Pressure effects on cation migration in 2,5-di-tert-butyl-1,4-benzoquinone radical anion

✍ Scribed by Masamichi Kasahara; Yoshimi Sueishi; Shunzo Yamamoto

• Book ID: 102444224
• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 122 KB
• Volume: 33
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.1034

✦ Synopsis

Pressure effects on the two-site jumping of sodium and potassium cations in a 2,5-di-tert-butyl-1,4-benzoquinone ion pair have been studied using a high-pressure EPR technique. The rate constants of the intramolecular and intermolecular migrations for Na ϩ and K ϩ were determined from an EPR spectral simulation. The migration rates were found to be accelerated by increasing the external pressure. Using the pressure dependence of the migration rates, we estimated the activation volumes of the intramolecular (⌬V 1 ‡ ) and intermolecular (⌬V 2 ‡ ) processes for the Na ϩ and K ϩ migrations: ⌬V 1 ‡ ϭ Ϫ5.3 cm 3 mol Ϫ1 and ⌬V 2 ‡ ϭ Ϫ29 cm 3 mol Ϫ1 for Na ϩ , and ⌬V 1 ‡ ϭ Ϫ8.3 cm 3 mol Ϫ1 and ⌬V 2 ‡ ϭ Ϫ0.85 cm 3 mol Ϫ1 for K ϩ . Based on the results, the mechanisms for the two-site jumping of Na ϩ and K ϩ are discussed in terms of volume.