EP1179612A1 - Cathode for electrolytic cells - Google Patents
Cathode for electrolytic cells Download PDFInfo
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- EP1179612A1 EP1179612A1 EP01117681A EP01117681A EP1179612A1 EP 1179612 A1 EP1179612 A1 EP 1179612A1 EP 01117681 A EP01117681 A EP 01117681A EP 01117681 A EP01117681 A EP 01117681A EP 1179612 A1 EP1179612 A1 EP 1179612A1
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- Prior art keywords
- lead
- cathode
- cystine
- compound
- organic
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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
- C25B3/25—Reduction
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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
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
Definitions
- the present invention relates to a cathode for electrochemical reduction of organic compounds is used, processes for their preparation and their Use for electrochemical reduction of organic Links.
- Electrode is often used as the cathode, which is characterized by a high overvoltage against hydrogen distinguished.
- lead cathodes are Reduction of aldehydes, ketones, carboxylic acids and carboxylic acid esters to alcohols, the reduction of heterocycles and Dehalogenations (overview: M.M. Baizer in Organic Electrochemistry, Marcel Dekker, New York 1991, p. 362 ff., I. Nishiguchi et al., Electroorg. Synth. 1991, p. 331). Numerous processes are also carried out on an industrial scale using lead cathodes (overview: "Industrial Electrochemistry” by Pletcher and Walsh, Chapman and Hall, London 1989, pp. 313-319).
- lead-plated carrier cathodes for example made of copper or titanium (M.M. Baizer in Organic Electrochemistry, Marcel Verlag Dekker, New York 1991, p.274).
- Corresponding coating processes are expensive and complicated, however. in this connection you have to rely on flat geometries so that the Coating receives good adhesion to the carrier.
- lead surfaces are easily deactivated be (EP 0 931 856), whereby the current efficiency and the Area-time benefits decrease. Corrosion is also described by lead electrodes. To regenerate the The electrolytic cell must have a complete cathode surface be dismantled. The resulting high downtime severely restrict economic usability.
- the object of the present invention is therefore to provide a high hydrogen overvoltage cathode, the is easy to manufacture and regenerate and which is the Reduction of organic compounds on an industrial scale suitable.
- the object is achieved by a cathode consisting of an electrically conductive support with a coating of electrochemically deposited lead with a density between 0.001 and 2 g / cm 3 .
- This lead layer has a loose structure with a density which is greatly reduced compared to solid lead in the range between 0.001 and 2 g / cm 3 , preferably between 0.01 and 1 g / cm 3 .
- the increase in surface area documented by the reduced density has an advantageous effect on the area-time performance of chemical processes.
- the carrier of the cathode according to the invention consists of a electrically conductive material, preferably made of a metal excluding an alkali or alkaline earth metal or one Metal alloy or graphite.
- the electrically conductive carrier particularly preferably consists of a metal or a metal alloy selected from the Group copper, nickel, tin, zinc, titanium, iron, steel, Stainless steel, cadmium and lead.
- Elements can also be selected as alloy components from the group tungsten, chrome, cobalt, molybdenum, manganese, Bismuth, aluminum, mercury, zirconium, vanadium, silicon, Boron, niobium, tantalum, antimony, phosphorus and carbon, to be available.
- metal also includes metal alloys, as stated above.
- Such a carrier can be combined with one or more others of the metals mentioned.
- For the coating are all methods known to the person skilled in the art, e.g. Electroplate or sputtering.
- the shape of the electrically conductive carrier is not critical. she is preferably selected from the large number of known or available electrode geometries, e.g. Plate, net, foam, Washer, tube, sieve plate, rod etc. selected.
- the lead layer deposited on the electrically conductive carrier is distinguished by a reduced density in the range from 0.001 to 2 g / cm 3 , preferably between 0.01 and 1 g / cm 3 , compared to solid lead.
- the invention further relates to a method of manufacture a cathode according to the invention.
- the production of a cathode according to the invention is thereby characterized in that in a known electrolysis cell on an electrically conductive support that acts as a cathode is switched from an aqueous catholyte solution containing lead salt a layer of lead by means of electrochemical deposition is deposited with reduced density.
- Any cell known to the person skilled in the art is an electrolytic cell suitable.
- a selection of frequently used cells can be found in textbooks, e.g. B. in "Industrial Electrochemistry” by Pletcher and Walsh, Chapman and Hall, London 1989, pp. 141-166.
- the lead in the second level included, e.g. Lead (II) carbonate, lead (II) chloride, Lead (II) fluoride, lead (II) acetate, lead (II) formate, Lead (II) oxalate, lead (II) nitrate and their basic salts, Lead (II) sulfate and lead (II) oxide.
- Mineral acids preferably hydrochloric acid, sulfuric acid and Phosphoric acid in a concentration between 0.5 M and 12 M, in the case of hydrochloric acid up to 8.5 M (conc. hydrochloric acid).
- Other possible additives are organic acids, e.g. Acetic acid, formic acid, citric acid, lactic acid or their salts with ammonium, tetraalkylammonium, sodium or Potassium ions, or complexing agents for divalent lead ions, for example EDTA or NTA in amounts of 1 to 3 Equivalents based on the amount of lead present.
- the solution containing lead salt can additionally contain inorganic salts as conductive salts.
- inorganic salts as conductive salts. Examples of this are all alkali, alkaline earth metal and ammonium salts, e.g. B. Sodium chloride, sodium sulfate, ammonium chloride, Lithium perchlorate.
- the aqueous solution containing lead salt can also be used water-miscible cosolvents such as ethanol, methanol, i-propanol, n-propanol, acetonitrile, ethylene glycol, Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Tetrahydrofuran, 1,4-dioxane, methyl acetate, Ethyl acetate, formic acid, dimethylformamide, Sulfolane, ethylene carbonate, N, N'-dimethylpropyleneurea, N, N'-dimethylethylene urea, N-methylpyrrolidone, Tetramethylurea and hexamethylphosphoric triamide in Concentrations of 0.1 to 80% by weight, preferably 1 to 50% by weight. % contain.
- water-miscible cosolvents such as ethanol, methanol, i-propanol, n-propanol, acetonitrile,
- the lead ion concentration lies in the lead salt-containing one aqueous solution preferably between 1 ppm and 20 g / l, especially preferably between 10 ppm and 10 g / l.
- the pH of the electrolysis solution is preferably between 1 and 6, particularly preferably between 1 and 3.
- the deposition of the lead layer is preferably achieved by applying a cathode potential between -0.1 V and the value at which hydrogen evolution starts at the cathode.
- Current densities of 0.1 A / m 2 to 4000 A / m 2 , preferably 10 to 3000 A / m 2 are set here.
- the temperature is when performing the procedure critical. It can be freely selected in a wide range. A lower temperature limit is due to the freezing point Given catholyte solution, an upper limit due to the stability the electrolytic cell. In the case of membrane cells, this is especially the thermal stability of the membrane. In this In this case, the temperature is limited to a maximum of 60 ° C.
- the formation of the lead layer can be before or at the same time with the reduction of an organic compound.
- the invention therefore also relates to a method for electrochemical Reduction of an organic compound, thereby characterized in that instead of a conventional cathode solid lead or a cathode with a solid Lead coating, e.g. a lead film, the invention Cathode is used.
