EP0370920B1 - Process for the production of quinone from hydroquinone by electrolysis - Google Patents
Process for the production of quinone from hydroquinone by electrolysis Download PDFInfo
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- EP0370920B1 EP0370920B1 EP89420383A EP89420383A EP0370920B1 EP 0370920 B1 EP0370920 B1 EP 0370920B1 EP 89420383 A EP89420383 A EP 89420383A EP 89420383 A EP89420383 A EP 89420383A EP 0370920 B1 EP0370920 B1 EP 0370920B1
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- hydroquinone
- quinone
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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
- C25B3/20—Processes
- C25B3/23—Oxidation
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- the present invention relates to a process for the preparation of quinone from hydroquinone by electrolysis.
- the present invention presents a new electrolytic process making it possible to prepare, with industrial yields, a quinone by electrolysis of an aqueous medium containing a hydroquinone; this new process is characterized in that one carries out the electrolysis of an aqueous dispersion or emulsion containing, in addition to said aqueous solution of hydroquinone, a stable co-solvent poorly soluble in water which is a good solvent for quinone and a poor solvent for hydroquinone.
- the cosolvent must allow easy recovery of the quinone produced.
- relatively high-boiling cosolvents may be of interest, since electrolysis will be possible at high temperatures, it is generally desirable to choose a relatively low-boiling product as co-solvent as this may facilitate the subsequent recovery of the quinone by simple evaporation of the cosolvent.
- co-solvents having such properties, mention may be made of aromatic carbides (in particular toluene and benzene), cycloalkanes, alkanes and halogenated aliphatic carbides (such as methylene chloride and 1,2-dichloroethane). These halogenated aliphatic carbides seem to be the most interesting solvents.
- aromatic carbides in particular toluene and benzene
- cycloalkanes such as methylene chloride and 1,2-dichloroethane
- halogenated aliphatic carbides seem to be the most interesting solvents.
- the solubilities of para-benzoquinone in various solvents will be mentioned below, by way of examples: whereas, in these same solvents, hydroquinone is only soluble at a rate of a few g / l. Mixtures of these cosolvents may also be used
- the relative amounts of water and of cosolvent can vary with the nature of the cosolvent and possibly of the reactants (hydroquinone and quinone).
- these relative quantities should be adjusted to take into account, on the one hand, the conductivity of the emulsion (which would require a high proportion of aqueous phase) and, on the other hand, the amount of p-benzoquinone to be extracted (which would require a high proportion of organic phase).
- the ratio, by volume, of the aqueous and organic phases is from 0.1 to 50 and preferably from 0.5 to 10. When said ratio is less than 0.1, the aqueous phase being in very low proportion, the conductivity of the mixture is poor. When said ratio is greater than 50, the possibilities of solubilization of the quinone are insufficient.
- the "quality" (that is to say in fact the fineness and the stability) of the dispersion of the cosolvent in the aqueous phase can play a role in the yield of the reaction. It will be easy for the specialist, taking into account the preparation processes used to produce the dispersion or the emulsion (for example using a pump or a static mixer), to optimize said dispersion, possibly in it. adding inert emulsifiers or surfactants, to obtain maximum yield.
- the temperature at which electrolysis takes place has a known influence (the increase in temperature improving the conductivity of the emulsion, improving the solubility of the reagents in their media and improving the kinetics of the reaction); however, if for quinone recovery problems a cosolvent with a relatively low boiling point is used, one will be limited by the boiling point of this cosolvent. In practice, temperatures of 10 to 80 ° C will be used.
- the concentration of hydroquinone in water does not seem to be a decisive factor concerning the rate of conversion of hydroquinone to quinone with equal electrical yield, but any increase in said concentration (within the limit of the solubility of hydroquinone ) will promote volume yield.
- the electric current density it is generally of the order of 5 to 40 A / dm2.
- the reaction is carried out in a conventional electrolysis cell preferably comprising a separator.
- a separator the latter is preferably of the cationic type such as for example a membrane of registered trademark NAFION.
- the cathode compartment as known, reduction of water made conductive by an acid such as sulfuric acid is carried out (but it is also possible to carry out, in this cathode compartment any other electrochemical reduction reaction); the cathode must be non-corrodible and with as low an overvoltage as possible.
- the dispersion or emulsion according to the invention is therefore admitted, comprising therefore an aqueous phase, the conductivity of which has been improved by the addition of an inert acid with respect to the reactants (such as the acid sulfuric, phosphoric acid or nitric acid) and / or a salt and an organic phase dispersed or emulsified in said aqueous phase.
