Cu(II) bipyridine and phenantroline complexes: Tailor-made catalysts for the selective oxidation of tetralin Original Research Article

Mononuclear Cu(II) complexes have been synthesized, and their structure thoroughly characterized by electrospray ionization mass spectrometry (ESI-MS). These 2,2′-bipyridine and 1,10-phenantroline mononuclear Cu(II) complexes have been tested as catalysts in the partial oxidation of tetralin (1,2,3,4-tetrahydronaphthalene), using hydrogen peroxide as oxidant in acetonitrile/water as solvent.The complexes [Cu(bipy)3]Cl2·6H2O (1), [Cu(bipy)2Cl]Cl·5H2O (2), [Cu(bipy)Cl2] (3), [Cu(phen)3]Cl2·6H2O (4), [Cu(phen)2Cl]Cl·5H2O (5), [Cu(phen)Cl2] (6) were able to oxidize tetralin at room temperature, at high degrees of conversion (62.1% with 2) into α-tetralol and α-tetralon at 91% selectivity (81% in 1-tetralon).Depending on nature and number of ligands (bipyridine or phenantroline) surrounding Cu2+ cation, one was able to tailor both the activity toward tetralin oxidation, and the selectivity toward 1-tetralol and 1-tetralone products, but also to raise the yield in valuable α-tetralone.