Collect. Czech. Chem. Commun. 1985, 50, 2743-2752

Photochemical chlorotrifluoroethylation of 1,2-, 1,3-, and 1,4-diols

Václav Dědek and Ivan Hemer

Department of Organic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6


The UV light-initiated reaction of chlorotrifluoroethylene with 1,2-ethanediol (I) proceeds only in the presence of acetone and affords 2-(2-chloro-1,1,2-trifluoroethyl)-2-methyl-1,3-dioxolane (VI). It has been proved that I is first photolyzed to acetaldehyde. Its acetalization in the reaction mixture gives 2-methyl-1,3-dioxolane (V) which then undergoes chlorotrifluoroethylation. The chlorotrifluoro derivative of 1,2-ethanediol XII was prepared by hydrolysis of 4-(2-chloro-1,1,2-trifluoroethyl)-2,2-dimethyl-1,3-dioxolane (XIII). 1,3-Propanediol (II) reacted to give 5-chloro-4,4,5-trifluoro-1,3-pentanediol (XVI). Analogous reaction of 1,4-butanediol (III) and 1,3-butanediol (IV) afforded, in addition to derivatives with chlorotrifluoroethyl group at the hydroxyl-bearing carbon atom (XVII from III, XIX and XX from IV), also the respective bis-chlorotrifluoroethyl derivatives XVIII and XXI as products arising by the 1,5- or 1,6-transfer in the radical intermediates.