Catalytic screening of the cascade reductive amination reaction of furfural and acetonitrile

The reductive amination reaction of furfural with acetonitrile has been explored employing various catalytic systems based on supported Rh, Ru, Pt and Pd nanoparticles. The synthesis of Rh and Ru nanoparticles supported on titania was accomplished following an environmentally friendly two step-protocol, based on the microwave assisted preparation of TiO2 and its subsequent functionalization by an impregnation/chemical reduction method. Commercial Pd/C, Pt/C and Ru/C were additionally evaluated to get insights into the effect of the metal component into the reaction progress and the products selectivity. Interestingly, the metal component resulted to have a drastic influence into the selectivity of the reaction. In particular, catalytic materials based on rhodium supported on TiO2, led to the selective formation of the reductive amination products, namely towards the secondary and tertiary amines, derived from the hydrogenated furfural ring. In turn, ruthenium-based materials drove the reaction progress towards the hydrogenation of the carbonyl functionality and did not favor the hydrogenation of the furan ring, similar to the behavior observed for platinum system. Furthermore, palladium-based catalyst favored the hydrogenation of the aldehyde group and, moreover, led to the hydrogenation of the furan ring. Products characterization was carried out by GC-MS and NMR spectroscopies. Outstanding conversion (>99%) and selectivity (76%) values towards the N-ethyl-N-((tetrahydrofuran-2-yl)methyl)ethanamine were reached for the TiO2-Rh1% catalyst.