Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B3/00—Electrolytic production of organic compounds
  • C25B3/20—Processes
  • C25B3/23—Oxidation
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/10—Bleaching ; Apparatus therefor
  • D21C9/1021—Electrochemical processes
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06L—DRY-CLEANING, WASHING OR BLEACHING FIBRES, FILAMENTS, THREADS, YARNS, FABRICS, FEATHERS OR MADE-UP FIBROUS GOODS; BLEACHING LEATHER OR FURS
  • D06L4/00—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs
  • D06L4/50—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs by irradiation or ozonisation
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/10—Bleaching ; Apparatus therefor
  • D21C9/1026—Other features in bleaching processes
  • D21C9/1036—Use of compounds accelerating or improving the efficiency of the processes

Definitions

• the invention relates to a system for the electrochemical splitting of compounds as well as procedures for its Application.
• lignin Under the generic term 'materials containing lignin' it adds up a variety of renewable raw materials, e.g. Wood, grass, other non-wood-forming plants such as hemp or cotton and the like intermediate and final products, e.g. Pulp, pulp, Paper and textiles.
• the materials containing lignin are general water-insoluble. Lignin is involved in these materials in complex structures, e.g. Fibers. Frequently, those containing lignin Materials e.g. for the production of high quality papers be 'delignified', i.e. the contained lignin must be completely or partially depolymerized so that it is completely or partially extracted from the lignin-containing materials can. This process must depolymerize lignin as selectively as possible, because the substances combined with lignin like celluloses and hemicelluloses usually should not be destroyed.
• the mostly multi-stage process of removing residual lignin is called bleaching.
• Lignin is removed and / or decolorized.
• three different bleaching processes can be distinguished.
• chlorine bleaching lignin can be removed very selectively and inexpensively using elemental chlorine.
• ECF bleaching 'elemental chlorine free'
• bleaching is achieved chlorine-free with chlorine dioxide.
• the so-called TCF bleaching total chlorine free'
• the bleaching is carried out completely without chlorine-containing compounds.
• Lignin oxidation is achieved, for example, by treatment with oxygen and / or ozone and / or peroxide and / or peracids.
• Chlorine bleach is now only used in old plants. Although technically and economically advantageous, this process must be substituted because the associated environmental pollution is no longer accepted.
• the release of chlorinated aromatic hydrocarbons is particularly problematic for the environment. With ECF processes, the environmental impact of chlorinated compounds is significantly lower than with chlorine bleach, but chlorinated hydrocarbons are also formed with this process.
• the Cl - content makes it difficult to 'close', ie the wastewater-free or wastewater-reduced operation of ECF bleaching plants, since a concentration of Cl - can lead to corrosion of the plants.
• TCF bleaching is preferable to the two processes described. It is problematic, however, that the totally chlorine-free bleaching agents have a lower selectivity than chlorine-containing compounds, ie in addition to the lignin polymerization, there is also damage to the cellulose and the hemicelluloses. This leads to loss of yield and fiber damage that can only be minimized by not performing the delignification completely.
• TCF bleached pulp paper is either of lower fiber quality or (and) lower brightness than ECF bleached pulp paper.
• TCF processes are economically unfavorable because they require large amounts of relatively expensive process chemicals (e.g. H 2 O 2 , peracetic acid, etc.).
• Hemicellulases such as xylanases or mannanases support by an indirect mechanism of action is the delignification of pulp.
• Wood essentially consists of cellulose, lignin and hemicelluloses. Through the enzymatic hydrolysis of hemicellulose chemical bleachability of pulp can be facilitated (Chang & Farrell (1995) Proceedings of the 6th International Conference on Biotechnology in the pulp and paper Industry: Advances in Applied and fundamental research, p. 75 ff; Suurnäkki et al. (1995) Proceedings of the 6th International Conference on Biotechnology in the pulp and paper Industry: Advances in Applied and fundamental research, p.69 ff).
• Active mediators are, for example, ABTS (Bourbonnais & Paice (1990) FEBS Letters 267: p. 99 ff), HOBT (WO-A-94/29510) and phenothiazines (WO-A-95/01426).
• the laccase is able to oxidize four mediator molecules and thereby takes up four electrons that ultimately come from the lignin. Then the four electrons are transferred to oxygen in a reaction step and two molecules of water are formed.
• the system of laccase and mediator thus catalyzes an oxygen-dependent lignin oxidation.
• the oxidized lignin can then be extracted, for example, by an alkaline treatment (WO-A-94/29510).
