It is an attractive but formidable challenge in the chemical recycling of polystyrene (PS) wastes to the value-added aromatic compounds due to the inertness of C-C bonds in polymer backbone. Here we develop a light-driven, copper-catalyzed protocol to achieve aerobic oxidation of various alkylarenes or real-life PS wastes to benzoic acid and oxidized styrene oligomers. The resulting oligomers can be further transformed under heating condition, thus achieving benzoic acid in up to 65% total yields through an integrated one-pot two-step procedure. Mechanistic studies show that the CuCl₂ catalyst undergoes Ligand-to-Metal Charge Transfer (LMCT) to generate a chlorine radical, which triggers the activation of C-H bond and subsequent oxidative cleavage of C-C bonds. The practicality and scalability of this strategy are demonstrated by depolymerization of real-life PS foam on a gram scale, thus showing promising application potentials in chemical recycling of PS wastes.

中文翻译：

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通过铜基催化剂将烷基芳烃和聚苯乙烯废料有氧氧化为苯甲酸


由于聚合物主链中 C-C 键的惰性，在将聚苯乙烯 （PS） 废料化学回收为增值芳香族化合物的过程中，这是一个有吸引力但艰巨的挑战。在这里，我们开发了一种光驱动的铜催化方案，以实现各种烷基芳烃或现实生活中的 PS 废物的有氧氧化为苯甲酸和氧化的苯乙烯低聚物。所得低聚物可以在加热条件下进一步转化，从而通过集成的一锅两步程序以高达 65% 的总收率获得苯甲酸。机理研究表明，CuCl₂ 催化剂发生配体-金属电荷转移 （LMCT） 以产生氯自由基，从而触发 C-H 键的激活和随后的 C-C 键氧化裂解。该策略的实用性和可扩展性通过克级真实 PS 泡沫的解聚得到证明，从而在 PS 废物的化学回收方面显示出有前途的应用潜力。