PROCESS FOR THE PREPARATION OF TRIPHENODIOXAZINE PIGMENTS

Abstract: The invention relates to a novel process for the preparation of triphenodioxazine compounds of general formula (I) in which both X represent hydrogen or halogen atoms and the heterocyclic rings labeled A are fused on in 1,2-, 2,3- or 3,4- and 8,9-, 9,10- or 10,11- position and contain at least one nitrogen atom which is unsubstituted or substituted by alkyl, cycloalkyl or aryl radicals, which is characterized by a cyclisation and an oxidation step conducted in the presence of a base in a polar, aprotic solvent.

Description: PROCESS FOR THE PREPARATION OF TRIPHENODIOXAZINE PIGMENTS The invention relates to a particularly advantageous process for preparing tripheno- dioxazine compounds by oxidation in organic solvents, to the products obtained by such process and to their use as pigments. Triphenodioxazine compounds and processes for their preparation are disclosed in GB 2284427 A, DE 4442291 A1 and DE 19727079 A1. The process described in GB 2284427 A and DE 19727079 A1 starts from amino compounds, which are ortho-substituted by an alkoxy group and are obtainable only by way of a relatively complex synthesis. The pigments disclosed in GB 2284427 A are furthermore difficultly dispersible and cannot easily be brought into pigment form. The process described in DE 4442291 A1 starts from unsubstituted intermediates i.e. amino compounds, which are easily obtainable. The pigment synthesis is performed with manganese dioxide in concentrated sulfuric acid and requires the isolation of intermediate products. That process forms considerable amounts of salts of the heavy metal manganese. The use of sulfuric acid requires a costly regeneration. In addition, an aftertreatment of the crude pigment in an organic solvent is often necessary to obtain the required pigment properties. Another commonly used process for the preparation of triphenodioxazine compounds is the one described in USP 4,751 ,300 in which the intermediate 2,5-bisaryl-1 ,4-benzo- quinones are heated in the presence of inorganic acid in an inert non-polar organic solvent. This process is, however, not applicable to compounds with a heterocyclic ring containing an unsubstituted nitrogen atom. The invention relates to a novel process to obtain triphenodioxazine pigments by oxidation of 2,5-bisarylamino-1 ,4-benzoquinones in polar, aprotic organic solvents. Very surprisingly, these pigments can be prepared in polar, aprotic solvents, but only in the presence of a base by means of various methods. This process also avoids the isolation of 2,5-bisarylamino-1 ,4-benzoquinones and allows the preparation of triphenodioxazines directly from aromatic amines by subsequent condensation with 2,3,5,6-tetrachloro benzoquinone (chloranil) and oxidation of the resulting intermediate product in an organic solvent. The use of heavy metals is avoided or at least limited to catalytical quantities. The regeneration of polar organic solvents is a routine process in chemical plants. With the obtained pigment it is possible to generate highly advantageous shifts in shades, which are of great interest. Moreover, the pigments obtained in this invention possess excellent dispersability, high color strength, high weather and light fastness, high saturation and outstanding heat stability in engineering plastics. The present patent application provides a process for the preparation of compounds of the general formula (I) in which both X represent hydrogen or halogen atoms and the heterocyclic rings labeled A are fused on in 1 ,2-, 2,3- or 3,4- and 8,9-, 9, 10- or 10, 11 - position and contain at least one nitrogen atom which is unsubstituted or substituted by alkyl, cycloalkyl or aryl radicals, by oxidation of 2,5-bisarylamino-1 ,4-benzoquinones in polar, aprotic organic solvents in the presence of a base. In particular both X represent hydrogen or halogen atoms and the rings labeled A are fused on in 1,2-, 2,3- or 3,4- and 8,9-, 9,10- or 10,11- position and selected from the group consisting of the moieties (1) to (8) wherein R n and R 2 are, independently from each other, hydrogen, C^alkyl, C 5 . 