Mixture analysis is among the most important areas of chemistry research: most of Mother Nature's interesting problems present themselves as mixtures. In the work proposed here a novel approach to the use of NMR spectroscopy to monitor organic reactions will be investigated. NMR is well suited to following chemical reactions, especially when signals are well resolved. However, when signals in spectra do overlap, which is common, advanced data analysis tools are needed. One of the most widely used techniques for intact mixture analysis by NMR is diffusion-ordered spectroscopy (DOSY), but even here spectral overlap is a problem. Fortunately, the combination of DOSY and advanced statistical methods (chemometrics) has been shown to handle such overlap surprisingly well. The experimental part of the project will monitor the formation of N-acylhydrazones, running DOSY experiments during the reaction course. The use of DOSY, rather than simple proton NMR, allows the use of powerful chemometric approaches such as the PARAFAC (PARAllel FACtor analysis) multi-way decomposition method. This uses the trilinear structure of the data to obtain separate matrices containing the N spectra, diffusion decays, and concentration time courses, respectively. This approach should allow us to obtain both accurate kinetic data for reactants, intermediates and products, and an isolated 1H NMR spectrum of each species involved in the reaction, together with information on its diffusion, even where the experimental spectra are severely overlapped.
News published in Agência FAPESP Newsletter about the scholarship: