Abstract: The present invention relates to a process for the preparation of 2,5-di-phenylamino-terephthalic acid and its dialkyl esters of the formula ##STR1## in which R is a hydrogen atom or a methyl or an ethyl group, by reaction of a succinic acid dialkyl ester with a sodium alcoholate in xylene, treatment of the resulting 2,5-dihydroxy-cyclohexadiene-1,4-di-carboxylic acid dialkyl ester with acid and aniline, dehydrogenation of the resulting 2,5-di-phenylamino-dihydro-(3,6)-terephthalic acid dialkyl ester by means of oxygen, if appropriate hydrolysis of the 2,5-di-phenylamino-terephthalic acid dialkyl ester formed and liberation of the 2,5-di-phenylamino-terephthalic acid from the di-sodium salt formed. The 2,5-di-phenylamino-dihydro-(3,6)-terephthalic acid dialkyl ester is reacted with pure oxygen in the presence of an alkali metal ion and/or an alkaline earth metal ion. This significantly decreases undesirable impurities.

Abstract: The invention relates to a process for the preparation of 2-fluorophenylhydrazine or 2-fluorophenylhydrazine hydrochloride, which comprises diazotizing 2-fluoroaniline, reducing the resulting diazonium salt with alkaline bisulfite solution to give 2-fluorophenylhydrazine .alpha..beta.-disulfonate, hydrolyzing the latter with hydrochloric acid to give 2-fluorophenylhydrazine hydrochloride, adding alkali metal solution to neutralize the mixture, subsequently cooling the mixture, removing the 2-fluorophenylhydrazine precipitate by filtration and, if appropriate, reacting the latter with hydrochloric acid to give 2-fluorophenylhydrazine hydrochloride.

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 tetrachloro-1,4-benzoquinone of high purity by the action of chlorine and concentrated hydrochloric acid on hydroquinone, by introducing a part of the hydroquinone to be employed into an initially introduced 4- to 6-fold molar amount--based on the total amount of hydroquinone--of 20 to 37 % aqueous hydrochloric acid containing catalytic amounts of iron(III) ions and an anionic dispersant, introducing 1.5 to 2.0 times the molar amount--based on total hydroquinone--of chlorine as a gas into this solution at a temperature of 20.degree. to 90.degree. C., then adding the residual amount of hydroquinone as a solid or in dissolved form, introducing 1.5 to 2.0 times the molar amount of chlorine as a gas, keeping the concentration of the hydrochloric acid here at 23-25% by addition of water and finally raising the temperature to 100.degree. to 107.degree. C. with further introduction of chlorine as a gas (1.7 to 2.

Abstract: The present invention relates to a process for the preparation of crystalline, salt-free, chlorine-substituted 3-nitrobenzenesulfonic acid hydrates from sulfonation mixtures containing chlorine-substituted 3-nitrobenzenesulfonic acid, in which the sulfonation mixture is mixed with from 8 to 25% strength by weight aqueous sulfuric acid at from 40.degree. C. to 100.degree. C., the resulting suspension is cooled to from 5.degree. C. to 20.degree. C., the precipitate is filtered off and dissolved with water at from 30.degree. C. to 100.degree. C., filtration is carried out if desired, the solution is cooled to from 5.degree. to 40.degree. C. and filtered, and the sulfuric acid-containing filtrate is recycled if desired.

Abstract: An ecologically and economically improved process for the preparation of 2,5-di-phenylamino-terephthalic acid and its di-alkyl esters of the formula (1) ##STR1## in which R is a hydrogen atom or a methyl group and R' is a hydrogen atom or a methyl or ethyl group.

Abstract: A process for the preparation of 2,5-di(phenylamino)terephthalic acid and its dialkyl esters of formula (I): ##STR1## in which R is a hydrogen atom or a methyl group and R' is a hydrogen atom or a methyl or ethyl group.

Abstract: A process for the preparation of high-purity tetrachloro-1,4-benzoquinone by the action of hydrogen peroxide and hydrochloric acid on hydroquinone, which comprises causing 3.8 top 4.2 times the molar quantity of 30 to 37% hydrochloric acid and 1.9 to 2.1 times the molar quantity of 50 to 35% hydrogen peroxide, to act at 5 to 50.degree. C. on 1 mole of hydroquinone in at least 12 times the molar quantity of 30 to 37% hydrochloric acid, then heating the resulting suspension, which essentially contains 2,5-dichlorohydroquinone, to 45 to 55.degree. C. and again causing to act on it, at 50 to 95.degree. C., 3.8 to 4.2 times the molar quantity of 30 to 37% hydrochloric acid and 1.9 to 2.1 times the molar quantity of 50 to 35% hydrogen peroxide, in each case based on the hydroquinone used, and finally adding to the suspension, which is now essentially composed of trichloro-1,4-benzoquinone, 1.9 to 2.1 times the molar quantity of hydrochloric acid of the said concentration range, and 0.95 to 1.

