Triphenyloxonium tetrafluoroborate

That some modification to the position so far described might be necessary was indicated by some experiments of Nesmeyanov and his co-workers. Amongst other compounds they nitrated phenyl trimethyl ammonium and triphenyloxonium tetrafluoroborates with mixed acid the former gave 96 % of m- and 4 % of -nitro compound (88 % total yield), whilst the latter gave 80% of the tri-(p-nitrophenyl)oxonium salt. Ridd and his co-workers have made a quantitative study of the phenyl trimethyl ammonium ion. Their results, and those of other recent workers on the nitration of several cations, are collected in table 9.3. 

In contrast to trialkyloxonium salts, the triphenyloxonium salt 34 can be obtained by the reaction of benzenediazonium tetrafluoroborate with diphenyl ether in poor (2%) yield [Eq. (4.20)] and is extremely inert toward nucleophiles. This fact is clearly demonstrated by the remarkable stability of triphenyloxonium halides (Cl, Br, ... 

Noble metals such as Ag, Hg, and Pt do not react in this manner. Neither the iodide nor the tetrafluoroborate of the triphenyloxonium cation react with any of the metal powders, apparently because oxygen cannot expand its octet. 

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See also in sourсe #XX -- [ ]

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