- Insights into Sonogashira cross-coupling by high-throughput kinetics and descriptor modeling
- Chemistry - A European Journal
- Volume | Issue number
- 14 | 9
- Pages (from-to)
- Document type
- Faculty of Science (FNWI)
- Swammerdam Institute for Life Sciences (SILS)
A method is presented for the high-throughput monitoring of reaction kinetics in homogeneous catalysis, running up to 25 coupling reactions in a single reaction vessel. This method is demonstrated and validated on the Sonogashira reaction, analyzing the kinetics for almost 500 coupling reactions. First, one-pot reactions of phenylacetylene with a set of 20 different meta- and para-substituted aryl bromides were analyzed in the presence of 17 different Pd-phosphine complexes. In addition, the temperature-dependent Sonogashira reactions were examined for 21 different ArX (X=Cl, Br, I) substrates, and the corresponding activation enthalpies and entropies were determined by means of Eyring plots: ArI (Delta H-double dagger = 48-62 kJ mol(-1); Delta S* = -71--39 Jmol(-1) K; NO2 -> OMe), ArBr (Delta H-double dagger=54-82 kJmol(-1), Delta S-double dagger = -55-11 Jmol(-1) K), and ArCl (Delta H-double dagger = 95-144 kJ mol(-1), Delta S-double dagger = -6-100 J mol(-1) K). DFT calculations established a linear correlation of Delta H* and the Kohn-Sham HOMO energies of ArX (X = Cl, Br, I) and confirmed their involvement in the rate-limiting step. However, despite different C-X bond energies, aryl iodides and electron-deficient aryl bromides showed similar activation parameters.
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