Consideration of the recycling of homogeneous catalysts at an early process development stage enables their integration in continuous processes.
The transfer of homogeneous, transition metal-catalysed reactions for the functionalisation of basic and intermediate products into continuously operating processes in the chemical industry remains a challenging task. Although the potential of homogeneous transition metal catalysis in terms of added value and sustainability has been proven many times over, its widespread use faces the fundamental challenge of the efficient separation of product and catalyst at the end of the reaction. However, only if this succeeds, and thus also an effective catalyst recycling is realised, the full potential can be exploited.
We recently presented, for instance, the development of catalytic auto tandem reactions into continuous-flow processes on the example of homogeneously catalyzed reductive amination and hydroaminomethylation (consisting of hydroformylation and subsequent reductive amination) as case studies. The synthesis of higher aliphatic amines was successfully operated in a continuous-flow miniplant. Key to success was the development of an integrated catalyst recycling for the homogeneous Rhodium catalyst.
(Künnemann, et al., Org. Process Res. Dev. 2020, 24, 1, 41–49)
(Bianga, et al., ACS Catal. 2020, 10, 11, 6463–6472).