RESUMO
Three carbonyl-containing extracts of essential oils from Eucalyptus citriodora (Myrtaceae), Cymbopogon citratus (Gramineae) and Lippia multiflora (Verbenaceae) were used for the preparation of oximes. The reaction mixtures were analyzed by GC-MS and different compounds were identified on the basis of their retention times and mass spectra. We observed quantitative conversion of aldehydes to their corresponding oximes with a purity of 95 to 99%. E and Z stereoisomers of the oximes were obtained and separated by GC-MS. During GC analysis, the high temperature in the injector was shown to cause partial dehydratation of oximes and the resulting nitriles were readily identified. Based on FT-IR spectroscopy, that revealed the high stability and low volatility of these compounds, the so-obtained oximes could be useful for future biological studies.
Assuntos
Aldeídos/química , Cymbopogon/química , Eucalyptus/química , Lippia/química , Oximas/análise , Cromatografia Gasosa-Espectrometria de Massas , Nitrilas/química , Oximas/química , Extratos Vegetais/química , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo , VolatilizaçãoRESUMO
Ion-molecule reactions involving methyl isocyanide and methyl cyanide have been performed in a new rf-only hexapole collision cell inserted in a large-scale tandem mass spectrometer. Beside protonation processes, N-methyl cyanogen ions (CH(3)N(+)CCN) and 1-methyleneiminium-1- ethylenium ions (CH(2)CN(+)CH(2)) have been produced in high yield and fully characterized by high-energy collisional activation. The unimolecular chemistry of the molecular ions of caffeine (1,3,7-trimethyl xanthine) has been revisited on the basis of these new results.
