Hoechst Aktiengesellschaft

Hoechstaktiengesellschaft

Rudolf Neeb

Reinhard Mohr

Heinrich Volk

Wolfgang Ironich

Siegbert Rittner

Michael Meier

Helmold Von Plessen

Kurt Hohmann

Werner Wykypiel

The invention relates to a process for the preparation of 3-hydroxy-N-benzimidazolon-5-yl-2-naphthamide, which comprises reacting 5-aminobenzimidazolone and sodium carbonate in N-methylpyrrolidone with a solution of 3-hydroxy-2-naphthoyl chloride in xylene or toluene, filtering, washing with xylene or toluene, introducing the filter cake into water to which sodium carbonate has been added and steam-distilling, filtering off the residue with suction, washing and drying.

Process for the preparation of

The invention relates to a process for purification of 2-hydroxynaphthalene-6-carboxylic acid by recrystallization. In this process, the crude acid is recrystallized from water-miscible linear or cyclic aliphatic ethers, aliphatic polyethers or aliphatic hydroxy ethers or from at least 10% strength by weight aqueous solutions of these ethers. Recrystallization from a 35-90% strength by weight aqueous solutions of 1,4-dioxane is particularly preferred.

Process for the purification of 2-hydroxynaphthalene-6-carboxylic acid

2-Hydroxydibenzofuran-3-carboxylic acid and its alkali metal salts are prepared by reacting an alkali metal salt of 2-hydroxydibenzofuran with carbon dioxide, where appropriate under pressure, at a temperature above 120.degree. C. in an aliphatic alcohol of 4 to 8 carbon atoms.

Process for preparing 2-hydroxydibenzofuran-3-carboxylic acid and alkali

Chlorozincate salts of benzothiazonium azo compounds are prepared by reacting benzothiazolium azo compounds with an dialkylsulfate having from 1 to 4 carbon atoms in the alkyl radicals, which process comprises carrying out the reaction in an aqueous medium at a temperature of from 10.degree. to 80.degree. C. in the presence of an acid acceptor and the alkylation with the use of from 1.8 to 2.5 mols of the dialkylsulfate, calculated on the starting azo dyestuff, at a pH not exceeding 7. The prepared benzothiazolium azo compound is precipitated as chlorozincate salt, especially with the use of an alkali metal chloride. According to this process, the chlorozincate salts are obtained in higher purity. A perceptible decomposition of the benzothiazolium azo compound does not occur. Chemicals, for example the alkylation agent and acid-binding agents need be used in a small quantity. In addition to this economy and to the less pollution of the waste water, the process has the advantage that it can be carried out with the use of a small reaction volume.

Process for the preparation of chlorozincate salts of benzo thiazolium

6-Hydroxy-2-naphthoic acid can be selectively acetylated to 6-acetoxy-2-naphthoic acid, in particular in the presence of admixtures of isomeric hydroxy-naphthoic acids, and thus be separated from those isomeric admixtures. The acetylation is affected in aqueous alkaline solution by reaction with acetic anhydride. By hydrolysis of the 6-acetoxy-2-naphthoic acid, a pure 6-hydroxy-2-naphthoic acid is obtained.

Process for preparing 6-acetoxy-2-naphthoic-acid and pure

Zinc chloride complex compounds to which the structure of the general formula (1) ##STR1## can be assigned, in which the individual radicals in the formula have the following meanings: Rhu 1 is a hydrogen atom or an optionally substituted lower alkyl group; R.sup.2 is a hydrogen atom, an optionally substituted lower alkyl group or an optionally substituted phenyl radical; R.sup.3 is a hydrogen atom or an optionally substituted lower alkyl group; R.sup.4 is a hydrogen atom, an optionally substituted lower alkyl group or an optionally substituted phenyl radical; R.sup.5 is a hydrogen atom or a halogen atom or a lower alkyl group or a lower alkoxy group, or R.sup.1 and R.sup.5 together form the o-phenylene radical; R.sup.6 is a hydrogen atom or a halogen atom or a lower alkyl group or a lower alkoxy group; Z is a hydrogen atom or a halogen atom or a lower alkyl group or a cyano, carboxylic acid, carbamoyl or sulfamoyl group or a carbamoyl or sulfamoyl group which is monosubstituted or disubstituted by lower alkyl, or a trifluoromethyl or lower carbalkoxy group, a lower alkoxy group which can be substituted by cyano, an acyloxy group, an acylamino group, a lower alkylamino group or a lower dialkylamino group. They are prepared by reacting a nitroso compound of the formula (2) ##STR2## in which R.sup.3, R.sup.4, R.sup.6 and Z have the meanings mentioned above, with an m-aminophenol of the formula (3) ##STR3## in which R.sup.1, R.sup.2 and R.sup.5 have the meanings mentioned above, in the presence of zinc chloride and in the absence of a base. The zinc chloride complex compounds of the formula (1) can be converted by eliminating the radical Z in the formula or by removing, by oxidative means, this radical Z, in the formula, which is in the ortho-position in relation to the nitrogen atom, or the other hydrogen atom which is in the ortho-position, into the phenoxazine dyestuffs of the formula (4) ##STR4## in which R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 have the meanings mentioned above and Z.sub.1 denotes a halogen atom, a lower alkyl group, a cyano, carboxylic acid, carbamoyl or sulfamoyl group, a carbamoyl or sulfamoyl group which is monosubstituted or disubstituted by lower alkyl, or a trifluoromethyl or lower carbalkoxy group or a hydrogen atom and X.sup.(-) represents and anion.

Zinc chloride complex compounds

Chlorozincate salts of thiazolium azo compounds are prepared by reacting thiazolium azo compounds with an dialkylsulfate having from 1 to 4 carbon atoms in the alkyl radicals, which process comprises carrying out the reaction in an aqueous medium at a temperature of from about 10.degree. to 50.degree. C. in the presence of a zinc compound capable of binding acid, and with the use of from 1.8 to 2.5 mols of the dialkylsulfate, calculated on the starting azo dyestuff, at a pH not exceeding 8, preferably at 3-7. The prepared thiazolium azo compound is precipitated as chlorozincate salt, especially by means of an alkali metal chloride. According to this process, the chlorozincate salts are obtained in higher purity. A perceptible decomposition of the thiazolium azo compound does not occur. Chemicals, for example the alkylation agent and acid-binding agents need be used in a small quantity. In addition to this economy and to the less pollution of the waste water, the process has the advantage that it can be carried out with the use of a small reaction volume.

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Offenbach, Germany

Rudolf Neeb