Fluorous biphasic catalysis (FBC) is a relatively new concept for homogeneous catalysis where the fluorocarbon soluble catalyst resides in a separate phase from the substrate and products. Therefore, separation of the catalyst and the products occurs by a facile decantation process. In this contribution, we present the synthesis of new Rf-fluoroponytailed synthons, 2-iodo-1-perfluorooctyl-3-propanol (1), 3-perfluorooctyl-1-propanol (2), and 3-perfluorooctyl-1-iodopropane (3), a variety of new Rf-fluoroponytailed ligands (48), with starting amines, 1,4,7-triazacyclononane, bis-picolylamine, and bis-picolylaminoethylenediamine, as well as new RfMn2+ and RfCo2+ fluoroponytailed carboxylate synthons, [Mn(O2C(CH2)2C8F17)2] (9), and [Co(O2C(CH2)2C8F17)2] (10), where Rf is C8F17. The only totally perfluoralkane soluble ligand we found was 1,4,7-tris-N-(4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecyl)-1,4,7-triazacyclononane (RfTACN, 4), and it was utilized, along with synthons 9 and 10, to generate in situ RfMn2+RfTACN and RfCo2+RfTACN complexes as precatalysts for functionalization of alkanes and alkenes. We will demonstrate that indeed this novel FBC approach for the separation of the precatalyst from the substrates and (or) products is viable for oxidation of alkanes and alkenes in the presence of the necessary oxidants, tert-butyl hydroperoxide (TBHP), and O2 gas. We will also show that these oxidation reactions occur via an autoxidation mechanism under our FBC conditions, while using electron spin resonance (ESR) techniques to ascertain the redox chemistry occurring with the starting mononuclear RfMn2+RfTACN complex.Key words: fluorous solvents, biphasic catalysis, alkane/alkene oxidation.
Biomimetic Cu/Nitroxyl Catalyst Systems for Selective Alcohol Oxidation
