A process for preparing 2-(2,4-dihydroxyphenyl)-4.6-diaryl-s-triazines or related compounds in three steps starting with cyanuric halide or corresponding phenoxy or alkoxy substituted triazine is described. Step 1 involves the nucleophilic displacement of one or two leaving groups in the triazine with a phenolic moiety. Step 2 involves a Friedel-Crafts reaction using a Lewis acid catalyst (preferably aluminum chloride) to replace the remaining leaving group(s) with aryl groups such as xylyl. Finally, step 3 involves replacing the phenolic moiety with a phenol such as resorcinol using preferably a protic acid catalyst or a combination of a Lewis acid and a protic acid catalyst. Alternatively, step 3 may be performed alone, e.g. starting from materials from other processes, or leading directly to a tris-hydroxyphenyl-s-triazine. The s-triazines prepared are useful as UV absorbers for the stabilization of organic substrates against the adverse effects of actinic light.
本发明描述了一种以卤化
氰或相应的苯氧基或烷氧基取代的三嗪为起点,分三步制备 2-(2,4-二羟基苯基)-4.6-二芳基-s-三嗪或相关化合物的工艺。步骤 1 涉及三嗪中一个或两个离去基团与
酚基的亲核置换。第 2 步是使用
路易斯酸催化剂(最好是
氯化铝)进行 Friedel-Crafts 反应,用芳基(如 xylyl)取代剩余的离去基团。最后,第 3 步是用
苯酚(如
间苯二酚)取代
酚基,最好使用原酸催化剂或
路易斯酸和原酸催化剂的组合。另外,步骤 3 也可以单独进行,例如从其他工艺的原料开始,或直接生成三羟基苯基-s-三嗪。制备出的 s-三嗪可用作
紫外线吸收剂,用于稳定有机基质,使其免受放 射光的不利影响。