Recyclable ionic iron-substituted ceria: a precious metal-free, ligand-free, and versatile catalyst for C–C coupling and ipso-hydroxylation of arylboronic acid

Abstract

Fluorite-type nanocrystalline 5% iron-substituted ceria (Ce_0.95Fe_0.05O_2−δ) was synthesized by the solution combustion method with an average crystallite size of 15 nm. The catalyst was well characterized by SEM, EDX, XPS, XRD, and H₂-TPR studies, which confirmed the substitution of Fe³⁺ in the CeO₂ lattice. This precious metal-free catalyst was developed for the selective conversion of various arylboronic acids to the corresponding biphenyls and phenols employing K₂S₂O₈ and H₂O₂, respectively. This catalyst could be coated on cordierite monolith, which acts as a catalyst cartridge employed efficiently in recycling experiments up to seven cycles. The scale-up reaction was also carried out with a catalyst cartridge, affording a good yield of the desired product.