- the anode is made of a stable material (that is to say non-corrodible) which is advantageously an oxide or an alloy of lead or, preferably, a stop metal such as, for example, titanium whose surface is covered with metals or metal oxides, one or less of which belongs to the platinum family.
- the structure of the anode can be very diverse; we will use anodes deployed or perforated, or full.
- hydroquinones which can be used according to the invention can be defined as all those which, in an aqueous medium give rise, in the presence of the corresponding quinone, to a quinhydrone.
- Examples 1 to 16 were carried out batchwise, that is to say by carrying out the electrolysis of a certain volume of dispersion (or emulsion), this dispersion being either contained in the suitably agitated anode compartment of the electrolyser , or put into circulation in a closed loop on said anode compartment.
- Example 17 was carried out continuously.
- a cell comprising a NAFION 423 separation membrane, a catholyte consisting of an aqueous solution of H2SO4 at 0.5 N, an INCOLOY 825 cathode an anode which is either made of coated titanium or of lead ; an amount of cosolvent has always been used in the anolyte such that the ratio, by volume, of the organic phase to the aqueous phase is 0.5, said aqueous phase being at 0.1 N of sulfuric acid.
- Example 1 The results obtained in the transformation of hydroquinone into para-benzoquinone are collated in Table 1;
- Example 1 was carried out with a titanium anode coated with solid platinum;
- Examples 2 to 7 were carried out using an anode in expanded titanium covered with platinum;
- Examples 8 to 11 were carried out using a perforated titanium anode on which oxides of iridium, cobalt and tantalum were simultaneously deposited;
- Example 12 was carried out with a perforated lead electrode;
- Example 13 was carried out with an aperture in palladium titanium covered with platinum-iridium.
- Example 2 In Examples 2, 3, 5, 6, and 7, the voltage ⁇ V varied during the test from approximately 6 to approximately 8 V; this voltage remained constant and equal to 4.5 V in Example 4; at 4.25 V in Example 8; at 5 V in Example 9; at 2.8 V in Examples 10 and 11; at 4.9 V in Example 12 and at 3.2 V in Example 13.
- Example 2 The conditions of Example 2 were reproduced using, in place of hydroquinone, toluhydroquinone in a concentration of 10 g / l. The corresponding toluquinone was obtained with a faradic yield of 84% and a chemical yield of 88%.
- the other experimental conditions are the following:
- the faradic yield was 85%.
- a titanium anode coated with platinum and an anolyte were used, the aqueous phase of which has an acidity of 0.1 N in sulfuric acid.
- the other experimental conditions are the following: Volume ratio of the organic phase to the aqueous phase: 1.2.
- the faradic yield of the reaction was 68.5% and the chemical yield 100%.
- the installation includes an electrolyser with two compartments separated by a cationic type separator (NAFION brand membrane).
- NAFION brand membrane a cationic type separator
- a mixture of 0.1 N sulfuric acid, dichloromethane (ratio of the organic phase to the aqueous phase of 0.5) and hydroquinone (hydroquinone concentration 20 g / l) is sent.
- the mixture is decanted, the organic phase is evacuated in order to recover the quinone produced there, and the aqueous phase is recycled (and supplemented by a supply of water, hydroquinone and dichloromethane).
- the anode is made of titanium coated with platinum and iridium.
- the temperature is 35 ° C, the current density of 10A / dm2 and the potential difference of 4.25 V.
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Abstract
Description
La présente invention concerne un procédé de préparation de quinone, à partir d'hydroquinone, par électrolyse.The present invention relates to a process for the preparation of quinone from hydroquinone by electrolysis.
On sait que l'électrolyse d'une solution aqueuse d'une hydroquinone peut conduire à la formation de la quinone correspondante. Mais, cela est notamment le cas lorsqu'on réalise l'électrolyse d'une solution aqueuse de l'hydroquinone, on constate que le rendement de cette réaction est très faible du fait de la précipitation d'un composé résultant de l'addition d'une molécule d'hydroquinone sur une molécule de quinone, ledit composé étant dénommé quinhydrone.It is known that the electrolysis of an aqueous solution of a hydroquinone can lead to the formation of the corresponding quinone. However, this is particularly the case when the electrolysis of an aqueous solution of hydroquinone is carried out, it is found that the yield of this reaction is very low due to the precipitation of a compound resulting from the addition of a hydroquinone molecule on a quinone molecule, said compound being called quinhydrone.
