Isomeric Characterization of Gaseous Ions. Minimizing C4H8.+ Rearrangment by Dissociating the Corresponding Neutrals

Article abstract of DOI:10.1021/ja00188a006

With use of neutralization-reionization (NR) mass spectrometry, five gaseous C4H8^.+ isomers can be structurally characterized by neutralization with sodium to produce excited C4H8 molecules whose dissociation products are reionized to both negative and positive ions.Such NR mass spectra are less characteristic when produced by Cs neutralization, which forms more highly exicted C4H8, or by Hg neutralization followed by dissocation of C4H8 using multiple collisions; on average each collision adds ca. 1.7 eV to the molecule, so that isomerization may occur between collisions.The Na NR spectra show that C4H8^.+ ions from all butyl acetate isomers have the expected structure except that 2-C4H8^.+ is formed from n-butyl acetate. 2-C4H8^.+ and methylcyclopropane^.+ appear to be the major products from methylcyclopentane^.+. 1-Butanol^.+ and cyclohexane^.+ predominatly form cyclobutane^.+, while β- and γ-valerolactone^.+ give 1-C4H8^.+ and methylocyclopropane^.+, respectively, as major products.