Structurally Diagnostic Ion-molecule Reactions: Acylium Ions With Alpha-, Beta- And Gamma-hydroxy Ketones.

dc.creatorMoraes, L A B
dc.creatorEberlin, Marcos N
dc.date2002-Feb
dc.date2015-11-27T12:49:29Z
dc.date2015-11-27T12:49:29Z
dc.date.accessioned2018-03-29T00:56:56Z
dc.date.available2018-03-29T00:56:56Z
dc.identifierJournal Of Mass Spectrometry : Jms. v. 37, n. 2, p. 162-8, 2002-Feb.
dc.identifier1076-5174
dc.identifier10.1002/jms.270
dc.identifierhttp://www.ncbi.nlm.nih.gov/pubmed/11857760
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/195254
dc.identifier11857760
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1295487
dc.descriptionGas-phase reactions of four acylium ions and a thioacylium ion with three isomeric alpha-, beta- and gamma-hydroxy ketones are performed by pentaquadrupole mass spectrometric experiments. Novel structurally diagnostic reactions are observed, and found to correlate directly with interfunctional group separation. All five ions tested (CH(3)CO(+), CH(2)(double bond)CHCO(+), PhCO(+), (CH(3))(2)NCO(+) and (CH(3))(2)NCS(+)) react with the gamma-hydroxy ketone (5-hydroxy-2-pentanone) to form nearly exclusively a cyclic oxonium ion of m/z 85 that formally arises from hydroxy anion abstraction. With the beta-hydroxy ketone (4-hydroxy-2-pentanone), CH(2)(double bond)CHCO(+), PhCO(+) and (CH(3))(2)NCO(+) form adducts that undergo fast cyclization via intramolecular water displacement, yielding resonance-stabilized cyclic dioxinylium ions. With the alpha-hydroxy ketone (3-hydroxy-3-methyl-2-butanone), PhCO(+), (CH(3))(2)NCO(+) and (CH(3))(2)NCS(+) form stable adducts. Evidence that these adducts display cyclic structures is provided by the triple-stage mass spectra of the (CH(3))(2)NCS(+) adduct; it dissociates to (CH(3))(2)NCO(+) via a characteristic reaction-dissociation pathway that promotes sulfur-by-oxygen replacement. If cyclizations are assumed to occur with intramolecular anchimeric assistance, relationships between structure and reactivity are easily recognized.
dc.description37
dc.description162-8
dc.languageeng
dc.relationJournal Of Mass Spectrometry : Jms
dc.relationJ Mass Spectrom
dc.rightsfechado
dc.rightsCopyright 2001 John Wiley & Sons, Ltd.
dc.sourcePubMed
dc.subjectAcetals
dc.subjectKetones
dc.subjectMass Spectrometry
dc.subjectMolecular Structure
dc.subjectVolatilization
dc.titleStructurally Diagnostic Ion-molecule Reactions: Acylium Ions With Alpha-, Beta- And Gamma-hydroxy Ketones.
dc.typeArtículos de revistas


Este ítem pertenece a la siguiente institución