Rearrangement and loss of bromine radical and CO from some bromobenzyl alcohols following electron ionisation

The electron ionisation spectra of bromine-containing derivatives of benzyl alcohol are often dominated by ions which do not contain bromine. We use the experimental data on a series of selected bromobenzyl alcohols to elucidate the easy loss of bromine atoms. In this process, arene-bonded bromines are displaced by hydrogens which originate from the benzyl group. Thus, we conclude that this reaction occurs during the “hydrogen ring-walk”. The suggested reaction mechanism and structures of intermediates, which can be considered, are discussed and graphically illustrated.