EP0129795B1 - Process for manufacturing benzaldehyde dialkylacetals - Google Patents

Process for manufacturing benzaldehyde dialkylacetals Download PDF

Info

Publication number
EP0129795B1
EP0129795B1 EP84106858A EP84106858A EP0129795B1 EP 0129795 B1 EP0129795 B1 EP 0129795B1 EP 84106858 A EP84106858 A EP 84106858A EP 84106858 A EP84106858 A EP 84106858A EP 0129795 B1 EP0129795 B1 EP 0129795B1
Authority
EP
European Patent Office
Prior art keywords
weight
tert
electrolysis
acid
electrolyte
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
EP84106858A
Other languages
German (de)
French (fr)
Other versions
EP0129795A2 (en
EP0129795A3 (en
Inventor
Dieter Dr. Degner
Heinz Hannebaum
Hardo Dr. Siegel
Walter Dr Gramlich
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 EP0129795A2 publication Critical patent/EP0129795A2/en
Publication of EP0129795A3 publication Critical patent/EP0129795A3/en
Application granted granted Critical
Publication of EP0129795B1 publication Critical patent/EP0129795B1/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

  • 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.
  • z. B collidine as an auxiliary base for the electrolyte.
  • yields of only 64 and 55% are achieved using 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.
  • 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 a H0 3 S group Acid exist.
  • the electrooxidation of P-xylene gives a mixture by this process which, in addition to ether and ester compounds, also contains 4-methylbenzaldehyde but no 4-methylbenzaldehyde dimethyl acetal.
  • 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 1 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.
  • Acids containing H0 3 S groups come e.g. B .. Acids of the formula R 3- SO 3 H in which -R3 represents an alkyl, aryl, hydroxy 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, an alkyl toluene content of 8.5 to 30% by weight and an acid content 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.
  • 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-butyl-benzaldehyde dimethyl acetal. This corresponds to a yield of 74.3%.

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 b w. p-Xylol durch anodische Oxidation in Anisaldehyddimethylacetal bzw. 4-Methylbenzaldehyddimethyla eta 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 % erreicht. 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 b w. can convert p-xylene by anodic oxidation into anisaldehyde dimethyl acetal or 4-methylbenzaldehyde dimethyl eta. 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%. In addition, the processing of the basic electrolyte is 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 from falling below 7, z. B. collidine as an auxiliary base for the electrolyte. In the electrooxidation of p-xylene and 4-tert-butyl-toluene, yields of only 64 and 55% are achieved using 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, poorer yields are obtained in the electrooxidation of p-xylene 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 enthalten. 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 . 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 %) 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. Schließlich wird in der japanischen Offenlegungsschrift 20 174/1981 eine Elektrooxydation von p-tert.-Butyltoluol beschrieben, bei der in Gegenwart von Methanol und eines Leitsalzes elektrolysiert wird. Als Leitsalz werden auch Schwefelsäure und deren Monoester verwendet. Nach diesem Verfahren ist p-tert.-Butylbenzaldehyddimethylacetal erhältlich.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 a H0 3 S group Acid exist. The electrooxidation of P-xylene (see Example 11) gives a mixture by this process which, in addition to ether and ester compounds, also contains 4-methylbenzaldehyde but no 4-methylbenzaldehyde dimethyl acetal. Finally, Japanese Patent Application No. 20 174/1981 describes an electrooxidation of p-tert-butyltoluene, in which electrolysis is carried out in the presence of methanol and a conductive salt. Sulfuric acid and its monoesters are also used as the conductive salt. P-tert-butylbenzaldehyde dimethyl acetal can be obtained by this process.

Es wurde nun gefunden, daß man Benzaldehyddialkylacetale der allgemeinen Formel

Figure imgb0001
in der R1 einen Alkylrest mit 1 bis 8 G-Atomen und R2 Methyl oder Ethyl bedeuten, durch Elektrooxidation von Alkyltoluolen der allgemeinen Formel
Figure imgb0002
in einem Alkanol der Formel R20H und in Gegenwart einer die H03S-Gruppe enthaltenden Säure, wobei man das überschüssige Alkanol anschließend abdestilliert, 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 G atoms and R 2 is methyl or ethyl, by electrooxidation of alkyltoluenes of the general formula
Figure imgb0002
 in an alkanol of the formula R 2 0H and in the presence of an acid containing the H0 3 S group, the excess alkanol then being distilled off, can be prepared particularly advantageously if the electrooxidation is carried out with an electrolyte whose alkanol content is 60 to 90 % By weight of alkyltoluene is 8.5 to 40% by weight and of acid is 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 1 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-SO3H 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 1 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. Acids containing H0 3 S groups come e.g. B .. Acids of the formula R 3- SO 3 H in which -R3 represents an alkyl, aryl, hydroxy 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.-%, an Alkyltoluol von 8,5 bis 30 Gew.-% 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, an alkyl toluene content of 8.5 to 30% by weight and an acid content 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, vorzugsweis 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 z. B. so that one neutralizes the small amount of acid with an equivalent amount of an alkali. So you give z. B. 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

