Photochemistry of 1-alkoxy- and 1-(benzyloxy)-9,10-anthraquinones in methanol: a .delta.-hydrogen atom abstraction process that exhibits a captodative effect
作者:Ronald L. Blankespoor、Randall L. De Jong、Robert Dykstra、Daniel A. Hamstra、David B. Rozema、Derek P. VanMeurs、Paul Vink
DOI:10.1021/ja00009a042
日期:1991.4
support a mechanism in which a biradical intermediate is formed by an intramolecular δ-hydrogen atom transfer that occurs in one step but not a reaction pathway in which the hydrogen atom transfer is accomplished in two discrete steps via separate electron and proton transfers. Apparent rate constants for the disappearance of 1-(p-XPhCH 2 O)-2-methyl-9,10-anthraquinone (X=H, Cl, CH 3 , NO 2 , OCH 3 , CF
各种 1-烷氧基-和 1-(苄氧基)-9,10-蒽醌在甲醇中的光化学已被检查。在没有氧气的情况下,这些反应的主要光产物是 9,10-蒽氢醌,分别在 1 位具有 MeOCH 2 O 和 ArCH(OMe)O 基团。淬火研究人员将激发态的多重性确定为三重态。氘同位素效应、取代基效应和溶剂极性研究支持了一种机制,其中双自由基中间体是通过分子内 δ-氢原子转移形成的,该转移发生在一个步骤中,而不是氢原子转移在两个离散的反应路径中完成的反应途径。通过单独的电子和质子转移步骤。1-(p-XPhCH 2 O)-2-methyl-9,10-anthraquinone (X=H, Cl, CH 3 , NO 2 , OCH 3 , CF 3 , 和CN)被测量并且发现从最大(X=NO 2 )到最小(X=OCH 3 )以3.4的因子变化。Captodative 相互作用解释了这些速率常数的微小差异