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

Abstract

The effects of crown ethers were examined for the intramolecular two-site jumping rates of sodium cations in 2,5-di-tert-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 (ΔV ₁ ^‡) and the inclusion complex of the sodium cation with crown ethers (ΔV ₂ ^‡) were estimated to be −7.4 and 9.5–13.8 cm³ mol⁻¹, respectively. Further, the reaction volumes (ΔV) for the Na⁺/crown-ether complex formation were determined as 15.6–17.5 cm³ 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.

Keywords:

• High-pressure ESR
• Kinetic study
• Cation migration
• Crown ether