DE1202421B - Process for the production of pigments - Google Patents

Description

Process for making pigments The present invention relates to the production of new pigments and specifically to the manufacture from those used for coloring paints, printing inks, rubber and artificial ones polymeric fabrics as well as for the mass dyeing of fiber-forming materials are.

The pigments which can be prepared according to the invention can be referred to as Thiaeromono (2,3-b) acridone. In the following description, the name given to the ring system is used for the starting ring system of this new polycyclic compound bindings applied. 14th 0 12 11 11 S 13 "c 1 10 2 9 3 ), \ / '/' O \\ C NH 5 7th The cyclization of 2,5-diarylaminoterephthalic acids with the aid of polyphosphoric acid is known from Belgian patent 579525, linear quinacridones being obtained. The thiachromonoacridone pigments of the present invention produce colors which, in terms of their fastness properties and in particular with regard to their weather resistance, are equivalent to the colors produced using linear quinacridone pigments. The paints produced using thiacromonoaeridones, however, have a yellow-red or brown-red hue which differs from the purple-red hue of the quinacridone-based paints. The thiaehromonoacridones therefore complement the quinacridone pigments and allow the production of colors which have the desired fastness properties of the quinacridone pigments, but which include a wider range of colors.

According to the process according to the invention, new pigments are obtained, which are composed of one or more Compounds of Formula 0 left / s C CC \\ C / NH consist, in which X and Y each denote the atoms which are necessary to complete a benzene ring or a naphthalene ring system or such a ring system which carries nonionic substituents.

The benzene ring or naphthalene ring systems must be free of ionic be solubilizing groups. such as sulfonic acid, carboxylic acid and quaternary ammonium groups.

As examples of nonionic substituents which can be selected from X and Y The following may be mentioned: halogen, for example chlorine or bromine; Nitro; Alkyl, for example methyl and ethyl; substituted alkyl, for example Trifluoromethyl-aryl, for example phenyl and p-tolyl; Carbamyl and substituted Carbamyl, for example N-methylcarbamyl, N, N-dimethylcarbamyl and N-phenylcarbamyl, Carbalkoxy, e.g. carbmethoxy; Sulfamyl and substituted sulfamyl, for example N-methylsulfamyl, N-fl-hydroxyethyisulfamyl and N, N-dimethylsulfamyl; Amino, alkylamino, for example methylamino; Dialkylamino, for example dimethylamino; Arylamino, for example anilino; Acylamido, for example acetylamido, α-furoylamido, p-toluoisulphonamido and aroylamido such as benzoylamido and substituted benzoylamido (e.g. o-, m- and p-chloro, methoxy or nitrobenzoylamido)., phthalimido and fl-naphthoylamido, Alkyl and aryl ureido and thioureido, for example n-butyl and phenyl ureido and thioureido, Arylideneamines, for example benzylidinamino, alkanesulfonyl, for example methanesulfonyl and chloromethane sulfonyl, hydroxy; Alkoxy, for example methoxy, ethoxy and β-hydroxyethoxy and aryloxy, e.g. phenoxy and cresoxy. It should be noted that more than one of these substituents can be present.

The process according to the invention is characterized in that one or more dicarboxylic acids of the formula wherein X and Y have the meaning given above, cyclized by treatment with a condensing agent, it being possible, if desired, to obtain the dicarboxylic acid from a 2,5-dihalo terephthalate by condensation with a mercapto compound and an amine.

The cyclization can be carried out, for example, by heating with dehydrating agents such as sulfuric acid, phosphoric acid, polyphosphoric acid or chlorosulfonic acid. When carrying out the method according to the invention, the dicarboxylic acid can, for example, be dissolved in concentrated sulfuric acid, and the solution is heated to a temperature between 70 and 150 ° C. for a short time, for example between 130 and 140 ° C. for 15 minutes.

