Nitrogenative Degradation of Polystyrene Waste

Abstract

Owing to massive production and poor end-of-life management, plastic waste pollution has become one of the most pressing environmental crises. In response to the mounting crisis, the past several decades have witnessed the development of numerous methods and technologies for plastic recycling. However, most of the current recycling technologies often produce low-quality or low-value products, making it difficult to recover the operating costs. To this end, we report a novel preoxygenation-induced strategy for the nitrogenative degradation of real-life polystyrene plastics into high-value aromatic nitrogen compounds in a cost-effective manner. Thus, expensive and highly demanding benzonitrile as well as benzamide were obtained in up to 74% overall isolated yield from polystyrene waste by using CuBr as the catalyst, O₂ as the oxidant, and CH₃CN as the nitrogen source. Detailed mechanistic investigations indicate that hydroxyl radicals from O₂ activation play a role in this selective aerobic degradation process. Furthermore, multiple reaction pathways contribute to the formation of benzonitrile and benzamide.