The remarkable dissociation chemistry of 2-aminoxyethanol ions NH2OCH2CH2OH+studied by experiment and theory

Abstract

Low-energy 2-aminoxyethanol molecular ions NH 2 OCH 2 CH 2 OH•+ 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 2 CH(OH) + (protonated glycolaldehyde), HOCH 2 C( O)H •+ (ionized glycolaldehyde), HC(OH)NH 2 + (protonated formamide), CH 2 OH 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 2 C( O)H•+ ]· · ·[NH 3 ] which acts as the reacting configuration for the five exothermic dissociation processes. Analysis of the D-labelled isotopomer ND 2 OCH 2 CH 2 OD•+ , 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•+ .

Formation of Protonated Glycine Isomers in the Interstellar Medium

“…It should be noted that the PES for the P3 isomer was previously studied 44 in an experimental and theoretical work using the CBS-QB3 complete basis set model chemistry. 45 From that study, the existence of a relationship with glycolaldehyde through a dissociative process is suggested.…”

Catalysis in Hydrogen-Bridged Radical Cations

“…Proton-transport catalysis as a key step in the dissociation of organic ions PTC not only occurs under certain conditions in bimolecular reactions (see above), it is also a key step in the dissociative rearrangement of a variety of oxygen-containing [30][31][32][33][34][35][36][37] and nitrogen-containing [38][39][40][41][42] radical cations. The dissociation chemistry of ionized ethylene glycol 31 represents an early example of this point.…”

Identification of Halohydrins as Potential Disinfection By‐Products in Treated Drinking Water

“…However, the dearth of information [6] available on the dissociation characteristics of ionized aminoxyalcohols made such a proposal rather speculative, especially since the proposed structures would not be expected to be stable. This prompted our subsequent experimental and computational studies [7,8] Following the study of [5], the updated NIST02 database was released. This version of the database included the EI mass spectra of the halohydrins 4-chloro-2-methylbutan-2-ol and 3-bromo-2-methylbutan-2-ol shown in Scheme 2.…”