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.