A time-resolved study of the methyl elimination from ionized homoadamantane in combination with 2H- and 13C-labelling

Abstract

It is shown by field ionization kinetics and specific 2H- and 13C-labelling that the molecular ions of homoadamantane eliminate a methyl radical via at least three different channels. In two of these channels, the methyl group lost contains one of the methylene groups of positions 4 and 5 and of the bridgehead hydrogen atoms of positions 3 and 6, while in the other channel, the methyl group originates from other positions. It is further demonstrated that, contrary to a previous report, the molecular ions of 1-methyl-adamantane do not rearrange to those of homoadamantane over the whole range of ion lifetimes studied, i.e. from 10 −11 to 10 −5 s, prior to the exclusive loss of the original methyl group.