DETERMINATION OF THE FORMATION CONSTANT FOR ADDUCT FORMATION BETWEEN WATER AND THE RADICAL ANION OF 3,5-DI-tert-BUTYL-1,2-BENZOQUINONE

摘要

The reduction of 3,5-di-tert-butyl-1,2-benzoquione has been studied in acetonitrile. Attention was directed to the first step of the reduction, electron transfer to the neutral quinone to form the radical anion. Water was added to the anhydrous acetonitrile and it was observed that the apparent standard potential moved in the positive direction as expected for complexation of the radical anion by water. The shifts in potential indicated that only one water molecule interacted with the radical anion up to 0.10 M water. Studies at various temperatures allowed the evaluation of the changes in enthalpy and entropy of the complexation reaction, viz., ΔH° = -12 kJ mol~(-1) and ΔS° = -18 J mol~(-1) K~(-1).