Dissociative Electron Transfer to Diphenyl-Substituted Bicyclic Endoperoxides: The Effect of Molecular Structure on the Reactivity of Distonic Radical Anions and Determination of Thermochemical ParametersReportar como inadecuado




Dissociative Electron Transfer to Diphenyl-Substituted Bicyclic Endoperoxides: The Effect of Molecular Structure on the Reactivity of Distonic Radical Anions and Determination of Thermochemical Parameters - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

1

Department of Chemistry, University of Malta, Msida, MSD 2080, Malta

2

Department of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada





*

Authors to whom correspondence should be addressed.



Abstract The heterogeneous electron transfer reduction of the bicyclic endoperoxide 1,4-diphenyl-2,3-dioxabicyclo2.2.1hept-5-ene 4 was investigated in N,N-dimethylformamide at a glassy carbon electrode. The endoperoxide reacts by a concerted dissociative ET mechanism resulting in reduction of the O-O bond with an observed peak potential of −1.4 V at 0.2 V s−1. The major product 90% yield resulting from the heterogeneous bulk electrolysis of 4 at −1.4 V with a rotating disk glassy carbon electrode is 1,4-diphenyl-cyclopent-2-ene-cis-1,3-diol with a consumption of 1.73 electrons per mole. In contrast, 1,4-diphenyl-2,3-dioxabicyclo2.2.2oct-5-ene 1, undergoes a two-electron reduction mechanism in quantitative yield. This difference in product yield between 1 and 4 is suggestive of a radical-anion mechanism, as observed with 1,4-diphenyl-2,3-dioxabicyclo-2.2.2 octane 2 and 1,4-diphenyl-2,3-dioxabicyclo2.2.1heptane 3. Convolution potential sweep voltammetry is used to determine unknown thermochemical parameters of 4, including the O-O bond dissociation energy and the standard reduction potential and a comparison is made to the previously studied bicyclic endoperoxides 1–3 with respect to the effect of molecular structure on the reactivity of distonic radical anions. View Full-Text

Keywords: dissociative electron transfer; distonic radical ion; endoperoxide; convolution analysis; electrode interface; cyclic voltammetry dissociative electron transfer; distonic radical ion; endoperoxide; convolution analysis; electrode interface; cyclic voltammetry





Autor: David C. Magri 1,* and Mark S. Workentin 2,*

Fuente: http://mdpi.com/



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