Green chemical transformations of bio-sourced molecules

Many modern synthetic organic chemicals and materials are made from non-renewable feedstocks. Given today's environmental concerns, the search for sustainable feedstocks capable of conversion into these chemicals is of increasing importance. In terms of sustainability, the way in which the reaction is carried out is another important consideration. With these concerns in mind, a group of 14 different bio-sourced, renewable feedstocks (homoserine, glutamic acid, aspartic acid, 2,5-furandicarboxylic acid, fumaric acid, oxalacetic acid, tartaric acid, malic acid, succinic acid, levulinic acid, γ-hydroxybutyrolactone, xylitol, mannitol, sorbitol) were examined for their solubility/miscibility in a variety of ‘green’ solvents, including water, supercritical carbon dioxide, and ionic liquids. Two other bio-based compounds (5-hydroxymethylfurfural and D-xylose) were also studied in selected solvents. Trends in solubility were then assessed so that the data might be extrapolated to help predict solubilities of other related compounds. Some of this work has been published in Green Chemistry: S. M. Payne and F. M. Kerton, Green Chem. , 2010, 12, 1648 . -- Levulinic acid is a renewable chemical with great potential and has been identified as a ‘platform’ chemical by the US Department of Energy. Bio -sourced xylitol was transformed into levulinic acid in water using microwave heating at temperatures greater than 200°C, with yields of up to 45%. This reaction was heterogeneously catalyzed by an acidic sulfonated polymeric resin, Amberlyst-15, which, despite a colour change from grey to black, was easily regenerated with sulfuric acid for reuse in subsequent reactions. Energy-dispersive X-ray analysis of the post-reaction catalyst showed increased carbon, suggesting that carbonaceous materials formed from xylitol decomposition deposit on the catalyst surface. This reagent decomposition could also explain why maximum yields of 45-50% were obtained despite reactions progressing with 100% xylitol conversion. Even with the moderate yields obtained, the green nature of the system makes this process promising