On a cherché à diminuer les risques de formation de cette molécule d'addition (quinhydrone) en opérant soit dans des solutions très diluées, ce qui conduit à des rendements faradiques très faibles, soit à température élevée mais il y a alors risque de dégradation de la quinone obtenue.We tried to reduce the risks of formation of this addition molecule (quinhydrone) by operating either in very dilute solutions, which leads to very low faradic yields, or at high temperature but there is then a risk of degradation of the quinone obtained.
La présente invention présente un procédé électrolytique nouveau permettant de préparer, avec des rendements industriels, une quinone par électrolyse d'un milieu aqueux contenant une hydroquinone ; ce procédé nouveau est caractérisé en ce que l'on réalise l' électrolyse d'une dispersion ou émulsion aqueuse contenant, outre ladite solution aqueuse de l'hydroquinone, un cosolvant stable peu soluble dans l'eau qui est un bon solvant de la quinone et un mauvais solvant de l'hydroquinone.The present invention presents a new electrolytic process making it possible to prepare, with industrial yields, a quinone by electrolysis of an aqueous medium containing a hydroquinone; this new process is characterized in that one carries out the electrolysis of an aqueous dispersion or emulsion containing, in addition to said aqueous solution of hydroquinone, a stable co-solvent poorly soluble in water which is a good solvent for quinone and a poor solvent for hydroquinone.
Pour sélectionner le cosolvant à utiliser, il conviendra donc de tenir compte des nécessités suivantes :
- ledit cosolvant doit être stable ; il s'agit bien entendu d'une stabilité chimique vis-à-vis de l'ensemble des produits présents et d'une stabilité électrochimique dans les conditions opératoires utilisées. Cette stabilité du cosolvant est importante dans la mesure où toute instabilité de ce produit se traduira par l'apparition d'impuretés (qu'il faudra ultérieurement éliminer) et par une baisse du rendement,
- ledit cosolvant doit être peu soluble dans l'eau et réciproquement ; ledit cosolvant est en effet employé pour constituer une phase indépendante de la phase aqueuse, la solubilité de ce cosolvant dans l'eau doit donc être aussi faible que possible. Cette faible solubilité du cosolvant dans l'eau implique que l'électrolyse s'effectuera sur un milieu présentant deux phases (émulsion),
- ledit cosolvant doit être un mauvais solvant pour l'hydroquinone, et un bon solvant pour la quinone. En effet, un des rôles de ce cosolvant sera d'assurer, au cours de l'électrolyse, une séparation effective de l'hydroquinone d'avec la quinone de façon à éviter la formation, connue, d'un produit d'addition du type quinhydrone.
- said co-solvent must be stable; it is of course a chemical stability with respect to all of the products present and an electrochemical stability under the operating conditions used. This stability of the co-solvent is important insofar as any instability of this product will result in the appearance of impurities (which will have to be removed later) and in a drop in yield,
- said co-solvent must be sparingly soluble in water and vice versa; said co-solvent is in fact used to constitute a phase independent of the aqueous phase, the solubility of this co-solvent in water must therefore be as low as possible. This low solubility of the cosolvent in water implies that the electrolysis will be carried out on a medium having two phases (emulsion),
- said cosolvent must be a bad solvent for hydroquinone, and a good solvent for quinone. Indeed, one of the roles of this cosolvent will be to ensure, during electrolysis, an effective separation of hydroquinone from quinone so as to avoid the known formation of an adduct of the quinhydrone type.
Outre ces propriétés essentielles à la bonne marche du procédé selon l'invention, le cosolvant doit permettre de réaliser une récupération facile de la quinone produite. Bien que les cosolvants à point d'ébullition relativement élevé puissent être intéressants, du fait qu'il sera possible d'effectuer l'électrolyse à des températures élevées, il est généralement souhaitable de choisir comme cosolvant un produit à point d'ébullition relativement bas car cela pourra faciliter la récupération ultérieure de la quinone par simple évaporation du cosolvant.In addition to these essential properties for the proper functioning of the process according to the invention, the cosolvent must allow easy recovery of the quinone produced. Although relatively high-boiling cosolvents may be of interest, since electrolysis will be possible at high temperatures, it is generally desirable to choose a relatively low-boiling product as co-solvent as this may facilitate the subsequent recovery of the quinone by simple evaporation of the cosolvent.
