Thermoanalytical and preparative investigations of the decomposition of potassium perfluoroorganyl(fluoro)borate salts, K[RFBF3] (RF = perfluoroalkyl, -alkenyl, -alkynyl, and -aryl groups) and K[(RF)2BF2] (RF = C6F5 and C6F13)

• K[RFBF3] salts (RF = perfluoroalkyl, -alkenyl, -alkynyl, and -aryl groups) and K[(RF)2BF2] salts (RF = C6F5 and C6F13) are characterized by TG and DSC.
• The preparative thermolysis of prototypical K[RFBF3] salts informs about the nature of products.
• The thermolysis of K[RFBF3] salts (RF = perfluoroalkyl, -alkenyl) shows a close similarity to that of perfluorocarboxylates.

Potassium perfluoroalkenyl(fluoro)borates, K[RFBF3], (RF = CF2C(CF3), cis-CF3CFCF, and cis-C6F13CFCF) decomposed at 208–225 °C (Tmax, dTG). The K[RFBF3] salts (RF = C3F7, C6F13, trans-CF3CFCF, and trans-C4F9CFCF) decomposed at 273–312 °C (Tmax, dTG). Both groups of salts formed volatile polyfluoroorganics and K[BF4] as solid residue. The preparative thermolysis of selected prototypical salts K[RFBF3] showed that the polyfluoroorganics consisted of a mixture of internal perfluorohexenes, C6F12, and 1-H-tridecafluorohexane, C6F13H, in case of K[C6F13BF3], and of perfluorooctynes, C8F14, and cis-C6F13CFCFH in case of K[cis-C6F13CFCFBF3]. The salts K[(C6F5)2BF2] and K[RFBF3] (RF = CF3CC, CF3CFCFCC, C6F5CC, C6F5, 2,3,5,6-C5NF4) decomposed in the temperature range 249–337 °C (Tmax, 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.

The products of thermolysis of neat perfluoro-organyl(trifluoro)borate salts, K[RFBF3], depend on the type of RF group. The thermolysis of K[RFBF3] salts (RF = perfluoroalkyl and -alkenyl) shows a close similarity to that of perfluorocarboxylates.Figure optionsDownload as PowerPoint slide