EP0117371A1 - Process for the production of aminobenzoic acids from corresponding nitrotoluenes - Google Patents
Process for the production of aminobenzoic acids from corresponding nitrotoluenes Download PDFInfo
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- EP0117371A1 EP0117371A1 EP83400366A EP83400366A EP0117371A1 EP 0117371 A1 EP0117371 A1 EP 0117371A1 EP 83400366 A EP83400366 A EP 83400366A EP 83400366 A EP83400366 A EP 83400366A EP 0117371 A1 EP0117371 A1 EP 0117371A1
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- C25B3/00—Electrolytic production of organic compounds
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
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- the present invention relates to a new process for preparing aminobenzoic acids, and in particular para-aminobenzoic acid, by oxidation of nitrotoluenes, followed by electrochemical reduction of the nitrobenzoic acids obtained.
- the benzene ring can also carry other substituents remaining unchanged during the reaction.
- Aminobenzoic acids obtained according to the process of the present invention, are chemicals mainly used in the pharmaceutical industry and in the dye industry.
- chromic acid is an expensive and particularly toxic reagent which is preferred to be replaced in industry by oxygen in the presence of a catalyst or by nitric acid.
- Electrochemistry does not have these drawbacks: pure amiriobenzoic acid sulfate can be recovered by simple filtration after electrolysis.
- the originality of the present invention resides in the fact that the oxidizing agent used for the implementation of the first step is regenerated at the anode of an electrolyser simultaneously ensuring the electrochemical reduction of the second step.
- the sulfochromic solution used to ensure the oxidation of nitrotoluenes can, for example, advantageously consist of an aqueous solution of 3 to 20% by weight of chromic oxide and 10 to 95% by weight of sulfuric acid which may contain chromium sulfate, and possibly other additives.
- the nitrobenzoic acid is introduced into the cathode compartment of the electrolyser in the form of a suspension in sulfuric acid of concentration 5 to 40% by weight (optionally containing metal salts serving as catalysts), while the "used" sulfochromic solution is introduced into the anode compartment.
- the electrochemical process can for example be advantageously implemented in an electrolysis cell whose electrodes are lead plates, and the diaphragm which separates them, a cation exchange membrane.
- This membrane is chosen according to. its chemical resistance and its selectivity: it must resist the corrosive action of the sulfochromic mixture and only allow itself to be crossed, under the action of an electric current, by hydrogen ions.
- a circulation of the anodic and cathodic solutions between the electrodes and the diaphragm makes it possible to create sufficient agitation in the vicinity of the electrodes for the good progress of the electrochemical reactions.
- the temperature is maintained between 20 and 100 ° C and preferably between 50 and 80 ° C, the current density between 3 and 15 A / dm2.
- the electrolysis voltage is generally between 3 and 5 V.
- the amount of current theoretically necessary to reduce one mole of mono-nitrated product at the cathode makes it possible to manufacture, at the anode, a quantity of chromic acid. corresponding to the oxidation of one mole of nitrotoluene (it takes 6 electrons to reduce a nitrated function and 6 electrons to oxidize a methyl function).
- the catholyte After electrolysis, that is to say when the catholyte no longer contains nitrated product and when the chromic solution has reached the desired concentration, the catholyte is cooled and filtered. The precipitate is aminobenzoic acid in the form of sulfate. The filtrate is re-acidified with concentrated sulfuric acid to compensate for the departure of acid bound to the amine. He can again serve as a catholyte.
- the anodic solution will be used for a new oxidation of nitrotoluene.
- the solution is stirred at 80 ° C for 48 hours.
- the filtrate is dosed and contains 31% sulfuric acid, 2% chromium trioxide and 11.3% chromium sulphate.
- the solid is suspended in 500 ml of water which is basified to pH 13 by progressive addition of sodium hydroxide. The mixture is filtered.
- the precipitate containing 8.5 g of unprocessed nitrotoluene and 1.7 g of chromium hydroxide (from insufficient filtration) will be recycled in the following experiment.
- the filtrate containing the sodium salt of nitrobenzoic acid is acidified to pH 1 and then filtered. 16.2 g of para-nitrobenzoic acid are thus recovered, which corresponds to a yield of 85% compared to the para-nitrotoluene consumed and 82% compared to the chromic acid consumed.