6 cycloalkyl, benzyl, benzanilide, phenyl or naphthyl whereby benzanilide, phenyl and naphthyl groups may be mono- or poly-substituted by radicals selected from the group halogen, nitro, C 1 . 8 alkyl, C 5 . 6 cycloalkyl, benzyl, phenyl or naphthyl, COOalkyl, C^ alkoxy or t fluoromethyl and R' is, independently from R- and R 2 , hydrogen, hydroxy, Cι. 8 alkyl, C 5 . 6 cycloalkyl, benzyl, benzanilide, phenyl or naphthyl whereby benzanilide, phenyl and naphthyl groups may be mono- or poly-substituted by radicals selected from the group halogen, nitro, C^alkyl, C 5 . 6 cycloalkyl, benzyl, phenyl or naphthyl, COOalkyl, Cι. 3 alkoxy or trifluoromethyl, with the proviso that the pigment contains at least one unsubstituted NH-CO-group. These compounds are particularly useful as pigments for coloring plastics mass including both solvent-free and solvent-containing masses of plastics or plastics resins. These include oil-based or aqueous paint systems and lacquers of various kinds. These compounds are also suitable for spin coloring of viscose or cellulose acetate, for pigmenting of polyethylene, polystyrene, polyvinylchloride, rubber or artificial leather. They can also be used for printing graphic fabrics, for coloring paper masses, for coating of textiles or for any other pigment printing process. The resulting pigmentations have excellent fastness to heat, light and weathering and chemicals. The pigments retain good strength of color and have good application properties. In particular, they have good fastness to migration, blooming, overcoating and solvents. Preferred compounds of formula (I) are those with formulae (la), (lla), (Ilia) and (lllb) where X is hydrogen or halogen, Ri, R 2 , R 3 and R , independently from one another, are hydrogen, a C . 8 alkyl radical, a substituted or unsubstituted phenyl, benzyl, benzanilide or naphthyl radical, a substituted or unsubstituted C 5 . 6 cycloalkyl radical with the proviso that the pigment contains at least one unsubstituted NH-CO-group. The substituents R,, R 2 , R 3 and R , independently from one another, are preferably hydrogen, methyl, ethyl, n- or i-propyl, n-, i-, sec- or tert-butyl, cyclohexyl, substituted or unsubstituted benzanilide, naphthyl, unsubstituted phenyl or phenyl substituted one or more times by radicals selected from the group consisting of halogen, preferably chlorine, nitro, Cι_ 8 alkyl radicals, preferably C^ alkyl radicals, and d-β alkoxy radicals with the abovementioned proviso. The process of the invention is performed in polar, aprotic organic solvents, preferably dimethylformamide, dimethylsulfoxide, tetramethylurea, dimethylacetamide and N- methyl-pyrrolidone at temperatures from 0 - 200 °C, preferably 100 - 180 °C. The oxidation requires the presence of a base, preferably potassium carbonate, sodium carbonate, calcium carbonate or sodium phosphate and can be performed by various oxidation methods, preferably by introduction of air or oxygen, by sodium or potassium chlorate in the presence of vanadiumpentoxide or by sodium hypochlorite in the presence of manganese (III) complexes or by use of potassium or sodium peroxodisulfate. The pigments formed by a process according to the invention are suitable for the mass pigmentation of suitable substrates including synthetic polymers, synthetic resins and regenerated fibers optionally in the presence of solvents. These substrates more particularly include oil, water and solvent based surface coatings, polyester spinning melts, polyethylene, polystyrene and polyvinyl chloride molding materials, rubber and synthetic leather. Furthermore, the pigments can be used in the manufacture of printing inks, for the mass coloration of paper and for coating and printing textiles. The pigments obtained by the process according to this invention are also suitable as colorants in electrophotographic toners and developers, such as one- or two-compo- nent powder toners (also called one- or two-component developers), magnetic toners, liquid toners, polymerization toners and specialty toners (literature: L.B. Schein, "Electro-photography and Development Physics"; Springer Series in Electrophysics 14, Springer Verlag, 2 nd Edition, 1992). Typical toner binders are addition polymerization, polyaddition and polycondensation resins, such as