Conversion of 1,1,2-trichlorotrifluoroethane to 1,1,1-trichlorotrifluoroethane and 1,1-dichlorotetrafluoroethane over aluminium-based catalysts

A Thallium Coated Dianion: Trigonal Bipyramidal [F2Al(OR)3]2— Coordinated to Three Tl+ Cations in the Ion Pair [Tl3F2Al(OR)3]+[Al(OR)4]— [R = CH(CF3)2]Dedicated to Professor Dieter Naumann on the Occasion of his 60th Birthday

“…Our calculations further indicate that the alane Al(ORЈ) 3 (FIA ϭ 561 kJ/mol) is an even stronger Lewis acid than SbF 5 (FIA ϭ 503 kJ/mol [32]). Another proof for the high acidity of alanes of type Al(OR F ) 3 2 and [(C 6 F 4 )(C 6 F 5 )] groups are comparable and, therefore, the dimerization and formation of 2 is governed by the higher Lewis acidity of Al(OR F ) 3 vs. Al(Ar) 3 .…”

“…To understand the energetics of the formation of 1 and to verify the structure of the [Tl 3 F 2 Al(OR) 3 ] ϩ cation we optimized several relevant species at the BP86/SVP (DFT-) level: [Tl 3 F 2 Al(ORЈ) 3 …”

“…Moreover we showed [18] alanes of type Al(OR F ) 3 (OR F ϭ poly or perfluorinated aliphatic alkoxide) to be one of the strongest Lewis acids known. To compare the Lewis acidity of Al(ORЈ) 3 with that of other Lewis acids we calculated the FIA (Fluoride Ion Affinity) of Al(ORЈ) 3 and AlF 3 using the same isodesmic reaction as in the literature [30, 32,35], i.e. X ϩ OCF 3 Ϫ Ǟ XF Ϫ ϩ COF 2 X ϭ Al(ORЈ) 3 , AlF 3…”

“…It is suggested that in the reaction leading to 1 initially Tl[Al(OR) 4 ] is formed, followed by an abstraction of TlOR and Al(OR) 3 . The latter very strong Lewis acid reacts subsequently with an excess of TlF yielding 1.…”

“…The latter very strong Lewis acid reacts subsequently with an excess of TlF yielding 1. 3 . Die letztere sehr starke Lewis-Säure reagiert nachfolgend mit dem Überschuß an TlF und bildet 1.…”