- the reaction is carried out in an electrolyser consisting of two parallel lead sheets separated by a cation exchange membrane.
- a pump allows the circulation of electrolytes between each of the electrodes and the membrane.
- anode compartment circulates the sulfochromic solution used to oxidize the nitrotoluene.
- the cathode solution is a suspension of the 16.2 g of nitrobenzoic acid previously obtained in 500 g of a solution which had already served as a catholyte in a previous experiment and containing 125 g of sulfuric acid and 15 g of titanyl sulfate .
- the temperature is maintained at 60 ° C, the current density at 10 A / dm2.
- the electrolysis voltage is close to 4 V.
- the catholyte When twice the amount of electricity necessary for the reduction of nitrobenzoic acid has passed through the electrolyzer, the catholyte is cooled before filtering it.
- the titanium salt solution will be reused in subsequent reductions after adding 4 g of concentrated sulfuric acid.
- the anodic solution contains 6.7% chromic acid and can be used for other oxidations (current efficiency 48%).
- Example 1 The procedure is the same as in Example 1.
- the chromic solution used is the regenerated solution in Example 1. 13 g of para-nitrotoluene are added thereto and the mixture of nitrotoluene and chromous hydroxide recovered at the end of the chemical reaction of Example 1.
- nitrobenzoic acid 12.7 g of nitrobenzoic acid are obtained, which represents a yield of 80% relative to the nitrotoluene consumed and 81% relative to the chromic acid consumed.
- the concentration of the chromic solution goes from 2.01% to 5.81%, ie a current yield of 40%.
- reaction medium After reaction with 30.1 g of para-nitrotoluene for 10 hours at 95 ° C, the reaction medium is extended with 380 g of water and then filtered.
- the chromic solution contains 0.3% chromic acid.
- the yield is therefore 97% compared to nitrotoluene and 96% compared to chromic acid.
- Example 2 The procedure is identical to that of Example 1. 0.5% of copper sulphate is added to the catholyte, which has the effect of lowering the electrolysis voltage to 3.3 V.
- the concentration of the chromic solution goes from 0.3% to 5.3%, giving a current yield of 49%.
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Abstract
Description
La présente invention concerne un procédé nouveau pour préparer les acides aminobenzoiques, et en particulier l'acide para-aminobenzoique, par oxydation de nitrotoluènes, suivie de réduction électrochimique des acides nitrobenzoiques obtenus.The present invention relates to a new process for preparing aminobenzoic acids, and in particular para-aminobenzoic acid, by oxidation of nitrotoluenes, followed by electrochemical reduction of the nitrobenzoic acids obtained.
Ce procédé, permettant de préparer divers acides aminobenzoiques, peut être illustré par le schéma réactionnel suivant :
- où : n représente un nombre entier égal à 1, 2 ou 3, et la liaison pénétrante dans le cycle benzénique représente une possibilité de substitution de ce dernier en position ortho, méta et/ou para,
- where: n represents an integer equal to 1, 2 or 3, and the penetrating bond in the benzene cycle represents a possibility of substitution of the latter in ortho, meta and / or para position,
le cycle benzénique pouvant également porter d'autres substituants demeurant inchangés au cours de la réaction.the benzene ring can also carry other substituents remaining unchanged during the reaction.
Les acides aminobenzoïques, obtenus conformément au procédé de la présente invention, sont des produits chimiques principalement utilisés dans l'industrie pharmaceutique et dans l'industrie des colorants.Aminobenzoic acids, obtained according to the process of the present invention, are chemicals mainly used in the pharmaceutical industry and in the dye industry.
L'oxydation du nitrotoluène en acide nitrobenzoique par un agent chimique oxydant (acide nitrique, permanganate, acide chromique, oxygène), puis réduction de l'acide nitrobenzoique ainsi obtenu en acide aminobenzoique par l'hydrogène, par les métaux ou par électrolyse constituent un procédé de préparation de ces composés bien connu dans la technique antérieure.The oxidation of nitrotoluene to nitrobenzoic acid by an oxidizing chemical agent (nitric acid, permanganate, chromic acid, oxygen), then reduction of the nitrobenzoic acid thus obtained into aminobenzoic acid by hydrogen, by metals or by electrolysis constitute a process for the preparation of these compounds well known in the prior art.
