An unprecedented ortho effect in mass spectrometric fragmentation of even-electron negative ions from hydroxyphenyl carbaldehydes and ketones

A mass spectrometric peak for a carboxylate anion is observed in collision-induced dissociation (CID) mass spectra recorded from negative ions derived from ortho isomers of hydroxyphenyl carbaldehydes and ketones. For example, CID spectra of 2-hydroxy derivatives of benzaldehyde, acetophenone, propiophenone, isobutyrophenone, and pivalophenone show peaks at m/z 45, 59, 73, 87, and 101 for the formate, acetate, propionate, isobutyrate, and pivalate anions, respectively.