Low-energy, low-temperature mass spectra. Part 7. Terminal alkenols

Abstract

The 12.1 eV, 75 °C, electron-impact mass spectra of four homologous alkenols CH₂CH[CH₂]_nOH (n= 1–4) are reported and discussed. For n= 1, simple cleavage of the molecular ion constitutes the major reaction; however, the importance of simple cleavages diminishes rapidly on ascending the homologous series. Rearrangement processes of three general kinds dominate the spectra of the higher homologues. Hydrogen transfer in CH₂CHCH₂CH₂OH⁺˙ leads to CH₂O expulsion; loss of H₂O gives rise to the base peak in the spectra of ionised pentenol and hexenol; and elimination of CH₃˙ occurs to some extent from the molecular ion of butenol. Distonic ions are implicated as important intermediates in the reactions of these ionised alkenols.