H and in the presence of an acid containing the H0 3S group, can be produced particularly advantageously if the electrooxidation is carried out with an electrolyte whose alkanol content is 60 to 90% by weight and 8.5% of alkyltoluene up to 40% by weight and of acid from 0.01 to 1.5% by weight.

Überraschenderweise erhält man nach dem erfindungsgemäßen Verfahren die Benzaldehyddialkylacetale unter Vermeidung der geschilderten Nachteile auf besonders wirtschaftliche Weise und in guten Ausbeuten.Surprisingly, the benzaldehyde dialkyl acetals are obtained by avoiding the disadvantages described in a particularly economical manner and in good yields by the process according to the invention.

Alkylreste mit I bis 8 C-Atomen sind z.B. Methyl, Ethyl, Isopropyl, n-, iso- und tert.-Butylgruppen. Bevorzugte Alkyltoluole sind Xylole und Butyltoluole, wie p-Xylol und 4-tert.-Butyltoluol. Von den beiden Alkanolen ist Methanol von besonderem technischem Interesse. Als H03S--Gruppen enthaltende Säuren kommen z.B. Säuren der Formel R3-S03H, in der R3 für eine Alkyl-, Aryl-, Hydroxy oder Alkoxygruppe steht, in Betracht. Bevorzugte Säuren sind Methansulfonsäure, Benzolsulfonsäure und Methylschwefelsäure, insbesondere Schwefelsäure.Alkyl radicals with I to 8 carbon atoms are, for example, methyl, ethyl, isopropyl, n-, iso- and tert-butyl groups. Preferred alkyltoluenes are xylenes and butyltoluenes, such as p-xylene and 4-tert-butyltoluene. Of the two alkanols, methanol is of particular technical interest. Suitable acids containing H 3 S groups are, for example, acids of the formula R 3 SO 3 H , in which R 3 represents an alkyl, aryl, hydroxyl or alkoxy group. Preferred acids are methanesulfonic acid, benzenesulfonic acid and methylsulfuric acid, especially sulfuric acid.

Das erfindungsgemäße Verfahren benötigt keine besondere Elektrolysezelle, es wird bevorzugt in ungeteilten Elektrolysezellen durchgeführt. Als Elektrolyte sind solche bevorzugt, welche einen Gehalt an Alkanol von 70 bis 90 Gew.X, an Alkyltoluol von 8,5 bis 30 Gew.X und an Säuren von 0,05 bis 1,5 Gew.% aufweisen.The method according to the invention does not require a special electrolysis cell; it is preferably carried out in undivided electrolysis cells. Preferred electrolytes are those which have an alkanol content of 70 to 90% by weight, alkyltoluene of 8.5 to 30% by weight and acids of 0.05 to 1.5% by weight.

Als Anoden können alle an sich üblichen Anodenmaterialien eingesetzt werden, die unter den Elektrolysebedingungen stabil sind, bevorzugt verwendet man Graphitanoden. Als Kathodenmaterialien können beispielsweise Stahl, Nickel, Edelmetalle oder Graphit verwendet werden. Die Stromdichten betragen beispielsweise 2 bis 20 A/dm2, vorzugsweise wird bei Stromdichten von 2 bis 12 A/dm2 elektrolysiert. Die Elektrolysetemperatur ist durch den Siedepunkt des Alkanols begrenzt. Bei der Verwendung von Methanol wird beispielsweise bei Temperaturen bis 60°C, vorzugsweise bei 20 bis 60'C elektrolysiert. Es wurde überraschend festgestellt, daß das erfindungsgemäße Verfahren die Möglichkeit bietet, die Alkyltoluole und die als Zwischenstufen durchlaufenen Alkylbenzylalkylether weitgehend umzusetzen, ohne daß es zu einer erheblichen Verschlechterung der Selektivitäten der Elektrooxidation kommt. So wird die Elektrolyse z.B. mit 2,8 bis 7, vorzugsweise 4 bis 6,5 F pro Mol Alkyltoluol durchgeführt. Das Verfahren kann man sowohl diskontinuierlich als auch kontinuierlich durchführen.All anode materials which are customary per se and are stable under the electrolysis conditions can be used as anodes, graphite anodes are preferably used. For example, steel, nickel, precious metals or graphite can be used as cathode materials. The current densities are, for example, 2 to 20 A / dm 2 , and electrolysis is preferably carried out at current densities of 2 to 12 A / dm 2 . The electrolysis temperature is limited by the boiling point of the alkanol. When using methanol, electrolysis is carried out, for example, at temperatures up to 60 ° C., preferably at 20 to 60 ° C. It was surprisingly found that the process according to the invention offers the possibility of largely converting the alkyltoluenes and the alkylbenzylalkyl ethers which have passed through as intermediates without the selectivities of the electrooxidation being significantly impaired. For example, the electrolysis is carried out with 2.8 to 7, preferably 4 to 6.5 F per mole of alkyl toluene. The process can be carried out batchwise or continuously.