L'oxydation des nitrotoluènes par des solutions sulfochromiques est connue depuis fort longtemps (voir par exemple : KAMM, MATTHEWS, Org. Syn. 2, 53 (1922) ; KASTENS, KAPLAN, Ind. Eng. Chem. 42, 402 (1950) ; Vogel's textbook of practical_organic chemistry - édité par LONGMAN (1978) p. 819).The oxidation of nitrotoluenes by sulfochromic solutions has been known for a very long time (see for example: KAMM, MATTHEWS, Org. Syn. 2, 53 (1922); KASTENS, KAPLAN, Ind. Eng. Chem. 42, 402 (1950) ; Vogel's textbook of practical_organic chemistry - edited by LONGMAN (1978) p. 819).
Cependant, l'acide chromique est un réactif coûteux et particulièrement toxique que l'on préfère remplacer dans l'industrie par l'oxygène en présence d'un catalyseur ou par l'acide nitrique.However, chromic acid is an expensive and particularly toxic reagent which is preferred to be replaced in industry by oxygen in the presence of a catalyst or by nitric acid.
La régénération électrochimique de solutions sulfochromiques ayant servi à des oxydations de produits organiques est une réaction industrielle fort ancienne (voir par exemple les brevets allemand n° 103.860 et américain n° 2.450.858). Elle permet d'éviter les problèmes de coût et de toxicité des sels de chrome en les recyclant intégralement.The electrochemical regeneration of sulfochromic solutions having served for oxidations of organic products is a very old industrial reaction (see for example the German patents n ° 103.860 and American n ° 2.450.858). It avoids the cost and toxicity problems of chromium salts by recycling them entirely.
Quant à la réduction électrochimique des acides nitrobenzoiques, elle permet d'obtenir d'excellents rendements (voir par exemple : N.A. Izgaryshev, M. Ya. Fioshin - Doklady. Akad. Nauk. SSSR, 90, 189-90 (1953) ; J. Phillips, A. Lowy, Trans. Electrochem. Soc. 71, 494 (1937) ; brevet indien 145096 (1976).As for the electrochemical reduction of nitrobenzoic acids, it makes it possible to obtain excellent yields (see for example: NA Izgaryshev, M. Ya. Fioshin - Doklady. Akad. Nauk. SSSR, 90, 189-90 (1953); J Phillips, A. Lowy, Trans. Electrochem, Soc. 71, 494 (1937); Indian patent 145096 (1976).
Une telle réduction électrochimique présente également des avantages sur les méthodes classiques :
- - la réduction par le fer en milieu acide, qui donne un produit mêlé à des oxydes de fer,
- - l'hydrogénation catalytique, qui nécessite des conditions de pH assez précises et donne un produit mêlé avec du catalyseur.
- - reduction by iron in an acid medium, which gives a product mixed with iron oxides,
- - catalytic hydrogenation, which requires fairly precise pH conditions and gives a product mixed with catalyst.
L'électrochimie ne présente pas ces inconvénients : le sulfate d'acide amiriobenzoique pur peut être récupéré par simple filtration après électrolyse.Electrochemistry does not have these drawbacks: pure amiriobenzoic acid sulfate can be recovered by simple filtration after electrolysis.
L'originalité de la présente invention réside dans le fait que l'agent oxydant utilisé pour la mise en oeuvre de la première étape est régénéré à l'anode d'un électrolyseur assurant simultanément la réduction électrochimique de la seconde étape.The originality of the present invention resides in the fact that the oxidizing agent used for the implementation of the first step is regenerated at the anode of an electrolyser simultaneously ensuring the electrochemical reduction of the second step.
L'intérêt de réunir dans le même électrolyseur les deux réactions, régénération de l'acide chromique et réduction de l'acide nitrobenzoique est parfaitement clair. En effet, par rapport à ces réactions effectuées dans deux électrolyseurs distincts :
- - l'investissement dû à l'électrolyse est diminué de moitié (une seule installation au lieu de deux), et
- - l'énergie nécessaire pour conduire les deux réactions est diminuée de plus de la moitié, la tension de l'électrolyse commune étant légèrement inférieure à chacune des tensions d'électrolyses séparées.
- - the investment due to electrolysis is halved (one installation instead of two), and
- - The energy required to conduct the two reactions is reduced by more than half, the voltage of the common electrolysis being slightly lower than each of the separate electrolysis voltages.