Parmi les cosolvants possédant de telles propriétés, on pourra citer des carbures aromatiques (notamment toluène et benzène) des cycloalcanes, des alcanes et des carbures aliphatiques halogénés (tels que le chlorure de méthylène et le dichloro-1,2-éthane). Ces carbures aliphatiques halogénés semblent être les solvants les plus intéressants. On mentionnera ci-après, à titre d'exemples, les solubilités de la para-benzoquinone dans divers solvants :
alors que, dans ces mêmes solvants, l'hydroquinone n'est soluble qu'à raison de quelques g/l. On pourra également utiliser des mélanges de ces cosolvantsAmong the co-solvents having such properties, mention may be made of aromatic carbides (in particular toluene and benzene), cycloalkanes, alkanes and halogenated aliphatic carbides (such as methylene chloride and 1,2-dichloroethane). These halogenated aliphatic carbides seem to be the most interesting solvents. The solubilities of para-benzoquinone in various solvents will be mentioned below, by way of examples:
whereas, in these same solvents, hydroquinone is only soluble at a rate of a few g / l. Mixtures of these cosolvents may also be used
Dans le procédé selon l'invention, les quantités relatives d'eau et de cosolvant peuvent varier avec la nature du cosolvant et éventuellement des réactifs (hydroquinone et quinone). Pour des réactifs donnés (par exemple l'électrolyse de l'hydroquinone donnant naissance à la p-benzoquinone), il conviendra d'ajuster ces quantités relatives pour tenir compte, d'une part, de la conductibilité de l'émulsion (qui nécessiterait une proportion élevée de phase aqueuse) et, d'autre part, de la quantité de p-benzoquinone à extraire (ce qui nécessiterait une proportion élevée de phase organique). Dans la pratique, le rapport, en volume, des phases aqueuse et organique est de 0,1 à 50 et de préférence de 0,5 à 10. Lorsque ledit rapport est inférieur à 0,1, la phase aqueuse se trouvant en très faible proportion, la conductibilité du mélange est mauvaise. Lorsque ledit rapport est supérieur à 50, les possibilités de solubilisation de la quinone sont insuffisantes.In the process according to the invention, the relative amounts of water and of cosolvent can vary with the nature of the cosolvent and possibly of the reactants (hydroquinone and quinone). For given reagents (for example the electrolysis of hydroquinone giving rise to p-benzoquinone), these relative quantities should be adjusted to take into account, on the one hand, the conductivity of the emulsion (which would require a high proportion of aqueous phase) and, on the other hand, the amount of p-benzoquinone to be extracted (which would require a high proportion of organic phase). In practice, the ratio, by volume, of the aqueous and organic phases is from 0.1 to 50 and preferably from 0.5 to 10. When said ratio is less than 0.1, the aqueous phase being in very low proportion, the conductivity of the mixture is poor. When said ratio is greater than 50, the possibilities of solubilization of the quinone are insufficient.
On notera également que la "qualité" (c'est-à-dire en fait la finesse et la stabilité) de la dispersion du cosolvant dans la phase aqueuse peut jouer un rôle sur le rendement de la réaction. Il sera aisé pour le spécialiste, compte tenu des procédés de préparation utilisés pour réaliser la dispersion ou l'émulsion (par exemple à l'aide d'une pompe ou d'un mélangeur statique), d'optimiser ladite dispersion, éventuellement en lui ajoutant des agents émulsifiants ou tensio-actifs inertes, pour obtenir un rendement maximum.It will also be noted that the "quality" (that is to say in fact the fineness and the stability) of the dispersion of the cosolvent in the aqueous phase can play a role in the yield of the reaction. It will be easy for the specialist, taking into account the preparation processes used to produce the dispersion or the emulsion (for example using a pump or a static mixer), to optimize said dispersion, possibly in it. adding inert emulsifiers or surfactants, to obtain maximum yield.
La température à laquelle a lieu l'électrolyse a une influence connue (l'augmentation de la température améliorant la conductivité de l'émulsion, améliorant la solubilité des réactifs dans leurs milieux et améliorant la cinétique de la réaction) ; cependant, si pour des problèmes de récupération de la quinone on utilise un cosolvant à point d'ébullition relativement bas, on sera limité par le point d'ébullition de ce cosolvant. Dans la pratique, on utilisera des températures de 10 à 80°C.The temperature at which electrolysis takes place has a known influence (the increase in temperature improving the conductivity of the emulsion, improving the solubility of the reagents in their media and improving the kinetics of the reaction); however, if for quinone recovery problems a cosolvent with a relatively low boiling point is used, one will be limited by the boiling point of this cosolvent. In practice, temperatures of 10 to 80 ° C will be used.