Die Aufarbeitung der Elektrolyseausträge ist auf sehr einfache Weise möglich. Man verfährt z.B. so, daß man die geringe Menge Säure mit einer äquivalenten Menge einer Lauge neutralisiert. So gibt man z.B. bei der Verwendung von Schwefelsäuren Natriumhydroxid oder Natriummethylat zu. Danach werden das Alkanol und evtl. noch vorhandene Alkyltoluole und Alkylbenzylalkylether abdestilliert und ggf. zur Elektrolyse zurückgeführt. Die Alkylbenzaldehyddialkylacetale können dann durch Vakuumdestillation weiter gereinigt werden.The electrolysis discharges can be worked up in a very simple manner. One proceeds e.g. so that the small amount of acid is neutralized with an equivalent amount of an alkali. So you give e.g. when using sulfuric acids sodium hydroxide or sodium methylate. The alkanol and any alkyltoluenes and alkylbenzylalkyl ethers which may still be present are then distilled off and, if appropriate, returned to the electrolysis. The alkylbenzaldehyde dialkyl acetals can then be further purified by vacuum distillation.

Bei der Durchführung des erfindungsgemäßen Verfahrens hat es sich gezeigt, daß man die Elektrooxidation über längere Zeit durchführen kann, ohne daß es zu Elektrodenproblemen oder zu einer Verschlechterung der Selektivitäten bei der Elektrooxidation kommt. Das ist erstaunlich, da der technischen Durchführbarkeit einer organischen Elektrolyse oft das Verhalten der Elektroden, die insbesondere bei gleichzeitiger Rückführung des Elektrolyten zu einer höchst unerwünschten Belagbildung neigen, entgegensteht.When carrying out the process according to the invention, it has been shown that the electrooxidation can be carried out over a long period of time without there being any electrode problems or a deterioration in the selectivities in the electrooxidation. This is astonishing, since the technical feasibility of organic electrolysis often conflicts with the behavior of the electrodes, which, particularly when the electrolyte is recycled at the same time, tends to form a highly undesirable deposit.

Die nach dem neuen Verfahren erhältlichen Benzaldehyddialkylacetale sind wertvolle Vorprodukte für Riechstoffe und Fungizide.The benzaldehyde dialkyl acetals obtainable by the new process are valuable precursors for fragrances and fungicides.

Beispiel 1example 1

Figure imgb0003
Der Elektrolyt wird während der Elektrolyse mit 200 1/h über einen Wärmetauscher gepumpt.
Figure imgb0003
 The electrolyte is pumped through a heat exchanger at 200 l / h during the electrolysis.

Aufarbeitung:

  • Der Elektrolyt wird mit Natriummethylat neutralisiert, Methanol bei Normaldruck abdestilliert, das ausgefallene Salz abfiltriert und das Rohacetal bei 15 bis 20 mbar und 50 bis 120°C reindestilliert. Hierbei erhält man 76,4 g p-Xylol, 69,1 g 4-Methylbenzylether und 366,6 g 4-Methylbenzaldehyddimethylacetal. Dies entspricht einer Ausbeute von 79,4 % (bezogen auf eingesetztes p-Xylol).
Refurbishment:
  • The electrolyte is neutralized with sodium methylate, methanol is distilled off at normal pressure, the precipitated salt is filtered off and the crude acetal is distilled in at 15 to 20 mbar and 50 to 120 ° C. This gives 76.4 g of p-xylene, 69.1 g of 4-methylbenzyl ether and 366.6 g of 4-methylbenzaldehyde dimethyl acetal. This corresponds to a yield of 79.4% (based on p-xylene used).

