Effects of the fluorination degree in alcohols on the interaction with fluoride ions

Abstract

Taming F⁻ with a hydrogen bond donor such as alcohols can moderate its high basicity and hardness, enabling its use in some chemical and electrochemical reactions. Previous works discussed the strong interactions between fluorinated alcohols and F⁻ using a variety of analytical methods. In this study, non-fluorinated and fluorinated alcohols (ethanol, isopropanol, and tert-butanol and their fluorinated forms) are systematically investigated to elucidate the effects of the fluorination degree in alcohols on the interaction with F⁻. Quantum mechanical calculations revealed that fluorinated alcohols exhibit larger interaction energies with F⁻ compared to the corresponding non-fluorinated ones, and hexafluoroisopropanol has the strongest interaction in this series. Although several different factors contribute to the interaction energy, energy decomposition analysis revealed that the electrostatic term plays the most significant role among the attractive constituent terms and the exchange-repulsion between the CF₃ group and F⁻ is prominent in a bulky alcohol system.