Attempted hydrogen–deuterium exchange of the protio-trimethyloxonium dication (CH(3))(3)OH(2+), study of methylating ability of (CH(3))(3)O(+) in superacids and theoretical investigations

Attempted hydrogen–deuterium exchange of trimethyloxonium ion, (CH(3))(3)O(+) with excess of 1:1 (2)HF/SbF(5) superacid at −30°C over a period of 30 days showed no exchange. Theoretical calculations at the MP2/6–31G** level are in accord with the lack of hydrogen–deuterium exchange in the methyl group of the (CH(3))(3)O(+) cation as protonation (protosolvation) prefers the oxygen lone pair of electrons, instead of a C—H bond. Methylation of aromatics with the (CH(3))(3)O(+)CF(3)SO(3)(−) in CF(3)SO(3)H and 2CF(3)SO(3)H:B(O(3)SCF(3))(3) was also studied. Whereas in triflic acid no alkylation was observed, in triflatoboric acid, a powerful superacid, alkylation takes place, indicating protolytic activation of the trimethyloxonium ion.