• laccases do not require the addition of H 2 O 2 and can therefore be used industrially.
• thermostable Xylanases isolated from thermophilic microorganisms that meet these conditions (Winterhalter et al. (1995) Molecular Microbiology 15: p. 431 ff) could still No laccases or peroxidases are developed that are sufficient have high temperature stability.
• the one for the laccase mediator system described range of application are 45 ° C and pH 4.5 (WO-A-94/29510).
• electrochemical processes are known which are used for paper bleaching be used. These procedures either Chemicals for conventional bleaching processes on site produced electrochemically and optionally regenerated, or metal complexes are used as mediators, which after activation react with the lignin at an electrode.
• the first group includes e.g. LN Spiridonova, VA Babkin, MI Anisimova, GS Mikhailov and TP Belovam, 'Delignification of high-yield larchwood pulp by oxidants generated by electrolysis', Khim. Drev. (1982), pp. 16-19.
• NaCl electrolysis produces oxidizing species such as ClO - , ClO 2 - and ClO 3 - .
• JM Gray 'Process for producing chlorine dioxide from chlorate in acidic medium' (Akzo Nobel Inc.) CA-A-2156125 and H. Falgen, G. Sundstroem, J. Landfors and JC Sokol, 'Electrolytic process of producing chlorine dioxide ', US-A-5487881.
• WO-A-90/15182 discloses solutions in solution Azo dyes using mediators and at least two electrodes to be modified electrochemically so that they are subsequently Wool or similar substrates react.
• the present invention relates to an electrochemical system Cleavage of compounds according to claim 1.
• the system according to the invention preferably enables delignification of pulp without the use of enzymes and without the Use of chlorine-containing compounds and without the use of complexes containing heavy metals.
• the aqueous mixture is aqueous Pulp with lignin material.
• system according to the invention is also suitable for cleavage and solubilizing other substances such as dyes.
• Such textiles can be used, for example, with different commercial dyes, in particular, can be colored with Indigo or indigo-related dyes such as thioindigo.
• the system according to the invention for the electrochemical activation of Mediators is structured as follows:
• the electrodes used can be the same or different.
• the electrodes consist for example of carbon, vanadium, Iron, chrome, cobalt, lead, copper, nickel, zinc, tantalum, titanium, Silver, platinum, platinum platinum, rhodium, gold or others Transition or precious metals and alloys from the above Compounds that may contain other elements.
• the electrodes are preferably made of materials selected from the group of precious metals, steels, stainless steels and carbon.
• the electrodes made of steel, Hastelloy®, Chrome nickel, chrome steel, aluminum chrome, Incoloy®, tantalum or titanium, Rhodium, platinum, gold or another precious metal.
• the electrodes are particularly preferably made of stainless steel again stainless steel of group 1.4xxx (according to DIN 17850) preferred are.
• the electrodes can optionally be coated with the oxygen compounds one or more of the specified components exhibit.
• the electrodes can be evaporated, sputtered, Electroplating, ion implantation or similar procedures with other substances are coated or doped.
• the surface of the electrodes can be made by suitable methods have been enlarged, e.g. by grinding, polishing, Sandblasting, etching or eroding.
• the system according to the invention therefore contains a or several so-called mediator molecules, which have the task after electrochemical activation by means of an electrode mediated reactivity, e.g. Oxidizing power, reducing power or radical property to transfer to the lignin.
• mediator molecules e.g. Oxidizing power, reducing power or radical property to transfer to the lignin.
• the mediator is selected from the group of aliphatic, cycloaliphatic, heterocyclic or aromatic NO, NOH or Links.
• the mediator is preferably at least one compound selected from the group of aliphatic, cycloaliphatic, heterocyclic or aromatic compounds which contains at least one N-hydroxy, oxime, nitroso, N-oxyl or N-oxi function.
• Examples of such compounds are the compounds of the formula I, II, III or IV mentioned below, the compounds of the formulas II, III and IV being preferred and the compounds of the formula III and IV being particularly preferred.
