Reaction mechanism of asymmetric catalysts by mass spectrometry and gas-phase vibrational ion spectroscopy

Abstract

This project intends to evaluate the reaction mechanisms of catalysts both in condensed and in the gas phase experimentally, by the use of mass spectrometry techniques like reaction intermediate fishing and vibrational ion spectroscopy (IRMPD), which is unprecedented in Brazil.IRMPD spectroscopy consists on the evaluation of ion dissociation in the gas phase promoted by a tunable infrared radiation, which is proportional to the absorption of energy at a given wavelength. The infrared spectrum obtained by this technique can be used to evaluate the conformational equilibrium and connectivity of ions, tasks that cannot be carried out by ordinary mass to charge ratio (m/z) measurements.The target systems of this proposal will be: i) the metal center catalysts, of which the Sharpless chiral reaction mediated by titanium alkoxides and chiral tartrates will be the first system to be evaluated, ii) the coordination of metal and model ligands, allowing the evaluation of the pre-catalyst assembly and activation in solution and, iii) the evaluation of organocatalysts and their reaction intermediates, like the iminium based MacMillan's imidazolidinones.Instrumentation design also plays an important role in this project, once the infrared ion spectroscopy in the gas phase is not available in commercial instruments and is, in fact, a novel technique in BrazilThis project will be supported by varied theoretical calculation methodologies, allowing the evaluation of conformer stabilities and reaction energy landscapes, giving a detailed picture of the systems in the molecular level.This proposal aims to elucidate the reaction mechanism of diverse catalysts by the synergic use of a novel technique and theoretical calculations, not only allowing the description of important reactions mechanism for widespread catalysts, but also helping in the development of new reactions and catalysts. (AU)