D'autres caractéristiques et avantages du procédé, objet de la présente invention, apparaîtront à la lecture de la description détaillée faite ci-après, notamment en référence à la figure annexée, représentant le schéma de principe dudit procédé.Other characteristics and advantages of the process which is the subject of the present invention will appear on reading the detailed description given below, in particular with reference to the appended figure, representing the block diagram of said process.
La réaction chimique d'oxydation du nitrotoluène par l'acide sulfochromique, peut être conduite de deux façons, suivant la réactivité du nitrotoluène :
- 1) le nitrotoluène est maintenu en émulsion ou en suspension dans la solution sulfochromique provenant de l'électrolyse par une agitation violente. La réaction est d'autant plus rapide que la température est plus élevée et que la solution est plus concentrée en acide sulfurique et en acide chromique. L'acide nitrobenzoique, contenant éventuellement du nitrotoluène non transformé est récupéré par filtration après refroidissement.
- 2) Si le nitrotoluène est trop peu réactif, il est nécessaire de concentrer la solution sulfochromique par évaporation, avant de la mettre en présence du nitrotoluène. Après réaction, le milieu réactionnel est étendu d'eau glacée jusqu'à une concentration en chrome inférieure à 2,5 atomegrammes par litre et une concentration en acide sulfurique inférieure à 50 % en poids, puis filtré.
- 1) the nitrotoluene is maintained in emulsion or in suspension in the sulfochromic solution coming from the electrolysis by a violent agitation. The reaction is faster the higher the temperature and the more concentrated the sulfuric acid and chromic acid. The nitrobenzoic acid, optionally containing unprocessed nitrotoluene is recovered by filtration after cooling.
- 2) If the nitrotoluene is too reactive, it is necessary to concentrate the sulfochromic solution by evaporation, before bringing it into contact with the nitrotoluene. After reaction, the reaction medium is extended with ice water to a chromium concentration of less than 2.5 atomograms per liter and a sulfuric acid concentration of less than 50% by weight, then filtered.
La solution sulfochromique utilisée pour assurer l'oxydation des nitrotoluènes peut par exemple être avantageusement constituée par une solution aqueuse de 3 à 20 % en poids d'oxyde chromique et 10 à 95 % en poids d'acide sulfurique pouvant contenir du sulfate de chrome, et éventuellement d'autres additifs.The sulfochromic solution used to ensure the oxidation of nitrotoluenes can, for example, advantageously consist of an aqueous solution of 3 to 20% by weight of chromic oxide and 10 to 95% by weight of sulfuric acid which may contain chromium sulfate, and possibly other additives.
Après séparation éventuelle du nitrotoluène résiduel, l'acide nitrobenzoique est introduit dans le compartiment cathodique de l'électrolyseur sous forme de suspension dans de l'acide sulfurique de concentration 5 à 40 % en poids (contenant éventuellement des sels métalliques servant de catalyseurs), alors que la solution sulfochromique "usée" est introduite dans le compartiment anodique .After optional separation of the residual nitrotoluene, the nitrobenzoic acid is introduced into the cathode compartment of the electrolyser in the form of a suspension in sulfuric acid of concentration 5 to 40% by weight (optionally containing metal salts serving as catalysts), while the "used" sulfochromic solution is introduced into the anode compartment.
Le procédé électrochimique peut par exemple être avantageusement mis en oeuvre dans une cellule d'électrolyse dont les électrodes sont des plaques de plomb, et le diaphragme qui les sépare, une membrane échangeuse de cations. Cette membrane est choisie en fonction de. sa résistance chimique et de sa sélectivité : elle doit résister à l'action corrosive du mélange sulfochromique et ne se laisser traverser, sous l'action d'un courant électrique, que par les ions hydrogène.The electrochemical process can for example be advantageously implemented in an electrolysis cell whose electrodes are lead plates, and the diaphragm which separates them, a cation exchange membrane. This membrane is chosen according to. its chemical resistance and its selectivity: it must resist the corrosive action of the sulfochromic mixture and only allow itself to be crossed, under the action of an electric current, by hydrogen ions.
