A combined time‐resolved and stereospecific deuterium labelling study of the elimination of methanol from the molecular ion of methoxycyclohexane

Abstract

AbstractIt is shown by field ionization kinetics in combination with both site‐specific and stereospecific D‐labelling that the loss of a molecule of methanol from the molecular ion of methoxycyclohexane can occur via 1,4‐ and 1,3‐eliminations. The 1,4‐elimination predominates at molecular ion lifetimes of ≥10−10.1 s. It is found that ∼19% of this reaction channel corresponds to a stereospecific cis‐elimination, whereas the remaining 81% is only site‐specific. At molecular ion lifetimes of between 10−10 and 10−9 s, a very sudden increase of the 1,3‐elimination is observed at the expense of the 1,4‐elimination. A stereospecific loss of methanol, however, is not observed at all for the 1,3‐elimination within the limits of error. Possible intermediates and reaction pathways, which can account for the observations made, are discussed.