EP0278219A2 - Process for producing (poly)oxatetramethylene-dicarboxylic acids - Google Patents
Process for producing (poly)oxatetramethylene-dicarboxylic acids Download PDFInfo
- Publication number
- EP0278219A2 EP0278219A2 EP88100145A EP88100145A EP0278219A2 EP 0278219 A2 EP0278219 A2 EP 0278219A2 EP 88100145 A EP88100145 A EP 88100145A EP 88100145 A EP88100145 A EP 88100145A EP 0278219 A2 EP0278219 A2 EP 0278219A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- poly
- oxatetramethylene
- electrolysis
- redox catalyst
- dicarboxylic acids
- 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.)
- Withdrawn
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 present invention relates to a new process for the preparation of (poly) oxatetramethylene dicarboxylic acids by electrochemical oxidation of polytetrahydrofurans.
- the invention had for its object to find a process which allows (poly) oxatetramethylene dicarboxylic acids to be produced in a technically simple and environmentally friendly manner.
- the new process had to meet further requirements, such as almost quantitative conversion, complete oxidation of both hydroxyl groups (monocarboxylic acids as chain terminators in the subsequent polycondensation would prevent the formation of polymers with a high molecular weight), as well as avoidance of oxidative decomposition and degradation reactions.
- (poly) oxatetramethylene dicarboxylic acids of the general formula are prepared HOOCC3H6 (OC4H8) n -OC3H6COOH (I), in which n is an integer from 0 to 20, by oxidation of polytetrahydrofurans of the general formula HOCH2C3H6 (OC4H8) n -OC3H6CH2OH (II) in which n has the meaning given above, in that the oxidation is carried out by electrolysis in an aqueous alkaline medium and in the presence of an electrochemically regenerable redox catalyst.
- An electrochemically regenerable redox catalyst which e.g. also known as a redox mediator, can be dissolved in the electrolyte or in suspended form. It is preferably located as a firmly adhering layer on the anode.
- Redox catalysts of the type mentioned are e.g. the oxides of iron, silver, cobalt, nickel or copper, or mixed oxides such as e.g. between nickel and cobalt.
- nickel oxide nickel peroxide, nickel oxide hydroxide
- the (poly) oxatetramethylene dicarboxylic acids of the formula I can be prepared so advantageously by the electrochemical oxidation of the polytetrahydrofurans of the formula II by the process according to the invention, and that, for example, the electrolysis is technically so advantageously galvanostatically at room temperature and at current densities to be able to carry out between 20 and 40 mA / cm2 electrode surface without oxidative ether cleavages being detectable (for example by lowering the molecular weight).
- the polytetrahydrofurans are electrolyzed by the process according to the invention in an aqueous alkaline medium, preferably at a pH from 9 to 14, in particular from 12 to 14.
- the electrolyte e.g. Alkali and / or alkaline earth metal hydroxides, carbonates, hydrogen carbonates, phosphates, hydrogen phosphates and borates, but preferably the hydroxides and / or carbonates of sodium or potassium. Since hydroxyl ions are consumed in equimolar amounts to form the dicarboxylic acids, the molar ratio of polytetrahydrofuran to the alkali or alkaline earth metal salt should be between 1: 2.0 and 1: 3.0. However, higher alkali or Alkaline earth concentrations can be applied.
- Suitable electrolytes are accordingly aqueous alkaline solutions of polytetrahydrofuran, which e.g. have a polytetrahydrofuran content of 1 to 40, preferably 3 to 20% by weight and an alkali or alkaline earth content which corresponds to the required molar ratio and the desired conversion.
- An inert organic, water-miscible solvent can be added to the electrolyte to improve the solubility, especially in the case of higher molecular weight polytetrahydrofurans.
- Suitable solvents are nitriles such as acetonitrile, ethers such as tetrahydrofuran, or alcohols such as tert-butanol.
- the method according to the invention does not require a special electrolysis cell. It can advantageously be carried out in an undivided flow cell. All cathode materials which are customary per se and are stable under the electrolysis conditions, such as stainless steel, nickel, copper or noble metals such as platinum, can be used as cathodes.
- the preferred cathode material is steel and nickel.
