Electrochemical Fluorination of Partially Fluorinated Dialkylethers. Synthesis of Sevoflurane Derivatives (CF3)2CHOCHF2, (CF3)2CHOCF3, and (CF3)2CFOCF3.

Electrochemical fluorination in anhydrous hydrogen fluoride (ECF in aHF) according to the Simons process was used for the fluorination of the anesthetic sevoflurane (CF3)2CHOCH2F to yield (CF3)2CHOCHF2, (CF3)2CHOCF3, and (CF3)2CFOCF3. The related ethers RFOCH3 (RF = nC3F7, a mixture of nC4F9/iC4F9, iC4F9, tC4F9) were fluorinated to result in the respective mono-, di-, and trifluoromethyl ethers. The vapor pressure curves of selected fluorinated ethers, including (CF3)2CHOCHF2, (CF3)2CHOCF3, and (CF3)2CFOCF3, were determined, and the Antoine fit parameters were used for the extrapolation of the normal boiling points and the enthalpies of vaporization. In addition, the crystal structures of sevoflurane, (CF3)2CHOCH3, (CF3)2CHOCHF2, (CF3)2CHOCF3, and (CF3)2CFOCF3 were determined by x-ray diffraction, providing a detailed insight into trends of the bond parameters and the intermolecular interactions in the solid state. The interpretation of the bond parameters is supported by calculated values (density functional theory, DFT).