Abstract: | On the basis of field ionization kinetic and deuterium labelling experiments, it is shown that the molecular ions of isobutyl alcohol generate [CH5O]+ ions at 10?11 s via a 1,4-shift of a hydrogen atom from one of the methyl groups to the oxygen atom, followed by a 1,2-elimination of protonated methanol with a hydrogen atom of the other methyl group. At times > 10?11 s two distinct interchange processes between hydrogen atoms appear to compete with this reaction, as shown from field ionization kinetic experiments and metastable decompositions. Ion cyclotron resonance experiments on the long-lived [CH5O]+ ions further demonstrate that they are protonated methanol ions. Arguments are put forward that the ions, generated by a specific 1,3-elimination of a molecule of water from metastable decomposing molecular ions, have an isobutene structure. |