- Nickel oxide hydroxide is a thin layer on anode support materials such as carbon, steel or copper. Such anodes can e.g. after the in J. Appl. Electrochemical. 9, 707 (1979). However, nickel oxide hydroxide layers on nickel are preferred as the anode carrier material. According to the information e.g. in Tetrahedron 38, 3299 (1982), such a nickel oxide hydroxide anode is produced in that a nickel electrode in an aqueous solution with 0.1 N nickel sulfate, 0.1 N sodium acetate and 0.005 N sodium hydroxide at current densities between 5 mA / cm2 and 1 mA / cm2 reversed several times for a short time.
- the electrolysis is preferably carried out with 8 to 10 F / mol polytetrahydrofuran.
- the current density is e.g. B. 0.5 to 6 A / dm2 electrode surface, preferably 1 to 4 A / dm2 electrode surface. You do that Process according to the invention at temperatures which are, for example, at most 10 ° C. below the boiling point of the electrolyte used.
- Electrolysis is preferably carried out in the temperature range between 20 and 70 ° C., in particular between 20 and 40 ° C.
- the electrolysis can be carried out batchwise or continuously.
- the processing of the alkaline electrolysis discharges for the isolation of the (poly) oxatetramethylene dicarboxylic acids can be carried out in the usual way.
- the electrolyzed solution is brought to a pH of 1 to 2 with an inorganic acid, such as hydrochloric acid or sulfuric acid, and the (poly) oxatetramethylene dicarboxylic acids released are extracted with a solvent, such as an aliphatic ether.
- the (poly) oxatetramethylene dicarboxylic acids can be isolated from this extract by distilling off the solvent in a purity of> 95%.
- the electrooxidations were carried out galvanostatically in an undivided electrolysis cell with steel and / or nickel electrodes.
- the electrolyte the composition of which can be seen from the examples, was pumped through the cell at 150 to 200 l / h via a heat exchanger.
- the anodes were placed in an aqueous solution of the composition 0.1 N nickel (II) sulfate, 0.1 N sodium acetate and 0.005 N sodium hydroxide at a current density of 1 mA / cm2 alternately switched as anode and cathode (5 to 10 sec). After a charge of 0.5 A sec / cm 2 had passed through, the anodes, which had been coated with a black, firmly adhering coating of nickel (II) oxide hydroxide, were rinsed with distilled water and used for the electrolysis.
- the electrolyte had a pH between 13.7 and 12.8.
- Example 1 The electrolysis described in Example 1 was carried out at a temperature of 40 ° C., a current density of 4 A / dm2 and at 9.5 F / mol polytetrahydrofuran.
- the processing of the electrolysis discharge described in Example 1 gave 6.7 g of polytetrahydrofuran, corresponding to a conversion of 98%, and 346 g of high purity (poly) oxatetramethylene dicarboxylic acid with a molecular weight of 296 corresponding to a yield of 83%.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
- Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)
Abstract
Description
Die vorliegende Erfindung betrifft ein neues Verfahren zur Herstellung von (Poly)oxatetramethylendicarbonsäuren durch elektrochemische Oxidation von Polytetrahydrofuranen.The present invention relates to a new process for the preparation of (poly) oxatetramethylene dicarboxylic acids by electrochemical oxidation of polytetrahydrofurans.
Aus der DE-OS 26 58 714 ist bekannt, daß man (Poly)oxatetramethylendicarbonsäuren aus Polytetrahydrofuran durch Oxidation in Aceton mit einem Überschuß Chromsäurenanhydrid in Gegenwart von Schwefelsäure und Wasser herstellen kann. Bei diesem Verfahren tritt während der Oxidation eine Zersetzung des Ausgangsproduktes ein, so daß Reaktionsprodukte mit kleinerem Molekulargewicht erhalten werden. Außerdem ist der Umgang mit dem toxischen Chromsäureanhydrid von Nachteil.From DE-OS 26 58 714 it is known that (poly) oxatetramethylene dicarboxylic acids can be prepared from polytetrahydrofuran by oxidation in acetone with an excess of chromic acid anhydride in the presence of sulfuric acid and water. In this process, decomposition of the starting product occurs during the oxidation, so that reaction products with a smaller molecular weight are obtained. In addition, dealing with the toxic chromic anhydride is disadvantageous.
(Poly)oxatetramethylendicarbonsäuren finden Interesse für die Synthese thermoplastischer Polyetheramide und Polyetherester.(Poly) oxatetramethylene dicarboxylic acids find interest in the synthesis of thermoplastic polyether amides and polyether esters.