If phosphoric acid or polyphosphoric acid is used as the dehydrating agent, it is generally necessary to heat the solution of the dicarboxylic acid or the ester to a higher temperature for a long time, for example to a temperature between 160 and 180 ° C. for 10 hours. When chlorosulfonic acid is used as a dehydrating agent, it is usually not necessary to heat the solution of the dicarboxylic acid or the ester at all, and the cyclization can usually take place after a few minutes of stirring at 20 ° C or for 1 hour at temperatures between -5 and 0 ' C.

After the cyclization has taken place, the pigment can be removed from the Solution in sulfuric, phosphoric, polyphosphoric or chlorosulphonic acid precipitated by pouring the solution into water and the product is then filtered off and washed.

Other condensing agents can also be used for the cyclization of the dicarboxylic acid Acting agents are used, such as phosphorus tri- and pentachloride and aluminum chloride. It is sometimes advantageous to use an agent that is customary for the preparation of acid chlorides is used, for example thionyl chloride or phosphorus trichloride in conjunction with a condensing agent such as aluminum chloride.

Examples of dicarboxylic acids which can be cyclized by the process according to the invention are: 2-aniline-5-phenylmereaptoterephthalic acid, 2- (4'-chlorophenylamino) -5 - phenylmereaptoterephthalic acid, 2 - phenylamino-5- (4'- chlorphenylmereapt0) -terephthalic acid and 2- (4'-chlorophenylamino) -5- (4 "-chiorphenyhnercapto) -terephthalic acid.

The dicarboxylic acids used in the process according to the invention can be obtained from 2-chloro-5-nitroterephthalic acid thereof by Condensation with the appropriate mercapto compound or the amine, followed by the nitro group is reduced to the amino group, the amino group by a halogen atom, for example chlorine, is replaced by the Sandmeyer reaction and finally a condensation with the corresponding amine or the mercapto compound takes place. The dicarboxylic acids can also be obtained from dialkyl-2,5-dihalo terephthalates by condensation with a mercapto compound and an amine, if desired the intermediate condensation product is not separated. During this condensation hydrolysis of the ester groups can take place, so that the dicarboxylic acid directly is obtained.

Those pigments according to the invention in which the X and Y expressed rings or ring systems carry acylamido groups as substituents, can also by acylating the corresponding, the amino groups using a Acid chloride, anhydride or ester are produced.

The products made according to the invention generally have crystalline structure, and they can be finely divided in a manner known per se Pigrnentform be converted, either alone or in a mixture with others Thiachromono (2,3-b) acridones or with other pigments, such as lin-quinacridones or Benzobisthiaeromonen, for example by grinding, pasting with sulfuric acid, salt grinding or by treatment with an organic liquid such as phenol, cresol, xylene, Dimethyl sulfone or dimethylformamide, if desired at an elevated temperature. In certain cases the crystalline form of the pigments according to the invention can through Application of these working methods can be modified.

The pigments prepared according to the invention can be used for coloring Printing inks, paints, lacquers, stoved enamels and for coloring rubber and artificial polymeric compositions such as cellulose acetate, polyvinyl chloride, polyethylene and polystyrene or fiber-forming materials such as polyesters and polyamides are used will. These pigments produce yellow to purple tints, which are very good ones Have authenticity properties.

Thiachromono (2,3-b) acridone, in which one or both of the external Rings having halogen atoms, in particular chlorine atoms, as substituents are as Pigments are particularly valuable because they have an exceptional resistance to them Have ventilation.

The parts and percentages given in the examples are weight units.

Example 1 4.7 parts of 2 - phenylamino - 5 - phenylmercaptoterephthalic acid are gradually added to 25 parts of tetraphosphoric acid at 150 ° C. with stirring. The mixture is stirred for 1 hour at 150'C and then allowed to cool to about 100'C and slowly. diluted with 100 parts of water. The orange-colored product present in suspension is filtered off, washed free of acid, stirred with 250 parts of 2% sodium carbonate solution and boiled with 200 parts of 50% alcoholic potassium hydroxide solution. The deep scarlet-colored solution which is obtained here is filtered and hot, dilute hydrochloric acid is added. The precipitated clear orange thiachromono (2,3-b) aeridon is filtered off, washed and dried. The product contains 72.5% carbon, 3.3% hydrogen, 4.2% nitrogen and 10% sulfur. A compound of the formula C20H1i (D # NS contains 73.0% carbon, 3.301a hydrogen, 4.25% nitrogen and 9.7014 sulfur. The light absorption curve of a solution of this compound in sulfuric acid shows maxima at 398, 580 and 639 mIL.