Abstract: A process for the production of high-purity tetrachloro-1,4-benzoquinone by the action of chlorine and hydrochloric acid on hydroquinone which comprises causing 1.9 to 2.1 times the molar quantity of gaseous chlorine to act at temperatures from 5.degree. to 15.degree. C. on 1 mol of hydroquinone in 6 to 7 times the molar quantity of 30 to 37% hydrochloric acid, then diluting the resulting suspension, essentially containing 2,5-dichlorohydroquinone, with 2 to 3 parts of water, relative to hydroquinone employed, and initially warming to a temperature from 20.degree. to 30.degree. C., subsequently introducing 1.9 to 2.1 times the molar quantity of chlorine gas in an air atmosphere while raising the temperature to 90.degree.-100.degree. C. with simultaneous dilution with 3.5 to 4.5 parts of water, relative to hydroquinone employed, and finally introducing 1 to 2 times the molar quantity of gaseous chlorine, relative to hydroquinone employed, at temperatures from 100.degree. to 115.degree. C.

Abstract: A single-vessel process for preparing 2-acetaminonaphthalene-6-sulfonic acid of high purity by sulfonating 2-hydroxynaphthalene with concentrated sulfuric acid, converting the 2-hydroxynaphthalenesulfonic acid formed with ammonia in the presence of ammonium hydrogensulfite into 2-amino-naphthalene-6-sulfonic acid (Bucherer reaction) and N-acetylating the latter to give 2-acetaminonaphthalene-6-sulfonic acid, which comprises, after diluting the sulfonating melt with water, substantially removing any impurities still present in the resulting aqueous solution of 2-hydroxynaphthalene-6-sulfonic acid, in particular 2-hydroxynaphthalene, by extraction with toluene or xylene and/or clarification using active carbon.

Abstract: Process for the preparation of naphthostyril by dissolving 1,8-naphthalimide in an aqueous solution of lithium hydroxide and potassium hydroxide while heating at 40.degree. C. to 80.degree. C., cooling the solution obtained to 14.degree. C. and seeding it at said temperature with a maximum of 1 mol-% of sodium 1,8-naphthalimide per 1 mol of 1,8-naphthalimide used, then adding chlorine bleaching liquor at 10.degree. C. to 20.degree. C., reductively removing excess active chlorine after the reaction has taken place, adjusting the alkaline aqueous solution produced of the alkali-metal salt of the 1-aminonaphthal-ene-8-carboxylic acid formed to a pH of 2.0 by adding acid and isolating the naphthostyril which precipitates in this process.

Abstract: A process for the preparation of 2,6-dichlorobenzoxazole, which comprises reacting 6-chlorobenzoxazolone in the presence of chlorine, phosphorus trichloride and phosphoryl chloride, or in mixtures of phosphorus pentachloride and phosphoryl chloride, at temperatures of 150.degree. to 170.degree. C., under pressure, the weight ratio of chlorine and phosphorus trichloride to phosphoryl chloride or of phosphorus pentachloride to phosphoryl chloride being 0.15:1 to 0.60:1.

Abstract: Process for the preparation of 6-chloro-2,4-dinitroaniline by chlorination of 2,4-dinitroaniline with sodium hypochlorite in water using acid, which comprises carrying out the chlorination in the presence of a mineral acid or strong organic acid at a pH value .ltoreq.0 and in the presence of a dispersing agent at temperatures of about 40.degree. to 50.degree. C. and, when the chlorination has ended, either (a) filtering the resulting acid aqueous dispersion hot and washing the filtered reaction product with hot aqueous alkali solution, or (b) initially rendering the resulting acid aqueous dispersion alkaline with aqueous alkali solution and then filtering the mixture hot and subsequently washing the filtered reaction product with hot dilute mineral acid.

Abstract: Process for the preparation of 2,6-dichloro-4-nitroaniline by chlorination of 4-nitroaniline with chlorine bleaching liquor in water using acids, which comprises chlorinating 1 mole of 4-nitroaniline in 3-6 moles of hydrochloric acid (HCl) or nitric acid (HNO.sub.3) in the form of a dilute, aqueous acid in the presence of a dispersing agent which is stable under the reaction conditions, the chlorination initially being carried out at 5.degree. to 10.degree. C. and then at 15.degree.-20.degree. C. and, finally, after 90-95% of the 2-chloro-4-nitroaniline intermediately formed has been converted into 2,6-dichloro-4-nitroaniline, the temperature of the aqueous suspension being increased from 15.degree.-20.degree. C. to 70.degree. C., without further addition of chlorine bleaching liquor, and then by post-chlorinating, by renewed addition of chlorine bleaching liquor, at temperatures between 20.degree. and 70.degree. C., bringing the pH of the aqueous suspension to 9.

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: A process for the preparation of 6-chloro-2,4-dinitrophenol in a high yield and in a high degree of purity by saponifying 2,4-dinitrochlorobenzene and/or 2,4-dinitrophenyl alkyl ethers of the formula ##STR1## in which m denotes the number 2, 3 or 4 and n denotes the number 1 or 2, by means of aqueous sodium hydroxide or potassium hydroxide solution and chlorinating the resulting 2,4-dinitrophenol with sodium hypochlorite, which comprises chlorinating the 2,4-dinitrophenol, without prior isolation as an intermediate, in aqueous suspension at a pH value of 3.5-7 by means of chlorine bleach liquor at temperatures of 5.degree. to 20.degree. C.

Abstract: The invention relates to salt-free N-acetylaminoarylsulfonic acids, their preparation by acetylation with acetic anhydride or acetyl chloride, sulfuric acid, which can also contain a small amount of water and/or dimethylformamide and/or N-methylpyrrolidone, serving as the solvent, and the use of the N-acetylaminoarylsulfonic acids for the preparation of their acid chlorides.

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.