Der Erfindung lag die Aufgabe zugrunde, ein Verfahren zu finden, das es gestattet, (Poly)oxatetramethylendicarbonsäuren auf technisch einfache und umweltfreundliche Weise herzustellen. Außerdem waren an das neue Verfahren weitere Anforderungen zu stellen, wie nahezu quantitativer Umsatz, vollständige Oxidation beider Hydroxylgruppen (Monocarbonsäuren würden als Kettenterminatoren bei nachfolgender Polykondensation die Bildung von Polymeren mit hohem Molekulargewicht verhindern), als auch Vermeidung oxidativer Zersetzungs-und Abbaureaktionen.The invention had for its object to find a process which allows (poly) oxatetramethylene dicarboxylic acids to be produced in a technically simple and environmentally friendly manner. In addition, the new process had to meet further requirements, such as almost quantitative conversion, complete oxidation of both hydroxyl groups (monocarboxylic acids as chain terminators in the subsequent polycondensation would prevent the formation of polymers with a high molecular weight), as well as avoidance of oxidative decomposition and degradation reactions.
Nach dem neuen Verfahren, das diese Anforderungen erfüllt, stellt man (Poly)oxatetramethylendicarbonsäuren der allgemeinen Formel
HOOCC₃H₆(OC₄H₈)n-OC₃H₆COOH (I),
in der n für eine ganze Zahl von 0 bis 20 steht, durch Oxidation von Polytetrahydrofuranen der allgemeinen Formel
HOCH₂C₃H₆(OC₄H₈)n-OC₃H₆CH₂OH (II)
in der n die obengenannte Bedeutung hat, dadurch her, daß man die Oxidation durch Elektrolyse in wäßrig alkalischem Medium und in Gegenwart eines elektrochemisch regenerierbaren Redoxkatalysators durchführt.According to the new process which meets these requirements, (poly) oxatetramethylene dicarboxylic acids of the general formula are prepared
HOOCC₃H₆ (OC₄H₈) n -OC₃H₆COOH (I),
in which n is an integer from 0 to 20, by oxidation of polytetrahydrofurans of the general formula
HOCH₂C₃H₆ (OC₄H₈) n -OC₃H₆CH₂OH (II)
in which n has the meaning given above, in that the oxidation is carried out by electrolysis in an aqueous alkaline medium and in the presence of an electrochemically regenerable redox catalyst.
Das erfindungsgemäße Verfahren läßt sich durch die folgenden Reaktionsgleichungen beschreiben:
Ein elektrochemisch regenerierbarer Redoxkatalysator, der z.B. auch als Redoxmediator bezeichnet wird, kann im Elektrolyten gelöst oder in suspendierter Form vorliegen. Bevorzugt befindet er sich als festhaftende Schicht auf der Anode. Redoxkatalysatoren der genannten Art sind z.B. die Oxide des Eisens, Silbers, Cobalts, Nickels oder Kupfers, oder Mischoxide wie z.B. zwischen Nickel und Cobalt. Bevorzugt wird jedoch Nickeloxid (Nickelperoxid, Nickeloxidhydroxid).An electrochemically regenerable redox catalyst which e.g. also known as a redox mediator, can be dissolved in the electrolyte or in suspended form. It is preferably located as a firmly adhering layer on the anode. Redox catalysts of the type mentioned are e.g. the oxides of iron, silver, cobalt, nickel or copper, or mixed oxides such as e.g. between nickel and cobalt. However, nickel oxide (nickel peroxide, nickel oxide hydroxide) is preferred.