A mixture of 4 parts of the product and 40 parts of dry sodium chloride is milled in a ball mill with steel balls for 48 hours. The salt-pigment mixture is separated from the spheres and stirred with about 50 parts of dimethylformamide at 50 ° C. for 24 hours. The mixture is then diluted with water and filtered, and the filter material is stirred for 30 minutes at a temperature between 90 and 95 ° C. with 500 parts of 5% strength sulfuric acid in order to remove traces of iron. The solid residue is then filtered off and washed free of acid, and the paste is stirred with 0.4 parts of pine oil and dried at 50.degree. In this way, a clear, orange-colored pigment is obtained which, when stirred into paint, gives clear orange-colored shades which have very good fastness properties. Example 2 6.6 parts of 2- (4-chlorophenylamino) -5-phenylmercaptoterephthalic acid are gradually added to 33 parts of tetraphosphoric acid with stirring at 180.degree . The mixture is then stirred for 1 hour at 180 ° C. and cooled to about 100 ° C. and then slowly diluted with 100 parts of water. The red product is filtered off, washed free of acid, stirred with 250 parts of 2% strength sodium carbonate solution and boiled with 200 parts of a 5% strength alcoholic potassium hydroxide solution. The deep scarlet-colored solution is filtered and acidified and the precipitated 2-chloro-thiacromono (2,3-b) aeridon is filtered off. This product is converted into a pigment form by grinding with common salt and treating with dimethylformamide in the manner described in Example 1. A scarlet-colored pigment with very good fastness properties is obtained in this way. The light absorption curve of a solution of this product in sulfuric acid shows maxima at 391, 430, 595 and 644m [L. The X-ray diffraction pattern of this material shows a strong line corresponding to a crystal plane spacing of 3.44 Å units, middle lines at 5.95, 5.7, 3.76, 3.23 and 3.07 Å, and weak lines at 8.15.5 , 0, 4.85, 4.03, 3.37 and 3, IOE.

Instead of performing the above extraction with 200 parts of 5% strength alcoholic potassium hydroxide solution, the crude product can also be purified by dissolving 9.1 parts of the same in 165 parts of concentrated sulfuric acid, 25 parts of water being gradually added with thorough stirring and cooling. The sulfate of 2-chlorothiachromono (2,3-b) aeridon is deposited in powerful prisms, which are filtered off and washed with 95% sulfuric acid. These crystals decompose with dilute ammonia. In this way, a clear scarlet-colored powder is obtained which has a different X-ray diffraction pattern as the cleaned with alcoholic sodium hydroxide material, the diffraction pattern shows a strong line corresponding to a crystal plane spacing of 3.23 A, medium lines at 7.9, 6.3, 5.7 and 3.75 Å 'and faint lines at 4.75 and 3.95 Å.

The material cleaned with sulfuric acid can be converted into a pigment form by grinding with salt and treating with dimethylformamide in the manner described in Example 1. The pigment obtained in this way shows in the X-ray diffraction investigation strong lines corresponding to a crystal plane distance of 3.43 and 3.39 Å, middle lines at 15.0, 10.0, 6.75, 4.17, 3.81, 3, 69 and 3.19 Å and faint lines at 6.5, 6.1, 5.5, 5.0, 4.95, 4.76, 4.49, 4.28, 3.22, 3.20, 3, 11, 3.05, 2.93 and 2.84 Å. When this pigment is incorporated into paints and other surface coverings, clear scarlet shades are obtained which have excellent fastness properties to solvents, the action of heat and light and which have excellent resistance to weathering. This product can also be used to dye plastic fabrics and fiber-forming materials very real red. Example 3 4.7 parts of 2 - phenylamino - 5 - (4 '- chlorphenylmercapto) terephthalic acid gradually uuter stirring are added at a temperature between 150 and 160'C 23.5 parts of tetra phosphoric acid. The mixture is stirred for a further hour at a temperature between 150 and 160 ° C., cooled to about 100 ° C. and slowly diluted with 100 parts of water. The product is separated off and purified in the manner described in Example 1.

