Regiospecificity for water elimination. A mass spectral study of 1‐tetralol and 2‐tetralol

In order to provide a comparison with the extensive research on the mechanism for elimination of water from various cyclohexanols, the mass spectra of 1‐tetralol(1,2,3,4,‐tetrahydro‐1‐naphthalenol) and 2‐tetralol(1,2,3,4‐tetrahydro‐2‐naphthalenol) have been investigated. Deuterium labeling experiments show that the 1‐tetralol molecular ion expels water by a highly specific 1,4 elimination, whereas 2‐tetralol undergoes a 1,3 elimination. Both of these processes are competitive with cycloreversion reactions. The ionization potentials and appearance potentials for the major fragments \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm M - H}_{\rm 2} {\rm O}} \right]_{}^{_.^ + } $\end{document} and the cycloreversion products hae been measured using the Electron Distribution Difference method. In addition, the kinetic energy release in the metastable decompositions to lose water have been measured. It has been found that the 1,4 elimination for 1‐tetralol releases over 50% of the available energy in the transition state, which is unexpected in view of the 6‐membering ring transition state involved. This research also includes an investigation of the nature of the various \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 10}} {\rm H}_{{\rm 10}} } \right]_{}^{_.^ + } $\end{document} ions formed in the rearrangement reaction to lose water.