Es ist bekannt, z.B. aus Synthesis 1979, 513, daß sich Alkohole an mit Nickeloxidhydroxid beschichteten Anoden oxidieren lassen. In Tetrahedron 38, 3299 (1982) ist beschrieben, daß die elektrochemische Oxidation an Nickeloxidhydroxid-Anoden von (Poly)ethylenglykolen in erheblichen Maße zu oxidativen Etherspaltungen führt. So erhält man bei der Oxidation von Tetraethylenglykol selbst unter sehr schonenden Bedingungen, wie sie durch potentialkontrollierte Elektrolyse bei sehr niedrigen Stromdichten von 3,8 m A/cm² Elektrodenoberfläche und einer Temperatur von 5°C erreicht werden, ein Produktgemisch, das nur zu 50 % aus der gewünschten 3,6,9-Trioxaundecandisäure besteht und das aufgrund oxidativer Etherspaltungen 16 % 3,6-Dioxaoctandisäure und 3 % 3-Oxapentandisäure enthält.It is known e.g. from Synthesis 1979, 513 that alcohols can be oxidized on anodes coated with nickel oxide hydroxide. Tetrahedron 38, 3299 (1982) describes that the electrochemical oxidation on nickel oxide hydroxide anodes of (poly) ethylene glycols leads to oxidative ether cleavage to a considerable extent. In the oxidation of tetraethylene glycol, even under very gentle conditions, such as are achieved through potential-controlled electrolysis at very low current densities of 3.8 m A / cm² electrode surface and a temperature of 5 ° C, a product mixture that is only 50% consists of the desired 3,6,9-trioxaundecanedioic acid and which contains 16% 3,6-dioxaoctanedioic acid and 3% 3-oxapentanedioic acid due to oxidative ether cleavage.
Es ist daher überraschend, daß sich die (Poly)oxatetramethylendicarbonsäuren der Formel I durch die elektrochemische Oxidation der Polytetrahydrofurane der Formel II nach dem erfindungsgemäßen Verfahren so vorteilhaft herstellen lassen, und daß es z.B. gelingt, die Elektrolyse technisch so vorteilhaft galvanostatisch bei Raumtemperatur und bei Stromdichten zwischen 20 und 40 mA/cm² Elektrodenoberfläche durchführen zu können, ohne daß oxidative Etherspaltungen nachweisbar sind (z.B. durch Molekulargewichtserniedrigung).It is therefore surprising that the (poly) oxatetramethylene dicarboxylic acids of the formula I can be prepared so advantageously by the electrochemical oxidation of the polytetrahydrofurans of the formula II by the process according to the invention, and that, for example, the electrolysis is technically so advantageously galvanostatically at room temperature and at current densities to be able to carry out between 20 and 40 mA / cm² electrode surface without oxidative ether cleavages being detectable (for example by lowering the molecular weight).
Man elektrolysiert die Polytetrahydrofurane nach dem erfindungsgemäßen Verfahren in wäßrig-alkalischem Medium vorzugsweise bei einem pH-Wert von 9 bis 14, insbesondere von 12 bis 14.The polytetrahydrofurans are electrolyzed by the process according to the invention in an aqueous alkaline medium, preferably at a pH from 9 to 14, in particular from 12 to 14.
Zur Einstellung des pH-Wertes gibt man zum Elektrolyten z.B. Alkali und/oder Erdalkalimetallhydroxide, -carbonate, -hydrogencarbonate, -phosphate, -hydrogenphosphate und -borate, bevorzugt aber die Hydroxide und/oder Carbonate des Natriums oder des Kaliums. Da Hydroxylionen in äquimolaren Mengen zur Bildung der Dicarbonsäuren verbraucht werden, sollte das Molverhältnis Polytetrahydrofuran zum Alkali- bzw. Erdalkalisalz zwischen 1:2,0 und 1:3,0 liegen. Es können aber auch höhere Alkali- bzw. Erdalkalikonzentrationen angewendet werden.To adjust the pH, add to the electrolyte e.g. Alkali and / or alkaline earth metal hydroxides, carbonates, hydrogen carbonates, phosphates, hydrogen phosphates and borates, but preferably the hydroxides and / or carbonates of sodium or potassium. Since hydroxyl ions are consumed in equimolar amounts to form the dicarboxylic acids, the molar ratio of polytetrahydrofuran to the alkali or alkaline earth metal salt should be between 1: 2.0 and 1: 3.0. However, higher alkali or Alkaline earth concentrations can be applied.
