The unorthodox loss of propyl from the molecular ions of methoxycyclohexane

It is shown by field ionization kinetics, D and ¹³C labelling and metastable ion studies that the loss of a propyl radical from the molecular ion of methoxycyclohexane occurs via two routes. At a molecular ion lifetime of <10^?10 s propyl is eliminated in the ‘classic’ way, i.e. by successive cleavage of the C(1)? C(2) bond, 1,5-H shift from C(6) to C(2) and cleavage of the C(4)? C(5) bond. At 10^?10 s the other pathway for propyl loss starts to take place, which is initiated by a hydrogen shift from position 3 or 5 to the methoxy group. This leads in a series of steps to the formation of the 3-methoxyhexene-1 ion, which eventually eliminates a propyl radical. In some of the steps specific hydrogen-deuterium exchange processes have been observed.