Une circulation des solutions anodique et cathodique entre les électrodes et le diaphragme permet de créer une agitation suffisante au voisinage des électrodes pour le bon déroulement des réactions électrochimiques.A circulation of the anodic and cathodic solutions between the electrodes and the diaphragm makes it possible to create sufficient agitation in the vicinity of the electrodes for the good progress of the electrochemical reactions.
La température est maintenue entre 20 et 100°C et de préférence entre 50 et 80°C, la densité de courant entre 3 et 15 A/dm2. La tension d'électrolyse est généralement comprise entre 3 et 5 V.The temperature is maintained between 20 and 100 ° C and preferably between 50 and 80 ° C, the current density between 3 and 15 A / dm2. The electrolysis voltage is generally between 3 and 5 V.
La quantité de courant théoriquement nécessaire pour réduire une mole de produit mono-nitré à la cathode permet de fabriquer, à l'anode, une quantité d'acide chromique correspondant à l'oxydation d'une mole de nitrotoluène (il faut 6 électrons pour réduire une fonction nitrée et 6 électrons pour oxyder une fonction méthyle).The amount of current theoretically necessary to reduce one mole of mono-nitrated product at the cathode makes it possible to manufacture, at the anode, a quantity of chromic acid. corresponding to the oxidation of one mole of nitrotoluene (it takes 6 electrons to reduce a nitrated function and 6 electrons to oxidize a methyl function).
Cependant, le rendement de la réaction anodique est voisin de 50 %, et donc :
- - dans le cas d'un mono-nitrotoluène, on fabriquera pendant l'électrolyse trois moles d'hydrogène par mole d'acide mono-nitrobenzoique,
- - dans le cas d'un poly-nitrotoluêne, on fabriquera très peu d'hydrogène pendant la réaction, mais on fabriquera de l'oxygène à l'anode.
- - in the case of a mono-nitrotoluene, three moles of hydrogen will be produced during the electrolysis per mole of mono-nitrobenzoic acid,
- - In the case of a poly-nitrotoluene, very little hydrogen will be produced during the reaction, but oxygen will be produced at the anode.
Après l'électrolyse, c'est-à-dire quand le catholyte ne contient plus de produit nitré et quand la solution chromique a atteint la concentration désirée, le catholyte est refroidi et filtré. Le précipité est l'acide aminobenzoique sous forme de sulfate. Le filtrat est réacidifié avec de l'acide sulfurique concentré pour compenser le départ d'acide lié à l'amine. Il pourra de nouveau servir de catholyte.After electrolysis, that is to say when the catholyte no longer contains nitrated product and when the chromic solution has reached the desired concentration, the catholyte is cooled and filtered. The precipitate is aminobenzoic acid in the form of sulfate. The filtrate is re-acidified with concentrated sulfuric acid to compensate for the departure of acid bound to the amine. He can again serve as a catholyte.
La solution anodique servira à une nouvelle oxydation de nitrotoluène..The anodic solution will be used for a new oxidation of nitrotoluene.
Ces différentes étapes élémentaires du procédé de l'invention sont clairement illustrées sur le schéma de principe annexé à la présente description.These different elementary steps of the method of the invention are clearly illustrated in the block diagram appended to this description.
On mentionnera ci-après quelques exemples non limitatifs de mise en oeuvre du procédé selon l'invention.Some non-limiting examples of implementation of the method according to the invention will be mentioned below.
A 400 g d'une solution chromique provenant de la régénération électrochimique des eaux résiduelles d'une expérience précédente, et contenant 30 % d'acide sulfurique, 7,9 % de trioxyde de chrome et 3 % de sulfate de chrome, on ajoute 24 g de paranitrotoluène.24 g of a chromic solution originating from the electrochemical regeneration of the residual waters of a previous experiment, and containing 30% of sulfuric acid, 7.9% of chromium trioxide and 3% of chromium sulfate, are added 24 g of paranitrotoluene.
La solution est agitée à 80°C pendant 48 heures.The solution is stirred at 80 ° C for 48 hours.
Après refroidissement, les produits organiques sont filtrés. Le filtrat est dosé et contient 31 % d'acide sulfurique, 2 % de trioxyde de chrome et 11,3 % de sulfate de chrome.After cooling, the organic products are filtered. The filtrate is dosed and contains 31% sulfuric acid, 2% chromium trioxide and 11.3% chromium sulphate.
