Chemipro Kasei Kaisha, Limited

Kunitoshi Iguchi

Naohiko Fukuoka

Kazunobu Kubota

A method of preparing 2-phenylbenzotriazoles expressed by Formula I: ##STR1## (wherein R.sub.1 denotes a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, a carboxyl group or a sulfonic acid group; R.sub.2 denotes a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms or a lower alkoxyl group having 1 to 4 carbon atoms; R.sub.3 denotes a hydrogen or chlorine atom, an alkyl group having 1 to 12 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, a phenyl group, a phenyl group substituted by an alkyl group having 1 to 8 carbon atoms, a phenoxy group or a phenylalkyl group with an alkyl part having 1 to 4 carbon atoms; R.sub.4 denotes a hydrogen or chlorine atom, a hydroxyl group or an alkoxyl group having 1 to 4 carbon atoms; and R.sub.5 denotes a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or a phenylalkyl group with an alkyl part having 1 to 4 carbon atoms) comprises reduction with hydrogen of o-nitroazobenzene derivatives expressed by Formula II: ##STR2## (wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 each denote the same as in Formula I), the reduction being effected in a solvent containing water.

Method of preparing 2-phenyl benzotriazoles

A method of preparing 2-phenylbenzotriazoles expressed by Formula I: ##STR1## (wherein R.sub.1 denotes a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, a carboxyl group or a sulfonic acid group; R.sub.2 denotes a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms or a lower alkoxyl group having 1 to 4 carbon atoms; R.sub.3 denotes a hydrogen or chlorine atom, an alkyl group having 1 to 12 carbon atoms, a lower alkoxy group having 1 to 4 carbon atoms, a phenyl group, a phenyl group substituted by an alkyl group having 1 to 8 carbon atoms, a phenoxy group or a phenylalkyl group with an alkyl part having 1 to 4 carbon atoms; R.sub.4 denotes a hydrogen or chlorine atom, a hydroxyl group or an alkoxyl group having 1 to 4 carbon atoms; and R.sub.5 denotes a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or a phenylalkyl group with an alkyl part having 1 to 4 carbon atoms) comprises reducing with hydrogen 2-phenylbenzotriazole-N-oxides expressed by Formula II: ##STR2## (wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 each denotes the same as in Formula I).

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Osaka, Japan

Kunitoshi Iguchi