- the compound to be reduced is preferably an organic sulfur compound, e.g. B. a disulfide compound, a sulfinic acid, sulfoxide or a thioether, or an organic carbonyl compound, for example an aldehyde or ketone.
- Particularly preferred disulfide compounds are cystine, N-alkanoyl-cystine, homocystine and N-alkanoyl homocystine.
- the concentration of the compound to be reduced is 0.01 M to 10 M, preferably 0.1 to 5 M.
- the solvent used is preferably an aqueous solution of mineral acid, for example hydrochloric acid, sulfuric acid or phosphoric acid, or of sodium or potassium hydroxide, sodium or potassium carbonate or acetate , Ammonia, ammonium chloride or ammonium acetate used in concentrations between 0.1 M and 12 M.
- the electrochemical reduction of cystine and homocystine is preferably carried out in aqueous hydrochloric acid, sulfuric acid, sodium or potassium hydroxide solution or in an ammoniacal solution.
- the concentration of the cystine can be between 0.1 M and the saturation concentration. Saturated cystine or homocystine solutions are particularly preferred.
- the reduction of N-acetylcystine is preferably carried out at pH values between 5 and 13.
- the electrolysis is carried out at temperatures between 0 ° C and 70 ° C, preferably at temperatures between 10 ° C and 50 ° C.
- Current densities are 0.1 A / m2 to 20,000 A / m2, preferably 10-5000 A / m2.
- cysteine hydrochloride from cystine in a hydrochloric acid electrolysis solution the unusually high current density of 2000 A / qm with a Area-time performance of 7.3 kg of cysteine hydrochloride hydrate per hour and sqm of membrane area are produced (see G1.1 in scheme 1). This area-time performance is up to at least 5 Days of operation constant. In the electrolysis solution is at a detection limit of 0.5 ppm no lead was detectable.
- the cathode according to the invention is its easy regenerability.
- the regeneration is without Disassembly of the cell possible.
- the lead layer is in an embodiment by rinsing the catholyte space with Water or mechanically removed with the catholyte.
- the lead layer becomes partial or completely dissolved.
- Aqueous solutions are suitable for this of mineral acids or organic acids in concentrations between 0.1 and 10 M except for sulfuric acid. Examples of this are hydrochloric acid, phosphoric acid or acetic acid. Possibly can the aqueous acid solution complexing Increasing the solubility of the resulting lead salt in quantities between 0.5 and 5 equivalents based on that to be resolved Amount of lead can be added.
- Complexing agent for lead (II) ions are e.g. EDTA, NTA and citric acid. The temperatures are here within the working area of electrochemical Cell.
- Example 1 Production of a cathode according to the invention
- Cell used a cell divided by means of a membrane made of Nafion 324 (electrode or membrane area 0.01 m 2 ) with electrodes arranged plane-parallel and consisting of a copper cathode, an oxygen-developing DSA anode (DeNora GmbH, anolyte: 20 percent sulfuric acid).
- the electrode-membrane distance was 1.8 cm.
- Catholyte and anolyte solutions were pumped through the cell from reservoirs (batch recycle operation).
- Example 2 Analogously to Example 1, the electrolytic deposition of the lead on the copper cathode was carried out from a solution of 2.00 g of basic lead carbonate in a solution of 360 g of cystine and 367 g of conc. HCl in 1314 g water at 6.9 A. Response time: 15 h. Residual content of lead in solution ⁇ 0.5 ppm. Conversion of cystine to cysteine hydrochloride: 99.7% (measured with HPLC and rotation value ⁇ ).
- Example 2 Analogously to Example 1, 750 mg of dissolved lead white was used loose lead deposited on a lead cathode. 1.00 kg As in Example 3, cystine became cysteine hydrochloride reduced. Total reaction time: 21.8 hours. Calculated area-time performance: 6.71 kg cysteine hydrochloride monohydrate per square meter Membrane area and per hour.
- Example 7 Reduction of cystine to cysteine hydrochloride - comparative example
- Example 8 Reduction of cystine to cysteine hydrochloride - comparative example to example 3
- an electrolysis apparatus consisting of an electrolysis cell with disc-shaped electrodes (anode: DSA titanium expanded metal, cathode: lead sieve plate with loosely separated lead, electrodes used on both sides and each suspended with the help of concentrically welded rods, diameter 7.5 cm) and the As in the periphery constructed in Example 1, a solution of 1.523 g of L-cysteine sulfinic acid monohydrate in 600 ml of 2N hydrochloric acid was reacted at 10 A and a reaction temperature of 15 ° C. for 4.5 hours. The reaction solution contains 60% cystine (S, S) dioxide, 20% cystine sulfinic acid and 20% cystine ( 1 H-NMR spectroscopic examination).
- a solution was found in the electrolysis apparatus according to Example 10 of 130.0 g of 2,4-dicarboxy-2-methyl-thiazolidine in one Mixture of 526 ml water and 144 g hydrochloric acid at 9.5 A and Temperatures of 16-20 ° C implemented. After a reaction time of 5 hours 66% N- (1-carboxyethyl) cysteine, 19% lactic acid and 15 % Cysteine received. The reaction solution was evaporated and the solid from 0.5 M hydrochloric acid with exclusion of oxygen recrystallized. N- (1-carboxyethyl) cysteine is obtained in the form of colorless crystals.
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Abstract
Description
Die vorliegende Erfindung betrifft eine Kathode, die zur elektrochemischen Reduktion organischer Verbindungen eingesetzt wird, Verfahren zu ihrer Herstellung und ihre Verwendung zur elektrochemischen Reduktion organischer Verbindungen.The present invention relates to a cathode for electrochemical reduction of organic compounds is used, processes for their preparation and their Use for electrochemical reduction of organic Links.
Die elektrochemische Reduktion organischer Verbindungen ist eine wichtige Methode zur Darstellung einer Vielzahl von Produkten. Häufig wird hierbei Blei als Kathode verwendet, welches sich durch eine hohe Überspannung gegenüber Wasserstoff auszeichnet.The electrochemical reduction of organic compounds is an important method of representing a variety of Products. Lead is often used as the cathode, which is characterized by a high overvoltage against hydrogen distinguished.
An Bleiplatten werden beispielsweise Reduktionen von Disulfidverbindungen (A. Aldaz et al. in Electrochemical Processing Technologies, 1997, Miami, Florida), zu den entsprechenden Thiolen durchgeführt. Großtechnisch wird Cysteinhydrochlorid durch Reduktion von Cystin an Bleikathoden erhalten. (Übersicht: T.R. Ralph et al., J. Electroanal. Chem. 1994, 375, 17). Hohe chemische Ausbeuten erhält man hierbei bei Stromdichten bis zu 700 A/qm. Bedingt durch die konkurrierende Wasserstoffentwicklung sind die Stromausbeuten auf ca. 46% begrenzt. Verschiedene Autoren beschreiben eine fortschreitende Passivierung der Bleioberfläche bei dieser Umsetzung (C. Daobao in Jingxi Huagong 1998, 15, S. 258ff. und S. 297ff, M. Li ibid., S. 294) bereits bei Stromdichten von 200-500 A/qm.For example, reductions of disulfide compounds (A. Aldaz et al. In Electrochemical Processing Technologies, 1997, Miami, Florida) to the corresponding thiols are carried out on lead plates. On an industrial scale, cysteine hydrochloride is obtained by reducing cystine on lead cathodes. (Review: TR Ralph et al., J. Electroanal. Chem. 1994 , 375, 17). High chemical yields are obtained with current densities up to 700 A / sqm. Due to the competing development of hydrogen, the electricity yields are limited to approx. 46%. Various authors describe a progressive passivation of the lead surface during this implementation (C. Daobao in Jingxi Huagong 1998, 15, p. 258ff. And p. 297ff., M. Li ibid., P. 294) even at current densities of 200-500 A / sqm.