Beispiel 2Example 2

Figure imgb0004
Man elektrolysiert und arbeitet auf wie in Beispiel 1 angegeben. Dabei erhält man 51,6 g p-Xylol, 34,4 g 4-Methylbenzylether und 366,9 g 4--Methylbenzaldehyddimethylacetal. Dies entspricht einer Ausbeute von 67,6 %.
Figure imgb0004
 It is electrolyzed and worked up as indicated in Example 1. This gives 51.6 g of p-xylene, 34.4 g of 4-methylbenzyl ether and 366.9 g of 4-methylbenzaldehyde dimethyl acetal. This corresponds to a yield of 67.6%.

Beispiel 3Example 3

Figure imgb0005
Man elektrolysiert und arbeitet auf wie in Beispiel 1 beschrieben. Es werden 95,6 g p-Xylol, 112,2 g p-Methylbenzylmethylether und 293,3 g p-Methylbenzaldehyddimethylacetal erhalten. Dies entspricht einer Ausbeute von 77,4 X.
Figure imgb0005
 It is electrolyzed and worked up as described in Example 1. 95.6 g of p-xylene, 112.2 g of p-methylbenzyl methyl ether and 293.3 g of p-methylbenzaldehyde dimethyl acetal are obtained. This corresponds to a yield of 77.4 X.

Beispiel 4Example 4

Figure imgb0006
Der Elektrolyt wird während der Elektrolyse mit 200 1/h über einen Wärmetauscher gepumpt.
Figure imgb0006
 The electrolyte is pumped through a heat exchanger at 200 l / h during the electrolysis.

Aufarbeitung:

  • Der Elektrolyseaustrag wird mit Natriummethylat neutralisiert, Methanol bei Normaldruck abdestilliert und das ausgefallene Salz über eine Drucknutsche abgetrennt. Das Filtrat wird bei 1 bis 5 mbar und 70 bis 120°C reindestilliert. Hierbei erhält man 17,1 g 4-tert.-Butyltoluol, 89,9 g 4-tert.-Butylbenzylmethylether (die zur Elektrolyse rückgeführt werden können) und 461,6 g 4-tert.-Butylbenzaldehyddimethylacetal. Dies entspricht einer Ausbeute von 73,3 % (bezogen auf eingesetztes p-tert.-Butyl- toluol).
Refurbishment:
  • The electrolysis discharge is neutralized with sodium methylate, methanol is distilled off at normal pressure and the precipitated salt is separated off using a pressure filter. The filtrate is distilled at 1 to 5 mbar and 70 to 120 ° C. This gives 17.1 g of 4-tert-butyltoluene, 89.9 g of 4-tert-butylbenzylmethyl ether (which can be recycled to the electrolysis) and 461.6 g of 4-tert-butylbenzaldehyde dimethyl acetal. This corresponds to a yield of 73.3% (based on p-tert-butyl-toluene).

Beispiel 5Example 5

Figure imgb0007
Man elektrolysiert und arbeitet auf wie in Beispiel 4 angegeben. Es werden 10,7 g 4-tert.-Butyltoluol, 37,2 g 4-tert.-Butylbenzylmethylether und 483,4 g 4-tert.-Butylbenzaldehyddimethylacetal erhalten. Dies entspricht einer Ausbeute von 69 %.
Figure imgb0007
 It is electrolyzed and worked up as indicated in Example 4. 10.7 g of 4-tert-butyltoluene, 37.2 g of 4-tert-butylbenzyl methyl ether and 483.4 g of 4-tert-butylbenzaldehyde dimethyl acetal are obtained. This corresponds to a yield of 69%.