  • Elektrolysezelle: ungeteilte Zelle mit 9 Graphitelektroden (Fläche pro Anode: 1,7 dm2)Electrolysis cell: undivided cell with 9 graphite electrodes (area per anode: 1.7 dm 2 )
  • Elektrodenabstände: 0,5 mmElectrode spacing: 0.5 mm
  • Elektrolyt: 425 g p-Xylol (15,1 Gew.-%) 2 370 g Methanol (84,4 Gew.-%) 14 g H2S04 (0,5 Gew.-%)Electrolyte: 425 g p-xylene (15.1% by weight) 2 370 g methanol (84.4% by weight) 14 g H 2 S0 4 (0.5% by weight)
  • Stromdichte: 3,3 A/dm2 Current density: 3.3 A / dm 2
  • Zellspannung: 56 bis 69 VCell voltage: 56 to 69 V.
  • Temperatur: 20 bis 30°CTemperature: 20 to 30 ° C
  • Elektrolyse mit 5,3 F/Mol p-XylolElectrolysis with 5.3 F / mol p-xylene

Der Elektrolyt wird während der Elektrolyse mit 200 I/h über einen Wärmetauscher gepumpt.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-Methyl-benzaldehyddimethylacetal. Dies entspricht einer Ausbeute von 79,4 % (bezogen auf eingesetztes p-Xylol).Working up: 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-methyl-benzaldehyde dimethyl acetal. This corresponds to a yield of 79.4% (based on p-xylene used).

Beispiel 2Example 2

  • Elektrolysezelle: ungeteilte Zelle mit 11 Graphitelektroden (Fläche pro Anode: 1,7 dm2)Electrolysis cell: undivided cell with 11 graphite electrodes (area per anode: 1.7 dm 2 )
  • Elektrodenabstände: 0,5 mmElectrode spacing: 0.5 mm
  • Elektrolyt: 425 g p-Xylol (15,1 Gew.-%) 2 370 g Methanol (84,4 Gew.-%) 14 g CH3S03H (0,5 Gew.-%)Electrolyte: 425 g p-xylene (15.1% by weight) 2,370 g methanol (84.4% by weight) 14 g CH 3 S0 3 H (0.5% by weight)
  • Stromdichte: 3,3 A/dm2 Current density: 3.3 A / dm 2
  • Zellspannung: 45 bis 61 VCell voltage: 45 to 61 V.
  • Temperatur: 20 bis 30° CTemperature: 20 to 30 ° C
  • Elektrolyse mit 6,3 F/Mol p-XylolElectrolysis with 6.3 F / mol p-xylene

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 %. 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

  • Elektrolysezelle: ungeteilte Zelle mit 11 Graphitelektroden (Fläche pro Anode: 1,7 dm2)Electrolysis cell: undivided cell with 11 graphite electrodes (area per anode: 1.7 dm 2 )
  • Elektrodenabstände: 0,5 mmElectrode spacing: 0.5 mm
  • Elektrolyt: 425 g p-Xylol (15 Gew.-%) 2 370 g Methanol (84 Gew.-%) 28 g C6H5SO3H (1 % Gew.-%)Electrolyte: 425 g p-xylene (15% by weight) 2,370 g methanol (84% by weight) 28 g C 6 H 5 SO 3 H (1%% by weight)
  • Stromdichte: 3,3 A/dm2 Current density: 3.3 A / dm 2
  • Zellspannung: 55 bis 62 VCell voltage: 55 to 62 V.
  • Temperatur: 20 bis 30°CTemperature: 20 to 30 ° C
  • Elektrolyse mit 4,7 F/Mol p-XylolElectrolysis with 4.7 F / mol p-xylene

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 %.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%.