La concentration de l'hydroquinone dans l'eau ne paraît pas être un facteur décisif concernant le taux de conversion de l'hydroquinone en quinone à rendement électrique égal, mais toute augmentation de ladite concentration (dans la limite de la solubilité de l'hydroquinone) favorisera le rendement volumique.The concentration of hydroquinone in water does not seem to be a decisive factor concerning the rate of conversion of hydroquinone to quinone with equal electrical yield, but any increase in said concentration (within the limit of the solubility of hydroquinone ) will promote volume yield.
En ce qui concerne la densité de courant électrique, elle est généralement de l'ordre de 5 à 40 A/dm².As regards the electric current density, it is generally of the order of 5 to 40 A / dm².
La réaction est effectuée dans une cellule d'électrolyse classique comportant, de préférence, un séparateur. Lorsque ladite cellule comporte un séparateur, celui-ci est de préférence de type cationique tel que par exemple une membrane de marque déposée NAFION. Dans le compartiment cathodique, on réalise, comme connu, la réduction d'une eau rendue conductrice par un acide tel que l'acide sulfurique (mais il est aussi possible de réaliser, dans ce compartiment cathodique toute autre réaction de réduction électrochimique) ; la cathode doit être non corrodable et avec une surtension aussi faible que possible. Dans le compartiment anodique, on admet la dispersion ou l'émulsion selon l'invention comportant donc une phase aqueuse dont on a amélioré la conductibilité grâce à l'addition d'un acide inerte vis-à-vis des réactifs (comme l'acide sulfurique, l'acide phosphorique ou l'acide nitrique) et/ou d'un sel et une phase organique dispersée ou émulsionnée dans ladite phase aqueuse. L'anode est réalisée en un matériau stable (c'est-à-dire non corrodable) qui est avantageusement un oxyde ou un alliage de plomb ou, de préférence, un métal d'arrêt tel que, par exemple, du titane dont la surface est recouverte de métaux ou d'oxydes métalliques dont l'un ou moins appartient à la famille du platine. La structure de l'anode peut être très diverse ; on utilisera des anodes déployées ou trouées, ou pleines.The reaction is carried out in a conventional electrolysis cell preferably comprising a separator. When said cell comprises a separator, the latter is preferably of the cationic type such as for example a membrane of registered trademark NAFION. In the cathode compartment, as known, reduction of water made conductive by an acid such as sulfuric acid is carried out (but it is also possible to carry out, in this cathode compartment any other electrochemical reduction reaction); the cathode must be non-corrodible and with as low an overvoltage as possible. In the anode compartment, the dispersion or emulsion according to the invention is therefore admitted, comprising therefore an aqueous phase, the conductivity of which has been improved by the addition of an inert acid with respect to the reactants (such as the acid sulfuric, phosphoric acid or nitric acid) and / or a salt and an organic phase dispersed or emulsified in said aqueous phase. The anode is made of a stable material (that is to say non-corrodible) which is advantageously an oxide or an alloy of lead or, preferably, a stop metal such as, for example, titanium whose surface is covered with metals or metal oxides, one or less of which belongs to the platinum family. The structure of the anode can be very diverse; we will use anodes deployed or perforated, or full.
On peut opérer, bien évidemment, en discontinu ou en continu, ce dernier mode de mise en oeuvre étant préféré ; on peut également, pour optimiser les rendements, utiliser plusieurs réacteurs montés en série dans chacun desquels les conditions opératoires pourront être adaptées aux mélanges à traiter.One can operate, of course, discontinuously or continuously, this latter mode of implementation being preferred; it is also possible, to optimize the yields, to use several reactors connected in series in each of which the operating conditions may be adapted to the mixtures to be treated.
Les hydroquinones, utilisables selon l'invention, peuvent être définies comme toutes celles qui, en milieu aqueux donnent naissance, en présence de la quinone correspondante, à une quinhydrone.The hydroquinones which can be used according to the invention can be defined as all those which, in an aqueous medium give rise, in the presence of the corresponding quinone, to a quinhydrone.
Le cas particulier type est celui où l'on prépare la para-benzoquinone à partir de l'hydroquinone. C'est essentiellement ce cas particulier qui sera illustré ci-après.The typical special case is that where para-benzoquinone is prepared from hydroquinone. It is essentially this particular case which will be illustrated below.
