Recoverable Organic Catalysts

Room temperature aerobic oxidation of alcohols using CuBr2 with TEMPO and a tetradentate polymer based pyridyl-imine ligand

“…The exact mechanistic details are still under investigation, but likely involve a di-copper species. With these initial homogeneous catalyst based results as a starting point, in the future, we aim to use pyridyl-imine ligands within heterogeneous or recyclable homogeneous catalyst systems for aerobic oxidation reactions [66]. A combination of PEGmodified Cu catalyst and PEG-modified TEMPO catalyst have previously been used to good effect [67], and therefore, there is the potential to use Cu-L1 with a modified-TEMPO or other stable radical co-catalyst in future studies.…”

Poly(methylhydrosiloxane)-supported chiral imidazolinones: new versatile, highly efficient and recyclable organocatalysts for stereoselective Diels–Alder cycloaddition reactions

“…4 Polymers of discreet solubility can be extremely convenient because they allow us to realize a ''monophase'' (that is, homogeneous) catalysis while still enjoying the advantage of biphase separations. 5,6 We have recently turned our attention to polymethylhydrosiloxane (PMHS) that presents several positive features such as low cost, commercial availability, easy fuctionalization, and very favourable solubility profile. Indeed, PMHS is soluble in many organic solvents and insoluble in a few other solvents, like hexanes, thus allowing us to run a catalyzed reaction under homogeneous conditions and to isolate and recover the catalyst as if it were bound to an insoluble polymer.…”

Synthesis of Aminoindolizidines through the Chemoselective and Diastereoselective Catalytic Hydrogenation of Indolizines

“…Given the heterogeneous nature of both catalysts, they are potentially recoverable and recyclable. 25 PtO 2 could be easily reused by decantation, supernatant removal and catalyst washing in the same hydrogenation flask. In contrast, further manipulation and centrifugation were required for Pt(5 wt%)/C.…”