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Photo‐ and Radiation‐Chemical Formation and Electrophilic and Electron Transfer Reactivities of Enolether Radical Cations in Aqueous Solution
Author(s) -
Bernhard Klaus,
Geimer Judith,
CanleLopez Moises,
Reynisson Johannes,
Beckert Dieter,
Gleiter Rolf,
Steenken Steen
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20011105)7:21<4640::aid-chem4640>3.0.co;2-e
Subject(s) - electrophile , aqueous solution , chemistry , photochemistry , electron transfer , radiation chemistry , chemical reaction , organic chemistry , catalysis
In aqueous solution, enolether radical cations (EE . + ) were generated by photoionization ( λ ≤222 nm) or by electron transfer to radiation‐chemically produced oxidizing radicals. Like other radical cations, the EE . + exhibit electrophilic reactivity with respect to nucleophiles such as water or phosphate as well as electron transfer reactivity, for example, towards one‐electron reductants such as phenols, amines, vitamins C and E, and guanine nucleosides. The reactivity of these electron donors with the radical cation of cis ‐1,2‐dimethoxyethene .+ (DME .+ ) can be described by the Marcus equation with the reorganization energy λ =16.5 kcal mol −1 . By equilibrating DME .+ with the redox standard 1,2,4‐trimethoxybenzene, the reduction potential of DME .+ is determined to be 1.08±0.02 V/NHE. The oxidizing power of the radical cation of 2,3‐dihydrofuran, which can be considered a model for the enolether formed on strand breakage of DNA, is estimated to be in the range 1.27–1.44 V/NHE.