Fluoride Ion in Alcohols: Isopropanol vs Hexafluoroisopropanol

The utility of alcohol as a hydrogen bonding donor is considered a providential avenue for moderating the high basicity and reactivity of the fluoride ion, typically used with large cations. However, the practicality of alcohol–fluoride systems in reactions is hampered by the limited understanding of the pertinent interactions between the OH group and F^–. Therefore, this study comparatively investigates the thermal, structural, and physical properties of the CsF–2-propanol and CsF–1,1,1,3,3,3-hexafluoro-2-propanol systems to explicate the effects of the fluoroalkyl group on the interaction of alcohols and F^–. The two systems exhibit vastly different phase diagrams despite the similar saturated concentrations. A combination of spectroscopic analyses, alcohol activity coefficient measurements, and theoretical calculations reveal the fluorinated alcohol system harbors the stronger OH···F^– interactions between the two systems. The diffusion coefficient and ionic conductivity measurements attribute the present results to disparate states of ion association in the two systems.