Geeignete Elektrolyten sind demnach wäßrige alkalische Lösungen des Polytetrahydrofurans, die z.B. einen Gehalt an Polytetrahydrofuran von 1 bis 40, vorzugsweise 3 bis 20 Gew.% und einen Gehalt an Alkali bzw. Erdalkali aufweisen, wie er dem geforderten Molverhältnis und dem gewünschten Umsatz entspricht. Man kann dem Elektrolyten zur Verbesserung der Löslichkeit vor allem bei höher molekularem Polytetrahydrofuranen ein inertes organisches, mit Wasser mischbares Lösungsmittel zusetzen. Geeignete Lösungsmittel sind Nitrile wie Acetonitril, Ether, wie Tetrahydrofuran, oder Alkohole wie tert.-Butanol.Suitable electrolytes are accordingly aqueous alkaline solutions of polytetrahydrofuran, which e.g. have a polytetrahydrofuran content of 1 to 40, preferably 3 to 20% by weight and an alkali or alkaline earth content which corresponds to the required molar ratio and the desired conversion. An inert organic, water-miscible solvent can be added to the electrolyte to improve the solubility, especially in the case of higher molecular weight polytetrahydrofurans. Suitable solvents are nitriles such as acetonitrile, ethers such as tetrahydrofuran, or alcohols such as tert-butanol.
Das erfindungsgemäße Verfahren erfordert keine besondere Elektrolysezelle. Vorteilhaft kann man es in einer ungeteilten Durchflußzelle durchführen. Als Kathoden können alle an sich üblichen Kathodenmaterialien verwendet werden, die unter den Elektrolysebedingungen stabil sind, wie Edelstahl, Nickel, Kupfer oder Edelmetalle wie Platin. Bevorzugtes Kathodenmaterial sind Stahl und Nickel.The method according to the invention does not require a special electrolysis cell. It can advantageously be carried out in an undivided flow cell. All cathode materials which are customary per se and are stable under the electrolysis conditions, such as stainless steel, nickel, copper or noble metals such as platinum, can be used as cathodes. The preferred cathode material is steel and nickel.
Nickeloxidhydroxid befindet sich als dünne Schicht auf Anodenträgermaterialien wie Kohlenstoff, Stahl oder Kupfer. Solche Anoden lassen sich z.B. nach dem in J. Appl. Electrochem. 9, 707 (1979) beschriebenen Verfahren herstellen. Bevorzugt werden jedoch Nickeloxidhydroxid-Schichten auf Nickel als Anodenträgermaterial. Nach den Angaben z.B. in Tetrahedron 38, 3299 (1982) wird eine derartige Nickeloxidhydroxid-Anode dadurch hergestellt, daß man eine Nickelelektrode in einer wäßrigen Lösung mit 0,1 N Nickelsulfat, 0,1 N Natriumacetat und 0,005 N Natriumhydroxid bei Stromdichten zwischen 5 mA/cm² und 1 mA/cm² kurzzeitig mehrmals umpolt.Nickel oxide hydroxide is a thin layer on anode support materials such as carbon, steel or copper. Such anodes can e.g. after the in J. Appl. Electrochemical. 9, 707 (1979). However, nickel oxide hydroxide layers on nickel are preferred as the anode carrier material. According to the information e.g. in Tetrahedron 38, 3299 (1982), such a nickel oxide hydroxide anode is produced in that a nickel electrode in an aqueous solution with 0.1 N nickel sulfate, 0.1 N sodium acetate and 0.005 N sodium hydroxide at current densities between 5 mA / cm² and 1 mA / cm² reversed several times for a short time.
Die Elektrolyse wird vorzugsweise mit 8 bis 10 F/mol Polytetrahydrofuran durchgeführt. Die Stromdichte beträgt z. B. 0,5 bis 6 A/dm² Elektrodenoberfläche, vorzugsweise 1 bis 4 A/dm² Elektrodenoberfläche. Man führt das erfindungsgemäße Verfahren bei Temperaturen durch, die z.B. höchstens 10°C unter dem Siedepunkt des eingesetzten Elektrolyten liegen. Vorzugsweise elektrolysiert man im Temperaturbereich zwischen 20 und 70°C, insbesondere zwischen 20 und 40°C. Die Elektrolyse kann sowohl diskontinuierlich als auch kontinuierlich durchgeführt werden.The electrolysis is preferably carried out with 8 to 10 F / mol polytetrahydrofuran. The current density is e.g. B. 0.5 to 6 A / dm² electrode surface, preferably 1 to 4 A / dm² electrode surface. You do that Process according to the invention at temperatures which are, for example, at most 10 ° C. below the boiling point of the electrolyte used. Electrolysis is preferably carried out in the temperature range between 20 and 70 ° C., in particular between 20 and 40 ° C. The electrolysis can be carried out batchwise or continuously.
