| 摘要 |
<p>A method for producing a 2-phenylbenzotriazole useful as an ultraviolet absorber and represented by the general formula (III), (III) wherein R1 represents a hydrogen or chlorine atom, or a C1-C4 lower alkyl or lower alkoxy, carboxy or sulfonic acid group, R2 represents a hydrogen or chlorine atom, or a C1-C4 lower alkyl or lower alkoxy group, and R3, R4 and R5 each represent a hydrogen or chlorine atom, or a C1-C12 alkyl, phenyl, C1-C8 alkyl group-substituted phenyl, phenyl-C1-C8 alkyl, hydroxy, phenoxy or C1-C4 alkoxy group, which comprises reducing a 2-phenylbenzotriazol-N-oxide represented by the general formula (II), (II) wherein R1, R2, R3, R4 and R5 represent the same meanings as described above, with one or more members selected from the group consisting of phosphorus, hypophosphorous acid and its salts in the presence of an alkali and a naphthoquinone in the absence or presence of a surface active agent, or comprises reducing an o-nitroazobenzene represented by the general formula (I), (I) wherein R1, R2, R3, R4 and R5 represent the same meanings as described above, with one or more members selected from the group consisting of phosphorus, hypophosphorous acid and its salts in the presence of an alkali and a naphthoquinone in the absence or presence of a surface active agent to obtain a 2-phenyl-benzotriazol-N-oxide represented by the general formula (II), (II) wherein R1, R2, R3, R4 and R5 represent the same meanings as described above, and reducing the resulting compound (II) with one or more members selected from the group consisting of phosphorus, hypophosphorous acid and its salts in the presence of an alkali and a naphthoquinone in the absence or presence of a surface active agent.</p> |
