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dc.contributor.CRUESPUniversidade Estadual de Campinaspt_BR
dc.typeArtigo de periódicopt_BR
dc.titleAbsolute configuration assignment of ortho, meta, or para isomers by mass spectrometrypt_BR
dc.contributor.authorMoraes, LABpt_BR
dc.contributor.authorSabino, AApt_BR
dc.contributor.authorMeurer, ECpt_BR
dc.contributor.authorEberlin, MNpt_BR
unicamp.authorState Univ Campinas, UNICAMP, Inst Chem, Thomson Mass Spectrometry Lab, BR-13083970 Campinas, SP, Brazilpt_BR
dc.subject.wosIon-molecule Reactionspt_BR
dc.subject.wosDiels-alder Cycloadditionpt_BR
dc.subject.wosGaseous Acylium Ionspt_BR
dc.subject.wosIon/molecule Reactionspt_BR
dc.description.abstractA general method based solely on mass spectrometric techniques for the absolute configuration assignment of ortho, meta, or para isomers of acyl nitrobenzenes and derivatives is described. Instead of comparing the mass spectra of the three intact molecules of each positional isomer and investigating each one of the many sets of positional isomers, the method generalizes the effort by performing structural analysis on configurationally diagnostic fragment ions that are common for a given class of compounds. These ions must therefore retain the positional information of the parent molecules and be unequivocally distinguished. Nitrobenzoyl cations are common and stable fragment ions of most acyl nitrobenzenes and derivatives retaining the respective ortho, meta, or para configuration of the precursor molecules. The different NO2 and CO+ ring alignments profoundly influence their collision-induced dissociation and bimolecular reactivity, and the isomeric 2-, 3-, and 4-nitrobenzoyl cations are found to be unequivocally distinguished using both approaches. Absolute ortho, meta, or para positional assignment by tandem MS of every isomeric molecule of the acyl nitrobenzene class and derivatives forming detectable amounts of any of those diagnostic nitrobenzoyl cations is, therefore, possible. The ability to perform absolute (non-comparative) configuration assignment using such diagnostic ions is exemplified for a single test molecule of (2R)-(-)-2-methylglycidyl 4-nitrobenzoate. The general application of this absolute MS-only method for other classes of positional isomers is discussed. (J Am Soc Mass Spectrorn 2005, 16, 431-436) (c) 2004 American Society for Mass Spectrometrypt
dc.relation.ispartofJournal Of The American Society For Mass Spectrometrypt_BR
dc.relation.ispartofabbreviationJ. Am. Soc. Mass Spectrom.pt_BR
dc.publisher.cityNew Yorkpt_BR
dc.publisherElsevier Science Incpt_BR
dc.identifier.citationJournal Of The American Society For Mass Spectrometry. Elsevier Science Inc, v. 16, n. 4, n. 431, n. 436, 2005.pt_BR
dc.sourceWeb of Sciencept_BR
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