Beispiel 6Example 6 Elektrolysezelle, Elektrodenabstände und Elektrolyt wie in Beispiel 5Electrolysis cell, electrode spacing and electrolyte as in example 5

Figure imgb0008
Man elektrolysiert und arbeitet auf wie in Beispiel 4 beschrieben. Es werden 12,9 g 4-tert.-Butyltoluol, 70,2 g 4-tert.-Butylbenzylmethylether und 470 g 4-tert.-Butylbenzaldehyddimethylacetal erhalten. Dies entspricht einer Ausbeute von 71,4 %.
Figure imgb0008
 It is electrolyzed and worked up as described in Example 4. 12.9 g of 4-tert-butyltoluene, 70.2 g of 4-tert-butylbenzylmethyl ether and 470 g of 4-tert.-butylbenzaldehyde dimethyl acetal are obtained. This corresponds to a yield of 71.4%.

Beispiel 7Example 7

Figure imgb0009
Man elektrolysiert und arbeitet auf wie in Beispiel 4 beschrieben. Es werden 55,9 g 4-tert.-Butyltoluol, 179,1 g 4-tert.-Butylbenzylmethylether und 303,5 g 4-tert.-Butylbenzaldehyddimethylacetal erhalten. Dies entspricht einer Ausbeute von 64,4 %.
Figure imgb0009
 It is electrolyzed and worked up as described in Example 4. There are 55.9 g of 4-tert-butyltoluene, 179.1 g of 4-tert-butylbenzyl methyl ether and 303.5 g of 4-tert-butylbenzaldehyde dimethyl acetal were obtained. This corresponds to a yield of 64.4%.

Beispiel 8Example 8

Figure imgb0010
Man elektrolysiert und arbeitet auf wie in Beispiel 4 beschrieben. Es werden 11,8 g 4-tert.-Butylbenzylmethylether und 353,6 g 4-tert.-Butyl- benzaldehyddimethylacetal. Dies entspricht einer Ausbeute von 74,3 %.
Figure imgb0010
 It is electrolyzed and worked up as described in Example 4. There are 11.8 g of 4-tert-butylbenzyl methyl ether and 353.6 g of 4-tert-butylbenzaldehyde dimethyl acetal. This corresponds to a yield of 74.3%.

Claims (6)

1. Verfahren zur Herstellung von Benzaldehyddialkylacetalen der allgemeinen Formel
Figure imgb0011
in der R1 einen Alkylrest mit 1 bis 8 C-Atomen und R2 Methyl oder Ethyl bedeuten, durch Elektrooxidation von Alkyltoluolen der allgemeinen Formel
Figure imgb0012
in einem Alkanol der Formel R20H und in Gegenwart einer die HO3S-Gruppe enthaltenden Säure, dadurch gekennzeichnet, daß man die Elektrooxidation mit einem Elektrolyten durchführt, dessen Gehalt an Alkanol 60 bis 90 Gew.X, an Alkyltoluol 8,5 bis 40 Gew.% und an Säure 0,01 bis 1,5 Gew.X beträgt.1. Process for the preparation of benzaldehyde dialkyl acetals of the general formula
Figure imgb0011
 in which R 1 is an alkyl radical having 1 to 8 carbon atoms and R 2 is methyl or ethyl, by electrooxidation of alkyltoluenes of the general formula
Figure imgb0012
 in an alkanol of the formula R 2 0H and in the presence of an acid containing the HO 3 S group, characterized in that the electrooxidation is carried out with an electrolyte whose alkanol content is 60 to 90% by weight and that of alkyltoluene 8.5 to 40% by weight and of acid from 0.01 to 1.5% by weight. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man einen Elektrolyten verwendet, dessen Gehalt an Alkanol 70 bis 90 Gew.X, an Alkyltoluol 8,5 bis 30 Gew.X und an Säure 0,05 bis 1,5 Gew.% beträgt.2. The method according to claim 1, characterized in that one uses an electrolyte, the content of alkanol 70 to 90 Gew.X, of alkyltoluene 8.5 to 30 Gew.X and acid 0.05 to 1.5 wt.% is. 3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man die Elektrolyse an Graphitanoden in einer ungeteilten Zelle durchführt.3. The method according to claim 1, characterized in that one carries out the electrolysis on graphite anodes in an undivided cell. 4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß der Elektrolyt als Säure Benzolsulfonsäure, Methansulfonsäure, Methylschwefelsäure oder Schwefelsäure enthält.4. The method according to claim 1, characterized in that the electrolyte contains benzenesulfonic acid, methanesulfonic acid, methylsulfuric acid or sulfuric acid as the acid. 5. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man als Alkyltoluol p-Xylol oder 4-tert.-Butyltoluol einsetzt.5. The method according to claim 1, characterized in that p-xylene or 4-tert-butyltoluene is used as the alkyltoluene. 6. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man als Alkanol Methanol verwendet.6. The method according to claim 1, characterized in that methanol is used as the alkanol.
EP84106858A 1983-06-22 1984-06-15 Process for manufacturing benzaldehyde dialkylacetals Expired EP0129795B1 (en)

