S. Fukuzumi, K. Ohkubo, A. Tokuda
Apr 21, 2000
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Journal
Journal of the American Chemical Society
Abstract
The reactivity of 9-substituted 10-methyl-9,10-dihydroacridine (AcrHR) in the reactions with hydride acceptors (A) such as p-benzoquinone derivatives and tetracyanoethylene (TCNE) in acetonitrile varies significantly spanning a range of 107 starting from R = H to But and CMe2COOMe. Comparison of the large variation in the reactivity of the hydride transfer reaction with that of the deprotonation of the radical cation (AcrHR•+) determined independently indicates that the large variation in the reactivity is attributed mainly to that of proton transfer from AcrHR•+ to A•- following the initial electron transfer from AcrHR to A. The overall hydride transfer reaction from AcrHR to A therefore proceeds via sequential electron−proton−electron transfer in which the initial electron transfer to give the radical ion pair (AcrHR•+ A•-) is in equilibrium and the proton transfer from AcrHR•+ to A•- is the rate-determining step. Charge-transfer complexes are shown to be formed in the course of the hydride transfer re...