Catalytic Applications of Heteropoly acid-Supported Nanomaterials in Synthetic Transformations and Environmental Remediation

ABSTRACT Heteropolyacids (HPAs) have been extensively investigated in view of their favorable attributes namely discrete ionic structure, high proton mobility, strong acidity, hydrothermal stability and reversible multi-electron redox behavior which renders them especially valuable in thermal and photocatalysis systems. Consequently, HPAs have found numerous appliances as catalysts for an array of selective synthetic transformations in organic synthesis. However, HPAs have detriments namely their extreme solubility in polar solvents and low specific surface area for a catalyst. To circumvent these drawbacks, many efforts have been made to support heteropoly acids on various nanomaterials. Herein, recent catalytic applications of HPA-supported on nanocatalysts are deliberated with a focus on useful synthesis and organic transformations including their use in conjunction with thermal/ microwaves and photochemical environment to accomplish the performance of some name reactions (Friedel -Crafts and Biginelli), the assembly of useful synthetic molecules (assorted heterocyclic compounds, acetalization, epoxidation, esterification and transesterification reactions and utilization of carbon dioxide) under sustainable and greener conditions including the safer remediation of recalcitrant pollutants (dyes, nitro compounds and antibiotics) and deactivation of bacterium in aqueous streams. GRAPHICAL ABSTRACT