Abstract The thermal decomposition of sodium 3-oxa-11-chloro-eicosafluoroundecane sulfinate (1) and potassium 3-oxa-11-chloroeicosafluoroundecane sulfonate (2) were studied. 7-Chlorotridecafluoroheptene-1 (3), 1-hydro-7-chloro-tetradecafluoroheptane (4), 1- hydro-3-oxa-11-chloro-eicosafluoroundecane (5), methyl 8-chloro-tetradecafluorooctanate (6), and methyl 3-oxa-11-chloro-octadecafluoroundecanate (7) were isolated and ...