Ciba-geigy Corporation

Jere K Kaplan

Wolfgang J Tritschler

Gary Clauson

2-(2-Hydroxyphenyl)-2H-benzotriazoles can be prepared particularly advantageously by catalytically reducing a suitable o-nitroazobenzene compound to the corresponding N-oxybenzotriazole compound in the presence of hydrazine hydrate, a metal catalyst selected from the group consisting of Raney-Ni and the noble metals, an organic or inorganic base, an organic solvent, and optionally water; followed by isolating said N-oxybenzotriazole compound and converting it to the corresponding 2-(2-hydroxyphenyl)-2H-benzotriazole.

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Mobile, AL, United States of America

Jere K Kaplan