styrene, styrene-acrylate, styrene-butadiene, acrylate, polyester and phenol-epoxy resins, polysulphones, polyurethanes, individually or in combination, and also polyethylene and polypropylene, which may comprise further constituents, such as charge control agents, waxes or flow assistants, or may be modified subsequently with these additives. The pigments formed by a process according to the invention are suitable, furthermore, as colorants in powders and powder coating materials, especially in triboelectrically or electrokinetically sprayable powder coating materials which are used for the surface coating of articles made, for example, from metal, wood, plastic, glass, ceramic, concrete, textile material, paper or rubber (J.F. Hughes, "Electrostatics Powder Coating" Research Studies, John Wiley & Sons, 1984). Powder coating resins that are typically employed are epoxy resins, carboxyl- and hydroxyl-containing polyester resins, polyurethane resins and acrylic resins, together with customary hardeners. Combinations of resins are also used. For example, epoxy resins are frequently employed in combination with carboxyl- and hydroxyl-containing polyester resins. Typical hardener components (as a function of the resin system) are, for example, acid anhydrides, imidazoles and also dicyanodiamide and its derivatives, blocked isocyanates, bisacylurethanes, phenolic and melamine resins, triglycidyl iso- cyanurates, oxazolines and dicarboxylic acids. In addition, pigments formed by a process according to the invention are suitable as colorants in ink-jet inks, both aqueous and non-aqueous, and in those inks, which operate in accordance with the hot-melt process. When applied to the above-mentioned substrates the pigments are found to be resistant to migration and fast to light, and show fastness to washing, chlorite, hypo- chlorite and peroxide bleaching, rubbing, overspraying and solvents. Notably, the pigments display high tinctorial power, good opacity and good heat stability. There now follows a series of examples which serves to illustrate the invention. One part by volume corresponds to the volume of one part by weight of water. EXAMPLE 1 6,14-Dichloro-3,1 1 -diethyl-1 ,3,9, 1 1 -tetrahydro-diimidazo[4,5-b:4',5'-m]tripheno- dioxazine-2, 10-dione a) 2,5-Dichloro-3,6-Bis(1-ethyl-2-oxo-1 ,3-dihydrobenzimidazol-5-yl)amino-1.4- benzo-quinone 90 parts of 5-amino-1-ethyl-1 ,3-dihydrobenzimidazol-2-one and 42 parts of anhydrous sodium hydrogencarbonate are suspended in 1000 parts of dimethyl- acetamide and the mixture is heated up to 70 °C. 62 parts of chloranil are added over 2 h. The mixture is heated under reflux for 1 h, cooled down to 100 °C, filtered at 100 °C, washed with 1000 parts of hot dimethylacetamide and washed with water until free of chloride. Drying at 80 °C under reduced pressure yields 105 parts of a brown powder of the following formula Mp > 300 °C 6,14-Dichloro-3, 1 1 -diethyl-1 ,3,9,1 1-tetrahvdro-diimidazor4.5-b:4',5'-m1tri-pheno- dioxazine-2, 10-dione by oxidation with air 53 parts of 2,5-Dichloro-3,6-Bis(1 -ethyl-2-oxo-1 ,3-dihydrobenzimidazol-5-yl)- amino-1 ,4-benzoquinone (as obtained in Example 1a) and 28 parts of potassium carbonate are suspended in 400 parts of dimethylacetamide and the mixture is heated up to reflux. Under inlet of air (ca. 50 I / h) the mixture is refluxed for 10 h, filtered at 100 °C, washed with 400 parts of hot dimethylacetamide and washed with water until free of chloride. Drying at 80 °C under reduced pressure yields 21 parts of a green-metallic powder of the following formula Mp > 300 °C EXAMPLE 2 ■ 6,14-Dichloro-3 l 1 1-diethyl-1 ,3,9,11-tetrahvdro-diimidazor4,5-b:4',5'-mltripheno-di- oxazine-2,10-dione (condensation with chloranil and following oxidation) 90 parts of 5-amino-1-ethyl-1 ,3-dihydrobenzimidazol-2-one and 43 parts of anhydrous sodium hydrogencarbonate are suspended in 1000 parts of dimethylacetamide and the mixture is heated up to 70 °C. 62 parts of chloranil are added over 2 h. The mixture is heated under reflux for 1 , cooled down to 100 °C, treated with 40 parts of potassium carbonate and heated to reflux again. Under inlet of air (ca. 50 I / min) the mixture is refluxed for 10 h, filtered at 100 °C, washed with 1000 parts of