Beispiel 4Example 4

  • Elektrolysezelle: ungeteilte Zelle mit 8 Graphitelektroden (Fläche pro Anode: 1,7 dm2)Electrolysis cell: undivided cell with 8 graphite electrodes (area per anode: 1.7 dm2)
  • Elektrodenabstände: 1 mmElectrode spacing: 1 mm
  • Elektrolyt: 540 g 4-tert.-Butyltoluol (15 Gew.%) 3 051 g Methanol (84,75 Gew.%) 9 g H2S04 (0,25 Gew.%)Electrolyte: 540 g of 4-tert-butyltoluene (15% by weight) 3,051 g of methanol (84.75% by weight) 9 g of H 2 SO 4 (0.25% by weight)
  • Stromdichte: 4,4 A/dm2 Current density: 4.4 A / dm 2
  • Zellspannung: 54 bis 58 VCell voltage: 54 to 58 V
  • Temperatur: 25 bis 38° CTemperature: 25 to 38 ° C
  • Elektrolyse mit 6,1 F/Mol 4-tert.-ButyltoluolElectrolysis with 6.1 F / mol of 4-tert-butyltoluene

Der Elektrolyt wird während der Elektrolyse mit 200 I/h über einen Wärmetauscher gepumpt.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.-Butyltoluol).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-butylbenzyl methyl 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-butyltoluene).

Beispiel 5Example 5

  • Elektrolysezelle: ungeteilte Zelle mit 6 Graphitelektroden (Fläche pro Anode: 1,7 dm2)Electrolysis cell: undivided cell with 6 graphite electrodes (area per anode: 1.7 dm2)
  • Elektrodenabstände: 1 mmElectrode spacing: 1 mm
  • Elektrolyt: wie Beispiel 4Electrolyte: as example 4
  • Stromdichte: 5,9 A/dm2 Current density: 5.9 A / dm 2
  • Zellspannung: 38 VCell voltage: 38 V
  • Temperatur: 35 bis 40° CTemperature: 35 to 40 ° C
  • Elektrolyse mit 6,1 F/Mol 4-tert.-ButyltoluolElectrolysis with 6.1 F / mol of 4-tert-butyltoluene

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.-Butylbenzaldehyddimethylacelal erhalten. Dies entspricht einer Ausbeute von 69 %.It is electrolyzed and worked up as indicated in Example 4. 10.7 g of 4-tert-butyltoluene, 37.2 g of 4-tert-butylbenzylmethyl ether and 483.4 g of 4-tert.-butylbenzaldehyde dimethylcelal are obtained. This corresponds to a yield of 69%.

Beispiel 6Example 6

Elektrolysezelle, Elektrodenabstände und Elektrolyt wie in Beispiel 5

  • Stromdichte: 10 A/dm2
  • Zellspannung: 49 bis 56 V
  • Temperatur: 45° C
  • Elektrolyse mit 6 F/Mol 4-tert.-Butyltoluol
Electrolysis cell, electrode spacing and electrolyte as in example 5
  • Current density: 10 A / dm 2
  • Cell voltage: 49 to 56 V
  • Temperature: 45 ° C
  • Electrolysis with 6 F / mol of 4-tert-butyltoluene

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 %.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

  • Elektrolysezelle: ungeteilte Zelle mit 11 Graphitelektroden (Fläche pro Anode: 1,7 dm2)Electrolysis cell: undivided cell with 11 graphite electrodes (area per anode: 1.7 dm 2 )
  • Elektrodenabstände: 0,5 mmElectrode spacing: 0.5 mm
  • Elektrolyt: wie in Beispiel 4Electrolyte: as in example 4
  • Stromdichte: 2,94 A/dm2 Current density: 2.94 A / dm 2
  • Zellspannung: 53 bis 54 VCell voltage: 53 to 54 V.
  • Temperatur: 24 bis 35° CTemperature: 24 to 35 ° C
  • Elektrolyse mit 5 F/Mol 4-tert.-ButyltoluolElectrolysis with 5 F / mol of 4-tert-butyltoluene

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 %.It is electrolyzed and worked up as described in Example 4. 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 are obtained. This corresponds to a yield of 64.4%.

Beispiel 8Example 8

  • Elektrolysezelle: ungeteilte Zelle mit 11 Graphitelektroden (Fläche pro Anode: 1,7 dm2)Electrolysis cell: undivided cell with 11 graphite electrodes (area per anode: 1.7 dm2)
  • Elektrodenabstände: 0,5 mmElectrode spacing: 0.5 mm
  • Elektrolyt: 419 g 4-tert.-Butylbenzylmethylether (15 Gew.-%) 7 g H2S04 (0,25 Gew.-%) 2 370 g Methanol (84,75 Gew.-%)Electrolyte: 419 g of 4-tert-butylbenzyl methyl ether (15% by weight) 7 g of H 2 SO 4 (0.25% by weight) 2,370 g of methanol (84.75% by weight)
  • Stromdichte: 2,94 A/dm2 Current density: 2.94 A / dm 2
  • Zellspannung: 40 bis 44 VCell voltage: 40 to 44 V
  • Temperatur: 22 bis 27° CTemperature: 22 to 27 ° C
  • Elektrolyse mit 3 F/Mol 4-tert.-ButylbenzylmethyletherElectrolysis with 3 F / mol of 4-tert-butylbenzyl methyl ether

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 %.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-butyl-benzaldehyde dimethyl acetal. This corresponds to a yield of 74.3%.

