Rh-Catalyzed Reductive Amination of Undecanal in an Aqueous Microemulsion System Using a Non-Ionic Surfactant

The homogeneously catalyzed reductive amination of the long-chain aldehyde undecanal with diethylamine was performed in an aqueous microemulsion system using the non-ionic surfactant Marlophen NP8. The experiments showed that the used water-soluble rhodium/SulfoXantphos catalyst system is suitable for this reaction. The Rh-catalyzed formation of the alcohol by-product can be completely suppressed by the use of carbon monoxide with its stabilizing effect of the catalyst system. In addition to pressure and temperature, the most important parameters for the reaction performance of the reductive amination are the concentrations of reactants. Especially, the initial concentration of the aldehyde has a strong impact on the chemoselectivity, and the formation of aldol by-product due to the fact that both, the enamine condensation and the aldol condensation are equilibrium reactions.

Automated summary

The study investigated the homogeneously catalyzed reductive amination of long-chain aldehyde undecanal with diethylamine in an aqueous microemulsion system. The water-soluble rhodium/SulfoXantphos catalyst system was found suitable for this reaction, and the formation of alcohol by-product could be suppressed by using carbon monoxide. Reactant concentrations were identified as a critical factor for reaction performance, especially the initial concentration of the aldehyde which strongly impacted chemoselectivity due to equilibrium reactions.