Fragmentação iônica do isobutanol: espectro de massas e energias de aparecimento

Abstract

Although ethanol is the most used biofuel, recent studies have been demonstrating that it is not the most ideal, being butanol, another alcohol that has numerous advantages over it, as a higher energy density, which gives it greater efficiency. However, the currently largest problem found for the intensive use of butanol as a biofuel is related to the difficulty of its production on an industrial scale. Therefore, knowing its characteristics and potentialities through fundamental research as the present study, is of paramount importance for the development of new technologies and applications. In this work, a high-resolution mass spectrum (MS) and the appearance energies (AEs) values of the cationic fragments formed in electron collisions with Isobutanol were produced, using a HIDEN EPIC 300 mass spectrometer. The MS was obtained for a fixed electron impact energy of 70 eV, in the mass region from 1 u.m.a. to 75 u.m.a., with resolution of 1 u.m.a.. Fourth five cationic fragments were recorded in this MS, being 6 of them unpublished in the literature. The AEs were determined for 15 of the most intense cations observed in the EM, recording the Isobutanol ionic fragmentation curves for the electron impact energies around the threshold energy region of the cationic fragment formation. Ten of the AE values obtained are new in the literature. The determinations of the AEs were carried out using the convolution of the extended Wannier's Law with the Gaussian energy dispersion of electrons incident on Isobutanol. We compare the data obtained in this work with results from literature obtaining good agreement, within the experimental error, where the small discrepancies found were attributed to the different experimental conditions applied by the other authors, favoring the formation of some specific cations.