Reactivity and thermochemical parameters for lactones: application in mass spectrometry studies

Abstract

Lactones are secondary metabolites quite widespread in the nature and an important synthetic target, because they are present in drugs, and demonstrate several activities of biological interest. Studies of the protonation and reactivity of small substituted lactones are interesting in order to understand the reactivity of these compounds when dissociated in the gas-phase. The site in which the protonation may occur should be estimated from the analysis of atomic charges, Fukui functions, frontier orbital, proton affinity (PA) and gas phase basicity (GB); which contributes to a better understanding of the acid-base phenomenon.Based on the computational results and characterization of the molecular protonation site, the mechanisms of fragmentation will be proposed, suggesting the main pathways of fragmentation based on the relative energies for the formation of the possible ions products observed in the mass spectra obtained by DFT calculations.Fragmentation pathways will be suggested by initiating the proposal by the main protonation sites and comparing the ions formed with the experimental results obtained by the electrospray ionization tandem mass spectrometry (ESI-MS/MS) analysis. The present project will contribute to understand of the reactivity and thermochemical properties of some substituted butyrolactones, whose interest in mass spectrometry will correlate the effect of the substituent on protonation and the gas phase chemsitry after collision-induced dissociation.