Die Aufarbeitung der alkalischen Elektrolyseausträge zur Isolierung der (Poly)oxatetramethylendicarbonsäuren kann auf übliche Weise durchgeführt werden. So wird beispielsweise die elektrolysierte Lösung mit einer anorganischen Säure, wie Salzsäure oder Schwefelsäure auf einen pH-Wert von 1 bis 2 gebracht und die freigesetzten (Poly)oxatetramethylendicarbonsäuren mit einem Lösungsmittel, wie einem aliphatischen Ether extrahiert. Aus diesem Extrakt lassen sich die (Poly)oxatetramethylendicarbonsäuren durch Abdestillieren des Lösungsmittels in einer Reinheit von > 95 % isolieren.The processing of the alkaline electrolysis discharges for the isolation of the (poly) oxatetramethylene dicarboxylic acids can be carried out in the usual way. For example, the electrolyzed solution is brought to a pH of 1 to 2 with an inorganic acid, such as hydrochloric acid or sulfuric acid, and the (poly) oxatetramethylene dicarboxylic acids released are extracted with a solvent, such as an aliphatic ether. The (poly) oxatetramethylene dicarboxylic acids can be isolated from this extract by distilling off the solvent in a purity of> 95%.
Die Elektrooxidationen wurden in einer ungeteilten Elektrolysezelle mit Stahl und/oder Nickelelektroden galvanostatisch durchgeführt. Während der Elektrolyse wurde der Elektrolyt, dessen Zusammensetzung den Beispielen zu entnehmen ist, mit 150 bis 200 l/h über einen Wärmetauscher durch die Zelle gepumpt.The electrooxidations were carried out galvanostatically in an undivided electrolysis cell with steel and / or nickel electrodes. During the electrolysis, the electrolyte, the composition of which can be seen from the examples, was pumped through the cell at 150 to 200 l / h via a heat exchanger.
Zur Aktivierung der Nickel-Anode bzw. Beschichtung der Stahl-Anode mit einer dünnen Nickeloxidhydroxid-Schicht wurden die Anoden in einer wäßrigen Lösung der Zusammensetzung 0,1 N Nickel(II)sulfat, 0,1 N Natriumacetat und 0,005 N Natriumhydroxid bei einer Stromdichte von 1 mA/cm² alternierend als Anode und Kathode geschaltet (5 bis 10 sec). Nach Durchgang einer Ladungsmenge von 0,5 A sec/cm² wurden die Anoden, die sich mit einem schwarzen, fest haftenden Belag von Nickel(II)oxidhydroxid überzogen hatten, mit destilliertem Wasser gespült und zur Elektrolyse eingesetzt.To activate the nickel anode or coating the steel anode with a thin layer of nickel oxide hydroxide, the anodes were placed in an aqueous solution of the composition 0.1 N nickel (II) sulfate, 0.1 N sodium acetate and 0.005 N sodium hydroxide at a current density of 1 mA / cm² alternately switched as anode and cathode (5 to 10 sec). After a charge of 0.5 A sec / cm 2 had passed through, the anodes, which had been coated with a black, firmly adhering coating of nickel (II) oxide hydroxide, were rinsed with distilled water and used for the electrolysis.
In einer mit Stahl-Kathoden und Nickeloxidhydroxid-Anoden bestückten Elektrolysezelle wurde eine Emulsion aus 353 g Polytetrahydrofuran vom Molekulargewicht 250, 176 g Natriumhydroxid und 3 000 g Wasser bei einer Stromdichte von 2 A/dm² und einer Temperatur von 25°C mit 9 F/mol Polytetrahydrofuran elektrolysiert. Der Elektrolyt hatte einen pH von zwischen 13,7 und 12,8.In an electrolysis cell equipped with steel cathodes and nickel oxide hydroxide anodes, an emulsion of 353 g polytetrahydrofuran with a molecular weight of 250, 176 g sodium hydroxide and 3,000 g water at a current density of 2 A / dm² and a temperature of 25 ° C. with 9 F / mol of polytetrahydrofuran electrolyzed. The electrolyte had a pH between 13.7 and 12.8.
