Industrial and Engineering Chemistry Research, 55 (50): 12765 – 12775 (link)
The first applications of aqueous surfactant-free multiphase emulsions as reaction media for rhodium-catalyzed hydroformylation of 1-dodecene and Suzuki coupling reaction of 1-chloro-2-nitrobenzene and 4-chlorobenzeneboronic acid are herein reported. The reaction systems were formulated from oil (reactant and solvent), aqueous catalyst solution, and diethylene glycol butyl ether [C4H9(C2H4O)2OH]. We investigated these multiphase systems with respect to reaction engineering and catalyst recycling to evaluate their application potential for new chemical processes based on switchable solvents. For the hydroformylation, conversion of 23.4% after 4 h reaction time could be achieved at mild reactions conditions of 95 °C and 15 bar syngas pressure. The applied Rhodium-SulfoXantPhos catalyst could be successfully recycled for four times, maintaining its very high linear-to-branched selectivity of 99:1. For the Suzuki coupling reaction yields up to 90% were achieved within a single run. The Pd/SPhos catalyst could be recycled three times, but activity decreased at almost stable selectivity due to higher ligand leaching during the separation steps.