In this way 9 - chloro - thiachromono- (2,3-b) acridone is obtained as a clear red powder. This product can be converted into pigment products by grinding with common salt and treating with dimethylformamide in the manner described in Example 1. In this way a clear red pigment is obtained which has very good fastness properties. The light absorption curve of a solution of this product in sulfuric acid shows maxima at 393, 600 and 650 mIx.

Example 4 4.6 parts of 2- (4'-chlorophenylamino) -5- (4 "-chlorphenylmercapto) -terephthalic acid are dissolved in 50 parts of concentrated sulfuric acid, and the solution is gradually heated to 130 to 140 ° C. over 30 minutes and then 15 The deep green solution is cooled to room temperature and 25 parts of water are gradually added with stirring and cooling. The precipitated 2,9-dichlorothiachromono- (2,3-b) aeridone sulfate is filtered off, again in 75 parts of concentrated sulfuric acid are dissolved and precipitated again by the gradual addition of 7 parts of water. The product is then filtered off and decomposed with dilute sodium carbonate. The resulting product is filtered off, washed alkali-free, dried and by grinding with salt and treating with dimethylformamide in stirred into a pigment form in the manner described in Example 1. The clear, scarlet pigment thus obtained shows an X-ray diffraction pattern with lines corresponding to the following crystal plane distances - strong lines at 12.8 and 3.41 Å, middle lines at 7.8, 6.2, 5.8, 5.4, 3.77 and 3.33 Å and weak lines at 11.0, 10.1, 7.2, 4.95, 4.25, 3.91, 3.22 and 3.08E.

2,9 - dichloro - can acridone thiachromono (2,3-b) can also be obtained by 16.3 parts of 2 - (2'-chloro-phenylamino) - 5 - (2 '- chlorphenylmercapto) terephthalic acid 11/2 hours with 81.5 parts of tetraphosphoric acid at 150 to 160 ° C. The crude product, which is separated off in the manner described in the previous examples, can be purified by precipitation from concentrated sulfuric acid. The product contains 59.6% carbon, 20 / 0 hydrogen and 3.6 # yo nitrogen. A compound of the formula C29H9a2NSC12 contains 60.30 / 0 carbon, 2.3 () / o hydrogen and 3.5% nitrogen. This product can be converted into are converted into a pigment in the manner described in Example 1. The pigment thus obtained shows an X-ray diffraction pattern with a strong line corresponding to a crystal plane spacing of 3.20 Å, middle lines at 5.9, 3.83 and 3.62 Å and weak lines at 5.4, 4, 55.4 # 1 3 # 3.79, 3.31 and 3.23 Å. If the pigments produced by one of these two processes are incorporated into paints or other surface covering materials, clear red shades of excellent fastness to the action of solvents, heat and light are obtained. which are also resistant to ventilation. These products also give extremely true red tones when used for coloring plastic bodies and bulk pigmentation of fiber-forming materials. Example 5 10.3 parts of 2- (4-chlorophenylamino) -5- (4 "-acetylaminophenylmercapto) -terephthalic acid are gradually added over the course of 1 hour with stirring, 52 parts of tetraphosphoric acid at 150 ° C. The temperature of 150 ° C. is maintained for 1 hour and the mixture is cooled to 100 ° C. and gradually diluted with about 50 parts of water A bluish-red powder is obtained. Example 6 11.6 parts of 2- (2'-chlorophenylamino) -5- (2 "-chlorophenylmercapto) -terephthalic acid are gradually added over the course of 2 hours with stirring, 58 parts of tetraphosphoric acid at a temperature of 150'C. The mixture is then heated to 180 to 200.degree. C. for 1 hour, cooled to about 100.degree. C. and slowly diluted with 150 parts of water. The filled product is filtered off, washed and purified by precipitation from sulfuric acid in the manner described in Example 2. This gives 4,1 1- dichloro-thiachromono (2,3-b) acridone in the form of a reddish-yellow powder which is insoluble in most organic solvents. This product can be converted into a pigment by grinding with salt and treating with dimethylformamide in the manner described in Example 1.

