Synthesis of biobased amines via Pd-catalysed telomerisation of the renewable β-myrcene in a water/ethanol multiphase system: catalyst recycling enabled by a self-separating product phase

Abstract

We developed an aqueous multiphase system for the synthesis of biobased alkyl amines via palladium-catalysed telomerisation based on the terpene β-myrcene. Ethanol was employed as a harmless co-solvent. With this “green” switchable multiphase solvent system, the recycling of the expensive homogeneous catalyst was successfully enabled by self-separating products at room temperature. The total turnover number (TON) was increased to almost 12 000 over 9 runs, with high selectivities towards the desired amine telomer products between 80 and 93% in each run. Furthermore, various amine nucleophiles were successfully used allowing to produce a wide variety of long-chain unsymmetrical alkyl amines with potential applications as, for instance, surfactant precursors or lubricants. In each case, the products self-separated after reaction from the aqueous multiphase system containing the homogeneous palladium catalyst allowing straightforward isolation by simple decantation. Finally, we proved the successful use of spirits (vodka) as solvents in this sustainable amine synthesis.