Selective Oxidation of Phenols to Hydroxybenzaldehydes and Benzoquinones with Dioxygen Catalyzed by Polymer-Supported Copper
作者:Ken Takaki、Yohei Shimasaki、Tetsuya Shishido、Katsuomi Takehira
DOI:10.1246/bcsj.75.311
日期:2002.2
Oxidation of 2,6-disubstituted 4-methylphenols with dioxygen by using a CuCl2-poly(4-methyl-4′-vinyl-2,2′-bipyridine) catalyst gave the corresponding 4-hydroxybenzaldehydes in high yields. The activity of the catalyst and the selectivity of the products significantly depended on the reaction conditions and the composition of the catalyst. When the molar ratio of the bipyridine unit of the polymer ligand to Cu was unity, i.e., N/Cu = 2, the best results were obtained. Moreover, the reaction is likely to be promoted by coordination of the products to the catalyst. Similarly, 2,3,6-trimethylphenol and related compounds were converted to p-benzoquinones selectively with a CuCl2-poly(4-vinylpyridine) catalyst. These polymer-supported catalysts were readily recovered and are reusable without noticeable decrease of their activity.
用CuCl2-聚(4-甲基-4'-乙烯基-2,2'-吡啶)催化剂与氧气氧化2,6-二取代4-甲基苯酚,得到了相应的4-羟基苯甲醛,高收率。催化剂的活性和产物的选择性显著依赖于反应条件和催化剂的组成。当聚合物配体的双吡啶单元与铜的摩尔比为1,即N/Cu = 2时,获得最佳结果。此外,反应可能通过产物与催化剂的配位得到促进。同样,2,3,6-三甲基苯酚及相关化合物在CuCl2-聚(4-乙烯基吡啶)催化剂的作用下选择性转化为对苯醌。这些聚合物支撑的催化剂容易回收,且在不显著降低活性的情况下可重复使用。