Weitere Beispiele für die Verwendung von Bleikathoden sind die Reduktion von Aldehyden, Ketonen, Carbonsäuren und Carbonsäureestern zu Alkoholen, die Reduktion von Heterocyclen und Dehalogenierungen (Übersicht: M.M. Baizer in Organic Electrochemistry, Verlag Marcel Dekker, New York 1991, S. 362 ff., I. Nishiguchi et al., Electroorg. Synth. 1991, S. 331). Zahlreiche Prozesse werden auch großtechnisch mit Bleikathoden durchgeführt (Übersicht: "Industrial Electrochemistry" von Pletcher und Walsh, Chapman and Hall, London 1989, S. 313-319).Other examples of the use of lead cathodes are Reduction of aldehydes, ketones, carboxylic acids and carboxylic acid esters to alcohols, the reduction of heterocycles and Dehalogenations (overview: M.M. Baizer in Organic Electrochemistry, Marcel Dekker, New York 1991, p. 362 ff., I. Nishiguchi et al., Electroorg. Synth. 1991, p. 331). Numerous processes are also carried out on an industrial scale using lead cathodes (overview: "Industrial Electrochemistry" by Pletcher and Walsh, Chapman and Hall, London 1989, pp. 313-319).
Aufgrund der geringen mechanischen Stabilität des Bleis bei hohem Eigengewicht und der schwierigen Kontaktierbarkeit werden für industrielle Anwendungen, bei denen große Elektrodenflächen benötigt werden, Blei-plattierte Träger-kathoden, beispielsweise aus Kupfer oder Titan, bevorzugt (M.M. Baizer in Organic Electrochemistry, Verlag Marcel Dekker, New York 1991, S.274). Entsprechende Beschichtungsverfahren sind allerdings kostspielig und kompliziert. Hierbei ist man auf ebene Geometrien angewiesen, damit die Beschichtung eine gute Haftfähigkeit auf dem Träger erhält. Es ist ferner bekannt, daß Bleioberflächen leicht desaktiviert werden (EP 0 931 856), wodurch die Stromausbeuten und die Flächen-Zeit-Leistungen sinken. Ebenfalls ist die Korrosion von Bleielektroden beschrieben. Zur Regenerierung der Kathodenoberfläche muß die Elektrolysezelle jeweils komplett demontiert werden. Die dadurch entstehenden hohen Ausfallzeiten schränken die wirtschaftliche Nutzbarkeit stark ein.Due to the low mechanical stability of the lead high weight and difficult to connect are used for industrial applications where large Electrode surfaces are needed, lead-plated carrier cathodes, for example made of copper or titanium (M.M. Baizer in Organic Electrochemistry, Marcel Verlag Dekker, New York 1991, p.274). Corresponding coating processes are expensive and complicated, however. in this connection you have to rely on flat geometries so that the Coating receives good adhesion to the carrier. It it is also known that lead surfaces are easily deactivated be (EP 0 931 856), whereby the current efficiency and the Area-time benefits decrease. Corrosion is also described by lead electrodes. To regenerate the The electrolytic cell must have a complete cathode surface be dismantled. The resulting high downtime severely restrict economic usability.
Der Patentschrift DE 1 024 518 ist zu entnehmen, daß an Zinnkathoden bei einer Stromdichte von 500 A/qm Cystin zu Cystein mit 100 % Stromausbeute reduziert werden kann. Eigene Versuche zeigen, daß durch Erhöhung der Stromdichten bis auf 2000 A/qm an Zinn die Stromausbeuten auf unter 30% sinken, weil unter diesen Bedingungen die Wasserstoffentwicklung wesentlich früher einsetzt. Zudem nimmt die Stromausbeute bei Folgeversuchen weiter ab.The patent specification DE 1 024 518 shows that Tin cathodes at a current density of 500 A / sqm cystine too Cysteine can be reduced with 100% electricity yield. own Experiments show that by increasing the current densities up to 2000 A / m2 of tin the electricity yields drop below 30%, because under these conditions the evolution of hydrogen starts much earlier. In addition, the electricity yield increases Follow-up attempts continue.
Aufgabe der vorliegenden Erfindung ist daher die Bereitstellung einer Kathode mit hoher Wasserstoffüberspannung, die leicht herstellbar und regenerierbar ist und die sich zur Reduktion organischer Verbindungen in industriellem Maßstab eignet.The object of the present invention is therefore to provide a high hydrogen overvoltage cathode, the is easy to manufacture and regenerate and which is the Reduction of organic compounds on an industrial scale suitable.
Die Aufgabe wird gelöst durch eine Kathode bestehend aus einem elektrisch leitenden Träger mit einem Überzug aus elektrochemisch abgeschiedenem Blei mit einer Dichte zwischen 0,001 und 2 g/cm3.The object is achieved by a cathode consisting of an electrically conductive support with a coating of electrochemically deposited lead with a density between 0.001 and 2 g / cm 3 .
Diese Bleischicht besitzt eine lockere Struktur mit einer gegenüber massivem Blei stark verringerten Dichte im Bereich zwischen 0,001 und 2 g/cm3, bevorzugt zwischen 0,01 und 1 g/cm3. Die durch die verringerte Dichte belegte Oberflächenvergrößerung wirkt sich vorteilhaft auf die Flächen-Zeit-Leistung chemischer Prozesse aus.This lead layer has a loose structure with a density which is greatly reduced compared to solid lead in the range between 0.001 and 2 g / cm 3 , preferably between 0.01 and 1 g / cm 3 . The increase in surface area documented by the reduced density has an advantageous effect on the area-time performance of chemical processes.
Der Träger der erfindungsgemäßen Kathode besteht aus einem elektrisch leitenden Material, bevorzugt aus einem Metall ausgenommen einem Alkali- oder Erdalkalimetall oder einer Metallegierung oder Grafit.The carrier of the cathode according to the invention consists of a electrically conductive material, preferably made of a metal excluding an alkali or alkaline earth metal or one Metal alloy or graphite.
Besonders bevorzugt besteht der elektrisch leitende Träger aus einem Metall bzw. einer Metallegierung ausgewählt aus der Gruppe Kupfer, Nickel, Zinn, Zink, Titan, Eisen, Stahl, Edelstahl, Cadmium und Blei.The electrically conductive carrier particularly preferably consists of a metal or a metal alloy selected from the Group copper, nickel, tin, zinc, titanium, iron, steel, Stainless steel, cadmium and lead.
Als Legierungsbestandteile können ferner Elemente, ausgewählt aus der Gruppe Wolfram, Chrom, Kobalt, Molybdän, Mangan, Wismut, Aluminium, Quecksilber, Zirkonium, Vanadium, Silicium, Bor, Niob, Tantal, Antimon, Phosphor und Kohlenstoff, vorhanden sein.Elements can also be selected as alloy components from the group tungsten, chrome, cobalt, molybdenum, manganese, Bismuth, aluminum, mercury, zirconium, vanadium, silicon, Boron, niobium, tantalum, antimony, phosphorus and carbon, to be available.