Les exemples non limitatifs illustrent l'invention. Les exemples 1 à 16 ont été réalisés en discontinu, c'est-à-dire en effectuant l'électrolyse d'un certain volume de dispersion (ou émulsion), cette dispersion étant soit contenue dans le compartiment anodique convenablement agité de l'électrolyseur, soit mise en circulation en une boucle fermée sur ledit compartiment anodique. L'exemple 17 a été effectué en continu.The nonlimiting examples illustrate the invention. Examples 1 to 16 were carried out batchwise, that is to say by carrying out the electrolysis of a certain volume of dispersion (or emulsion), this dispersion being either contained in the suitably agitated anode compartment of the electrolyser , or put into circulation in a closed loop on said anode compartment. Example 17 was carried out continuously.
Dans tous les exemples, on a utilisé une cellule comportant une membrane de séparation NAFION 423, un catholyte constitué par une solution aqueuse de H₂SO₄ à 0,5 N, une cathode en INCOLOY 825 une anode qui est soit en titane revêtu, soit en plomb ; on a toujours utilisé dans l'anolyte une quantité de cosolvant telle que le rapport, en volume, de la phase organique sur la phase aqueuse est 0,5 ladite phase aqueuse étant à 0,1 N d'acide sulfurique.In all the examples, a cell was used comprising a NAFION 423 separation membrane, a catholyte consisting of an aqueous solution of H₂SO₄ at 0.5 N, an INCOLOY 825 cathode an anode which is either made of coated titanium or of lead ; an amount of cosolvent has always been used in the anolyte such that the ratio, by volume, of the organic phase to the aqueous phase is 0.5, said aqueous phase being at 0.1 N of sulfuric acid.
Dans tous les essais, on a constaté que le rendement chimique, c'est-à-dire le pourcentage d'hydroquinone transformée que l'on retrouve sous forme de quinone (en moles), est très élevé de 91 à 100 %. Le rendement faradique, qui est très élevé (80 à 100 %) en début de réaction, diminue au bout d'un certain temps du fait de la diminution de la concentration de l'hydroquinone et du développement de réactions parasites (oxydation de l'eau).In all the tests, it was found that the chemical yield, that is to say the percentage of transformed hydroquinone which is found in the form of quinone (in moles), is very high from 91 to 100%. The faradic yield, which is very high (80 to 100%) at the start of the reaction, decreases after a certain time due to the decrease in the concentration of hydroquinone and the development of parasitic reactions (oxidation of the water).
Il faudrait donc, en toute logique, considérer les rendements de la réaction à chaque instant de la durée de cette réaction ; une telle étude, même si elle est intéressante pour optimiser la réaction sur le plan industriel, n'est pas actuellement terminée, on se contentera donc de fournir des résultats de rendements globaux en fin de réaction, ladite réaction ayant été arrêtée après qu'environ 70 à 95 % de l'hydroquinone de départ ont été consommés, c'est-à-dire après des durées de réaction de l'ordre de 50 à 80 minutes.It would therefore logically be necessary to consider the yields of the reaction at each instant of the duration of this reaction; such a study, even if it is interesting for optimizing the reaction on an industrial level, is not currently completed, we will therefore be content to provide results of overall yields at the end of the reaction, said reaction having been stopped after about 70 to 95% of the starting hydroquinone was consumed, that is to say after reaction times of the order of 50 to 80 minutes.
Les résultats obtenus dans la transformation de l'hydroquinone en para-benzoquinone sont rassemblés dans le tableau 1 ; l'exemple 1 a été réalisé avec une anode en titane revêtu de platine de forme pleine ; les exemples 2 à 7 ont été réalisés en utilisant une anode en titane déployé recouvert de platine ; les exemples 8 à 11 ont été réalisés en utilisant une anode trouée en titane sur lequel on a déposé simultanément des oxydes d'iridium, de cobalt et de tantale ; l'exemple 12 a été réalisé avec une électrode trouée en plomb ; l'exemple 13 a été réalisé avec une anode trouée en titane palladié recouvert de platine-iridium.The results obtained in the transformation of hydroquinone into para-benzoquinone are collated in Table 1; Example 1 was carried out with a titanium anode coated with solid platinum; Examples 2 to 7 were carried out using an anode in expanded titanium covered with platinum; Examples 8 to 11 were carried out using a perforated titanium anode on which oxides of iridium, cobalt and tantalum were simultaneously deposited; Example 12 was carried out with a perforated lead electrode; Example 13 was carried out with an aperture in palladium titanium covered with platinum-iridium.
