Highly fluorinated heterocycles. Part IV. The fluorination of tetrachlorothiophen, thiophen, and tetrahydrothiophen over cobaltic and manganic trifluorides and over potassium tetrafluorocobaltate(III)

Abstract

Tetrachlorothiophen reacts with cobalt trifluoride to give polychloropolyfluorobutanes and only small amounts of cyclic sulphur compounds. It reacts with potassium tetrafluorocobaltate(III) to give mainly 3,4-dichlorotetrafluoro-3-thiolen with little, if any, ring-opened products. Thiophen and tetrahydrothiophen are fluorinated by potassium tetrafluorocobaltate(III) to give product mixtures which are similar and which consist mainly of polyfluoro-thiolans and -3-thiolens. One of the major products, 3H/4H-hexafluorothiolan, can be used to prepare tetrafluorothiophen. Manganic trifluoride behaves like potassium tetrafluorocobaltate(III) with thiophen. The mechanisms of these fluorinations are discussed and it is suggested that tetrahydrothiophen is converted into thiophen before being fluorinated.