Rates of Proton Transfer between Pyridine Bases in the Gas Phase. Steric and Isotope Effects

Article abstract of DOI:10.1021/ja00529a007

The rates of proton and deuteron transfer between various pyridine bases have been studied in the gas phase by pulsed ion cyclotron resonance spectroscopy.The results show that as the reactants become increasingly substituted in the 2 and 6 positions the reaction efficiencies decrease.Some of the least efficient reactions show a small normal kinetic deuterium isotope effect.These results are interpreted in terms of a general mechanism which includes an intrinsic barrier to proton transfer.The reaction efficiencies and isotope effects are modeled using RRKM theory, and an estimate for the intrinsic barrier height is obtained.