Dans les exemples 2, 3, 5, 6, et 7, la tension ΔV a varié au cours de l'essai d'environ 6 à environ 8 V ; cette tension est restée constante et égale à 4,5 V dans l'exemple 4 ; à 4,25 V dans l'exemple 8 ; à 5 V dans l'exemple 9 ; à 2,8 V dans les exemples 10 et 11 ; à 4,9 V dans l'exemple 12 et à 3,2 V dans l'exemple 13.In Examples 2, 3, 5, 6, and 7, the voltage ΔV varied during the test from approximately 6 to approximately 8 V; this voltage remained constant and equal to 4.5 V in Example 4; at 4.25 V in Example 8; at 5 V in Example 9; at 2.8 V in Examples 10 and 11; at 4.9 V in Example 12 and at 3.2 V in Example 13.
On a reproduit les conditions de l'exemple 2 en utilisant, à la place de l'hydroquinone, la toluhydroquinone en concentration de 10 g/l. On a obtenu la toluquinone correspondante avec un rendement faradique de 84 % et un rendement chimique de 88 %.The conditions of Example 2 were reproduced using, in place of hydroquinone, toluhydroquinone in a concentration of 10 g / l. The corresponding toluquinone was obtained with a faradic yield of 84% and a chemical yield of 88%.
Dans cet exemple, on a utilisé une anode en titane palladié recouvert de platine et d'iridium et un anolyte dont la phase aqueuse a une acidité de 0,4 N en H₂SO₄.In this example, a palladium titanium anode coated with platinum and iridium was used and an anolyte whose aqueous phase has an acidity of 0.4 N in H₂SO₄.
Les autres conditions expérimentales sont les suivantes :
Le rendement faradique a été de 85 %.The faradic yield was 85%.
Dans cet exemple, on a utilisé une anode en titane revêtu de platine et un anolyte dont la phase aqueuse a pour acidité 0,1 N en acide sulfurique.In this example, a titanium anode coated with platinum and an anolyte were used, the aqueous phase of which has an acidity of 0.1 N in sulfuric acid.
Les autres conditions expérimentales sont les suivantes :
Rapport en volume de la phase organique à la phase aqueuse : 1,2.The other experimental conditions are the following:
Volume ratio of the organic phase to the aqueous phase: 1.2.
Le rendement faradique de la réaction a été de 68,5 % et le rendement chimique de 100 %.The faradic yield of the reaction was 68.5% and the chemical yield 100%.
Cet exemple a été réalisé "en continu".This example was done "continuously".
L'installation comporte un électrolyseur à deux compartiments séparés par un séparateur de type cationique (membrane de marque NAFION).The installation includes an electrolyser with two compartments separated by a cationic type separator (NAFION brand membrane).
Dans le compartiment cathodique on fait circuler une solution aqueuse d'acide sulfurique à 0,5 N.In the cathode compartment is circulated an aqueous solution of sulfuric acid at 0.5 N.
Dans le compartiment anodique, on envoie un mélange d'acide sulfurique 0,1 N, de dichlorométhane (rapport de la phase organique à la phase aqueuse de 0,5) et d'hydroquinone (concentration en hydroquinone 20 g/l). A la sortie de ce compartiment, le mélange est décanté, la phase organique est évacuée afin d'y récupérer la quinone produite, et la phase aqueuse est recyclée (et complétée par un apport d'eau, d'hydroquinone et de dichlorométhane).Into the anode compartment, a mixture of 0.1 N sulfuric acid, dichloromethane (ratio of the organic phase to the aqueous phase of 0.5) and hydroquinone (hydroquinone concentration 20 g / l) is sent. At the exit of this compartment, the mixture is decanted, the organic phase is evacuated in order to recover the quinone produced there, and the aqueous phase is recycled (and supplemented by a supply of water, hydroquinone and dichloromethane).
L'anode est en titane revêtu de platine et d'iridium.The anode is made of titanium coated with platinum and iridium.
La température est de 35°C, la densité de courant de 10A/dm² et la différence de potentiel de 4,25 V.The temperature is 35 ° C, the current density of 10A / dm² and the potential difference of 4.25 V.
On a obtenu un rendement faradique de 100 % et un taux de conversion de 78 %.