Im folgenden umfaßt der Begriff Metall auch Metallegierungen, wie sie vorstehend ausgeführt sind.In the following, the term metal also includes metal alloys, as stated above.
Ein derartiger Träger kann mit einem oder mehreren weiteren der genannten Metalle beschichtet sein. Für die Beschichtung sind alle dem Fachmann bekannten Verfahren, wie z.B. Galvanisieren oder Sputtern geeignet.Such a carrier can be combined with one or more others of the metals mentioned. For the coating are all methods known to the person skilled in the art, e.g. Electroplate or sputtering.
Die Form des elektrisch leitenden Trägers ist unkritisch. Sie wird vorzugsweise aus der Vielzahl der bekannten bzw. verfügbaren Elektrodengeometrien, z.B. Platte, Netz, Schaum, Scheibe, Rohr, Siebplatte, Stab usw. ausgewählt. The shape of the electrically conductive carrier is not critical. she is preferably selected from the large number of known or available electrode geometries, e.g. Plate, net, foam, Washer, tube, sieve plate, rod etc. selected.
Die auf dem elektrisch leitenden Träger abgeschiedene Bleischicht ist durch eine gegenüber massivem Blei verringerte Dichte im Bereich von 0,001 bis 2 g/cm3, bevorzugt zwischen 0,01 und 1 g/cm3 ausgezeichnet.The lead layer deposited on the electrically conductive carrier is distinguished by a reduced density in the range from 0.001 to 2 g / cm 3 , preferably between 0.01 and 1 g / cm 3 , compared to solid lead.
Die Erfindung betrifft ferner ein Verfahren zur Herstellung einer erfindungsgemäßen Kathode.The invention further relates to a method of manufacture a cathode according to the invention.
Die Herstellung einer erfindungsgemäßen Kathode ist dadurch gekennzeichnet, daß in einer an sich bekannten Elektrolysezelle an einem elektrisch leitenden Träger, der als Kathode geschaltet ist, aus einer Bleisalz-haltigen wäßrigen Katholyt-Lösung mittels elektrochemischer Abscheidung eine Bleischicht mit verringerter Dichte abgeschieden wird.The production of a cathode according to the invention is thereby characterized in that in a known electrolysis cell on an electrically conductive support that acts as a cathode is switched from an aqueous catholyte solution containing lead salt a layer of lead by means of electrochemical deposition is deposited with reduced density.
Als Elektrolysezelle ist jede dem Fachmann bekannte Zelle geeignet. Eine Auswahl häufig verwendeter Zellen findet sich in Lehrbüchern, z. B. in "Industrial Electrochemistry" von Pletcher und Walsh, Chapman and Hall, London 1989, S. 141-166.Any cell known to the person skilled in the art is an electrolytic cell suitable. A selection of frequently used cells can be found in textbooks, e.g. B. in "Industrial Electrochemistry" by Pletcher and Walsh, Chapman and Hall, London 1989, pp. 141-166.
Als Bleisalze für die Bleisalz-haltige wäßrige Lösung eignen sich alle Bleisalze, die Blei in der zweiten Wertigkeitsstufe enthalten, z.B. Blei(II)carbonat, Blei(II)chlorid, Blei(II)fluorid, Blei(II)acetat, Blei(II)formiat, Blei(II)oxalat, Blei(II)nitrat sowie deren basische Salze, Blei(II)sulfat und Blei(II)oxid.Suitable as lead salts for the aqueous solution containing lead salt all lead salts, the lead in the second level included, e.g. Lead (II) carbonate, lead (II) chloride, Lead (II) fluoride, lead (II) acetate, lead (II) formate, Lead (II) oxalate, lead (II) nitrate and their basic salts, Lead (II) sulfate and lead (II) oxide.
Es kann auch eine Kombination metallisches Blei mit einer entsprechenden Säure, aus welcher sich dann eine Bleisalz-haltige Lösung bildet, verwendet werden.It can also be a combination of a metallic lead corresponding acid, from which a lead salt containing is then obtained Solution forms can be used.
Als Lösungsmittel eignet sich Wasser unter Zusatz von Mineralsäuren, bevorzugt Salzsäure, Schwefelsäure und Phosphorsäure in einer Konzentration zwischen 0.5 M und 12 M, im Falle von Salzsäure bis zu 8.5 M (konz. Salzsäure) . Weitere mögliche Zusätze sind organische Säuren, z.B. Essigsäure, Ameisensäure, Citronensäure, Milchsäure oder deren Salze mit Ammonium-, Tetraalkylammonium, Natrium- oder Kaliumionen, oder Komplexbildner für zweiwertige Bleiionen, beispielsweise EDTA oder NTA in Mengen von 1 bis 3 Äquivalenten bezogen auf die vorhandene Menge an Blei.Water with the addition of is suitable as a solvent Mineral acids, preferably hydrochloric acid, sulfuric acid and Phosphoric acid in a concentration between 0.5 M and 12 M, in the case of hydrochloric acid up to 8.5 M (conc. hydrochloric acid). Other possible additives are organic acids, e.g. Acetic acid, formic acid, citric acid, lactic acid or their salts with ammonium, tetraalkylammonium, sodium or Potassium ions, or complexing agents for divalent lead ions, for example EDTA or NTA in amounts of 1 to 3 Equivalents based on the amount of lead present.
Gegebenenfalls kann die Bleisalz-haltige Lösung zusätzlich anorganische Salze als Leitsalze enthalten. Beispiele hierfür sind alle Alkali-, Erdalkalimetall- und Ammoniumsalze, z. B. Natriumchlorid, Natriumsulfat, Ammoniumchlorid, Lithiumperchlorat.If necessary, the solution containing lead salt can additionally contain inorganic salts as conductive salts. Examples of this are all alkali, alkaline earth metal and ammonium salts, e.g. B. Sodium chloride, sodium sulfate, ammonium chloride, Lithium perchlorate.
Gegebenenfalls kann die Bleisalz-haltige wäßrige Lösung ferner wassermischbare Cosolventien wie Ethanol, Methanol, i-Propanol, n-Propanol, Acetonitril, Ethylenglycol, Ethylenglycolmonomethylether, Ethylenglycolmonoethylether, Tetrahydrofuran, 1,4-Dioxan, Essigsäuremethylester, Essigsäureethylester, Ameisensäure, Dimethylformamid, Sulfolan, Ethylencarbonat, N,N'-Dimethylpropylenharnstoff, N,N'-Dimethylethylenharnstoff, N-Methylpyrrolidon, Tetramethylharnstoff und Hexamethylphosphorsäuretriamid in Konzentrationen von 0,1 bis 80-Gew.%, bevorzugt 1 bis 50 Gew. % enthalten.If appropriate, the aqueous solution containing lead salt can also be used water-miscible cosolvents such as ethanol, methanol, i-propanol, n-propanol, acetonitrile, ethylene glycol, Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Tetrahydrofuran, 1,4-dioxane, methyl acetate, Ethyl acetate, formic acid, dimethylformamide, Sulfolane, ethylene carbonate, N, N'-dimethylpropyleneurea, N, N'-dimethylethylene urea, N-methylpyrrolidone, Tetramethylurea and hexamethylphosphoric triamide in Concentrations of 0.1 to 80% by weight, preferably 1 to 50% by weight. % contain.
