Mechanochemical upcycling of poly (vinyl chloride) for alcohol halogenation

Polyvinyl chloride (PVC) has raised significant environment concerns due to its chlorine-rich composition. Mechanochemical dechlorination of PVC produces waste chlorides that remain largely unutilized. Herein, we demonstrate that contact-electro-catalysis-mediated dechlorination, in tandem with alcohol chlorination can enable the upcycling of PVC to produce value-added organic chlorides and enhance atomic efficiency. Anatase TiO2, as contact-electro-catalyst, mediates the single electron transfer process that promotes the dechlorination of PVC under ball milling, thereby enabling the cascade alcohol chlorination through in-situ generated HCl. This strategy is applicable to a variety of benzylic, alicyclic, aliphatic and heterocyclic alcohols, yielding the corresponding organic chlorides with yields up to 95% in 4 hours. This mechanochemical approach can be scaled up to a 40 g scale of PVC and applied to real PVC samples. Structural analysis confirms the effective degradation of PVC accompanied by dechlorination with molecular weight decreasing from 65.0 kDa to 4.6 kDa after five cycles. This mechanochemical approach opens avenues for the application of PVC as a convenient and safe chlorine source in chemical transformations. The mechanochemical dechlorination of poly(vinyl chloride) (PVC) can catalyse reactions through the release of chlorides. Here, the authors use TiO2 as a contact-electro-catalyst to achieve PVC dechlorination via ball-milling for the solvent-free, mechanochemical chlorination of alcohols.