The remarkable dissociation chemistry of 2-aminoxyethanol ions NH 2OCH 2CH 2OH [rad]+studied by experiment and theory

Abstract

Low-energy 2-aminoxyethanol molecular ions NH 2OCH 2CH 2OH + exhibit a surprisingly rich gas-phase ion chemistry. They spontaneously undergo five major dissociations in the microsecond timeframe, yielding ions of m/ z 61, 60, 46, 32 and 18. Our tandem mass spectrometry experiments indicate that these reactions correspond to the generation of HOCH 2CH(OH) + (protonated glycolaldehyde), HOCH 2C( O)H + (ionized glycolaldehyde), HC(OH)NH 2 + (protonated formamide), CH 2OH 2 + (the methylene oxonium ion) and NH 4 +. A mechanistic analysis of these processes using the CBS-QB3 model chemistry shows that the molecular ions undergo a 1,4- H shift followed by a facile isomerization into the ion–molecule complex [HOCH 2C( O)H +]⋯[NH 3] which acts as the reacting configuration for the five exothermic dissociation processes. Analysis of the D-labelled isotopomer ND 2OCH 2CH 2OD +, in conjunction with our computational results, shows that proton-transport catalysis may be responsible for the partial conversion of the m/ z 60 glycolaldehyde ions into the more stable 1,2-dihydroxyethene isomer HOC(H) C(H)OH +.