Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
Abstract:
Spectrophotometric pulse radiolysis experiments with cis- and trans-stilbene (Sc and St) in 2-propanol show that both isomers react with the solvated electron with a rate constant of 4.5 × 109 M?1 s?1. The absorption spectra of the two anion radicals have maxima at 496 and 486 nm, respectively. The absorbances at 400–550 nm disappear exponentially corresponding to a pseudo first order protonation of the anion radicals. The rate constants for the protonation of the cis isomer is 6.4 × 105 and of the trans isomer 0.7 × 105 s?1. In mixtures of cis- and trans-stilbene the electron transfer has a forward rate constant of 9 × 107 M?1 s?1 while the back reaction has a rate constant of 2.15 × 107 M?1 s?1. An equilibrium constant K = 4.2 is calculated.
