Premium
Energy dependence of the fragmentation of ester enolate ions
Author(s) -
Young Alex B.,
Harrison Alex G.
Publication year - 1987
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210220909
Subject(s) - fragmentation (computing) , ion , chemistry , proton affinity , dissociation (chemistry) , collision induced dissociation , mass spectrometry , mass spectrum , internal energy , proton , analytical chemistry (journal) , atomic physics , tandem mass spectrometry , physics , protonation , organic chemistry , nuclear physics , chromatography , quantum mechanics , computer science , operating system
The energy dependence of the fragmentation of a selection of ester enolate ions has been studied by variable, low‐energy collision‐induced dissociation experiments in the quadrupole collision cell of a hybrid BEQQ mass spectrometer. The dominant fragmentation reactions observed arewhere ΔH 1 − ΔH 2 =PA([RCCO] − ) − PA([ŔO] − ) (PA=proton affinity). The anion of lowest proton affinity is formed preferentially at low internal energies with the yield of the anion of higher proton affinity increasing with increasing internal energy. The [CH 3 OCOCOCH 2 ] − anion derived from methyl pyruvate forms [CH 3 OCO] − by reaction (2); this anion readily fragments to [CH 3 G] − + CO consistent with a structure represented by a dipole‐stabilized cluster of [CH 3 O] − and CO. Comparison of the 8‐keV with the 50‐eV collision‐induced dissociation mass spectra indicated that the average internal energy of the fragmenting ions is considerably lower in the high‐energy collisional experiments than it is in the low‐energy collisional experiments.