Le solide est mis en suspension dans 500 ml d'eau que l'on basifie à pH 13 par ajout progressif de soude. Le mélange est filtré.The solid is suspended in 500 ml of water which is basified to pH 13 by progressive addition of sodium hydroxide. The mixture is filtered.
Le précipité, contenant 8,5 g de nitrotoluène non transformé et 1,7 g d'hydroxyde chromeux (provenant d'une filtration insuffisante) sera recyclé dans l'expérience suivante.The precipitate, containing 8.5 g of unprocessed nitrotoluene and 1.7 g of chromium hydroxide (from insufficient filtration) will be recycled in the following experiment.
Le filtrat contenant le sel de sodium de l'acide nitrobenzoique est acidifié à pH 1 puis filtré. On récupère ainsi 16,2 g d'acide para-nitrobenzoique, ce qui correspond à un rendement de 85 % par rapport au para-nitrotoluène consommé et de 82 % par rapport à l'acide chromique consommé.The filtrate containing the sodium salt of nitrobenzoic acid is acidified to
La réaction est menée dans un électrolyseur constitué de deux feuilles de plomb parallèles séparées par une membrane échangeuse de cations. Une pompe permet la circulation des électrolytes entre chacune des électrodes et la membrane.The reaction is carried out in an electrolyser consisting of two parallel lead sheets separated by a cation exchange membrane. A pump allows the circulation of electrolytes between each of the electrodes and the membrane.
Dans le compartiment anodique circule la solution sulfochromique ayant servi à oxyder le nitrotoluène.In the anode compartment circulates the sulfochromic solution used to oxidize the nitrotoluene.
La solution cathodique est une suspension des 16,2 g d'acide nitrobenzoïque obtenus précédemment dans 500 g d'une solution ayant déjà servi de catholyte lors d'une expérience précédente et contenant 125 g d'acide sulfurique et 15 g de sulfate de titanyle.The cathode solution is a suspension of the 16.2 g of nitrobenzoic acid previously obtained in 500 g of a solution which had already served as a catholyte in a previous experiment and containing 125 g of sulfuric acid and 15 g of titanyl sulfate .
La température est maintenue à 60°C, la densité du courant à 10 A/dm2. La tension d'électrolyse est voisine de 4 V.The temperature is maintained at 60 ° C, the current density at 10 A / dm2. The electrolysis voltage is close to 4 V.
Quand deux fois la quantité d'électricité nécessaire à la réduction de l'acide nitrobenzoique ont traversé l'électrolyseur, on refroidit le catholyte avant de le filtrer.When twice the amount of electricity necessary for the reduction of nitrobenzoic acid has passed through the electrolyzer, the catholyte is cooled before filtering it.
On obtient ainsi 14,8 g de sulfate d'acide para-amino= benzoique (rendement en masse 82 %). L'acide para-aminobenzoïque peut être récupéré en basifiant une suspension aqueuse du sulfate à pH 4.14.8 g of para-amino acid = benzoic acid sulfate are thus obtained (mass yield 82%). Para-aminobenzoic acid can be recovered by basifying an aqueous suspension of the sulfate at pH 4.
La solution de sel de titane sera réutilisée dans les réductions ultérieures après ajout de 4 g d'acide sulfurique concentré.The titanium salt solution will be reused in subsequent reductions after adding 4 g of concentrated sulfuric acid.
La solution anodique contient 6,7 % d'acide chromique et peut resservir à d'autres oxydations (rendement en courant 48 %).The anodic solution contains 6.7% chromic acid and can be used for other oxidations (current efficiency 48%).
Le mode opératoire est le même que dans l'exemple 1. La solution chromique employée est la solution régénérée dans l'exemple 1. On lui ajoute 13 g de para-nitrotoluène et le mélange de nitrotoluène et d'hydroxyde chromeux récupéré à la fin de la réaction chimique de l'exemple 1.The procedure is the same as in Example 1. The chromic solution used is the regenerated solution in Example 1. 13 g of para-nitrotoluene are added thereto and the mixture of nitrotoluene and chromous hydroxide recovered at the end of the chemical reaction of Example 1.
On obtient 12,7 g d'acide nitrobenzoique, ce qui représente un rendement de 80 % par rapport au nitrotoluène consommé et de 81 % par rapport à l'acide chromique consommé.12.7 g of nitrobenzoic acid are obtained, which represents a yield of 80% relative to the nitrotoluene consumed and 81% relative to the chromic acid consumed.
