Attempted hydrogen-deuterium exchange of the protio-trimethyloxonium dication (CH3)3OH2+, study of methylating ability of (CH3)3O+ in superacids and theoretical investigations.

Attempted hydrogen-deuterium exchange of trimethyloxonium ion, (CH3)3O+ with excess of 1:1 (2)HF/SbF5 superacid at -30 degreesC 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 (CH3)3O+ cation as protonation (protosolvation) prefers the oxygen lone pair of electrons, instead of a C---H bond. Methylation of aromatics with the (CH3)3O+CF3SO3- in CF3SO3H and 2CF3SO3H:B(O3SCF3)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.