Hydrogen migrations in mass spectrometry. V—loss of olefin from n‐propyl esters following chemical ionization

Abstract

AbstractThe sources of the migrating hydrogen in the elimination of propylene from the protonated and ethylated n‐propyl acetate and n‐propyl benzoate molecules have been determined by studying the CH4 and H2 chemical ionization mass spectra of esters specifically deuterated in the propyl group. It is shown that the migrating hydrogen originates from C‐1 ( ∼ 27%), C‐2 ( ∼ 23%) and C‐3 ( ∼ 50%) of the propyl group, independent of ester and mode of ionization. It is argued that the observed reaction involves specific competing H‐migration reactions from each propyl position to the ether oxygen in a keto‐protonated (ethylated) ester molecule.