Highly chemoselctive dihydroxyacetone conversion to ethyl lactate by a montmorillonite-supported Pt(II)-diphosphane complex

Bis-cationic Pt(II)aqua complexes bearing phosphane ligands showed catalytic activity for the conversion of the C3 sugar dihydroxyacetone into ethyl lactate. The best result in terms of catalytic activity and chemoselectivity was obtained with a Pt(II)aqua complex bearing 1,2-bis(diphenylphosphanyl)ethane under homogenous reaction conditions. The heterogenization of the latter Pt(II) complex on montmorillonite by a simple cation-exchange process led to a robust in air atmosphere recyclable catalyst which showed almost 100% chemoselectivity for ethyl lactate in neat ethanol. This latter chemoselectivity was maintained during several recycling experiments. A combination of PXRD, HRTEM and XPS measurements on the recycled heterogeneous catalyst and ICP-OES analysis carried out on the catalytic ethanol solutions confirmed the stability of the anchored Pt(II) complex during catalysis (i.e. neither reduction to Pt-NPs, nor significant Pt leaching in solution was observed).