Method of making hydroxyarylbenzotriazoles and their N-oxides

Claim 1

A method of making a benzotriazole compound or N-oxide thereof comprising catalytically hydrogenating an o-nitrophenylazohydroxy starting compound in an alkaline medium by contacting the said o-nitrophenylazohydroxy starting compound with hydrogen in a liquid alkaline medium in the presence of a catalytic amount of a hydrogenation catalyst effective to catalyze said hydrogenation, the said medium being an aqueous medium or a polar organic solvent or mixture thereof containing an alkali metal hydroxide, the said hydrogenation catalyst being a metal which is a platinum metal, nickel, cobalt or molybdenum or an oxide or sulfide of such metal, the hydrogenation being carried out at a temperature within the range of from 15° to 100°C. under a pressure of from one atmosphere to 1000 psig, the said o-nitrophenylazohydroxy starting compound having structural formula ##SPC2## and the resulting benzotriazole compound or N-oxide thereof having the structural formula ##SPC3## wherein Ar is a phenyl or naphthyl moiety, A and B are hydrogen, chlorine, bromine or alkyl, n and m are from 1 to 4, and x is zero or 1, with the further proviso that when the A's or B's are chlorine or bromine in the starting compound their number may be reduced in the product by a number corresponding to the number of any chlorine or bromine atoms eliminated in the process.

Claim 2

A method of making a benzotriazole compound or N-oxide thereof comprising catalytically hydrogenating an o-nitrophenylazohydroxy starting compound in an alkaline medium by contacting the said o-nitrophenylazohydroxy starting compound with hydrogen in a liquid alkaline medium in the presence of a catalytic amount of a hydrogenation catalyst effective to catalyze said hydrogenation, the said medium being an aqueous medium or a polar organic solvent or mixture thereof containing an alkali metal hydroxide, the said hydrogenation catalyst being a metal which is a platinum metal, nickel, cobalt or molybdenum or an oxide or sulfide of such metal, the hydrogenation being carried out at a temperature within the range of from 15° to 100°C. under a pressure of from one atmosphere to 1000 psig, the said o-nitrophenylazohydroxy starting compound having structural formula ##SPC2## and the resulting benzotriazole compound or N-oxide thereof having the structural formula ##SPC3## wherein Ar is a phenyl or naphthyl moiety, A and B are hydrogen, chlorine, bromine or alkyl, n and m are from 1 to 4, and x is zero or 1, with the further proviso that when the A's or B's are chlorine or bromine in the starting compound their number may be reduced in the product by a number corresponding to the number of any chlorine or bromine atoms eliminated in the process.