Die Bleiionenkonzentration liegt in der Bleisalz-haltigen wäßrigen Lösung bevorzugt zwischen 1 ppm und 20 g/l, besonders bevorzugt zwischen 10 ppm und 10 g/l.The lead ion concentration lies in the lead salt-containing one aqueous solution preferably between 1 ppm and 20 g / l, especially preferably between 10 ppm and 10 g / l.
Der pH-Wert der Elektrolyselösung liegt bevorzugt zwischen 1
und 6, besonders bevorzugt zwischen 1 und 3.
Die Abscheidung der Bleischicht wird vorzugsweise durch
Anlegen eines Kathodenpotentials zwischen -0,1 V und des
Wertes, bei dem Wasserstoffentwicklung an der Kathode
einsetzt, erreicht. Stromdichten von 0,1 A/m2 bis 4000 A/m2,
bevorzugt 10 bis 3000 A/m2 werden hierbei eingestellt.The pH of the electrolysis solution is preferably between 1 and 6, particularly preferably between 1 and 3.
The deposition of the lead layer is preferably achieved by applying a cathode potential between -0.1 V and the value at which hydrogen evolution starts at the cathode. Current densities of 0.1 A / m 2 to 4000 A / m 2 , preferably 10 to 3000 A / m 2 are set here.
Die Temperatur ist bei der Durchführung des Verfahrens unkritisch. Sie kann in weiten Bereichen frei gewählt werden. Eine untere Temperaturgrenze ist durch den Gefrierpunkt der Katholytlösung gegeben, eine obere Grenze durch die Stabilität der Elektrolysezelle. Im Falle von Membranzellen ist dies insbesondere die thermische Stabilität der Membran. In diesem Fall ist die Temperatur auf maximal 60°C begrenzt.The temperature is when performing the procedure critical. It can be freely selected in a wide range. A lower temperature limit is due to the freezing point Given catholyte solution, an upper limit due to the stability the electrolytic cell. In the case of membrane cells, this is especially the thermal stability of the membrane. In this In this case, the temperature is limited to a maximum of 60 ° C.
Die Ausbildung der Bleischicht kann vor oder auch gleichzeitig mit der Reduktion einer organischen Verbindung erfolgen.The formation of the lead layer can be before or at the same time with the reduction of an organic compound.
Die Erfindung betrifft daher auch ein Verfahren zur elektrochemischen Reduktion einer organischen Verbindung, dadurch gekennzeichnet, daß anstelle einer herkömmlichen Kathode aus massivem Blei oder einer Kathode mit einer massiven Bleibeschichtung, z.B. eines Bleifilms, die erfindungsgemäße Kathode verwendet wird.The invention therefore also relates to a method for electrochemical Reduction of an organic compound, thereby characterized in that instead of a conventional cathode solid lead or a cathode with a solid Lead coating, e.g. a lead film, the invention Cathode is used.
Diese Verfahren können analog zu den bekannten elektrochemischen Verfahren zur Reduktion solcher Verbindungen unter Verwendung der erfindungsgemäßen Kathode durchgeführt werden. (Übersicht: M.M. Baizer in Organic Electrochemistry, Verlag Marcel Dekker, New York 1991, S. 362 ff.)These methods can be analogous to the known electrochemical ones Process for reducing such compounds under Use of the cathode according to the invention can be carried out. (Overview: M.M. Baizer in Organic Electrochemistry, publisher Marcel Dekker, New York 1991, pp. 362 ff.)
Die zu reduzierende Verbindung ist bevorzugt eine organische
Schwefelverbindung, z. B. eine Disulfidverbindung, eine
Sulfinsäure, Sulfoxid oder ein Thioether, oder eine organische
Carbonylverbindung, z.B. ein Aldehyd oder Keton.
Besonders bevorzugte Disulfidverbindungen sind Cystin, N-Alkanoyl-cystin,
Homocystin und N-Alkanoylhomocystin.
Die Konzentration der zu reduzierenden Verbindung beträgt 0.01
M bis 10 M, bevorzugt 0.1 bis 5 M. Als Solvens wird
vorzugsweise eine wässrige Lösung von Mineralsäure, z.B.
Salzsäure, Schwefelsäure oder Phosphorsäure, oder von Natrium -
oder Kaliumhydroxid, Natrium- oder Kaliumcarbonat oder
-acetat, Ammoniak, Ammoniumchlorid oder Ammoniumacetat in
Konzentrationen zwischen 0.1 M und 12 M verwendet.
Die elektrochemische Reduktion des Cystins und Homocystins
wird bevorzugt in wässriger Salzsäure, Schwefelsäure, Natrium-oder
Kaliumhydroxidlösung oder in ammoniakalischer Lösung
durchgeführt. Die Konzentration des Cystins kann zwischen 0.1
M und der Sättigungskonzentration liegen. Besonders bevorzugt
sind gesättigte Cystin- bzw. Homocystinlösungen.
Die Reduktion von N-Acetylcystin wird bevorzugt bei pH-Werten
zwischen 5 und 13 durchgeführt.
Die Elektrolysen werden bei Temperaturen zwischen 0°C und 70°C
durchgeführt, bevorzugt bei Temperaturen zwischen 10°C und
50°C.
Stromdichten betragen 0.1 A/qm bis 20000 A/qm, bevorzugt 10-5000
A/qm.The compound to be reduced is preferably an organic sulfur compound, e.g. B. a disulfide compound, a sulfinic acid, sulfoxide or a thioether, or an organic carbonyl compound, for example an aldehyde or ketone.
Particularly preferred disulfide compounds are cystine, N-alkanoyl-cystine, homocystine and N-alkanoyl homocystine.
The concentration of the compound to be reduced is 0.01 M to 10 M, preferably 0.1 to 5 M. The solvent used is preferably an aqueous solution of mineral acid, for example hydrochloric acid, sulfuric acid or phosphoric acid, or of sodium or potassium hydroxide, sodium or potassium carbonate or acetate , Ammonia, ammonium chloride or ammonium acetate used in concentrations between 0.1 M and 12 M.
The electrochemical reduction of cystine and homocystine is preferably carried out in aqueous hydrochloric acid, sulfuric acid, sodium or potassium hydroxide solution or in an ammoniacal solution. The concentration of the cystine can be between 0.1 M and the saturation concentration. Saturated cystine or homocystine solutions are particularly preferred.
The reduction of N-acetylcystine is preferably carried out at pH values between 5 and 13.
The electrolysis is carried out at temperatures between 0 ° C and 70 ° C, preferably at temperatures between 10 ° C and 50 ° C.
Current densities are 0.1 A / m2 to 20,000 A / m2, preferably 10-5000 A / m2.
Für die Reduktion von organischen Schwefel- und Sauerstoffverbindungen können alle dem Fachmann bekannten geteilten Zellen verwendet werden (Übersicht z. B. in "Industrial Electrochemistry" von Pletcher und Walsh, Chapman and Hall, London 1989, S. 141-166.).For the reduction of organic sulfur and Oxygen compounds can all be known to the person skilled in the art divided cells can be used (overview e.g. in "Industrial Electrochemistry" by Pletcher and Walsh, Chapman and Hall, London 1989, pp. 141-166.).
