Synthesis of High-Value Chemicals and Materials from Renewable Resources

Abstract

Over the past three decades, significant research has been focused on producing fuels and chemicals from renewable carbon resources to reduce the carbon footprint and its disastrous environmental impact. In this regard, the non-food terrestrial lignocellulosic biomass has emerged as the source of biogenic carbon since they are geographically diverse, available in plenty, inexpensive, and a component in many waste streams. Catalytic synthesis of organic chemicals from the carbohydrate fraction of biomass (e.g., cellulose, hemicellulose) through the furanic platforms has received particular attention. Acid-catalyzed dehydration of hexose sugars (e.g., glucose) and pentose sugars (e.g., xylose) derived from the cellulose and hemicellulose fractions lead to 5-(hydroxymethyl)furfural (HMF) and furfural (FUR), respectively. HMF and FUR have been established as commercially viable renewable chemical intermediates for synthesizing transportation fuels, organic chemicals, and synthetic polymers of commercial significance. The commercial production of HMF remains a challenge due to its inherent hydrophilicity and poor thermal and hydrolytic stability. In this regard, the hydrophobic congeners of HMF, such as 5- (acetoxymethyl)furfural (AcMF), have received much interest in recent years. The current focus is on the efficient production of AcMF and expanding its derivative chemistry. Several classes of products of commercial significance have been produced from FUR, HMF, and even AcMF. However, synthesizing denselyfunctionalized heterocycles from biorenewable furfurals is underexplored. The synthesis of heterocycles is a crucial area of synthetic organic chemistry since they are known for their biological activities and are found in many pharmaceuticals. Morita-Baylis-Hillman reaction, Biginelli reaction, and Hantzsch reaction can create remarkable structural complexities in a single step using structurally simple and easily available starting materials under catalytic conditions. Moreover, they are atomeconomical, high-yielding, scalable, and lead to important structural motifs for highvalue applications (e.g., pharmaceuticals). The substrate scope of these green transformations is typically limited to FUR. Therefore, a systematic study of these transformations using the 5-substituted-2-furaldehydes will not only improve the substrate scope of these reactions but also lead to novel products with interesting properties and expand the derivative chemistry of these biorenewable chemicals. In addition to the production of chemicals, the biogenic carbon in terrestrial cellulosic biomass can be transformed into renewable materials. For example, activated carbon (AC) can be produced by carbonizing biomass followed by activation. AC has a variety of conventional and emerging applications ranging from energy storage to catalyst support to water purification. Renewable synthesis of AC helps to mitigate the issue of managing waste biomass while generating value-added commodities. Therefore, producing valuable chemicals and materials from biomass is of interest from both academic and industrial perspectives.