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Type: Artigo de periódico
Title: Ion-molecule Reactions And Collision-activated Dissociation Of C 4h 4 +. Isomers: A Case Study In The Use Of The Ms 3 Capabilities Of A Pentaquadrupole Mass Spectrometer
Author: Shay B.J.
Eberlin M.N.
Cooks R.G.
Wesdemiotis C.
Abstract: Isomeric C 4H 4 +. radical cations vinylacetylene (a), butatriene (b), methylene cyclopropene (c), and the nonaromatic cyclobutadiene (d), generated, respectively, from the neutral precursors 3-butyn-1-ol (1), 1,4-dichloro-2-butyne (2), benzene (3), and 7,8-benzotricyclo [ 2,5]deca-3,7,9-triene (4), undergo diagnostically different ion-molecule reactions with allene, isoprene, furan, and thiophene. It is speculated that adducts are generated by [2 + 2] cycloadditions with the first reagent and [4 + 2] Dials-Alder cycloadditions with isoprene, furan, and thiophene. The initially formed cycloaddition adducts fragment rapidly, isomerize, or undergo further addition of neutral reagent to yield a complex set of products. With a pentaquadrupole mass spectrometer, MS 3 experiments that employ three stages of ion mass analysis are used to help elucidate the ion-molecule reactions and to distinguish the isomeric C 4H 4 +. ions. Among these experiments, the reaction intermediate spectrum reveals the nature of the intermediates connecting the reactant to a selected product while the sequential product spectrum provides mechanistic and structural information on the adducts and other ion-molecule products. The unique combination of ion-molecule reactions with collision-activated dissociation employed here provides valuable information on the chemistry of ionized cyclobutadiene, including its proclivity to undergo [2 + 2] and [4 + 2] cyc1oadditions. © 1992 American Society for Mass Spectrometry.
Rights: fechado
Identifier DOI: 10.1016/1044-0305(92)85029-J
Date Issue: 1992
Appears in Collections:Unicamp - Artigos e Outros Documentos

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