An unconventional iron oxide catalyst for 5-hydroxymethylfurfural oxidation to 2,5-diformylfuran.

Commonly used magnetic iron oxide (γ-Fe2O3) was examined for the first time as an unconventional catalyst for 5-hydroxymethylfurfural (5-HMF) oxidation to 2,5-diformylfuran (DFF). Fascinatingly, the magnetic support showed remarkable catalytic activity for this conversion, especially in nanoscale size (≤50 nm). The developed mild reagent system consisting of γ-Fe2O3 and molecular O2 in xylene solvent delivered DFF with 94% selectivity and 82% conversion at 135 °C for 12 h. A deep inspection of the mechanistic study through IR and XPS analysis revealed a phase transition (γ-Fe2O3 to Fe3O4) during the reaction, and then its reversal to the parent form after catalyst activation. The loss in crystallinity and increase in the particle size of the catalyst after the reaction were explicitly analysed by XRD and TEM studies, respectively. The excellent activity of the catalyst was even noticed by a recyclability test for six cycles. The method avoided the requirement of high-pressure equipment, costly noble and transition metals, and harsh basic environments.

Supported palladium catalyzed aminocarbonylation of aryl iodides employing bench-stable CO and NH3 surrogates.

A simple, efficient and phosphine free protocol for carbonylative synthesis of primary aromatic amides under polystyrene supported palladium (Pd@PS) nanoparticle (NP) catalyzed conditions has been demonstrated. Herein, instead of using two toxic and difficult to handle gases simultaneously, we have employed the solid, economical, bench stable oxalic acid as the CO source and ammonium carbamate as the NH3 source in a single pot reaction. For the first time, we have applied two non-gaseous surrogates simultaneously under heterogeneous catalyst (Pd@PS) conditions for the synthesis of primary amides using an easy to handle double-vial (DV) system. The developed strategy showed a good functional group tolerance towards a wide range of aryl iodides and afforded primary aromatic amides in good yields. The Pd@PS catalyst was easy to separate and can be recycled up to four consecutive runs with small loss in catalytic activity. We have successfully extended the scope of the methodology to the synthesis of isoindole-1,3-diones from 1,2-dihalobenzene, 2-halobenzoates and 2-halobenzoic acid following double and single carbonylative cyclization approaches.