Le mode opératoire est le même que dans l'exemple 1.The procedure is the same as in Example 1.
On utilise 2,5 fois la quantité d'électricité nécessaire pour réduire l'acide nitrobenzoique.2.5 times the amount of electricity needed to reduce nitrobenzoic acid is used.
La concentration de la solution chromique passe de 2,01 % à 5,81 %, soit un rendement en courant de 40 %.The concentration of the chromic solution goes from 2.01% to 5.81%, ie a current yield of 40%.
On obtient 12 g de sulfate d'acide para-aminobenzoique, soit un rendement de 85 % par rapport à l'acide nitrobenzoique.12 g of para-aminobenzoic acid sulfate are obtained, ie a yield of 85% relative to the nitrobenzoic acid.
1000 g d'une solution chromique contenant 4,6 % d'acide chromique et 25 % d'acide sulfurique provenant d'une régénération antérieure sont évaporés jusqu'à un poids de 500 g.1000 g of a chromic solution containing 4.6% chromic acid and 25% sulfuric acid from a previous regeneration are evaporated to a weight of 500 g.
Après réaction avec 30,1 g de para-nitrotoluène pendant 10 heures à 95°C, le milieu réactionnel est étendu de 380 g d'eau puis filtré.After reaction with 30.1 g of para-nitrotoluene for 10 hours at 95 ° C, the reaction medium is extended with 380 g of water and then filtered.
Le mode opératoire est ensuite identique à celui de l'exemple 1.The procedure is then identical to that of Example 1.
On obtient 35 g d'acide nitrobenzoique et on récupère 0,5 g de nitrotoluène non transformé.35 g of nitrobenzoic acid are obtained and 0.5 g of unprocessed nitrotoluene is recovered.
La solution chromique contient 0,3 % d'acide chromique.The chromic solution contains 0.3% chromic acid.
Le rendement est donc 97 % par rapport au nitrotoluène et 96 % par rapport à l'acide chromique.The yield is therefore 97% compared to nitrotoluene and 96% compared to chromic acid.
Le mode opératoire est identique à celui de l'exemple 1. Au catholyte est ajouté 0, 5 % de sulfate de cuivre, ce qui a pour effet d'abaisser la tension d'électrolyse à 3,3 V.The procedure is identical to that of Example 1. 0.5% of copper sulphate is added to the catholyte, which has the effect of lowering the electrolysis voltage to 3.3 V.
On utilise deux fois la quantité d'électricité nécessaire pour réduire l'acide nitrobenzoique.Twice the amount of electricity needed to reduce nitrobenzoic acid is used.
La concentration de la solution chromique passe de 0,3 % à 5,3 %, soit un rendement en courant de 49 %.The concentration of the chromic solution goes from 0.3% to 5.3%, giving a current yield of 49%.
On obtient 32,7 g de sulfate d'acide para-aminobenzoïque, soit un rendement de 84 % par rapport à l'acide nitrobenzoïque.32.7 g of para-aminobenzoic acid sulfate are obtained, ie a yield of 84% relative to the nitrobenzoic acid.
Bien entendu, la présente invention ne se limite nullement aux modes de mise en oeuvre particuliers précédemment décrits, mais il est parfaitement possible, sans pour autant sortir du cadre de la présente invention, d'en imaginer un certain nombre de variantes.Of course, the present invention is in no way limited to the particular modes of implementation described above, but it is perfectly possible, without departing from the scope of the present invention, to imagine a number of variants.