• the radicals R 7 to R 10 can be identical or different and independently of one another represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxy and salts and esters thereof, amino, nitro, C 1 -C 12 alkyl, C 1 -C 6- alkyloxy, carbonyl-C 1 -C 6 -alkyl, phenyl, sulfono, esters and salts thereof, sulfamoyl, carbamoyl, phospho, phosphono, phosphonooxy and their salts and esters and where the amino, carbamoyl and sulfamoyl Groups of the radicals R 7 to R 10 can furthermore be unsubstituted or mono- or disubstituted by hydroxy, C 1 -C 3 -alkyl, C 1 -C 3 -alkoxy and where the C 1 -C 12 -alkyl-, C 1 -C 6 -alkyloxy, carbonyl
• the radicals R 1 and R 4 to R 10 can be identical or different and independently of one another represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxy and salts and esters thereof, amino, nitro, C 1 -C 12 alkyl , C 1 -C 6 -alkyloxy, carbonyl-C 1 -C 6 -alkyl, phenyl, aryl, sulfono, esters and salts thereof, sulfamoyl, carbamoyl, phospho, phosphono, phosphonooxy and their salts and esters and where the amino, Carbamoyl and sulfamoyl groups of the radicals R 1 and R 4 to R 10 can furthermore be unsubstituted or substituted one or two times with hydroxy, C 1 -C 3 alkyl, C 1 -C 3 alkoxy and wherein the C 1 -C 12 alkyl, C 1 -C 6 alkyloxy, carbon
• R 14 can be: hydrogen, C 1 -C 10 alkyl, C 1 -C 10 alkylcarbonyl, their C 1 -C 10 alkyl and C 1 -C 10 alkylcarbonyl unsubstituted or with one or more R 15 radicals where R 15 can represent one of the following groups: hydrogen, halogen, hydroxy, formyl, carboxy and salts and esters thereof, amino, nitro, C 1 -C 12 alkyl, C 1 -C 6 alkyloxy, carbonyl C 1 -C 6 -alkyl, phenyl, sulfono, their esters and salts, sulfamoyl, carbamoyl, phospho, phosphono, phosphonooxy and their salts and esters, the amino, carbamoyl and sulfamoyl groups of the radical R 15 further being unsubstituted or can be substituted once or twice with hydroxy, C 1 -C 3 alkyl, C 1
• the radicals R 7 to R 10 can be identical or different and independently of one another represent one of the following groups: hydrogen, halogen, hydroxyl, formyl, carboxy and salts and esters thereof, amino, nitro, C 1 -C 12 alkyl, C 1 -C 6 -alkyloxy, carbonyl-C 1 -C 6 -alkyl, phenyl, sulfono, esters and salts thereof, sulfamoyl, carbamoyl, phospho, phosphono, phosphonooxy and their salts and esters and wherein the amino, carbamoyl and sulfamoyl Groups of the radicals R 7 to R 10 can furthermore be unsubstituted or mono- or disubstituted by hydroxy, C 1 -C 3 -alkyl, C 1 -C 3 -alkoxy and where the C 1 -C 12 -alkyl-, C 1 -C 6 -alkyloxy,
• the mediator can preferably also be selected from the group of cyclic N-hydroxy compounds with at least one optionally substituted five- or six-membered ring containing the structure mentioned in formula V. and their salts, ethers or esters, where B and D are the same or different and O, S, or NR 18 are where R 18 hydrogen, hydroxy, formyl, carbamoyl, Sulfonorest, ester or salt of Sulfonorests, sulfamoyl, nitro, amino, phenyl, aryl-C 1 - C 5 alkyl, C 1 -C 12 -Alkyl-, C 1 -C 5 -alkoxy-, C 1 -C 10 -carbonyl-, carbonyl-C 1 -C 6 -alkyl-, phospho-, phosphono-, phosphonooxy radical, ester or salt of the phosphonooxy radical, where carbamoyl, sulfamoyl, amino and
• mediators Formulas VI, VII, VIII or IX in which B and D O or S mean.
• N-hydroxy-phthalimide and optionally substituted N-hydroxy-phthalimide derivatives examples include N-hydroxymaleimide and optionally substituted N-hydroxymaleimide derivatives, N-hydroxy-naphthalimide and optionally substituted N-hydroxy-naphthalimide Derivatives, N-hydroxysuccinimide and optionally substituted N-hydroxysuccinimide derivatives, preferably those in which the radicals R 26 -R 29 are polycyclically linked.
• mediators are N-hydroxyphthalimide, 4-amino-N-hydroxyphthalimide and 3-amino-N-hydroxyphthalimide.