Claims (5)
- Process for the preparation of quinone from hydroquinone by electrolysis, characterized by performing the electrolysis, in the anode compartment of an electrolyser, of a dispersion or emulsion comprising a conductive aqueous solution of the hydroquinone and at least one stable cosolvent which is poorly soluble in water and which is a good solvent for the quinone produced and a poor solvent for the hydroquinone.
- Process according to claim 1, characterized in that a solution of hydroquinone is electrolysed with a view to obtaining para-benzoquinone.
- Process according to either of claims 1 and 2, characterized in that the said cosolvent is chosen from aromatic hydrocarbons, cycloalkanes, alkanes and halogenated aliphatic hydrocarbons and mixtures thereof.
- Process according to one of claims 1 to 3, characterized in that the electrolyser comprises a separator, preferably of a cationic type.
- Process according to one of claims 1 to 4, characterized in that the anode consists of a stable metal which is preferably a stop metal such as titanium whose surface is coated with metals or metal oxides, at least one of which belongs to the platinum group.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT89420383T ATE87040T1 (en) | 1988-10-14 | 1989-10-09 | PROCESS FOR THE PRODUCTION OF QUINONE FROM HYDROCHINONE BY ELECTROLYSIS. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8814361 | 1988-10-14 | ||
FR8814361A FR2637916B1 (en) | 1988-10-14 | 1988-10-14 | PROCESS FOR THE PREPARATION OF QUINONE FROM HYDROQUINONE BY ELECTROLYSIS |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0370920A1 EP0370920A1 (en) | 1990-05-30 |
EP0370920B1 true EP0370920B1 (en) | 1993-03-17 |
Family
ID=9371546
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP89420383A Expired - Lifetime EP0370920B1 (en) | 1988-10-14 | 1989-10-09 | Process for the production of quinone from hydroquinone by electrolysis |
Country Status (9)
Country | Link |
---|---|
US (1) | US4963234A (en) |
EP (1) | EP0370920B1 (en) |
JP (1) | JPH02141592A (en) |
AT (1) | ATE87040T1 (en) |
CA (1) | CA1330773C (en) |
DE (1) | DE68905443T2 (en) |
ES (1) | ES2041436T3 (en) |
FR (1) | FR2637916B1 (en) |
IE (1) | IE893306L (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2023161206A1 (en) * | 2022-02-25 | 2023-08-31 | Dsm Ip Assets B.V. | A process for producing benzoquinones |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3897319A (en) * | 1971-05-03 | 1975-07-29 | Carus Corp | Recovery and recycle process for anodic oxidation of benzene to quinone |
JPS57134581A (en) * | 1981-02-13 | 1982-08-19 | Shigeru Torii | Production of 1, 4-naphthoquinone derivative |
JPS57198283A (en) * | 1981-05-27 | 1982-12-04 | Asahi Glass Co Ltd | Electrolytic oxidation method for organic compound |
-
1988
- 1988-10-14 FR FR8814361A patent/FR2637916B1/en not_active Expired - Lifetime
-
1989
- 1989-09-25 CA CA000612834A patent/CA1330773C/en not_active Expired - Fee Related
- 1989-10-03 JP JP1257178A patent/JPH02141592A/en active Granted
- 1989-10-09 ES ES198989420383T patent/ES2041436T3/en not_active Expired - Lifetime
- 1989-10-09 AT AT89420383T patent/ATE87040T1/en not_active IP Right Cessation
- 1989-10-09 EP EP89420383A patent/EP0370920B1/en not_active Expired - Lifetime
- 1989-10-09 DE DE8989420383T patent/DE68905443T2/en not_active Expired - Fee Related
- 1989-10-13 IE IE893306A patent/IE893306L/en unknown
- 1989-10-16 US US07/421,833 patent/US4963234A/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
CA1330773C (en) | 1994-07-19 |
FR2637916A1 (en) | 1990-04-20 |
JPH034625B2 (en) | 1991-01-23 |
IE893306L (en) | 1990-04-14 |
FR2637916B1 (en) | 1990-12-07 |
JPH02141592A (en) | 1990-05-30 |
DE68905443D1 (en) | 1993-04-22 |
EP0370920A1 (en) | 1990-05-30 |
US4963234A (en) | 1990-10-16 |
DE68905443T2 (en) | 1993-06-24 |
ES2041436T3 (en) | 1993-11-16 |
ATE87040T1 (en) | 1993-04-15 |
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