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Pentafluoroethylation of Carbonyl Compounds by HFC-125 via the Encapsulation of the K Cation with Glymes

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journal contribution
posted on 2021-03-29, 14:05 authored by Yamato Fujihira, Kazuki Hirano, Makoto Ono, Hideyuki Mimura, Takumi Kagawa, Daniel M. Sedgwick, Santos Fustero, Norio Shibata
A simple protocol to overcome the explosive pentafluoroethylation of carbonyl compounds by HFC-125 is described. The use of potassium (K) bases with triglyme or tetraglyme as a solvent safely yields the pentafluoroethylation products in good to high yields. The experimental results suggest that an encapsulation of the K cation by glymes as K­(glyme)2 inhibits the contact between the K cation and the reactive anionic pentafluoroethyl counterion, preventing their transformation into KF and explosive tetrafluoroethylene (TFE). The generation of sterically demanding [K­(G3)2]+ and [K­(G4)2]+ is an effective way as an unstable pentafluoroethyl anion reservoir.