• G monovalent homo- or heteroaromatic mono- or dinuclear radical and L means double-bonded homo- or heteroaromatic mono- or dinuclear radical and these aromatics by one or more, identical or different radicals R 38 selected from the group halogen, hydroxyl, formyl, cyano, carbamoyl, carboxy radical, ester or salt of the carboxy radical, sulfone radical, ester or salt of the sulfonic radical, sulfamoyl -, Nitro, nitroso, amino, phenyl, aryl-C 1 -C 5 alkyl, C 1 -C 12 alkyl, C 1 -C 5 alkoxy, C 1 -C 10 carbonyl -, Carbonyl-C 1 -C 6 alkyl, phospho-, phosphono-, phosphono-oxy-oxy
• Ar 1 is preferably phenyl and Ar 2 ortho-phenylene radical, where Ar 1 by up to five and Ar 2 by up to four identical or different radicals selected from the group C 1 -C 3 alkyl, C 1 -C 3 alkylcarbonyl, carboxy, ester or Salt of the carboxy residue, sulfone residue, ester or salt of the sulfone residue, hydroxy, cyano, nitro, nitroso and amino residue can be substituted, amino residues being substituted with two different residues selected from the group consisting of hydroxy and C 1 -C 3 alkylcarbonyl could be.
• R 42 is preferably a monovalent radical selected from the group consisting of hydrogen, phenyl, C 1 -C 12 alkyl, C 1 -C 5 alkoxy, wherein the C 1 -C 12 alkyl radicals and C 1 -C 5 alkoxy radicals can be saturated or unsaturated, branched or unbranched.
• R 43 preferably denotes divalent radicals selected from the group consisting of ortho- or para-phenylene, C 1 -C 12 alkylene, C 1 -C 5 alkylenedioxy radicals, the aryl-C 1 -C 5 alkyl-, C 1 -C 12 alkyl, C 1 -C 5 alkoxy radicals may be saturated or unsaturated, branched or unbranched and may be substituted one or more times with a radical R 46 .
• R 46 preferably denotes carboxy radical, ester or salt of the carboxy radical, carbamoyl, phenyl, C 1 -C 3 alkoxy radical.
• Examples of compounds used as mediators are, N-hydroxyacetanilide, N-hydroxypivaloylanilide, N-hydroxyacrylanilide, N-hydroxybenzoylanilide, N-hydroxymethylsulfonylanilide, N-hydroxy-N-phenyl-methylcarbamate, N-hydroxy-3-oxo-butyrylanilide, N-hydroxy-4-cyanoacetanilide, N-hydroxy-4-methoxyacetanilide, N-hydroxyphenacetin, N-hydroxy-2,3-dimethylacetanilide, N-hydroxy-2-methylacetanilide, N-hydroxy-4-methylacetanilide, 1-Hydroxy-3,4-dihydroquinoline (1H) -2-one, N, N'-dihydroxy-N, N'-diacetyl-1,3-phenylenediamine, N, N'-dihydroxysuccinic acid dianilide, N, N'-dihydroxy-maleic acid dian
• Preferred mediators are N-hydroxyacetanilide, N-hydroxyformanilide, N-hydroxy-N-phenyl-methylcarbamate, N-hydroxy-2-methylacetanilide, N-hydroxy-4-methylacetanilide, 1-hydroxy-3,4-dihydroquinolin- (1H) -2-one and N-acetoxyacetanilide.
• the mediator can also be selected from the group of N-A1-alkyl-N-hydroxyamides.
