Abstract: The invention relates to a process for the preparation of tetrachloro-1,4-benzoquinone of high purity by the action of chlorine and concentrated hydrochloric acid on hydroquinone, which involves introducing a portion of the hydroquinone to be employed into initially introduced hydrochloric acid containing catalytic amounts of iron(III) ions and an anionic dispersant, introducing chlorine gas into this solution at a temperature from 20.degree. to 107.degree. C., then adding the residual quantity of hydroquinone as a solid or in solution, raising the temperature to from 80.degree. to 107.degree. C. while continuing to pass in gaseous chlorine, adding, after the introduction of gaseous chlorine has ended, a relatively high-boiling organic solvent which is not miscible with hydrochloric acid, and subsequently subjecting the reaction mixture to thermal aftertreatment.

Abstract: A process for the preparation of quinazoline-2,4-diones of the formula (I) ##STR1## in which R.sup.1 is aryl and R.sub.2, R.sup.3, R.sup.4, and R.sup.5 independently of one another are halogen, alkyl, alkoxy or hydrogen, by reacting anthranilic acid esters of the formula (II) ##STR2## in an aprotic reaction medium with aryl isocyanates R.sup.1 --N.dbd.C.dbd.O to give N-arylcarbamoyl-anthranilic acid esters of the formula (III) ##STR3## and cyclizing these in the presence of a base selected from the group of alkali metal or alkaline earth metal alkoxides, amides, hydrides or tetraalkylammonium hydroxides.

Abstract: Process for the preparation of alcohol fluorobenzoates of the formula (I) ##STR1## in which R is an alkyl radical and F.sub.n is 1 to 4 fluorine atoms which, independently of one another, are bonded to the aromatic ring, by reacting a fluorobenzyl chloride of the formula (II) ##STR2## in which F.sub.n is as defined above, with an at least stoichiometric amount of an alkali metal alcoholate ROM in which R is as defined above and M is an alkali metal from the group consisting of Li, Na and K, in the corresponding alcohol ROH at temperatures from -10.degree. C. to 150.degree. C., the solvent is distilled off, if appropriate, and the alkali metal chloride formed is separated off by treating the mixture with water or by filtration.

Abstract: Process for the preparation of compounds of the formula (1) ##STR1## in which R is an alkyl (C.sub.1 -C.sub.6) group and X is a hydrogen or alkali metal atom, in which compounds of the formula (2) ##STR2## in which R and X have the abovementioned meanings, are converted into the corresponding diazonium compound with a diazotizing agent in a mineral acid at temperatures of about -5.degree. C. to about +25.degree. C., this diazonium compound is then reacted, without or after intermediate isolation, with aqueous mineral acid at temperatures of about 70.degree. C. to about 120.degree. C. and the resulting compounds of the above formula (1) are isolated.

Abstract: A process for the preparation of aromatic sulfonyl chlorides of the formula I ##STR1## in which R.sub.1, R.sub.2 and R.sub.3 are identical or different and are hydrogen, fluorine, chlorine, bromine or iodine atoms, alkyl(C.sub.1 -C.sub.4), acetamido, nitro or carboxyl groups, or R.sub.1 and R.sub.2 together form an aromatic or heteroaromatic ring having 5 or 6 ring members, which can be substituted by fluorine, chlorine, bromine or iodine atoms, alkyl(C.sub.1 -C.sub.4), acetamido, nitro or carboxyl groups, by reaction of aromatic compounds of the formula II ##STR2## in which R.sub.1, R.sub.2 and R.sub.3 have the abovementioned meanings, with chlorosulfonic acid in excess or with chlorosulfonic acid or oleum and thionyl chloride, by reacting in the presence of sulfamic acid as a catalyst.

Abstract: Process for the preparation of 4,4'-dinitrodiphenylamine which comprises reacting 1 mole of 4-halonitrobenzene with about 1 to about 3 moles of an alkali metal cyanate in the presence of about 0.5 to about 5 moles of water in dimethylsulfoxide at temperatures of about 150.degree. to about 170.degree. C.

Abstract: Compounds of the formula I ##STR1## in which X denotes hydrogen, fluorine, chlorine or bromine, Y and Z denote hydrogen, lower alkyl or lower alkoxy, M denotes sodium, potassium or one equivalent of calcium and L denotes a dipolar aprotic solvent, are obtained from compounds of the formula II ##STR2## in which X, Y and Z have the abovementioned meanings, and a metal cyanamide of the formula IIIM.sub.2 N--CNin which M has the abovementioned meaning, in a dipolar aprotic solvent, which after the reaction is substantially removed, whereupon a lower molecular weight aliphatic alcohol is added to the residue and the product precipitated is isolated. Nitrophenylureas of the formula IV ##STR3## in which X, Y and Z have the abovementioned meanings, are obtained from the compounds of the formula I by acid hydrolysis.

Abstract: To prepare a 1-nitrobenzene-2-alkyloxycarbonyl-5-carboxylic acid, a dialkyl benzene-1,4-dicarboxylate is first nitrated in a customary manner and the dialkyl 1-nitrobenzene-2,5-dicarboxylate compound obtained is subjected to a partial acidic ester hydrolysis without isolating the nitro compound prepared as an intermediate. The acidic ester hydrolysis is carried out in the presence of a catalytic amount of an organic solvent which is completely or partially miscible with water and has a boiling point of above 90.degree. C. and/or of an emulsifier; it is preferably carried out at a temperature between 65.degree. and 110.degree. C.