Durch Extraktion des alkalischen Elektrolyseaustrages mit Methyl-tert.-butylether wurden 7,2 g Polytetrahydrofuran isoliert. Daraus errechnet sich ein Umsatz von 98,0 %. Ansäuern des Elektrolyten mit Schwefelsäure auf pH 1 und Extraktion mit Methyl-tert.-buthylether ergab nach Abziehen des Ethers im Vakuum 338 g (Poly)oxatetramethylendicarbonsäure in einer Reinheit > 95 % mit einem Molekulargewicht von 304 (bestimmt aus Hydroxyzahl = 0 und einer Säurezahl von 374 mg KOH/g Substanz). Die Materialausbeute betrug somit 79 %.7.2 g of polytetrahydrofuran were isolated by extraction of the alkaline electrolysis discharge with methyl tert-butyl ether. This results in sales of 98.0%. Acidification of the electrolyte with sulfuric acid to pH 1 and extraction with methyl tert-butyl ether gave, after removal of the ether in vacuo, 338 g (poly) oxatetramethylene dicarboxylic acid in a purity> 95% with a molecular weight of 304 (determined from hydroxyl number = 0 and an acid number of 374 mg KOH / g substance). The material yield was 79%.
Die im Beispiel 1 beschriebene Elektrolyse wurde bei einer Temperatur von 40°C, einer Stromdichte von 4 A/dm² und bei 9,5 F/mol Polytetrahydrofuran durchgeführt. Die in Beispiel 1 beschriebene Aufarbeitung des Elektrolyseaustrages ergab 6,7 g Polytetrahydrofuran, entsprechend einem Umsatz von 98 %, und 346 g (Poly)oxatetramethylendicarbonsäure hoher Reinheit mit einem Molekulargewicht von 296 entsprechend einer Ausbeute von 83 %.The electrolysis described in Example 1 was carried out at a temperature of 40 ° C., a current density of 4 A / dm² and at 9.5 F / mol polytetrahydrofuran. The processing of the electrolysis discharge described in Example 1 gave 6.7 g of polytetrahydrofuran, corresponding to a conversion of 98%, and 346 g of high purity (poly) oxatetramethylene dicarboxylic acid with a molecular weight of 296 corresponding to a yield of 83%.
Claims (7)
HOOCC₃H₆(OC₄H₈)n-OC₃H₆COOH (I)
in der n eine ganze Zahl von 0 bis 20 bedeutet, durch 0xidation von Polytetrahydrofuranen der allgemeinen Formel
HOCH₂C₃H₆(OC₄H₈)n-OC₃H₆CH₂OH (II)
in der n die oben genannte Bedeutung hat, dadurch gekennzeichnet, daß man die Oxidation durch Elektrolyse in wäßrig-alkalischem Medium und in Gegenwart eines elektrochemisch regenerierbaren Redoxkatalysators durchführt.1. Process for the preparation of (poly) oxatetramethylene dicarboxylic acids of the general formula
HOOCC₃H₆ (OC₄H₈) n -OC₃H₆COOH (I)
in which n denotes an integer from 0 to 20, by oxidation of polytetrahydrofurans of the general formula
HOCH₂C₃H₆ (OC₄H₈) n -OC₃H₆CH₂OH (II)
in which n has the meaning given above, characterized in that the oxidation is carried out by electrolysis in an aqueous alkaline medium and in the presence of an electrochemically regenerable redox catalyst.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3700709 | 1987-01-13 | ||
| DE19873700709 DE3700709A1 (en) | 1987-01-13 | 1987-01-13 | METHOD FOR PRODUCING (POLY) OXATETRAMETHYLENE DICARBONIC ACIDS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0278219A2 true EP0278219A2 (en) | 1988-08-17 |
| EP0278219A3 EP0278219A3 (en) | 1988-09-21 |
Family
ID=6318721
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP88100145A Withdrawn EP0278219A3 (en) | 1987-01-13 | 1988-01-08 | Process for producing (poly)oxatetramethylene-dicarboxylic acids |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0278219A3 (en) |
| JP (1) | JPS63176487A (en) |
| DE (1) | DE3700709A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109983162A (en) * | 2016-11-24 | 2019-07-05 | 阿凡田知识中心有限公司 | The method for handling furans -2,5- dicarboxylic acid composition |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP4368750A1 (en) * | 2021-07-09 | 2024-05-15 | Kao Corporation | Method for producing polyoxyalkylene alkyl ether acetate |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4488944A (en) * | 1983-10-19 | 1984-12-18 | The Dow Chemical Company | Electrocatalytic oxidation of (poly)alkylene glycols |