Mit Hilfe der erfindungsgemäßen Kathode kann Cysteinhydrochlorid aus Cystin in einer salzsauren Elektrolyselösung bei der ungewöhnlich hohen Stromdichte von 2000 A/qm mit einer Flächen-Zeit-Leistung von 7,3 kg Cysteinhydrochlorid-hydrat pro Std. und qm Membranfläche hergestellt werden (siehe G1.1 in Schema 1). Diese Flächen-Zeit-Leistung ist bis mindestens 5 Tage Betriebsdauer konstant. In der Elektrolyselösung ist bei einer Nachweisgrenze von 0,5 ppm kein Blei nachweisbar.With the help of the cathode according to the invention, cysteine hydrochloride from cystine in a hydrochloric acid electrolysis solution the unusually high current density of 2000 A / qm with a Area-time performance of 7.3 kg of cysteine hydrochloride hydrate per hour and sqm of membrane area are produced (see G1.1 in scheme 1). This area-time performance is up to at least 5 Days of operation constant. In the electrolysis solution is at a detection limit of 0.5 ppm no lead was detectable.
Ein Vergleichsexperiment mit einer herkömmlichen Kathode aus massivem Blei ergab bei 2000 A/qm eine Flächen-Zeit-Leistung von nur ca. 4 kg pro Std. und qm Membranfläche. Insbesondere bei Umsätzen von über 90 % tritt bei den hohen Stromdichten im Falle der herkömmlichen Bleikathode eine starke Verlangsamung der Umsetzung durch Vorherrschen der Wasserstoffentwicklung auf. Dies ist ebenso bei Verwendung der in DE 1 024 518 beschriebenen Zinn-Kathode zu beobachten (siehe Vergleichsbeispiele 7 und 8).A comparison experiment with a conventional cathode solid lead gave an area-time performance at 2000 A / sqm of only approx. 4 kg per hour and sqm membrane area. In particular with sales of over 90% occurs at the high current densities in the In the case of the conventional lead cathode, a strong slowdown implementation by prevailing hydrogen evolution on. This is also the case when using DE 1 024 518 to observe the tin cathode described (see Comparative Examples 7 and 8).
Mit der erfindungsgemäßen Kathode können auch weitere Reduktionen, wie z.B. die Homolyse von aktivierten C-S-Bindungen, die Reduktion von Sulfinsäuren oder die Reduktion von Ketogruppen sehr leicht durchgeführt werden.With the cathode according to the invention, others can also Reductions such as the homolysis of activated C-S bonds, the reduction of sulfinic acids or the reduction can be carried out very easily by keto groups.
Die folgenden Schemata (Schema 1) verdeutlichen beispielhaft weitere Anwendungsmöglichkeiten. The following schemes (scheme 1) illustrate examples of other possible uses.
Die Reduktion von Cysteinsulfinsäure führt zur Bildung des
Cystin-(S,S)-dioxids (Gleichung 2)
Die Reduktion von 2,4-Dicarboxy-2-methyl-thiazolidin führt zur
Bildung von N-(1-Carboxyethyl)cystein (Gleichung 3). Reduction of cysteine sulfinic acid leads to the formation of cystine (S, S) dioxide (Equation 2)
The reduction of 2,4-dicarboxy-2-methyl-thiazolidine leads to the formation of N- (1-carboxyethyl) cysteine (equation 3).
Brenztraubensäure wird quantitativ zu Milchsäure reduziert (Gleichung 4).Pyruvic acid is reduced quantitatively to lactic acid (Equation 4).
Ein weiterer Vorteil der erfindungsgemäßen Kathode ist ihre leichte Regenerierbarkeit. Die Regenerierung ist ohne Demontage der Zelle möglich. Die Bleischicht wird dabei in einer Ausführungsform durch Spülen des Katholytraums mit Wasser oder mit der Katholytflüssigkeit mechanisch entfernt.Another advantage of the cathode according to the invention is its easy regenerability. The regeneration is without Disassembly of the cell possible. The lead layer is in an embodiment by rinsing the catholyte space with Water or mechanically removed with the catholyte.
In einer weiteren Ausführungsform wird die Bleischicht teilweise oder ganz aufgelöst. Hierzu eignen sich wäßrige Lösungen von Mineralsäuren oder organischen Säuren in Konzentrationen zwischen 0,1 und 10 M außer Schwefelsäure. Beispiele hierfür sind Salzsäure, Phosphorsäure oder Essigsäure. Gegebenenfalls können der wäßrigen Säurelösung Komplexbildner zur Löslichkeitserhöhung des entstehenden Bleisalzes in Mengen zwischen 0,5 und 5 Äquivalenten bezogen auf die aufzulösende Bleimenge zugesetzt werden. Komplexbildner für Blei(II)ionen sind z.B. EDTA, NTA und Citronensäure. Die Temperaturen liegen hierbei innerhalb des Arbeitsbereichs der elektrochemischen Zelle.In a further embodiment, the lead layer becomes partial or completely dissolved. Aqueous solutions are suitable for this of mineral acids or organic acids in concentrations between 0.1 and 10 M except for sulfuric acid. Examples of this are hydrochloric acid, phosphoric acid or acetic acid. Possibly can the aqueous acid solution complexing Increasing the solubility of the resulting lead salt in quantities between 0.5 and 5 equivalents based on that to be resolved Amount of lead can be added. Complexing agent for lead (II) ions are e.g. EDTA, NTA and citric acid. The temperatures are here within the working area of electrochemical Cell.
Zum Schutz der Elektrode vor Korrosion wird während des Abtrags des Bleischicht eine Schutzspannung aufrechterhalten.To protect the electrode from corrosion during the Maintain a protective voltage to remove the lead layer.
Die folgenden Beispiele erläutern die Erfindung weiter.The following examples further illustrate the invention.
Verwendete Zelle: Eine mittels einer Membran aus Nafion 324
(Elektroden- bzw. Membranfläche 0,01 m2) geteilte Zelle mit
planparallel angeordneten Elektroden bestehend aus einer
Kupferkathode, einer Sauerstoff-entwickelnden DSA-Anode (Fa.
DeNora Deutschland GmbH, Anolyt: 20 proz. Schwefelsäure).
Der Elektroden-Membranabstand betrug 1,8 cm.
Katholyt- und Anolytlösung wurden aus Reservoirs durch die
Zelle gepumpt (batch-recycle-Betrieb). Cell used: a cell divided by means of a membrane made of Nafion 324 (electrode or membrane area 0.01 m 2 ) with electrodes arranged plane-parallel and consisting of a copper cathode, an oxygen-developing DSA anode (DeNora Deutschland GmbH, anolyte: 20 percent sulfuric acid). The electrode-membrane distance was 1.8 cm.
Catholyte and anolyte solutions were pumped through the cell from reservoirs (batch recycle operation).
Durch Umpumpen des Katholyten bestehend aus einer Lösung von 2,00 g basischem Bleicarbonat in 1,8 1 1N HCl bei Durchflußraten von 1-2 1/h und einer Stromstärke I von 5 A wurde Blei an der Kathode in lockerer Struktur abgeschieden. Nach 5 h Reaktionszeit betrug der Restgehalt an Blei in Lösung 21,8 ppm.By pumping the catholyte consisting of a solution of 2.00 g of basic lead carbonate in 1.8 1 1N HCl Flow rates of 1-2 1 / h and a current I of 5 A. lead was deposited on the cathode in a loose structure. After a reaction time of 5 h, the residual content of lead in solution was 21.8 ppm.
