Several 2(2-hydroxyphenyl)2H-benzotriazoles with more than one benzotriazole group substituted on di- and trihydroxybenzenes were synthesized by azo coupling ofo-nitrobenzenediazonium chloride with resorcinol or phloroglucinol followed by reductive cyclization with zinc powder and sodium hydroxide. By careful diazonium coupling witho-nitrobenzenediazonium chloride, the monobenzotriazyl compound, 4(2H-benzotriazole-2-yl)1,3-dihydroxybenzene 2(2,4-dihydroxyphenyl)2H-benzotriazole was obtained. All compounds have unusual spectral characteristics with high extinction coefficients, cut off of the absorption below 400 nm and are excellent candidates for ultraviolet stabilizers.
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