hot dimethylacetamide and washed with water until free of chloride. Drying at 80 °C under reduced pressure yields 46 parts of a green-metallic powder identical with the material obtained in example 1 b). Mp > 300 °C EXAMPLE 3 6,14-Dichloro-3, 11 -diethyl-1.3,9,11 -tetrahvdro-diimidazo| ,5-b:4'.5'-mltripheno-di- oxazine-2,10-dione (oxidation with sodium chlorate) 53 parts of 2,5-Dichloro-3,6-Bis(1-ethyl-2-oxo-1 ,3-dihydrobenzimidazol-5-yl)amino-1 ,4- benzoquinone (as obtained in Example 1a), 0.5 parts of vanadium pentoxide and 28 parts of potassium carbonate are suspended in 400 parts of dimethylacetamide and the mixture is heated up to 100 °C. At that temperature the mixture is treated with 21 parts of sodium chlorate during 2h, subsequently heated to reflux for 12 h, filtered at 100 °C, washed with 400 parts of hot dimethylacetamide and washed with water until free of chloride. Drying at 80 °C under reduced pressure yields 41 parts of a green-metallic powder, identical with that material obtained in example 1 b. Mp > 300 °C The violet to blue pigment so obtained show excellent pigment properties like dispersibility, color strength, excellent heat and light stability when applied in engineering plastics or coatings. EXAMPLE 4 Oxidation with potassium peroxodisulfate a) 6.14-Dichloro-3,11-diethyl-1 , 3.9,11-tetrahvdro-diimidazor4.5-b:4',5'-m1tripheno-di- oxazine-2, 10-dione 1 equimol of 2,5-Dichloro-3,6-Bis(1-ethyl-2-oxo-1 ,3-dihydrobenzimidazol-5-yi)- amino-1 ,4-benzoquinone (as obtained in Example 1a), 1 equimol of potassium carbonate are suspended in 25 equimols of N-methylpyrrolidone and the mixture is heated up to 120 °C. At that temperature the mixture is treated with 2.5 equimols of potassium peroxodisulfate during 5 min, subsequently heated to 160 °C for 12 h, filtered at 100 °C, washed with 25 equimols of hot N-methylpyrrolidone and washed with water until free of sulfate. Drying at 80 °C under reduced pressure yields ca. 20-30 % of a green-metallic powder, identical with that material obtained in example 1 b. The same procedure is applied to obtain the following examples: USE EXAMPLES The pigment obtained in example 1a was milled in water in a PML mill (Drais Werke Mannheim) for 20 min with zirconia beads, filtered and dried in vacuum before subjected to application. APPLICATION IN PVC MASSTONE The preparation of a 1 % colored PVC sheet is performed following the procedure: 100 parts of clear PVC are mixed with 0.1 part of pigment for 2 minutes. The mixture is passed between two rollers for 5 minutes, the front roller being heated at 130 °C and the rear roller being heated at 135 °C. Then the sheet is pressed under a pressure of 25 tones between two chromium-plated steel plates heated at 165 °C, for 5 minutes. The pressed sheet is colored with a reddish blue shade. APPLICATION IN PVC WHITE The preparation of a 0.1 % colored PVC sheet is performed following the procedure: 100 g of PVC-white (0.5 % TiO 2 ) are mixed with 0.1 g of pigment for 2 minutes. The mixture is passed between two rollers for 8 minutes, the front roller being heated at 160 °C and the rear roller being heated at 165 °C. Then the sheet is pressed under a pressure of 25 tones between two chromium-plated steel plates heated at 160 °C, for 5 minutes to obtain a reddish-blue shade. APPLICATION IN LACQUERS MASSTONE The preparation of the alkydmelamine (AM5) resin coating is performed following the procedure: 3.6 g of pigment, 26.4 g of clear AM5 (35 %) and 85 g of glass beads are stirred in a Skandex stirrer for 30 minutes. 30 g of this preparation are mixed with 60 g of clear AM5 (55.8 %). The dispersion is sprayed on a cardboard sheet, air-dried for 15 minutes and baked at 140 °C in an oven for 30 minutes to obtain a reddish-blue shade. APPLICATION IN LACQUERS WHITE The preparation of the alkydmelamine (AM5) resin coating is performed following the procedure: 3.6 g of pigment, 26.4 g of clear AM5 (35 %) and 85 g of glass beads are stirred in a Skandex stirrer for 30 minutes. 7.5 g of this preparation are mixed with 20 g of AM5- white (30 % TiO 2 ). The dispersion is sprayed on a cardboard sheet, air-dried for 15 minutes and baked at 140 °C in an oven for 30 minutes to obtain a reddish-blue shade.

