Characterization of the C3H 6O (+·) ion from 2-methoxyethanol. Mixture analysis by dissociation and neutralization-reionization.

The C3H6O(+·) ion formed upon the dissociative ionization of 2-methoxyethanol is identified by a combination of several tandem mass spectrometry methods, including metastable ion (MI) characteristics, collisionally activated dissociation (CAD), and neutralization-reionization mass spectrometry (NRMS). The experimental data conclusively show that 2-methoxyethanol molecular ion, namely, HOCH2CH2OCH 3 (+·) , loses H2O to yield mainly the distonic radical ion ·CH2CH2OCH 2 (+) along with a smaller amount of ionized methyl vinyl ether, namely, CH2=CHOCH 3 (+·) . Ring-closed products, such as the oxetane or the propylene oxide ion are not observed. The proportion of ·CH2CH2OCH 2 (+) increases with decreasing internal energy of the 2-methoxyethanol ion, which indicates a lower critical energy for the pathway leading to this product than for the competitive generation of CH2=CHOCH 3 (+·) . The present study also uses MI, CAD, and NRMS data to assess the structure of the distonic ion(+) (CH3)CHOCH2· (ring-opened ionized propylene oxide) and evaluate its isomerization proclivity toward the methyl vinyl ether ion.