-
1987
- 1987-01-13 DE DE19873700709 patent/DE3700709A1/en not_active Withdrawn
-
1988
- 1988-01-08 EP EP88100145A patent/EP0278219A3/en not_active Withdrawn
- 1988-01-11 JP JP63002652A patent/JPS63176487A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4488944A (en) * | 1983-10-19 | 1984-12-18 | The Dow Chemical Company | Electrocatalytic oxidation of (poly)alkylene glycols |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109983162A (en) * | 2016-11-24 | 2019-07-05 | 阿凡田知识中心有限公司 | The method for handling furans -2,5- dicarboxylic acid composition |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0278219A3 (en) | 1988-09-21 |
| JPS63176487A (en) | 1988-07-20 |
| DE3700709A1 (en) | 1988-07-21 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| DE1468149B1 (en) | PROCESS FOR THE PRODUCTION OF OLEFIN OXIDES | |
| EP0012215B1 (en) | 2-Hydroxybutanesulfonic acid choline and its use as conducting salt | |
| EP0011712B1 (en) | Preparation of benzaldehyde dialkyl acetals substituted in the 4-position | |
| Platen et al. | Mild and effective removal of dithioketal protecting groups by triarylamine cation radicals as homogeneous electron transfer agents | |
| Boujlel et al. | Cathodic cleavage of carbon-oxygen bonds (V). direct and indirect electrochemical reduction of epoxides | |
| EP1619273B1 (en) | Process for the synthesis of 2-alkyne-1-acetals | |
| EP1230433B1 (en) | Method for the electrolytic conversion of furane or furane derivatives | |
| DE3608853C2 (en) | ||
| EP0278219A2 (en) | Process for producing (poly)oxatetramethylene-dicarboxylic acids | |
| EP0638665B1 (en) | Process for the preparation of benzaldehyde dialkyl acetals | |
| DE3443303A1 (en) | METHOD FOR PRODUCING 3-HYDROXY-3-METHYLGLUTARIC ACID | |
| EP0339523B1 (en) | Process for manufacturing hydroxycarboxylic-acid esters | |
| EP0502372B1 (en) | 4-tert-Alkyl-2-Methylbenzaldehydedialkylacetals | |
| EP0250971A1 (en) | Process for manufacturing alkoxyacetic acids | |
| EP0040331B1 (en) | Method of preparing diacetoketogulonic acid | |
| EP0078004A1 (en) | Electrochemical process for the production of 2,5-dialcoxy-2,5-dihydrofurans | |
| DE2331712A1 (en) | PROCESS FOR THE PREPARATION OF 2METHOXY-3,6-DICHLOROBENZOIC ACID | |
| EP0053261B1 (en) | Process for the manufacture of a mixture of ketals of trimethyl-p-benzoquinone | |
| US4624758A (en) | Electrocatalytic method for producing dihydroxybenzophenones | |
| WO2001011111A1 (en) | METHOD FOR PRODUCING CARBONYL COMPOUNDS WHICH ARE OXIDIZED IN POSITION $g(a) | |
| DE2547386A1 (en) | (Para)-benzoquinone tetramethyl ketal prepn. - by anodic oxidn. of benzene or anisole in methanol contg. conductive salt, at alkaline pH | |
| DE2360494A1 (en) | PROCESS FOR THE PREPARATION OF ALKYL-SUBSTITUTED HYDROCHINONES | |
| DE2618276A1 (en) | Electrolytic redn. of naphthyl ethers in alcohol soln. - uses solid electrodes, giving enol ethers useful as pharmaceutical intermediates | |
| DE3619656A1 (en) | NEW 2,6-DIMETHYL-P-BENZOCHINONE TETRAALKYLKETALES AND THEIR PRODUCTION | |
| DE1643558B2 (en) | PROCESS FOR THE PRODUCTION OF HYDROQUINONE OR P-BENZOQUINONE |
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 |
Kind code of ref document: A2 Designated state(s): BE CH DE FR GB IT LI NL |
|
| AK | Designated contracting states |
Kind code of ref document: A3 Designated state(s): BE CH DE FR GB IT LI NL |
|
| 17P | Request for examination filed |
Effective date: 19880819 |
|
| 17Q | First examination report despatched |
Effective date: 19900112 |
|
| 18W | Application withdrawn |
Withdrawal date: 19900510 |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN |
|
| R18W | Application withdrawn (corrected) |
Effective date: 19900510 |