Aggregation in Aqueous Solutions of 2-(Tetrafluoro(trifluoromethyl)-λ⁶-sulfanyl-ethan-1-ol (CF₃SF₄-ethanol)): A Comparison with Aqueous Trifluoroethanol and Hexafluoroisopropanol Using Molecular Dynamics Simulations and Dynamic Light Scattering Experiments

Abstract

2-Tetrafluoro(trifluoromethyl)-λ 6 -sulfanylethan-1-ol (CF 3 SF 4ethanol) combines the polar hydrophobicity of tetrafluoro(trifluoromethyl)λ 6 -sulfanyl (CF 3 SF 4 ) group with the polarity of simple alcohols. The properties of aqueous solutions of the well-known fluorinated alcohols 2,2,2trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) were compared with those of aqueous solutions of the novel CF 3 SF 4 -ethanol. Those properties were computed using all atom molecular dynamics simulations with OPLS-compatible parameters. DFT ab initio calculations were used to accurately describe the nonsymmetrical, hypervalent sulfur in CF 3 SF 4 -ethanol. Although the molecular and conformational characteristics of CF 3 SF 4 -ethanol are like those of both TFE and HFIP, the greater hydrophobicity and lower polarity of CF 3 SF 4 -ethanol resulted in solution phase aggregation at a much lower concentration. The properties computed for TFE and HFIP in this work were consistent with published computational and experimental studies. CF 3 SF 4 -ethanol is predicted to be environmentally benign and hence an excellent green solvent candidate while possessing many of the same properties as TFE or HFIP.