• Preferred mediators are compounds of the general formulas (XVIII) or (XIX) as well as their salts, ethers or esters, where M is identical or different and means monovalent linear or branched or cyclic or polycyclic saturated or unsaturated alkyl radical with 1-24 C atoms and wherein this alkyl radical by one or more radicals R 48 , which are identical or different and are selected from the group hydroxyl, mercapto, formyl, carbamoyl, carboxy, ester or salt of the carboxy radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro -, Nitroso, amino, hydroxylamino, phenyl, C 1 -C 5 alkoxy, C 1 -C 10 carbonyl, phospho-, phosphono-, phosphonooxy, ester or salt of the phosphonooxy may be substituted and where carbamoyl, sulfamo
• Phosphoric acid, monoesters of phosphoric acid, diesters of phosphoric acid means and T is an amidic form of the double-bonded acid residue of acids selected from the group consisting of aliphatic, mono- or dinuclear aromatic or mono- or dinuclear heteroaromatic dicarboxylic acids with up to 20 carbon atoms, carbonic acid, sulfonic acid, phosphonic acid, phosphoric acid, monoesters of phosphoric acid and where alkyl radicals of the aliphatic acids N and T present in amidic form can be linear or branched and / or cyclic and / or polycyclic saturated or unsaturated and contain 0-24 carbon atoms and are unsubstituted or mono- or polysubstituted by the radical R 47 and Aryl and heteroaryl radicals of the aromatic or heteroaromatic acids N and T present in amidic form by one or more radicals R 49 , which are identical or different and are selected from the group hydroxyl, mercapto, formy
• Particularly preferred mediators are compounds with the general formulas (XX, XXI, XXII or XXIII): and their salts, ethers or esters, where Alk 1 is the same or different and means monovalent linear or branched or cyclic or polycyclic saturated or unsaturated alkyl radical with 1-10 C atoms, wherein this alkyl radical by one or more radicals R 50 , which are the same or different and are selected from the group hydroxyl, formyl, carbamoyl, carboxy, ester or salt of the carboxy radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, nitro, Nitroso, amino, hydroxylamino, phenyl, C 1 -C 5 alkoxy, C 1 -C 5 carbonyl radicals can be substituted and where carbamoyl, sulfamoyl, amino, hydroxylamino and phenyl radicals can be un
• Particularly preferred mediators are compounds of the general formula (XX - XXIII) in which Alk 'is the same or different and means monovalent linear or branched or cyclic saturated or unsaturated alkyl radical with 1-10 C atoms, wherein this alkyl radical by one or more radicals R 50 , which are the same or different and are selected from the group hydroxyl, carbamoyl, carboxy, ester or salt of the carboxy radical, sulfono radical, ester or salt of the sulfono radical, sulfamoyl, amino, phenyl , C 1 -C 5 alkoxy, C 1 -C 5 carbonyl radicals can be substituted and where carbamoyl, sulfamoyl, amino and phenyl radicals can be unsubstituted or substituted one or more times with a radical R 51 and the C 1 -C 5 alkoxy, C 1 -C 10 carbonyl radicals saturated or unsaturated,
• Examples of compounds that can be used as mediators are N-hydroxy-N-methyl-benzoic acid amide, N-hydroxy-N-methyl-benzenesulfonic acid amide, N-hydroxy-N-methyl-p-toluenesulfonic acid amide, N-hydroxy-N-methyl-furan-2-carboxylic acid amide, N- Hydroxy-N-methyl-thiophene-2-carboxamide, N, N'-dihydroxy-N, N'-dimethyl-phthalic acid diamide, N, N'-dihydroxy-N, N'-dimethyl-isophthalic acid diamide, N, N'-dihydroxy -N, N'-dimethyl-terephthalic acid diamide, N, N'-dihydroxy-N, N'-dimethyl-benzene-1,3-disulfonic acid diamide, N, N'-dihydroxy-N, N'-dimethyl-furan-3, 4-dicarboxylic acid diamide, N-hydroxy-
• Compounds are preferably selected as mediators from the Group N-hydroxy-N-methyl-benzoic acid amide, N-hydroxy-N-methylbenzenesulfonic acid amide, N-hydroxy-N-methyl-p-toluenesulfonic acid amide, N-hydroxy-N-methyl-furan-2-carboxamide, N, N'-dihydroxy-N, N'-dimethyl-phthalic acid diamide, N, N'-dihydroxy-N, N'-dimethyl-terephthalic acid diamide, N, N'-dihydroxy-N, N'-dimethyl-benzene-1,3-disulfonklarediamid, N-Hydroxy-N-tert.
• the mediator can also be selected from the group of oximes of the general formula XXIV or XXV and their salts, ethers, or esters, where U, is the same or different and O, S, or NR 55 where R 55 is hydrogen, hydroxyl, formyl, carbamoyl, sulfono, ester or salt of sulfono, sulfamoyl, nitro, amino, phenyl, Aryl-C 1 -C 5 -alkyl-, C 1 -C 12 -alkyl-, C 1 -C 5 -alkoxy-, C 1 -C 10 -carbonyl-, carbonyl-C 1 -C 6 -alkyl-, phospho- , Phosphono, phosphonooxy, ester or salt of the phosphonooxy, where carbamoyl, sulfamoyl, amino and phenyl radicals can be unsubstituted or substituted one or more times with
• Isonitroso derivatives are also particularly preferred as mediators of cyclic ureids of the general formula XXV.
• Examples for such compounds are 1-methylvioluric acid, 1,3-dimethylvioluric acid, thiovioluric acid, alloxan-4,5-dioxime.
• Alloxan-5-oxime hydrate is particularly preferred as mediator (Violuric acid) and / or its esters, ethers or salts.
