Microwave‐Assisted Reductive Amination of Aldehydes and Ketones Over Rhodium‐Based Heterogeneous Catalysts

Abstract

AbstractMicrowave (MW)‐assisted reductive aminations of aldehydes and ketones were carried out in the presence of commercial and homemade heterogeneous Rh‐based catalysts. Ultrasound (US) was used to improve dispersion and stability of metal nanoparticles, while commercial activated carbon and carbon nanofibers were used as supports. Moreover, various bio‐derived molecules were selected as substrates, and aqueous ammonia was used as a cheap and non‐toxic reagent. MW combined with heterogeneous Rh catalysts gave a 98.2 % yield in benzylamine at 80 °C with 10 bar H2for 1 h; and a 43.3 % yield in phenylethylamine at 80 °C and 5 bar H2for 2 h. Carbon nanofibers proved to be a better support for the metal active phase than simple activated carbon, since a limited yield in benzylamine (10.6 %) but a high selectivity for the reductive amination of ketones was obtained. Thus, raspberry ketone was converted to raspberry amine in a 63.0 % yield.