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EP0212509A1 (en) * 1985-08-14 1987-03-04 BASF Aktiengesellschaft Process for manufacturing benzoic-acid orthoesters, and compounds of this class
EP0554564A1 (en) * 1992-01-22 1993-08-11 BASF Aktiengesellschaft Process for preparing benzaldehyde acetals
US6787009B2 (en) 2000-12-19 2004-09-07 Basf Aktiengesellschaft Bipolar quasi-divided electrolysis cells
WO2010108874A1 (en) 2009-03-27 2010-09-30 Basf Se Electrochemical method for producing 3 tert.-butyl benzaldehyde- dimethylacetal
WO2011098432A2 (en) 2010-02-12 2011-08-18 Basf Se Method for producing 4-isopropylcyclohexylmethanol
US8889920B2 (en) 2010-02-12 2014-11-18 Basf Se Process for preparing 4-isopropylcyclohexylmethanol

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US5030276A (en) * 1986-10-20 1991-07-09 Norton Company Low pressure bonding of PCD bodies and method
DE3713732A1 (en) * 1987-04-24 1988-11-17 Basf Ag NEW BENZALDEHYD DIALKYL ACETALS, THEIR PRODUCTION AND USE
DE3814180A1 (en) * 1988-04-27 1989-11-09 Basf Ag METHOD FOR PRODUCING TETRAL IN DERIVATIVES AND NEW TETRAL IN DERIVATIVES

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0212509A1 (en) * 1985-08-14 1987-03-04 BASF Aktiengesellschaft Process for manufacturing benzoic-acid orthoesters, and compounds of this class
US4699698A (en) * 1985-08-14 1987-10-13 Basf Aktiengesellschaft Preparation of benzoic acid ortho-esters and novel compounds of this type
EP0554564A1 (en) * 1992-01-22 1993-08-11 BASF Aktiengesellschaft Process for preparing benzaldehyde acetals
US6787009B2 (en) 2000-12-19 2004-09-07 Basf Aktiengesellschaft Bipolar quasi-divided electrolysis cells
WO2010108874A1 (en) 2009-03-27 2010-09-30 Basf Se Electrochemical method for producing 3 tert.-butyl benzaldehyde- dimethylacetal
US8629304B2 (en) 2009-03-27 2014-01-14 Basf Se Electrochemical method for producing 3-tert-butylbenzaldehyde dimethyl acetal
WO2011098432A2 (en) 2010-02-12 2011-08-18 Basf Se Method for producing 4-isopropylcyclohexylmethanol
US8889920B2 (en) 2010-02-12 2014-11-18 Basf Se Process for preparing 4-isopropylcyclohexylmethanol

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EP0129795A3 (en) 1985-09-25
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DE3469444D1 (en) 1988-03-31
EP0129795B1 (en) 1988-02-24
JPH0641638B2 (en) 1994-06-01
JPS6052586A (en) 1985-03-25

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