• the mediator can also be selected from the group of vicinally nitroso-substituted aromatic alcohols of the general formulas XXVI or XXVII and their salts, ethers or esters, where R 63 , R 64 , R 65 and R 66 are the same or different and are hydrogen, halogen, hydroxy, formyl, carbamoyl, carboxy, ester or salt of carboxy, sulfono, ester or salt of sulfono, sulfamoyl, Nitro, nitroso, cyano, amino, phenyl, arylC 1 -C 5 alkyl, C 1 -C 12 alkyl, C 1 -C 5 alkoxy, C 1 -C 10 carbonyl -, carbonyl-C 1 -C 6 -alkyl, phospho-, phosphono-, phosphono-oxy radical, ester or salt of the phosphonooxy radical, where carbamoyl, s
• Aromatic alcohols are preferably phenols or more highly condensed ones To understand derivatives of phenol.
• Preferred mediators are compounds of the general formula XXVI or XXVII, the synthesis of which is substituted on the nitrosation Phenols can be recycled.
• Examples of such connections are 2-nitrosophenol, 3-methyl-6-nitrosophenol, 2-methyl-6-nitrosophenol, 4-methyl-6-nitrosophenol, 3-ethyl-6-nitrosophenol, 2-ethyl-6-nitrosophenol, 4-ethyl-6-nitrosophenol, 4-isopropyl-6-nitrosophenol, 4-tert-butyl-6-nitrosophenol, 2-phenyl-6-nitrosophenol, 2-benzyl-6-nitrosophenol, 4-benzyl-6-nitrosophenol, 2-hydroxy-3-nitrosobenzyl alcohol, 2-hydroxy-3-nitrosobenzoic acid, 4-hydroxy-3-nitrosobenzoic acid, 2-methoxy-6-nitrosophenol, 3,4-dimethyl-6-nitrosophenol, 2,4-dimethyl-6-nitrosophenol, 3,5
• mediators are o-nitroso derivatives condensed aromatic alcohols.
• Examples of such connections are 2-nitroso-1-naphthol, 1-methyl-3-nitroso-2-naphthol and 9-hydroxy-10-nitroso-phenanthrene.
• mediators are 1-nitroso-2-naphthol, 1-nitroso-2-naphthol-3,6-disulfonic acid, 2-nitroso-1-naphthol-4-sulfonic acid, 2,4-dinitroso-1,3-dihydroxybenzene and esters, ethers or salts of the connections mentioned.
• the mediator can also be selected from the group Hydroxypyridines, aminopyridines, hydroxyquinolines, aminoquinolines, Hydroxyisoquinolines, aminoisoquinolines, with the hydroxy or Amino groups in the ortho- or para-position nitroso or mercapto substituents, Tautomers of the compounds mentioned and theirs Salts, ethers and esters.
• Preferred mediators are compounds of the general formula (XXVIII), (XXIX) or (XXX) as well as tautomers, salts, ethers or esters of the compounds mentioned, where in the formulas XXVIII, XXIX or XXX two radicals R 72 which are ortho or para to one another are hydroxyl and nitroso or hydroxyl and mercapto or nitroso and amino and the other R 72 radicals are the same or different and are selected from the group consisting of hydrogen, halogen, hydroxy, mercapto, formyl, cyano, carbamoyl, carboxy, ester and salt of carboxy, sulfono, ester and salt of the sulfono radical, sulfamoyl, nitro, nitroso, amino, phenyl, aryl-C 1 -C 5 -alkyl-, C 1 -C 12 -alkyl-, C 1 -C 5 -alk
• Examples of compounds used as mediators can be 2,6-dihydroxy-3-nitrosopyridine, 2,3-dihydroxy-4-nitrosopyridine, 2,6-dihydroxy-3-nitrosopyridine-4-carboxylic acid, 2,4-dihydroxy-3-nitrosopyridine, 3-hydroxy-2-mercaptopyridine, 2-hydroxy-3-mercaptopyridine, 2,6-diamino-3-nitrosopyridine, 2,6-diamino-3-nitroso-pyridine-4-carboxylic acid, 2-hydroxy-3-nitrosopyridine, 3-hydroxy-2-nitrosopyridine, 2-mercapto-3-nitrosopyridine, 3-mercapto-2-nitrosopyridine, 2-amino-3-nitrosopyridine, 3-amino-2-nitrosopyridine, 2,4-dihydroxy-3-nitrosoquinoline, 8-hydroxy-5-nitrosoquinoline, 2,3-dihydroxy-4-nitrosoquinoline, 3-hydroxy-4-nitrosoisoquinoline, 4-hydroxy-3
• Preferred mediators are 2,6-dihydroxy-3-nitrosopyridine, 2,6-Diamino-3-nitrosopyridine, 2,6-dihydroxy-3-nitrosopyridine-4-carboxylic acid, 2,4-dihydroxy-3-nitrosopyridine, 2-hydroxy-3-mercaptopyridine, 2-mercapto-3-pyridinol, 2,4-dihydroxy-3-nitrosoquinoline, 8-hydroxy-5-nitrosoquinoline, 2,3-dihydroxy-4-nitrosoquinoline and Tautomers of these compounds.
