Tris aminium hexafluoroantimonate

An analogous stepwise mechanism was also proposed by Wohrle [36] for the cation-radical-initiated cycloaddition of electron-rich allenes with pentamethyl-cyclopentadiene in the presence of tris (p-tolyl) aminium hexafluoroantimonate (TTA SbF6 ) (Equation 1.15). 

The reaction rate has also been greatly increased by the addition of a one-electron oxidant tris-(4-bromophenyl)aminium hexafluoroantimonate Ar3N SbF (Ar = / -bromophenyl)." This reagent converts the substrate to a cation radical, which undergoes ring expansion much faster." ... 

Dinnocenzo and Conlon have described the remarkable effect of one-electron oxidation on the rate of certain vinylcyclopropane rearrangements. Exposure of several l-p-anisyl-2-vinylcyclopropane derivatives to a catalytic amount of tris(4-bromophenyl)aminium hexafluoroantimonate in acetonitrile at room temperature was found to induce ring expansion to form cyclopentenes (equation 25) temperatures in excess of 200 °C are required for the conventional thermal rearrangement cf these systems. At this time it is uncertain whether these reactions follow concerted mechanisms, or are stepwise processes involving trimethylene cation radical intermediates. 

Various other miscellaneous salts have been used from time to time to initiate cationic polymerisation. These include tris-p-bromophenyl aminium hexa-chloroantimonate (97), anilinium hexafluoroantimonate (98), nitronium tetra-fluoroborate (95), thianthrenium perchlorate (99), and hexachloroantimonate (100), and N-methyl acridinium and N-methylphenazonium salts (75). In general... 

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See also in sourсe #XX -- [ ]

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