摘要 |
<p>A method of preparing a 2-phenylbenzotriazole of formula I <CHEM> wherein R1 is H, Cl, C1-4 alkyl, C1-4 alkoxy, COOH or SO3H; R2 is H, Cl, C1-4 alkyl or C1-4 alkoxy; R3 is H, Cl, C1-12 alkyl, C1-4 alkoxy, phenyl, (C1-8 alkyl)phenyl, phenoxy or phenyl(C1-4 alkyl); R4 is H, Cl, OH or C1-4 alkoxy; and R5 is H, C1-12 alkyl or phenyl(C1-4 alkyl); which comprises reducing with hydrogen, in the presence of water, the corresponding o-nitroazobenzene of formula II <CHEM> H</p> |