One‐Pot Microwave‐Assisted Olefine Hydroaminomethylation over Bifunctional Heterogeneous Rh Catalysts

Commercial Rh/C and lab made Rh/CNTs catalysts were compared in the one-pot Microwave-assisted hydroaminomethylation of olefines to amines using EtOAc as the solvent. This reaction accounts for two steps: hydroformylation from the alkene followed by aldehyde reductive amination. Acid sites exposed at the surface of the support promote the formation of a metal-alkene coordination complex to form preferentially the linear aldehyde. Synthetic and natural olefines were converted with yields up to 99% in mild conditions (120 °C, 40 bar of syngas, 4 h). With the addition of catalytic amounts of acetic acid, the hydroformylation step proceeded with 99% yield over both catalysts. The catalysts were recovered and reused maintaining their activity for three reaction cycles (12 h). The hydroaminomethylation step gave again yields up to 99%, using 1-hexene as substrate (120 °C, 4 h, 40 bar of N2/H2 1:1). Subsequent tests with different nitrogen sources, resulted in amine yields ranging from 56 to 99% even with ammonia. FESEM. XRD and XPS were employed for an exhaustive surface characterization and structure-to-activity correlation of the catalysts.