Abstract: The preparation of 3-amino-1-phenylpyrazol-5-one by heating phenylhydrazine and a lower cyanoacetic acid alkyl ester in a polar solvent, using a lower alcoholate of an alkali metal as the condensation agent, leads to particularly high yields and quality, if the phenylhydrazine and 1 to 1.2 moles of the alcoholate are initially taken, the cyanoacetic ester is metered in and the reaction is carried out at 105.degree. to 140.degree. C., volatile alcohols which have been liberated from the ester and, if appropriate, from the alcoholate being distilled off at the reaction temperature. It is advantageous to employ the phenylhydrazine in an excess of up to about 200 mole % and to select, as the polar solvent, an alcohol or ether having a boiling point above 105.degree. C.

Abstract: N-o-nitro-phenyl- or -naphthyl-N'-halogensulfonyl ureas which may be substituted in their aromatic rings by a further nitro group (and the phenyl ureas also by fluoro, chloro, bromo, lower alkyl, lower alkoxy, trifluoromethyl, cyano or phenyl) are obtained by reacting the corresponding o-nitraniline with fluoro- or chlorosulfonylisocyanate. The products can be hydrolyzed to yield the corresponding nitroaryl ureas.

Abstract: 4-Nitro-4'-amino-diphenylamine-2-sulfonic acid, 2-nitro-4'-amino-diphenylamine-4-sulfonic acid and their sodium salts are obtained in good yield and high purity by condensing 6- or 4-chloro-3-nitro-benzene sulfonic acid and 1,4-phenylene diamine in a saturated aqueous sodium chloride solution. The products and their desulfonation derivatives are dye precursors.

Abstract: Diaminophenyl ureas of the formula ##STR1## in which R is an inert substituent, are obtained from the corresponding dinitrophenyl urea by way of reduction, especially catalytic hydrogenation. Through a cyclization process, while splitting off ammonia, these ureas yield the corresponding aminobenzimidazolones, advantageously without an intermediate isolation of the diaminophenyl ureas.

Abstract: This invention relates to a process for the preparation of a very pure copper phthalocyanine pigment of the .alpha.-modification which comprises dissolving crude copper phthalocyanine in a 80 to 86% sulfuric acid isolating the copper phthalocyanine sulfate formed, hydrolizing the sulfate and grinding the copper phthalocyanine thus obtained in an aqueous-organic medium.

Abstract: The N-acetoacetylamino compounds of 2,5-dimethoxy-4-chloro-aniline, 2,4-dimethyl-aniline and 2-methyl-5-chloroaniline are obtained in a good yield and excellent purity, if the above-mentioned anilines are reacted with diketene in an inert organic solvent or diluent in the presence of from 0.1 to 6%, calculated on the weight of the aniline, of water, while adding catalytic amounts of acid. An industrial aniline quality is preferably dried by heating it with a solvent forming with water an azeotropic mixture, and thereafter the amount of water required is added. The products may be used without purification as coupling components for the preparation of pigments.

Abstract: A process for the preparation of highly pure organic pigments which comprises converting organic dyestuffs having various degrees of purity into dyestuff salts capable of being isolated by means of suitable acids which dissolve the impurities contained in the dyestuff, separating them from the acid, recovering the dyestuffs in pure form from the dyestuff salts by the action of water and subjecting the isolated dyestuff in aqueous organic or aqueous-organic medium to a mechanical fine dispersion. By this process the dyestuff formed by the decomposition of the dyestuff sulfate is obtained in highly pure form and can extremely well be brought into a finely dispersed form so that it can be brought into pigment form already by short-time grinding. During the preparation and isolation of the dyestuff sulfate the sulfuric acid is obtained in such a high concentration that it can be regenerated in an economical manner and any ecological charge is avoided.

Abstract: A process for the purification of optionally substituted crude phthalocyanines wherein a phthalocyanine is introduced into a 84 to 88 % sulfuric acid, the phthalocyanine sulfate formed is subjected to a crystal growth at 60 - 100.degree. C in an inert gas atmosphere, the phthalocyanine sulfate is isolated and the phthalocyanine is recovered by hydrolysis with water. By this process a phthalocyanine sulfate is formed in a coarse crystalline form which can easily be filtered and which furtheron can easily be processed to a valuable pigment of the .alpha.-modification.

Abstract: A process for preparing very pure copper phthalocyanine pigments of the .alpha.-modification, wherein substituted or unsubstituted copper phthalocyanines having different degrees of purity are converted into copper phthalocyanine salts capable of being isolated, with the aid of suitable acids which dissolve the impurities contained in the dyestuff, wherein these salts are separated from the acid, the copper phthalocyanines of the .alpha.-modification are set free in a pure form from the copper phthalocyanine salts by the action of water and wherein the isolated copper phthalocyanine is subject in an aqueous suspension to a mechanical fine division. This process yields copper phthalocyanines of the .alpha.-modification in a very pure form without causing problems with respect to the waste water.