(580g) Simultaneous Vibrational Spectroscopic Monitoring of Glucose Transformation

Hydroxymethylfurfural (HMF) remains a target of interest in biomass upgrading as a critical steppingstone towards useful biomass-derived products. A unique challenge in HMF generation is understanding the impact of its starting material towards kinetics. Sugars take on a variety of tautomeric forms, with glucose and fructose each having five tautomers. Additionally, the literature has shown the relative concentration of the tautomers directly impacts yield and selectivity towards HMF. Therefore, there is a need to accurately monitor the transformations of sugars in situ in biomass reactions to fully understand their impact. The role of tautomer concentrations may further elucidate another facet of the highly convoluted impact of solvent interactions in such reactions.

Spectroscopy is a powerful tool that facilitates the ability to monitor concentration profiles of reactants in situ, providing detailed kinetics information. Additionally, the simultaneous usage of both Raman and infrared (IR) spectroscopies can provide a robust methodology for concentration tracking as well as molecular interaction insights that are not viable with other methods. The dual-spectroscopic approach also overcomes limitations that is present in each technique. In this work, we present the simultaneous in situ Raman and IR spectroscopy of glucose transformations. First, we present the kinetic experiments of glucose transformations in the absence and presence of catalysts. Next, chemometric analysis of the data and the critical importance of preprocessing spectroscopic data are discussed. Then, we can describe how to obtain kinetic information from the spectra. Finally, we will show correlation between the two spectroscopies via heterospectral two-dimensional correlation spectroscopy (2D-COS) to obtain further insights in the reaction system.