Zirconium(IV)-catalysed hydrosilylation of organic carbonates and polycarbonates household wastes into alcohol derivatives.

The Schwartz’s reagent Cp2Zr(H)Cl is a well known stoichiometric reagent for the reduction of unsaturated organic molecules but it has rarely been used in catalytic transformations. Herein, we describe the reduction of a variety of organic carbonates using the catalyst Cp2Zr(H)Cl in combination with Me(MeO)2SiH (DMMS) as reductant. This method was further applied to the reductive depolymerization of some polycarbonate materials and yielded sylilated alcohols and diols in mild conditions. A significant advantage of this recycling method of polycarbonates is its stability towards the additives contained in household plastics and its ability to selectively depolymerize polycarbonate in a mixture containing a polyester and a polycarbonate. Experimental investigations brought evidences on a mechanism based on the hydrozirconation of the carbonyl fragment, thermal σ C–O bond cleavage, and Zr–OR/Si–H σ-bond metathesis reactions to regenerate the hydride catalyst.