Estudo de reações ion/molecula na fase gasosa por espectrometria de massa de estagios multiplos (MS2 e MS3) em um espectrometro pentaquadrupolar

AUTOR(ES)
DATA DE PUBLICAÇÃO

1996

RESUMO

This work presents the results of four distinct projects which have been focused on combined studies of ion/molecule reactions, collision-induced dissociation of ions and ab initio calculations. In the first project it was verified the occurrence in the gas phase of novel ionic 1,3-dipolar cycloaddition reactions between carbonyl compounds and the simplest carbonyl ylide in its ionized form (CH2-O-CH2•). These reactions also lead to the formation of CH2• transfer products, which are also ionized forms of carbonyl ylides. The second project was then focused on the characterization of these ionized carbonyl ylides (and also of nitrile ylides). Such compounds are important intermediates in organic reactions in the condensed phase, but have never been isolated due to their instability. The third project involved the generation and characterization in the gas phase of eleven ionic isomeric of general composition PyC2H5•. Ab initio calculations have been employed to establish a more appropriate method for the classification of these isomers as conventional or distonic radical cations, and also to evaluate the occurrence of interconvertions in the experimental conditions employed. The last project was devoted to the study of the reactions between a series of carbonium ions of general composition CHnXmYn (X,Y = F, CI, Br, I) towards aromatic compounds. Most cases show a net transfer of CH and/or CX(Y) followed by ring expansion.

ASSUNTO(S)

espectrometro espectrometria de massas

ACESSO AO ARTIGO

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