(283d) Catalytic Mechanism Study of a Palladium-Cyclodextrin Complex for a Suzuki-Miyaura Cross-Coupling with a Microfluidic Reactor

Transition metal catalyzed Suzuki-Miyaura reactions are among the most versatile carbon-carbon bond forming methods, they have the advantages of ready availability of reactants, high product yields, plus mild reaction conditions.^1–4 Water soluble catalysts in heterogeneous Suzuki reactions allow for the easy separation of metal catalysts such as palladium from products, and the reuse of precious metal catalysts.^2,5,6 A highly selective as well as water-soluble DACH (cyclohexanediamine)-Pd-β-cyclodextrin (CD) complex as a catalyst for Suzuki reactions was synthesized and characterized following a previously reported procedure^7,8 Its catalytic activity was tested and its mechanism was studied in our lab.

The high surface-to-volume ratio of microfluidic device could significantly reduce the heat and mass transfer resistance of heterogeneous reactions.^9–11 And the use of continuous-flow system allows precise control of experimental parameters like residence time.¹² We tested the DACH-Pd-β-CD in a designed a capillary flow system. High yields were achieved within minutes compared to the hours required in a batch reactor.⁷ Kinetic information at different residence times and temperatures was also obtained rapidly. A methodology for the screening of possible catalytic cycles was developed with the dispersion in the reactor characterized by Levenspiel number.¹³ The results will be presented and discussed.

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