Quantum Phenomena and Solvent Effects on Addition of Hydrogen Isotopes to Benzene and to Dimethylbutadiene

Abstract

AbstractRate constants have been measured for the reaction of the light hydrogen isotope muonium with benzene and 2,3‐dimethylbutadiene‐1,3 in the gas phase and in several solvents. Comparison with H atom data reveals (1) appreciable kinetic isotope effects, (2) a strong contribution of tunnelling for the activated reaction with benzene, (3) encounter controlled reaction for Mu addition to the diene, (4) a mass dependence of the diffusion constant of hydrogen isotopes in solution, and (5) an enhancement of the rate constant in solution over that in the gas phase by a factor, except for water, of the inverse Ostwald solubility coefficient for hydrogen. The isotope‐dependent reduction of the solvent effect in water is tentatively ascribed to the dynamics of the clathrate‐like structure when the hydrogen atom reacts.