Ciba-geigy Corporation

Helmut Prestel

Rudolf Maul

Klaus Muller

Heinz Steiner

Wolfgang J Tritschler

2-(2-Hydroxyphenyl)-2H-benzotriazoles of the formula ##STR1## in which R is hydrogen, C.sub.1 -C.sub.12 alkyl or C.sub.1 -C.sub.4 alkoxy, R.sub.1 is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.6 cycloalkyl, phenyl or phenyl-C.sub.1 -C.sub.4 alkyl and R.sub.2 is C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.6 cycloalkyl, phenyl, phenyl-C.sub.1 -C.sub.4 alkyl or a group --C.sub.n H.sub.2n --COOR.sub.3, in which n is 0 to 4 and R.sub.3 is hydrogen or C.sub.1 -C.sub.12 alkyl, can be prepared particularly advantageously by catalytic hydrogenation of a suitable o-nitroazo compound in the presence of a Pt, Pd, Pt/Pd or Rh hydrogenation catalyst and an alkylenediamine or an acyclic or cyclic polyalkylene polyamine in a halogenated or nonhalogenated aromatic hydrocarbon as solvent.

Process for the preparation of benzotriazoles

A process for the preparation of compounds of formula I ##STR1## wherein R.sub.1 and R.sub.2 are each independently of the other hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.6 cycloalkyl or phenyl, and R.sub.3 and R.sub.4 are each independently of the other C.sub.1 -C.sub.18 alkyl, C.sub.5 -C.sub.6 cycloalkyl, phenyl, phenyl which is substituted by C.sub.1 -C.sub.6 alkyl and/or hydroxy, or phenyl-C.sub.1 -C.sub.4 alkyl. The process comprises reacting a compound of formula III ##STR2## with a nitrite in aqueous or aqueous/organic medium to a compound of formula II ##STR3## extracting said compound of formula II from the reaction solution with a solvent, hydrogenating said compound, without isolation, in the cited solvent and in the presence of a palladium catalyst, to the corresponding p-aminophenol, and reacting said aminophenol, without isolation, with cyanuric chloride and a compound of formula HSR.sub.3 or HSR.sub.4 or a mixture of compounds of formulae HSR.sub.3 and HSR.sub.4. The products are obtained in high yield and purity.

Process for the preparation of alkylhydroxyanilinothiotriazine

Hologenated 2-(2-hydroxyphenyl)-2H-benzotriazoles of the formula ##STR1## in which X is halogen, R.sub.1 is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.6 cycloalkyl, phenyl or phenyl-C.sub.1 -C.sub.4 alkyl and R.sub.2 is C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.6 cycloalkyl, phenyl, phenyl-C.sub.1 -C.sub.4 alkyl or a group --C.sub.n H.sub.2n --COOR.sub.3, in which n is 0 to 4 and R.sub.3 is hydrogen or C.sub.1 -C.sub.12 alkyl, can be prepared particularly advantageously by catalytic hydrogenation of a corresponding o-nitroazo compound in the presence of a hydrogenation catalyst consisting of 0.1 to 3% of Pt on a support and of an organic amine.

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Bruchsal, Germany

Helmut Prestel