Claims (4)

1. A process for the preparation of a benzaldehyde dialkyl acetal of the general formula
Figure imgb0005
where R1 is alkyl of 1 to 8 carbon atoms and R2 is methyl or ethyl, by electrochemical oxidation of an alkyltoluene of the general formula
Figure imgb0006
in an alkanol of the formula R20H and in the presence of an H03S-containing acid, wherein the electrochemical oxidation is carried out using an electrolyte which contains from 60 to 90 % by weight of the alkanol, from 8.5 to 40 % by weight of the alkyltoluene and from 0.01 to 1.5 % by weight of the acid.
2. A process as claimed in claim 1, wherein the electrolyte used contains from 70 to 90 % by weight of the alkanol, from 8.5 to 30 % by weight of the alkyltoluene and from 0.05 to 1.5 % by weight of the acid.
3. A process as claimed in claim 1, wherein the electrolyte contains, as the acid, benzenesulfonic acid, methanesulfonic acid, methylsulfuric acid or sulfuric acid.
4. A process as claimed in claim 1 or 2 or 3, wherein the alkyltoluene used is 4-tert.-butyltoluene and the mixture obtained after electrolysis is neutralized with an alkali.
EP84106858A 1983-06-22 1984-06-15 Process for manufacturing benzaldehyde dialkylacetals Expired EP0129795B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19833322399 DE3322399A1 (en) 1983-06-22 1983-06-22 METHOD FOR THE PRODUCTION OF BENZ ALDEHYDDIALKYLACETALEN
DE3322399 1983-06-22

Publications (3)

Publication Number Publication Date
EP0129795A2 EP0129795A2 (en) 1985-01-02
EP0129795A3 EP0129795A3 (en) 1985-09-25
EP0129795B1 true EP0129795B1 (en) 1988-02-24

Family

ID=6202042

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84106858A Expired EP0129795B1 (en) 1983-06-22 1984-06-15 Process for manufacturing benzaldehyde dialkylacetals

Country Status (4)

Country Link
US (1) US4539081A (en)
EP (1) EP0129795B1 (en)
JP (1) JPH0641638B2 (en)
DE (2) DE3322399A1 (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3529074A1 (en) * 1985-08-14 1987-02-19 Basf Ag METHOD FOR THE PRODUCTION OF BENZOESAEUREORTHOESTERS AND COMPOUNDS OF THIS CLASS
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
DE4201544A1 (en) * 1992-01-22 1993-07-29 Basf Ag METHOD FOR THE PRODUCTION OF BENZALDEHYDACETALES
DE10063195A1 (en) 2000-12-19 2002-06-20 Basf Ag Electrolysis cell, useful for production of organic and inorganic products, has electrochemically active counter electrode area that is smaller than that of working electrode
EP2411564B1 (en) 2009-03-27 2017-05-10 Basf Se Electrochemical process for producing 3-tert-butylbenzaldehyde-dimethylacetal
ES2719585T3 (en) * 2010-02-12 2019-07-11 Basf Se Procedure for the preparation of 4-isopropylcyclohexylmethanol
US8889920B2 (en) 2010-02-12 2014-11-18 Basf Se Process for preparing 4-isopropylcyclohexylmethanol

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2351932A1 (en) * 1976-05-21 1977-12-16 Rhone Poulenc Ind Anodic oxidn. of toluene and xylene(s) - to produce methyl benzyl ether(s) and methoxy benzaldehyde(s)
DE2851732A1 (en) * 1978-11-30 1980-06-12 Bayer Ag Substd. benzaldehyde di:alkyl acetal cpds. prodn. - by electrochemical oxidn. of substd. toluene in alcohol contg. tetra:alkyl-ammonium aryl-sulphonate
US4318783A (en) * 1978-11-30 1982-03-09 Bayer Aktiengesellschaft Process for the preparation of optionally substituted benzaldehyde dialkyl acetals
DE2912058A1 (en) * 1979-03-27 1980-10-09 Bayer Ag Substd. benzaldehyde di:alkyl acetal prodn. - by electrolysis of corresp. toluene dissolved in alcohol, with hydrogenation of by prod. before recycle
JPS5620174A (en) * 1979-07-27 1981-02-25 Fuso Kagaku Kogyo Kk Preparation of p-t-butylbenzaldehyde and its acetal
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.
JPS5687683A (en) * 1979-12-17 1981-07-16 Fuso Kagaku Kogyo Kk Manufacture of p-acetoxybenzaldehyde or its acetal

