Thermoanalytical and preparative investigations of the decomposition of potassium perfluoroorganyl(fluoro)borate salts, K[R_FBF_3] (R_F = perfluoroalkyl, -alkenyl, -alkynyl, and -aryl groups) and K[(R_F)_2BF_2](R_F = C6F5 and C_6F_(13))

摘要

Potassium perfluoroalkenyl(fluoro)borates, K[R_FBF3], (R_F = CF2=C(CF3), cis-CF3CF=CF, and cis-C6F_(13)CF=CF) decomposed at 208-225℃ (T_(max), dTG). The K[R_FBF3] salts (R_F = C3F7, C6F_(13), trans-CF3CF=CF, and trans-C4F9CF=CF) decomposed at 273-312 C (T_(max), dTG). Both groups of salts formed volatile polyfluoroorganics and K[BF4] as solid residue. The preparative thermolysis of selected prototypical salts K[R_FBF3] showed that the polyfluoroorganics consisted of a mixture of internal perfluorohexenes, C6F_(12), and 1-H-tridecafluorohexane, C6F_(13)H, in case of K[C6F_(13)BF3], and of perfluorooctynes, C8F_(14), and cis-C6F_(13)CF=CFH in case of K[cis-C6F_(13)CF=CFBF3]. The salts K[(C6F5)_2BF2] and K[R_FBF3] (R_F = CF3C=C, CF3CF=CFC=C, C6F5C=C, C6F5, 2,3,5,6-C5NF4) decomposed in the temperature range 249-337 ℃ (T_(max), dTG) and mainly resulted in non-volatile polyfluoroorganics besides K[BF4], The reaction path of the thermolysis of perfluoroalkyl-, perfluoroalkenyl-, and perfluorophenyl-(fluoro)borates is discussed and compared with that of perfluorocarboxylates.