Claims: CLAIMS A process for the preparation of triphenodioxazine pigments of the general formula (I) in which both X represent hydrogen or halogen atoms and the rings labeled A are fused on in 1,2-, 2,3- or 3,4- and 8,9-, 9,10- or 10,11- position and are selected from the group consisting of the moieties (1) to (8) wherein Ri and R 2 are, independently from each other, hydrogen, C^salkyl, C 5 . 6 cycloalkyl, benzyl, benzanilide, phenyl or naphthyl whereby benzanilide, phenyl and naphthyl groups may be mono- or poly-substituted by radicals selected from the group halogen, nitro, C h alky!, C 5 . 6 cycloalkyl, benzyl, phenyl or naphthyl, COOalkyl, C^ alkoxy or trifluoromethyl and R' is, independently from Ri and R 2 , hydrogen, hydroxy, Cι. 8 alkyl, C 5 . 6 cycloalkyl, benzyl, benzanilide, phenyl or naphthyl whereby benzanilide, phenyl and naphthyl groups may be mono- or poly-substituted by radicals selected from the group halogen, nitro, Cι. 8 alkyl, C 5 . 6 cycloalkyl, benzyl, phenyl or naphthyl, COOalkyl, C^alkoxy or trifluoromethyl, with the proviso that the pigment contains at least one unsubstituted NH-CO- group, by oxidation of 2,5-bisarylamino-1 ,4-benzoquinones in polar, aprotic organic solvents in the presence of a base. 2. A process according to claim 1 in which compounds of formula (I) are those with formulae (la), (II a), (III a) and (lllb) where X is hydrogen or halogen, R^ R 2 , R 3 and R , independently from one another, are hydrogen, a C L8 alkyl radical, a substituted or unsubstituted phenyl, benzyl, benzanilide or naphthyl radical, a substituted or unsubstituted C 5 . 6 cycloalkyl radical with the proviso that the pigment contains at least one unsubstituted NH-CO-group. 3. A process as defined in claim 1 comprising a condensation of arylamines with a benzoquinone and subsequent oxidation of the resulting intermediate in the presence of a base. 4. A process according to any one of claims 1-3 in which the organic solvent is di- methylformamide, dimethylsulfoxide, tetramethylurea, dimethylacetamide or N- methylpyrrolidone. A process according to any one of claims 1-3 in which the oxidation is performed by introduction of air or oxygen, by sodium or potassium chlorate in the presence of vanadiumpentoxide or by sodium hypochlorite in the presence of manganese (III) complexes or by potassium or sodium peroxodisulfate. 6. Triphenodioxazine compounds prepared by the process of claim 1. 7. Use of triphenodioxazine pigments prepared by the process of claim 1 for the mass pigmentation of substrates, preferably synthetic polymers, synthetic resins and regenerated fibers. Use of triphenodioxazine pigments prepared by the process of claim 1 as a colorant for printing inks or textiles. 9. Use of triphenodioxazine pigments prepared by the process of claim 1 , as a colorant for electrographic toners and developers. 10. Use of triphenodioxazine pigments prepared by the process of claim 1 as a colorant in powders and powder coating materials. 11. Use of triphenodioxazine pigments prepared by the process of claim 1 , as a colorant in ink-jet inks.

Inventors: KAUL BANSI LAL, PLUEG CARSTEN, KAUL, BANSI, LAL, PLUEG, CARSTEN
Applicants: CLARIANT FINANCE BVI LTD, CLARIANT INT LTD, KAUL BANSI LAL, PLUEG CARSTEN, CLARIANT FINANCE (BVI) LIMITED, CLARIANT INTERNATIONAL LTD, KAUL, BANSI, LAL, PLUEG, CARSTEN
Application year: 2001
Main classification: C09B19
IPC codes: C09B19