Process Development for the Rhodium-Catalyzed Reductive Amination in a Thermomorphic Multiphase System

For the first time, the successful application of the homogeneously catalyzed reductive amination in a thermomorphic multiphase system (TMS) and the first reported scale-up of this reaction into a continuous process, which recovers and recycles the homogeneous catalyst in flow, is presented. Herein, the model substrate 1-decanal reacts with the secondary amine diethylamine to form the corresponding product N,N-diethyldecylamine. A thermomorphic multiphase system (TMS) is established as a recycling strategy to recover and reuse the catalyst for the continuous process. After screening different solvents for the TMS and optimizing the reaction conditions in batch mode, the recycling of the rhodium catalyst was realized in a fully automated miniplant. Parameters influencing the stability of the process were identified and optimized to develop the continuous process. The process was operated in a steady state over 90 h with yields >90% of the desired product and low catalyst leaching <1%/h.