Fluorination of perchloro-2,5-dihydrofuran

Abstract

The exchange fluorination of perchloro-2,5-dihydrofuran (1) with antimony trifluoride and mixed antimony halides gives 2,3,4,5,5-pentachloro-2-fluoro-2,5-dihydrofuran (2), some tetrachlorodifluoro-2,5-dihydrofurans (3)–(5), 2,3,4-trichloro-2,5,5-trifluoro-2,5-dihydrofuran (6), and 3,4-dichloro-2,2,5,5-tetrafluoro-2,5-dihydrofuran (8) by successive replacement of allylic chlorine atoms. Fluorination with anhydrous hydrogen fluoride also results in the replacement of allylic chlorine atoms by fluorine, compounds (6) and (8) only being isolated. With potassium fluoride in N-methylpyrrolidone both vinylic and allylic chlorine atoms of perchloro-2,5-dihydrofuran (1) are replaced, giving 2,2,4-trichloro-3,5,5-trifluoro-2,5-dihydrofuran (7) and perfluoro-2,5-dihydrofuran (9). Some reactions of the products are described.