Exciplex and radical ion intermediates in the photochemical reaction of 9-cyanophenanthrene with 2,3-dimethyl-2-butene
作者:Frederick D. Lewis、Robert J. DeVoe
DOI:10.1016/0040-4020(82)80124-5
日期:1982.1
The photochemical reaction of 9-cyanophenanthrene and 2,3-dimethyl-2-butene, first reported by Mizuno, Pac and Sakurai, has been reinvestigated. The formation of a [2+2]-cycloadduct via a singlet exciplex is the exclusive reaction in the nonpolar solvents benzene and ethyl acetate. Photochemical behavior in polar solvents is far more complicated than previously reported. Mechanisms consistent with
由Mizuno,Pac和Sakurai首次报道的9-氰基菲和2,3-二甲基-2-丁烯的光化学反应已被重新研究。通过单重态激基复合物形成[2 + 2]-环加合物是在非极性溶剂苯和乙酸乙酯中的排他性反应。在极性溶剂中的光化学行为比以前报道的要复杂得多。提出了与溶剂极性,甲醇浓度,甲醇氘化和光强度对产物收率的影响一致的机理。9-氰基菲蒽阴离子基团和2,3-二甲基-2-丁烯阳离子基团的形成是极性溶剂中主要的光引发过程。阳离子可以进行去质子化反应,以产生烯丙基,或被甲醇进行亲核攻击以产生甲氧基烷基。这些基团和9-氰基菲菲阴离子基团的共价键合产生了在极性溶剂中获得的无环加合物。阴离子自由基也可以被质子化,最终导致9,10-二氢-9-氰基菲的形成。