When this pigment is incorporated into paints, varnishes or plastic materials, clear reddish-yellow shades of excellent fastness to the action of heat, light and solvents are obtained, which also have excellent resistance when exposed to atmospheric conditions. Example 7 9.1 parts of 2 - phenylamino - 5 - (2 ', 4'-dichlorophenylmereapto) -terephthalic acid are gradually added over the course of 15 minutes with stirring, 46 parts of tetraphosphoric acid at a temperature of 180.degree. The mixture is then stirred for 1 hour at 180.degree. C. and then allowed to cool to about 100.degree. C. and finally slowly diluted with about 200 parts of water. The red product is filtered off, washed free of acid, boiled with 1000 parts of 20% sodium carbonate solution, filtered, washed and dried. This product is then purified by precipitation from sulfuric acid in the manner described in Example 2. 9.1 1-dichloro-thiaehromonoacridone is thus obtained in the form of a clear, scarlet-colored powder which dissolves in sulfuric acid to give a clear greenish-blue solution. The light absorption curve of the sulfuric acid solution shows maxima at 394, 607 and 658 mu. This product can be converted into a pigment form by grinding with common salt and treating with dimethylformamide in the manner described in Example 1.

The following table contains further examples of thiachromonoacridone pigments which can be obtained by cyclizing the terephthalic acid derivatives listed in column 2 using the conditions given in columns 3 and 4. Substituents in Example TerephthaMurederivat dehydrating agent temperature and time (2,3-b) thiachro shade monoacridone pigment 8 2- (4-bromophenylamino) - Tetraphos- 150 to 160'C 2-bromine yellowish red 5-phenyl mercaptophoric acid 1 hour 9 2-Phenylanüno-5- (2'-chlorine- like the same. 1 1 -chlorine orange phenylmercapto) - Substituents in Example terephthalic acid derivative Dehydrierungsmitt.ei temperature and time (2,3-b) thiachro shade monoacridone pigment 10 2- (2'-Methoxyphenylamino) - the same. The same. 4-Meffioxy Red 5-phenyl mercapto- 11 2- (4'-chlorophenylamino) sulfuric acid 140 to 150'C 2,9-dichloro yellowish red 5- (4 "-chloro-2" -methyl- 1 hour 11 -methyl phenylmercapto) - 12 2- (ß-Naphthylamino) - Tetraphos- 140 to 1500C 1,2-Benz Orange 5-phenyl mercaptophoric acid 1 hour Example 13 5.5 parts of 2- (4'-chlorophenylamino) -5- (4 "'- chlorophenylmercapto) -lerephthalic acid are stirred with 20 parts of thionyl chloride and 75 parts of monochlorobenzene at 100 ° C. under reflux for 1 hour. The solution is then stirred cooled to room temperature, and with good stirring 11,2Teile be pulverized Aluminiumehlorid added. the reaction mixture is then stirred for 3 hours at 100 to HO'C, cooled, and the insoluble aluminum chloride complex compound is filtered off and decomposed by boiling with dilute hydrochloric acid. the 2, 9- dichloro - thiaehromono (2,3-b) acridone is filtered off, washed, boiled with dilute sodium carbonate solution, filtered again, washed alkali-free and dried. The product obtained is identical to that of Example 4, and it can be cleaned and be converted into a pigment form.

The following paragraphs describe the ways in which the terephthalic acid derivatives used in the above examples can be obtained can.

