Unifying the Solution Thermochemistry of Molecules, Radicals, and Ions

Article abstract of DOI:10.1021/ja00202a031

A general cycle was developed that defines the thermodynamics for all of the homolytic and heterolytic cleavage reactions of a hydrocarbon, R-R', in solution.Only seven experimental parameters were needed in order to define the energetics for all 11 of the possible cleavage reactions of R-R'.These parameters were the oxidation and reduction potentials of R-R', R(.), and R'(.) and the homolytic, R-R', bond energy.The utility of this approach was demonstrated for the case where R was an arylmethyl group and R' was hydrogen.The oxidation and reduction potentials of thearylmethyl radicals were measured by modulation voltammetry in acetonitrile, and the homolytic C-H bond energies of the corresponding hydrocarbons were measured by photoacoustic calorimetry.The cycle was also extended to a case where R-R' was a radical rather than a closed-shell molecule.