This work presents a sustainable and reusable heterogeneous palladium catalyst designed to reduce precious-metal consumption and minimize waste in fine-chemical halogenation processes. A polystyrene-anchored Schiff-base Pd(II) material (PS-NHLB-Pd(OAc)2) was synthesized through stepwise resin functionalization and metal coordination, and comprehensively characterized by FT-IR, PXRD, SEM/EDS, XPS, and TGA. The catalyst efficiently promotes regioselective ortho-halogenation of aromatic amides and anilines under mild conditions, delivering high yields (85–97%) with excellent selectivity. Owing to strong Pd−N/O coordination within the polymer matrix, the catalyst demonstrates outstanding reusability for at least four cycles with negligible Pd leaching, thereby significantly reducing palladium loss compared to homogeneous Pd(OAc)2. A sustainability assessment shows improved material efficiency, reduced heavy-metal discharge, and a lower E-factor relative to traditional halogenation protocols. The operational simplicity, recyclability, and reduced environmental release of Pd highlight the catalyst’s relevance to responsible resource utilization and align this methodology with United Nations Sustainable Development Goal 12 (Responsible Consumption and Production). This study demonstrates how rational catalyst immobilization can contribute to sustainable resource management while enabling efficient C−H functionalization chemistry.
Gujarati et al. (Fri,) studied this question.