The loss of water from ionized heptanols in the gas phase

The mechanism of water loss from the 1‐beptanol molecular ion was studied by using a set of deuterium 1‐heptanols labelled at each position of the chain. The carbon‐bound hydrogen atom lost in the water comes mainly from C(4) (69%) but also from C(2) and C(3) (10 and 13%, respectively), and from C(5) and C(6) (5 and 4%, respectively). No measurable contribution by an H atom from C(7) and C(l) was found. The structure of the resulting [C 7 H 14 ] +· ion was studied by using the MIKE and CAD/MIKE techniques applied to unlabelled, and 2 H and 13 C labelled compounds and by ionization energy and appearance energy measurements. The results clearly indicate that at the onset of the reaction, the [C 7 H 14 ] +· ion formed has the propylcyclobutane structure. At 70 eV electron energy, the [C 7 H 14 ] +· ion formed is indistinguishable from molecular ions of heptenes.