Pd(II) and Pt(II) catalysed selective synthesis of furfuryl alcohol: Solvent effects and insights into the mechanism

Selective conversion of furfural to furfural alcohol, a bio-based commodity chemical with applications in the agriculture, metal casting and polymer industries is presented. Pd(II) and Pt(II) complexes were synthesized and characterized using multi-nuclear magnetic resonance spectroscopy, infrared spectroscopy, high resolution electrospray ionisation mass spectrometry as well as elemental analysis. These complexes were found to serve as excellent pre-catalysts for furfural alcohol synthesis with excellent conversion and selectivity (>99%), more so under solvent-free conditions via transfer hydrogenation method. Catalysts C1 and C5 also showed enhanced activity and selectivity as pre-catalysts for the hydrogenation of furfural using formic acid as a hydrogen carrier. The platinum catalyst C5 was recycled twice (with consistent activity and selectivity), and proved to function as a molecular catalyst as evidenced by mercury poisoning experiments. In situ NMR studies were performed using C5 culminated in the proposition of plausible reaction mechanism, and a likely catalytically active species has been identified with the aid of ¹H and ³¹P{¹H} NMR.