2 - Nitro - 5 - phenylmereaptoterephthalic acid can be prepared by adding a solution of 12.5 parts of thiophenol and 7.0 parts of potassium hydroxide in 100 parts of water to a solution of 25 parts of 2-chloro-5-nitroterephthalic acid (prepared according to the method of the German Patent specification 512 228) and 12 parts of sodium carbonate in 250 parts of water are added. The solution is heated to 80 ° C. for 1 hour and, if necessary, additional sodium hydroxide is added in order to keep the solution alkaline. The reaction mixture is then acidified with dilute hydrochloric acid and the precipitated 2-nitro-5-phenylmercaptoterephthalic acid is filtered off. When this product is purified by recrystallization from aqueous alcohol, yellow prisms with a melting point of 290 ° C. are obtained. This product contains 53.0 () / o carbon, 2.1% hydrogen and 4.5% nitrogen. A compound of the formula C14H9O6NS contains 52.7% carbon, 2.8% hydrogen and 4.4 () / o nitrogen.

2-Amino-5-phenylmercaptoterephthalic acid can be obtained by gradually adding 18.7 parts of sodium hydrosulfite to a solution of 10 parts of 2-nitro-5-phenylmercaptoterephthalic acid in a solution of 5.9 parts of sodium carbonate in 240 parts of water with stirring at 20 ° C will. The reaction mixture is heated to a temperature between 40 and 50 ° C. for 5 minutes. then acidified with dilute hydrochloric acid, and the precipitated 2-amino-5-phenylmercaptoterephthalic acid is filtered off, washed and dried.

2 - chloro - 5 - phenylmercaptoterephthalic acid is prepared by dissolving 7.2 parts of 2-amino-5-phenylmercaptoterephthalic acid in 100 parts of a hot 3% strength aqueous sodium carbonate solution, whereupon 1.9 parts of sodium nitrite are added. The solution is cooled and gradually added, with thorough stirring, to a mixture of 14.5 parts of concentrated hydrochloric acid and 14.5 parts of water, which is cooled with ice in order to keep the temperature between 5 and 10 ° C. The thick, clear yellow suspension of the diazo compound is stirred for 1 hour at 5 to 10 ° C and then gradually a stirred solution of 2.5 parts of copper (I) chloride in 12 parts of concentrated hydrochloric acid and 6 parts of water at a temperature between 70 and 80 ' C added. The clear yellow 2-chloro-5-phenylmercaptoterephthalic acid is precipitated and filtered off.

The 2-phenylamino-5-phenylmercaptoterephthalic acid used in Example 1 can be obtained by mixing a stirred mixture of 5.0 parts of 2-chloro-5-phenylmercaptoterephthalic acid, 6.4 parts of potassium acetate, 0.1 part of copper powder, 0.1 part Copper (11) acetate, 4.5 parts of aniline and 50 parts of dimethylformamide is heated to a temperature between 140 and 150'C for 20 hours. The solution is diluted with 300 parts of water. made alkaline by adding sodium carbonate and filtered. The filtrate is acidified and the precipitated 2-phenylamino-5-phenylmercaptoterephthalic acid is filtered off, washed and dried.

If under similar conditions an analogous series of conversions is carried out. the following compounds can be obtained in this way: 2- (4'-chlorophenylamino) -5-phenylmercaptoterephthalic acid (Example 2) from 2-chloro-5-nitroterephthalic acid, thiophenol and 4'-chloroaniline.

2-Phenylamino-5- (4'-chlorophenylmercapto) -terephthalic acid (Example 3) from 2-chloro-5-nitroterephthalic acid, p-chlorothiophenol and aniline.

2- (4'-Chlorophenylamino) -5- (4 "-chlorophenylmercapto) -terephthalic acid (Example 4) from 2-chloro-5-nitroterephthalic acid, p-chlorothiophenol and p-chloroaniline.

2- (4'-Chlorophenylamino) -5- (4 "-acetylaminophenylmercapto) -terephthalic acid (Example 5) from 2-chloro-5-nitroterephthalic acid, N, S-diacetyl-p-aminothiophenol and p-chloroaniline. 2- (2 '-Chlorophenylamino) -5- (2 "-chlorphenylmercapto) -terephthalic acid (Example 7) from 2-chloro-5-nitroterephthalic acid, o-chlorothiophenol and o-chloroaniline.

2-Phenylamino-5- (2 ', "chlorophenylmercapte) -terephthalic acid (Example 8) from 2-chloro-5-nitroterephthalic acid, 2,4-dichlorothiophenol and aniline.