• the mediator can also be selected from the group of more stable Nitroxyl radicals (nitroxides), i.e. these free radicals can preserved, characterized and stored in pure form.
• Compounds of the general formula (XXXI), (XXXII) or (XXXIII) are preferably used as mediators in which Ar is a monovalent homo- or heteroaromatic mono- or dinuclear radical and wherein this aromatic radical is selected from the group halogen, formyl, cyano, carbamoyl, carboxy, ester or salt of carboxy, sulfono, ester or salt of sulfono, sulfamoyl by one or more, identical or different radicals R 77 , Nitro, nitroso, amino, phenyl, aryl C 1 -C 5 alkyl, C 1 -C 12 alkyl, C 1 -C 5 alkoxy, C 1 -C 10 carbonyl , Carbonyl-C 1 -C 6 alkyl-phospho-, phosphono-, phosphonooxy, ester or salt of the phosphonooxy may be substituted and where phenyl, carbamoyl and
• Particularly preferred mediators are nitroxyl radicals of the general formulas (XXXIV) and (XXXV), in which R 82 is identical or different and is phenyl-, aryl-C 1 -C 5 -alkyl-, C 1 -C 12 -alkyl-, C 1 -C 5 -alkoxy-, C 1 -C 10 -carbonyl-, carbonyl- C 1 -C 6 alkyl where phenyl radicals can be unsubstituted or substituted one or more times with a radical R 84 and the aryl-C 1 -C 5 -alkyl-, C 1 -C 12 -alkyl-, C 1 -C 5 -alkoxy-, C 1 - C 10 carbonyl, carbonyl C 1 -C 6 alkyl radicals can be saturated or unsaturated, branched or unbranched and can be substituted one or more times with a radical R 84 , where R 84 may be
• mediators are N-hydroxyphthalimide, 1-hydroxy-1H-benzotriazole, violuric acid, N-hydroxyacetanilide as well their derivatives listed above.
• 3-Amino-N-hydroxyphthalimide are very particularly preferred, 4-amino-N-hydroxyphthalimide, N-hydroxyphthalimide, 3-hydroxy-N-hydroxyphthalimide, 3-methoxy-N-hydroxyphthalimide, 3,4-dimethoxy-N-hydroxyphthalimide, 4,5-dimethoxy-N-hydroxyphthalimide, 3,6-dihydroxy-N-hydroxyphthalimide, 3,6-dimethoxy-N-hydroxyphthalimide, 3-methyl-N-hydroxyphthalimide, 4-methyl-N-hydroxyphthalimide, 3,4-dimethyl-N-hydroxyphthalimide, 3,5-dimethyl-N-hydroxyphthalimide, 3,6-dimethyl-N-hydroxyphthalimide, 3-isopropyl-6-methyl-N-hydroxyphthalimide, 3-nitro-N-hydroxyphthalimide, 4-nitro-N-hydroxyphthalimide, 1-hydroxy-1H-benzotriazole, violuric acid and N-hydroxyacetanilide.
• the mediator selected from the group of compounds 1-methylvioluric acid, 1,3-dimethylvioluric acid, thiovioluric acid, Alloxan-4,5-dioxime and alloxan-5-oxime hydrate (violuric acid).
• the mediator molecule reaches after activation at the electrode the lignin by thermal diffusion. This can be done by Mix e.g. Stirring, or other methods e.g. electrophoresis get supported.
• the system according to the invention can additionally contain other auxiliaries, e.g. Contain oxidants that delignify the lignin-containing Support materials.
• the invention further relates to a method for electrochemical Cleavage of compounds according to claim 6.
• the compound to be cleaved is in the process according to the invention preferably the delignification of lignin-containing materials understand.
• other connections such as for example, to cleave dyes.
