Abstract: Compounds of the general formula ##STR1## in which n denotes 1 or 2,X denotes an OMe group,Me denotes a proton, an alkali metal cation or an optionally substituted ammonium cation,R denotes hydrogen, a lower alkyl group or halogen, and, in the event thatn is 1,X also denotes an --NR.sup.1 R.sup.2 group in which R.sup.1 and R.sup.2 represent hydrogen or a lower alkyl group,a process for their preparation and their use as optical brighteners, especially for polyamide fibers and wool.

Abstract: Mixtures of optical brighteners consisting of 1 to 60% by weight of a brightener from the bisbenzoxazolylnaphthalene series and 99 to 40% by weight of one or more brighteners of the formulae 2 to 10 listed in the description.

Abstract: Mixtures of optical brighteners composed of(a) 1 to 99% by weight of one or more compounds of the formula (1) ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 can be identical or different and denote hydrogen, chlorine, C.sub.1 -C.sub.4 carbalkoxy, C.sub.1 -C.sub.4 -alkyl or C.sub.1 -C.sub.4 -alkoxy and(b) 99 to 1% by weight of one or more compounds of the formulae ##STR2## in which n denotes 0 or 1, R.sub.7 and R.sub.8 denote identical or different radicals from the group comprising hydrogen, fluorine, chlorine, phenyl, trifluoromethyl, C.sub.1 -C.sub.4 -alkyl, alkoxy, cyano, carboxyl, carboalkoxy, carboxamide or alkyl sulfonates, and two adjacent radicals R.sub.7 and R.sub.8 together can also represent a benzene ring, a lower alkylene group or a 1,3-dioxapropylene group, and B denotes a cyano group, a carboxylate group or a carboxamide group or a 1,2,4-oxadiazol-3-yl group, a 1,3,5-oxadiazol-2-yl group, a phenyl group or a 1,3,4-oxadiazol-2-yl group.

Abstract: Process for the preparation of naphthalene-1,4-dicarboxylic acid, wherein 4-bromo-1-naphthoic acid is reacted with at least 1 mole of copper-(I) cyanide per mole of 4-bromonaphthoic acid in a polar, aprotic solvent, and the copper salt complex of 4-cyanonaphthoic acid thus obtained is saponified in an alkaline medium.

Abstract: A process for the preparation of naphthalene-1,4-dicarboxylic acid, which comprises reacting 1,4-dihalogenonaphthalene with at least 2 moles of copper-I cyanide per mole of dihalogenonaphthalene in a polar, aprotic solvent and subjecting the copper salt complex of 1,4-dicyanonaphthalene thus obtained to alkaline hydrolysis.

Abstract: Colorless formulations of optical brighteners from the 4,4'-bis-triazinylamino-stilbene-disulfonic acid series, which are obtained by heating the brightener together with an oxyalkylate.

Abstract: Compounds of the formula ##STR1## wherein R.sup.1 to R.sup.8 each mean, independent from one another, a hydrogen atom or a non chromophoric substituent, R.sup.9 means a hydrogen atom, an alkyl group, a halogen atom, preferably a chlorine or bromine atom, an optionally functionally modified carboxy or sulfo group. They are prepared by reacting 1 mol of 1,7-naphthalene dicarboxylic acid or its acid chloride with 2 mols of an o-aminophenol and subsequent cyclization of the di-N,N'-acyl compounds obtained in the first step. These compounds are valuable optical brighteners.

Abstract: Compounds of the formula ##STR1## and the corresponding lower alkyl quaternary salts thereof in which A represents a group of the formula ##STR2## and in which R.sup.1 stands for a group of the formula ##STR3## whereby R represents a hydrogen atom or a lower alkyl group, R.sup.2 has the same meaning as R.sup.1 or stands for a hydrogen atom or a group of the formula ##STR4## whereby the aromatic rings may be substituted by non-chromophoric substituents. Due to their good fluorescence these compounds can be used as optical brighteners for organic materials, especially textile materials.