PROCESS FOR THE PREPARATION OF HIGHLY EFFICIENT AND STABILIZED COPPER (0) NANOPARTICLES FOR HECK-, SUZUKI-, SONOGASHIRA-, AND STILLE- TYPE COUPLING OF CHLOROARENES

摘要

The present invention relates to an a-alumina supported nanoCopper catalyst prepared from copper aluminium hydrotalcite precursor by reduction of copper aluminium hydrotalcites under the flow of hydrogen gas. This a-alumina supported nanoCopper catalyst exhibits higher activity and selectivity in C--C bond coupling reactions such as Heck, Suzuki, Sonogashira and Stille type reactions involving chloroarenes that include both electron poor and electron rich chloroarenes. A phosphine free new recyclable heterogeneous catalytic system is developed to dispense the use of expensive and air sensitive basic phosphines for palladium catalyzed coupling reactions of chloroarenes. In situ generated basic α-alumina (α-Al2O3) support not only stabilizes the nanocopper [Cu(0)]particles by seizing copper"s propensity for the oxidation but also provides the adequate electron density to the anchored Cu(0) species to facilitate oxidative addition of even the deactivated electron rich chloroarenes.