A kinetic study of sodium cation migration in 2,5-di-tert-butyl-1,4-benzoquinone radical anion in the presence of crown ethers as studied with high-pressure electron spin resonance

The effects of crown ethers were examined for the intramolecular two-site jumping rates of sodium cations in 2,5-ditert-1,4-benzoquinone ion pairs using a high-pressure electron spin resonance (ESR) technique. The activation volumes for the intramolecular migration of the sodium cation (DeltaV(1)(double dagger)) and the inclusion complex of the sodium cation with crown ethers (DeltaV(2)(double dagger)) were estimated to be -7.4 and 9.5-13.8 cm(3) mol(-1), respectively. Further, the reaction volumes (DeltaV) for the Na+/crown-ether complex formation were determined as 15.6-17.5 cm(3) mol(-1) in 1,2-dimethoxyethane. Based on the results, the mechanism for intramolecular sodium cation migration in the presence of crown ethers is discussed from the perspective of volume.