2- (4 # -Bromophenylamino) -5-phenylmereaptoterephthalic acid (Example 9) from 2-chloro-5-nitroterephthalic acid, thiophenol and p-bromoaniline.

2-Phenylamino-5- (2'-chlorophenylmercapto) -terephthalic acid (Example 10) from 2-Chfor-5-nitroterephthalic acid, o-chlorothiophenote and aniline.

2- (2'-Methoxyphenylamino-5-phenylmercapto) -terephthalic acid (Example 11) from 2-chloro-5-nitroterephthalic acid, thiophenel and o-anisidine.

2- (4'-Chlorophenylamino) -5- (4 "-chlor-2" m-methylphenylmercapto) -lerephthalic acid (Example 12) from 2-chloro-5-nitroterephthalic acid, 4-chloro-2-methylthiophenoi and p-chloroaniline.

2-fl-Naphthylamino-5-phenylmercaptoterephthalic acid from 2-chloro-5-nitroterephthalic acid, thiophene oil and fl-naphthylamine. The terephthalic acid derivatives can be prepared from dimethyl 2,5-dibromoterephthalate by the following procedure: A solution of 4.2 parts of p-chlorothiophenol in 55 parts of dry pyridine is boiled and stirred with 1.6 parts of powdered sodium hydroxide for 20 minutes. 14.0 parts of dimethyl 2,5-dibromoterephthalate are then added, and the mixture is stirred and refluxed for 20 hours. The reaction mixture is then diluted with water and the pyridine is removed by steam distillation. The residue is acidified and the solid is filtered off. This is hydrolyzed to 2-bromo-5- (p-chterphenylmercapto) -terephthalic acid by heating it to the boil for 3 hours with a solution of 5 g of potassium hydroxide in 100 parts of ethanol. The solution is diluted with water; filtered and the acid precipitated by adding dilute hydrochloric acid. The yellow precipitate is filtered off, washed and dried. The product thus obtained (10.5 parts) is mixed at 140 to 150 ° C. with 60 parts of dimethylformamide, 11.0 parts of potassium acetate, 0.2 part of copper powder, 0.2 part of copper, and 7.8 parts Stirred aniline for 20 hours. The mixture is then diluted with 500 parts of water, made alkaline by adding sodium carbonate and filtered. The filtrate is acidified with dilute hydrochloric acid and the precipitated p; -. Phenylamino - 5 - (4'-chlorophenylmercapto) - terephthalic acid is filtered off, washed and dried. The following procedure can also be used: 1.8 parts of powdered potassium hydroxide are added to a solution of 4.2 parts of p-chlorothiophenol in 30 parts of dimethylformamide and the mixture is stirred for 10 minutes while boiling. 14 parts of dimethyl - 2,5 - dibromoter terephthalate are then added and the mixture is stirred for 20 hours at 140 ° to 150 ° C. Then 12 parts of Anifin, 5.0 parts of potassium acetate, 0.3 part of copper powder and 0.3 g of cupric acetate are added and the mixture is stirred for a further 24 hours while boiling. The mixture is then diluted with about 500 parts of water, made alkaline with sodium carbonate, heated and filtered hot. The solid residue is re-extracted with hot dilute sodium carbonate solution and the extracts are combined with the main filtrates, acidified, and the resulting precipitate is filtered off, washed and dried. The yield is about 8 parts.

Claims (1)

Claim: Process for the production of pigments, consisting of one or more compounds of the form 0 "--- C / s C-- \ C) NH wherein X and Y each denote the atoms which are necessary to complete a benzene ring or naphthalene ring system or such a ring system which carries nonionic substituents, characterized in that one or more dicarboxylic acids of the formula wherein X and Y have the meaning given above, cyclized by treatment with a condensing agent, the dicarboxylic acid, if desired, can be obtained from a 2,5-dihalogen terephthalate by condensation with a mercapto compound and an amine. Documents considered: German Patent No. 475 688; Belgian Patent No. 579 525; USA. Pat. No. 1829 843rd