Analog zu Beispiel 1 erfolgte die elektrolytische Abscheidung
des Bleis an der Kupferkathode aus einer Lösung von 2,00 g
basischem Bleicarbonat in einer Lösung aus 360 g Cystin und
367 g konz. HCl in 1314 g Wasser bei 6,9 A.
Reaktionszeit: 15 h.
Restgehalt an Blei in Lösung < 0,5 ppm.
Umsatz von Cystin zu Cysteinhydrochlorid: 99,7 % (gemessen mit
HPLC und Drehwert α).Analogously to Example 1, the electrolytic deposition of the lead on the copper cathode was carried out from a solution of 2.00 g of basic lead carbonate in a solution of 360 g of cystine and 367 g of conc. HCl in 1314 g water at 6.9 A.
Response time: 15 h.
Residual content of lead in solution <0.5 ppm.
Conversion of cystine to cysteine hydrochloride: 99.7% (measured with HPLC and rotation value α).
In der Elektrolyseapparatur nach Beispiel 1 mit der nach Beispiel 1 vorbereiteten Kathode wurde 1,00 kg Cystin in 3,65 1 Wasser und 1019 g konz. HCl bei einer Stromdichte von 2000 A/qm und Umpumpraten von 10-12 1/h zu Cysteinhydrochlorid umgesetzt. Nach 11 h waren 90 % des Cystins zu Cysteinhydrochlorid umgesetzt. Die Umsetzung war nach 20 h vollständig. (Umsetzungsgrad >99,7 %, bestimmt mit HPLC). Chemische Ausbeute > 99,9 % (Untersuchung der nach mehrfach durchgeführter Kristallisation erhaltenen Mutterlauge). Errechnete Flächen-Zeit-Leistung: 7,31 kg Cysteinhydrochlorid-monohydrat pro Std. und qm Membranfläche.In the electrolysis apparatus according to example 1 with that according to example 1 prepared cathode was 1.00 kg cystine in 3.65 1 Water and 1019 g conc. HCl at a current density of 2000 A / qm and pumping rates of 10-12 1 / h to cysteine hydrochloride implemented. After 11 hours, 90% of the cystine was cysteine hydrochloride implemented. The reaction was complete after 20 hours. (Degree of conversion> 99.7%, determined by HPLC). Dry Yield> 99.9% (examination of the after several Crystallization obtained mother liquor). Calculated Area-time performance: 7.31 kg cysteine hydrochloride monohydrate per hour and sqm of membrane area.
In einer 0,01 qm ElectroMPCell (Fa. ElectroCell AB, Tåby,
Schweden) mit verzinnter Kupferkathode, DSA-Anode (Fa.
Parmascand, Schweden) und Nafion-324-Kationenaustauschermembran
wurde wie in Beispiel 2 beschrieben eine lockere
Bleischicht abgeschieden (Umpumprate 1-2 l/h). Anschließend
wurden analog zu Beispiel 3 4,0 kg Cystin bei 2000 A/qm zu
Cysteinhydrochlorid umgesetzt (Umpumprate 12 l/h). Die
Reaktionsdauer betrug 79 Std.
Errechnete Flächen-Zeit-Leistung 7,41 kg Cysteinhydrochlorid-monohydrat
pro qm Membranfläche und pro Std.In a 0.01 square meter ElectroMPCell (ElectroCell AB, Tåby, Sweden) with tinned copper cathode, DSA anode (Parmascand, Sweden) and Nafion 324 cation exchange membrane, a loose lead layer was deposited as described in Example 2 (pumping rate 1 -2 l / h). Then, analogously to Example 3, 4.0 kg of cystine were converted to cysteine hydrochloride at 2000 A / m 2 (pumping rate 12 l / h). The reaction time was 79 hours.
Calculated area-time performance 7.41 kg cysteine hydrochloride monohydrate per sqm membrane area and per hour
In einer 0,01 qm ElectroMPCell (Fa. ElectroCell AB, Tåby,
Schweden) mit Nickel-Kathode, einer Sauerstoff-entwickelnden
DSA-Anode (Fa. Parmascand, Schweden) und Nafion-324-Kationenaustauschermembran
wurde wie in Beispiel 2 beschrieben
eine lockere Bleischicht abgeschieden (Umpumprate 1-2 l/h).
Anschließend wurden 360 g Cystin zu Cysteinhydrochlorid analog
zu Beispiel 4 umgesetzt. Nach 7,0 h Reaktionszeit war die
Umsetzung vollständig. (Umsetzungsgrad >99,7 %, bestimmt mit
HPLC).
Errechnete Flächen-Zeit-Leistung 7,52 kg Cysteinhydrochlorid-monohydrat
pro qm Membranfläche und pro Std.In a 0.01 square meter ElectroMPCell (ElectroCell AB, Tåby, Sweden) with nickel cathode, an oxygen-developing DSA anode (Parmascand, Sweden) and Nafion-324 cation exchange membrane, a loose was as described in Example 2 Lead layer deposited (pumping rate 1-2 l / h). Then 360 g of cystine were converted to cysteine hydrochloride analogously to Example 4. The reaction was complete after a reaction time of 7.0 hours. (Degree of conversion> 99.7%, determined by HPLC).
Calculated area-time output 7.52 kg of cysteine hydrochloride monohydrate per square meter of membrane area and per hour.
Analog zu Beispiel 1 wurde aus 750 mg gelöstem Bleiweiß lockeres Blei auf einer Bleikathode abgeschieden. 1,00 kg Cystin wurde wie in Beispiel 3 zu Cysteinhydrochlorid reduziert. Gesamtreaktionsdauer: 21,8 Std. Berechnete Flächen-Zeit-Leistung: 6,71 kg Cysteinhydrochlorid-monohydrat pro qm Membranfläche und pro Std.. Analogously to Example 1, 750 mg of dissolved lead white was used loose lead deposited on a lead cathode. 1.00 kg As in Example 3, cystine became cysteine hydrochloride reduced. Total reaction time: 21.8 hours. Calculated area-time performance: 6.71 kg cysteine hydrochloride monohydrate per square meter Membrane area and per hour.
In einer Elektrolysezelle mit einer Bleiplatte als Kathode wurde wie in Beispiel 3 360 g Cystin zu Cysteinhydrochlorid reduziert. Gesamtreaktionsdauer 9,4 Std. Errechnete Flächen-Zeit-Leistung 4 kg Cysteinhydrochlorid-monohydrat pro qm Membranfläche und pro Std.In an electrolytic cell with a lead plate as the cathode 360 g of cystine became cysteine hydrochloride as in Example 3 reduced. Total reaction time 9.4 hours. Calculated area-time performance 4 kg of cysteine hydrochloride monohydrate per square meter Membrane area and per hour
In einer Elektrolyseapparatur nach Beispiel 4 mit einer
verzinnten Kupferplatte als Kathode wurde eine Katholytlösung
aus 360 g Cystin, 3,00 g Zinn(II)chlorid- dihydrat, bei einem
Durchfluß von 1-2 1/h und einer Stromstärke I von 5 A
umgesetzt. Nach einer Reaktionsdauer von 22 h betrug der
Umsatz zu Cystein 98,1% (HPLC-Analyse). Der Zinngehalt der
Lösung betrug nach dieser Zeit noch ca. 0,7 ppm (entspr. ca.
