O-Neophyl-type 1,2-phenyl rearrangement initiated by electron transfer: development of kinetic probes of dissociative electron transfer

Abstract

The first example of an O-neophyl-type rearrangement in a distonic radical anion was found in the electron transfer induced dissociative reduction of 9,10-diphenyl-9,10-epidioxyanthracene.

References

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12. Electrochemical experiments were performed using standard equipment and electrodes as described in ref. 1. All potentials were calibrated internally to ferrocene (E°_Fc⁺/Fc is 0.449 and 0.475 vs. SCE in MeCN and DMF, respectively). Data in DMF is similar and will be reported in the full account of this work.
13. The transfer coefficient (or symmetry factor)α is defined as ∂ΔG^‡/∂ΔG°, where ΔG^‡ is the free energy of activation and ΔG° is the free energy of the ET.
14. (a) The reduction of DPA-O₂ is a 1 F mol^–1 process except under the conditions indicated later. Full details including simulations will be reported separately. (b) Determined by comparison of the peak current (i_p) of PPA formed in an electrolysis with that measured with a known concentration of an authentic sample of PPA.
15. At higher scan rates the amount of PPA formed in the CV is less than quantitative; its presence by CV is absent at scan rates higher than 75 V s^–1. In product studies the amount of product derived from the O-neophyl rearrangement is always quantitative. This may be due to a rate limiting aromatization.
16. The reduction potential of the triphenylmethyl radical is at least –1.2V vs. SCE and that of tritolylmethyl radical is –1.36 V vs. SCE (S. Bank, C. Ehrlich and J. A. Zubieta, J. Org. Chem., 1979, 44, 1454).
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