Claims (14)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP83400366A EP0117371B1 (en) | 1983-02-22 | 1983-02-22 | Process for the production of aminobenzoic acids from corresponding nitrotoluenes |
DE8383400366T DE3371232D1 (en) | 1983-02-22 | 1983-02-22 | Process for the production of aminobenzoic acids from corresponding nitrotoluenes |
Applications Claiming Priority (1)
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EP83400366A EP0117371B1 (en) | 1983-02-22 | 1983-02-22 | Process for the production of aminobenzoic acids from corresponding nitrotoluenes |
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EP0117371A1 true EP0117371A1 (en) | 1984-09-05 |
EP0117371B1 EP0117371B1 (en) | 1987-04-29 |
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EP83400366A Expired EP0117371B1 (en) | 1983-02-22 | 1983-02-22 | Process for the production of aminobenzoic acids from corresponding nitrotoluenes |
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EP (1) | EP0117371B1 (en) |
DE (1) | DE3371232D1 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2665715A1 (en) * | 1990-08-07 | 1992-02-14 | Sandoz Sa | ELECTROCHEMICAL PROCESS FOR THE PREPARATION OF 4,4'-DINITROSTILBENE-2,2'-DISULFONIC ACID AND ITS SALTS. |
US6168172B1 (en) | 1993-07-19 | 2001-01-02 | K-2 Corporation | In-line roller skate |
WO2003072534A1 (en) * | 2002-02-26 | 2003-09-04 | Sk Chemicals Co., Ltd. | Method for preparing p-aminobenzoic acid |
CN111041516A (en) * | 2019-12-19 | 2020-04-21 | 湖南大学 | New preparation method of telmisartan intermediate of antihypertensive drug |
CN112251770A (en) * | 2020-10-14 | 2021-01-22 | 湖南大学 | Novel electrochemical preparation method of antihypertensive drug telmisartan intermediate |
CN113774414A (en) * | 2020-06-08 | 2021-12-10 | 清华大学 | Method and system for preparing p-aminobenzoic acid |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2512844A1 (en) * | 1981-09-14 | 1983-03-18 | Electricite De France | Amino:benzoic acid prodn. from nitrotoluene - by oxidn. to nitrobenzoic acid and electrochemical redn. to amino:benzoic acid with simultaneous regeneration of oxidising agent |
-
1983
- 1983-02-22 DE DE8383400366T patent/DE3371232D1/en not_active Expired
- 1983-02-22 EP EP83400366A patent/EP0117371B1/en not_active Expired
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2512844A1 (en) * | 1981-09-14 | 1983-03-18 | Electricite De France | Amino:benzoic acid prodn. from nitrotoluene - by oxidn. to nitrobenzoic acid and electrochemical redn. to amino:benzoic acid with simultaneous regeneration of oxidising agent |
Non-Patent Citations (4)
Title |
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CHEMICAL ABSTRACTS, vol. 79, 1973, page 366, no. 142274x, Columbus, Ohio, USA * |
CHEMICAL ABSTRACTS, vol. 93, no. 16, octobre 1980, page 498, no. 157868g, Columbus, Ohio, USA & JP - A - 80 50 471 (TOKUYAMA SODA CO., LTD.) 12-04-1980 * |
HOUBEN-WEYL: "Methoden der Organischen Chemie, vol. IV/1b, 1975, Georg Thieme Verlag, Stuttgart, DE. * |
THE GAZETTE OF INDIA, 19 août 1978, partie III, sec. 2, page 609, résumé no. 145096 * |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2665715A1 (en) * | 1990-08-07 | 1992-02-14 | Sandoz Sa | ELECTROCHEMICAL PROCESS FOR THE PREPARATION OF 4,4'-DINITROSTILBENE-2,2'-DISULFONIC ACID AND ITS SALTS. |
US6168172B1 (en) | 1993-07-19 | 2001-01-02 | K-2 Corporation | In-line roller skate |
WO2003072534A1 (en) * | 2002-02-26 | 2003-09-04 | Sk Chemicals Co., Ltd. | Method for preparing p-aminobenzoic acid |
CN111041516A (en) * | 2019-12-19 | 2020-04-21 | 湖南大学 | New preparation method of telmisartan intermediate of antihypertensive drug |
CN113774414A (en) * | 2020-06-08 | 2021-12-10 | 清华大学 | Method and system for preparing p-aminobenzoic acid |
CN113774414B (en) * | 2020-06-08 | 2023-04-14 | 清华大学 | Method and system for preparing p-aminobenzoic acid |
CN112251770A (en) * | 2020-10-14 | 2021-01-22 | 湖南大学 | Novel electrochemical preparation method of antihypertensive drug telmisartan intermediate |
CN112251770B (en) * | 2020-10-14 | 2021-07-27 | 湖南大学 | Novel electrochemical preparation method of antihypertensive drug telmisartan intermediate |
Also Published As
Publication number | Publication date |
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EP0117371B1 (en) | 1987-04-29 |
DE3371232D1 (en) | 1987-06-04 |
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