0,6 mg).
Die Katholytlösung wurde aus Zelle und Vorratsbehälter
abgelassen und durch eine Lösung von 1,00 kg Cystin, 1019 g
konz. HCl und 3651 g Wasser ersetzt. Diese wurde bei einer
Stromstärke von 20 A und einem Durchfluß von 11 l/h umgesetzt.
Nach einer Reaktionszeit von 15,2 Std. waren 90 % Cystin
umgesetzt. Nach 24 h enthielt die Lösung noch 2,7 % Cystin.In an electrolysis apparatus according to Example 4 with a tinned copper plate as the cathode, a catholyte solution of 360 g cystine, 3.00 g tin (II) chloride dihydrate was reacted at a flow rate of 1-2 l / h and a current I of 5 A. , After a reaction time of 22 h, the conversion to cysteine was 98.1% (HPLC analysis). After this time, the tin content of the solution was still approximately 0.7 ppm (corresponding to approximately 0.6 mg).
The catholyte solution was drained from the cell and reservoir and through a solution of 1.00 kg of cystine, 1019 g of conc. HCl and 3651 g of water replaced. This was implemented at a current of 20 A and a flow of 11 l / h. After a reaction time of 15.2 hours, 90% cystine had been converted. After 24 hours, the solution still contained 2.7% cystine.
In einer Elektrolyseapparatur bestehend aus einer Elektrolysezelle mit scheibenförmigen Elektroden (Anode: DSA-Titan-Streckmetall, Kathode: Blei-Siebplatte mit locker abgeschiedenem Blei, Elektroden beidseitig genutzt und jeweils mit Hilfe von konzentrisch angeschweißten Stäben aufgehängt, Durchmesser 7,5 cm) und der wie in Beispiel 1 aufgebauten Peripherie wurde eine Lösung aus 1,523 g L-Cysteinsulfinsäuremonohydrat in 600 ml 2N Salzsäure bei 10 A und einer Reaktionstemperatur von 15°C 4,5 h umgesetzt. Die Reaktionslösung enthält 60 % Cystin-(S,S)-dioxid, 20 % Cystinsulfinsäure und 20 % Cystin (1H-NMR-spektroskopische Untersuchung).In an electrolysis apparatus consisting of an electrolysis cell with disc-shaped electrodes (anode: DSA titanium expanded metal, cathode: lead sieve plate with loosely separated lead, electrodes used on both sides and each suspended with the help of concentrically welded rods, diameter 7.5 cm) and the As in the periphery constructed in Example 1, a solution of 1.523 g of L-cysteine sulfinic acid monohydrate in 600 ml of 2N hydrochloric acid was reacted at 10 A and a reaction temperature of 15 ° C. for 4.5 hours. The reaction solution contains 60% cystine (S, S) dioxide, 20% cystine sulfinic acid and 20% cystine ( 1 H-NMR spectroscopic examination).
In der Elektrolyseapparatur nach Beispiel 10 wurde eine Lösung von 130,0 g 2,4-Dicarboxy-2-methyl-thiazolidin in einer Mischung von 526 ml Wasser und 144 g Salzsäure bei 9,5 A und Temperaturen von 16-20°C umgesetzt. Nach 5 Std. Reaktionszeit wurden 66 % N-(1-carboxyethyl)cystein, 19 % Milchsäure und 15 % Cystein erhalten. Die Reaktionslösung wurde eingedampft und der Feststoff aus 0,5 M Salzsäure unter Sauerstoffausschluß umkristallisiert. Man erhält N-(1-Carboxyethyl)cystein in Form von farblosen Kristallen.A solution was found in the electrolysis apparatus according to Example 10 of 130.0 g of 2,4-dicarboxy-2-methyl-thiazolidine in one Mixture of 526 ml water and 144 g hydrochloric acid at 9.5 A and Temperatures of 16-20 ° C implemented. After a reaction time of 5 hours 66% N- (1-carboxyethyl) cysteine, 19% lactic acid and 15 % Cysteine received. The reaction solution was evaporated and the solid from 0.5 M hydrochloric acid with exclusion of oxygen recrystallized. N- (1-carboxyethyl) cysteine is obtained in the form of colorless crystals.
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US2422468A (en) * | 1942-07-04 | 1947-06-17 | Standard Oil Dev Co | Electrolytic production of pinacols |
DE1024518B (en) * | 1955-11-29 | 1958-02-20 | Aschaffenburger Zellstoffwerke | Process for the production of cysteine hydrochloride |
US2925371A (en) * | 1956-06-01 | 1960-02-16 | Carwin Company | Electrolytic cell |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2485258A (en) * | 1944-01-03 | 1949-10-18 | Standard Oil Dev Co | Electrodepositing lead on copper from a nitrate bath |
CA1232227A (en) * | 1982-02-18 | 1988-02-02 | Christopher Vance | Manufacturing electrode by immersing substrate in aluminium halide and other metal solution and electroplating |
DE4319951A1 (en) * | 1993-06-16 | 1994-12-22 | Basf Ag | Electrode consisting of an iron-containing core and a lead-containing coating |
US5626738A (en) * | 1995-11-17 | 1997-05-06 | American Health Foundation | Methods for the separation and detection of nitrosothiols |
ES2108654B1 (en) * | 1996-05-07 | 1998-07-01 | Univ Alicante | PROCEDURE FOR THE ELECTROCHEMICAL SYNTHESIS OF N-ACETILCISTEINA FROM CISTINA. |
DE19620861A1 (en) * | 1996-05-23 | 1997-11-27 | Basf Ag | Process for the electrochemical reduction of organic compounds |
-
2000
- 2000-08-10 DE DE10039171A patent/DE10039171A1/en not_active Withdrawn
-
2001
- 2001-07-26 EP EP01117681A patent/EP1179612B1/en not_active Expired - Lifetime
- 2001-07-26 ES ES01117681T patent/ES2213657T3/en not_active Expired - Lifetime
- 2001-07-26 DE DE50101464T patent/DE50101464D1/en not_active Expired - Lifetime
- 2001-08-09 JP JP2001242325A patent/JP3392125B2/en not_active Expired - Fee Related
- 2001-08-10 US US09/927,227 patent/US6669828B2/en not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2422468A (en) * | 1942-07-04 | 1947-06-17 | Standard Oil Dev Co | Electrolytic production of pinacols |
DE1024518B (en) * | 1955-11-29 | 1958-02-20 | Aschaffenburger Zellstoffwerke | Process for the production of cysteine hydrochloride |
US2925371A (en) * | 1956-06-01 | 1960-02-16 | Carwin Company | Electrolytic cell |
Also Published As
Publication number | Publication date |
---|---|
JP2002105686A (en) | 2002-04-10 |
US20020027083A1 (en) | 2002-03-07 |
JP3392125B2 (en) | 2003-03-31 |
ES2213657T3 (en) | 2004-09-01 |
EP1179612B1 (en) | 2004-02-11 |
DE10039171A1 (en) | 2002-02-28 |
US6669828B2 (en) | 2003-12-30 |
DE50101464D1 (en) | 2004-03-18 |
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