Process for the preparation of 2-(2'-hydroxyphenyl)benzo-triazoles

摘要

The process is used for the preparation of 2-(2'-hydroxyphenyl)-benzotriazoles from 2-nitro-2'-hydroxyazobenzene compounds by reductive cyclisation. The latter is carried out in a strongly basic medium. The reducing agent used is an alcohol having more than one carbon atom, e.g. isopropanol or sec-butanol. The reaction also requires the use of an aromatic dihydroxy or dioxo compound as a catalyst. Examples of such catalysts are benzodiols, naphthodiols, benzoquinones and naphthoquinones.