Reductive depolymerization of polycarbonates and polyesters using alkaline earth catalysts

• Recycling of polyester and polycarbonate plastic waste. • Valorization of plastic waste into valuable diols. • Use of inexpensive and eco-friendly catalysts for plastic recycling. This work presents the first methodology for reductive depolymerization of plastic waste promoted by barium and calcium compounds. The commercially available compounds Ba(OTf)₂ and Ca(OTf)₂ were successfully applied in the reductive depolymerization of various polyesters and the polycarbonate PC.BPA, producing the corresponding diols in excellent yields. The reactions were carried out using pinacolborane as the reducing agent under mild conditions. These catalysts maintained excellent activity over several consecutive reductive depolymerization reactions. The use of inexpensive alkaline earth metal catalysts represents a significant advancement in the conversion of plastic waste into value-added diols, which have a wide range of industrial applications. This study highlights the high efficiency of the abundant alkaline-earth metal compounds Ba(OTf)₂ and Ca(OTf)₂ in converting polyester and polycarbonate waste into a variety of valuable diols with excellent yields. Additionally, this method provides an attractive, environmentally friendly, efficient, and cost-effective alternative for the depolymerization of plastic waste.