Unrecyclable Polyethylene as a Catalytic Metal Support for Organic Reactions

Postconsumer plastic recycling represents both an urgent environmental challenge and an opportunity for the development of new functional materials. Here, we show that not only pristine but also used and, more importantly, the rejected fraction of polyethylene waste during its recycling process operate well as heterogeneous catalysts for different organic reactions, including Alder‐type, carbene insertion, and hydrosilylation reactions, after covalent functionalization with diester groups and incorporation of transition metals (Fe, Cu, Mg, and Pt). For instance, the Fe–polyethylene solid catalyst accelerates the Diels–Alder reaction of different dienes with trifluoropyruvates, a barely explored organic reaction as far as we know, at very mild temperatures and under solvent‐free reaction conditions, in a full atom economy process without any additives. Besides, the reaction can be engaged with diazocompounds in a cascade reaction, and the inertness of the polyethylene backbone enables its use as a catalytic support for Pt during the hydrosilylation of alkenes and alkynes with the highly reactive reactant trichlorosilane, an industrial reaction barely performed with solid catalysts. The heterogeneous catalysts are easily recoverable and can be recycled up to 10 times. These results open the way to employ polyethylene waste, particularly the unrecyclable fraction, as a highly stable support for metal‐catalyzed organic reactions.