Also Published As

Publication number Publication date
JPS6052586A (en) 1985-03-25
EP0129795A2 (en) 1985-01-02
EP0129795A3 (en) 1985-09-25
DE3469444D1 (en) 1988-03-31
DE3322399A1 (en) 1985-01-10
JPH0641638B2 (en) 1994-06-01
US4539081A (en) 1985-09-03

Similar Documents

Publication Publication Date Title
EP0011712B1 (en) Preparation of benzaldehyde dialkyl acetals substituted in the 4-position
EP0012240B1 (en) Process for manufacturing of optionally substituted benzaldehyd-dialkyl acetals
EP0129795B1 (en) Process for manufacturing benzaldehyde dialkylacetals
EP0072914B1 (en) Process for the production of alkyl-substituted benzaldehydes
EP0275489B1 (en) Benzaldehyde derivatives, their preparation and application
DE2855508A1 (en) METHOD FOR PRODUCING BENZALDEHYDES
EP0287954A2 (en) Benzaldehyde dialkyl acetals, their preparation and use
EP0029995B1 (en) Process for the preparation of 4-tert.-butylbenzaldehyde
EP0164705B1 (en) Process for manufacturing phthalaldehydacetals
EP0078004B1 (en) Electrochemical process for the production of 2,5-dialcoxy-2,5-dihydrofurans
EP0502372B1 (en) 4-tert-Alkyl-2-Methylbenzaldehydedialkylacetals
EP0152801B1 (en) Process for manufacturing benzaldehyde dialkylacetals
EP0393668B1 (en) Method of preparation of benzaldehyde dialkyl acetals and new benzaldehyde dialkyl acetals
EP0179377B1 (en) Process for the preparation of 1-alkoxyisochromanes, and 1-alkoxy alkylisochromanes
EP0554564A1 (en) Process for preparing benzaldehyde acetals
DE4407986A1 (en) Process for the preparation of o-phthalaldehyde tetraalkyl acetals
EP0339521B1 (en) Process for manufacturing tetralin derivatives, and tetralin derivatives
EP0252284B1 (en) 2,6-dimethyl-para-benzoquinone tetraalkyl ketals
EP0513577B1 (en) Method for the preparation of 1-alkoxyisochromans
DE2851732A1 (en) Substd. benzaldehyde di:alkyl acetal cpds. prodn. - by electrochemical oxidn. of substd. toluene in alcohol contg. tetra:alkyl-ammonium aryl-sulphonate
DE3708337A1 (en) METHOD FOR PRODUCING METHOXIACETALDEHYDDIALKYLACETALS
DE2923531A1 (en) Electrochemical prodn. of benzaldehyde di:alkyl acetal - by oxidn. of toluene deriv. in alcohol soln., converted to corresp. benzaldehyde by acid hydrolysis
DE4308846A1 (en) Process for the preparation of terephthalaldehyde tetraalkylacetals
EP0430055A1 (en) 2-tert.-butyl-p-benzoquinone-tetraalkyl-ketals and their preparation
DE3905243A1 (en) METHOD FOR PRODUCING LACTONES

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

AK Designated contracting states

Designated state(s): BE CH DE FR GB IT LI NL

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Designated state(s): BE CH DE FR GB IT LI NL

17P Request for examination filed

Effective date: 19851024

17Q First examination report despatched

Effective date: 19860506

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): BE CH DE FR GB IT LI NL

ITF It: translation for a ep patent filed

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

GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)
REF Corresponds to:

Ref document number: 3469444

Country of ref document: DE

Date of ref document: 19880331

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

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

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
ITTA It: last paid annual fee
REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

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

Ref country code: FR

Payment date: 20030516

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: 20030522

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: 20030526

Year of fee payment: 20

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

Ref country code: NL

Payment date: 20030527

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: 20030602

Year of fee payment: 20

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

Ref country code: BE

Payment date: 20030701

Year of fee payment: 20

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

Ref country code: CH

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20040614

Ref country code: LI

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20040614

Ref country code: GB

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20040614

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

Ref country code: NL

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20040615

BE20 Be: patent expired

Owner name: *BASF A.G.

Effective date: 20040615

REG Reference to a national code

Ref country code: GB

Ref legal event code: PE20

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

NLV7 Nl: ceased due to reaching the maximum lifetime of a patent

Effective date: 20040615