Rearrangement and fragmentation of isomeric C

₄H₅O anions upon collision activation: a combined experimental and ab initio study

Full-text article (85 kB)
(subscribers only)

Buy article on-line for £11.75
(get immediate access)

Eur. J. Mass Spectrom. 7, 7 - 14 (2001)

Rearrangement and fragmentation of isomeric C₄H₅O anions upon collision activation: a combined experimental and ab initio study

Suresh Dua, John H. Bowie and John M. Hevko
Department of Chemistry, The University of Adelaide, South Australia 5005, Australia

ABSTRACT:

The 3,4-epoxybutoxide anion on collisional activation in the gas phase forms an intermediate ion complex (vinyl ethylene oxide, HO) which eliminates water by two competitive pathways, viz. (i) by the HO ion deprotonating the neutral to produce a vinylethylene oxide anion deprotonated on the ring adjacent to the vinyl substituent: this anion then ring opens to give CH₂COCH=CH₂ and (ii) by the HO ion deprotonating at the ring methylene group to give a cyclic anion which ring opens to yield CH₂CH=CHCHO. In contrast, when vinyl ethylene oxide is allowed to react with HO in the source of the mass spectrometer, deprotonation occurs mainly, if not exclusively, at the ring methylene position (as shown by deuterium labelling) to yield the anion CH₂CH=CHCHO. The two ring-opening processes have been investigated using theoretical studies at the MP2 Fc/6-31+G(d) level of theory.

Keywords: isomeric C₄H₅O anions, rearrangement, depronated methyl vinyl ketone, deprotonated crotonaldehyde

You can now buy this paper on-line in PDF format; it costs only £11.75. Just click on the BUY on-line button. You can pay on-line through a secure server and get access immediately.