• bleaching of textiles by means of the invention Procedure possible.
• the application of the method is particularly preferred indigo-dyed denim and on products made from it become.
• the method according to the invention can advantageously at temperatures from about 20 ° C to 100 ° C.
• It preferably becomes special at a temperature of 40 to 100 ° C preferably carried out at 70 - 90 ° C.
• the method is preferably carried out at a voltage of 0.5- 40 V, particularly preferably 1V to 5V.
• the mediator is preferably used in amounts from 1kg to 100 kg / to pulp, particularly preferably 2 kg to 50 kg / to pulp.
• the pH is preferred when the method is carried out lower than pH 7.
• the breakdown of lignin in the delignification of pulp will quantified by determining the so-called kappa number.
• the kappa number is a measure of the lignin content of a pulp.
• Lowering the kappa number means reducing the Lignin content of the material.
• the kappa number determination can, for example using methods known from the literature, e.g. according to DIN 54357.
• the pre-washed pulp was again in the 800 ml beaker with bidest. Water washed and squeezed. The vessel was with Parafilm sealed and the washed pulp in it until use kept.
• the batch was tipped onto a nutsche, which became liquid sucked off and about 6 times with occasional stirring with bidest. Washed water until the filtrate was no longer colored. This pulp is used for kappa determination.
• the washed, still moist pulp is cut in half. A half is extracted and then used for kappa determination (DIN 54357); the kappa number of the other half is without extraction certainly.
• Example 1 Increasing the kappa number reduction by electrochemical Activation of the violuric acid
• Treatment with violuric acid alone also becomes a certain kappa number reduction achieved. Improving delignification is calculated as a factor indicating how much delignification with electrochemical activation the violuric acid is considered to be without electrochemical activation.
• Table 1 Increase in kappa number reduction by electrochemical activation of violuric acid Kappa number delignification factor without electricity 13.15 22.5% 1 with electricity 4.11 75.8% 3.37
• the efficiency of the system over time is characterized by the kappa number reduction achieved divided by the Electrolysis time. This value is in the right column of the table 3 entered.
• the kappa number reduction achieved by the system is over one wide temperature range from 45 ° C to 90 ° C practically constant.
• the mean delignification was for this range (45 ° C to 90 ° C) and the delignification at any temperature of calculated this mean. This value was called the temperature tolerance and is in the right column of Table 4 entered.
• Table 5 The results are summarized in Table 5.
• Table 5 The kappa number reduction depends on the pH of the reaction mixture PH value Kappa number delignification 4.5 4.11 75.8% 7 8.97 47.1% 11:00 11.58 31.8%
• the batch without buffer salt was made with sodium hydroxide or sulfuric acid after adding the pulp to the violuric acid solution to pH 4.5 titrated. There was no active stabilization of the pH carried out. The pH only changed during the reaction slightly.
• Dyed jeans fabric (9 g / 160 cm 2 ) in 0.1 M acetate buffer pH 4.5 and a dose of violuric acid of 35 g / kg of fabric was placed in a vessel without a diaphragm with two electrodes made of stainless steel 1.4571 (according to DIN 17580) treated at 900 ° C with stirring with a magnetic stirrer for defined times at normal pressure.
• a voltage of 5 V was applied to the electrodes.
• the fabric pieces were washed out under running water until the wash water showed no more color.
• the pieces of fabric were dried in a sheet dryer, then pressed and optically assessed with a suitable spectrophotometer.
• Comparative Example 1 Comparison of the electrochemical activation of violuric acid with enzymatic activation by laccase from Trametes versicolor
• Example 1 The electrochemical implementation of softwood pulp with violuric acid and with electrochemically activated violuric acid as in Example 1 performed. In addition, there is an approach with laccase in high doses (50 IU / 3g pulp) for enzymatic activation performed the violuric acid.
• the delignification was calculated. Measured against the treatment with violuric acid alone, the Enzymatic activation is essential despite the high enzyme dosage less acceleration of delignification than that electrochemical activation of violuric acid.
• Oxygen-delignified softwood pulp was at 45 ° C and 90 ° C for 4 h with 50 U of laccase from Trametes versicolor with stirring treated with a magnetic stirrer. The kappa number was then determined and the delignification is calculated from it.
• the kappa number reduction achieved increases with increasing temperature lower.
• the temperature optimum of the laccase is around 45 ° C. An increase in temperature leads to a deterioration of the result, since the enzyme is outside its optimum temperature is used and faster at the elevated temperature is deactivated.

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