Tetraoctylphosphonium tetrakis(pentafluorophenyl)borate room temperature ionic liquid toward enhanced physicochemical...

Presented herein is the facile preparation of a new room temperature ionic liquid (RTIL), tetraoctylphosphonium tetrakis(pentafluorophenyl)borate (P(8888)TB). Subsequently, its physicochemical properties such as density, viscosity, and conductivity were characterized relative to temperature, demonstrating values of 1.22 g·cm(-3), 727 mPa·s, and 180 μS·cm(-1), respectively, at 60 °C. The electrochemistry of P(8888)TB was also investigated using cyclic voltammetry at a Pt-disk ultramicroelectrode and at a microinterface between water and the RTIL; this analysis revealed a wide metal-electrolyte potential window, ∼3.5 V, and a large liquid|liquid polarizable potential window, ∼0.9 V, at a temperature of 60 °C. Additionally, electron transfer (ET) reactions at a metal electrode|RTIL interface along with ion transfer (IT) reactions at the water|P(8888)TB interface were examined; the kinetics of these reactions were explored using finite element analysis. Increased ET and IT kinetics combined with enhancements of physicochemical properties versus RTILs we made previously seemingly suggest modest improvements. However, taken as a whole, they demonstrate significant progress toward a hydrophobic RTIL that can be used in conventional electrochemistry and biphasic metal ion extractions.