A simple, phosphine free, reusable Pd(ii)–2,2′-dihydroxybenzophenone–SBA-15 catalyst for arylation and hydrogenation reactions of alkenes

Abstract

An efficient, simple, phosphine and co-catalyst free C–C coupling reaction heterogeneous catalyst via a post grafting method is developed and reported. A covalently anchored phosphine free Pd(II) based 2,2′-dihydroxybenzophenone (DHBP) complex over organofunctionalized SBA-15 has been synthesized by the reaction between aminofunctionalized SBA-15 (NH₂SBA-15) and a 2,2′-dihydroxybenzophenone (DHBP) ligand, and further complexation with Pd(II)Cl₂ to get Pd(II)–DHBP@SBA-15. The synthesized catalysts were characterized by elemental analysis, XRD, N₂ sorption analyses, TG, DTA, FT-IR, solid state ¹³C and ²⁹Si NMR spectra, XPS, UV-Visible, SEM, EDAX and TEM. The synthesized catalysts were screened in arylation (Heck reactions) and hydrogenation reactions of alkenes, and the results show that Pd(II)–DHBP@SBA-15 exhibits high conversion and selectivity towards arylation and hydrogenation reactions of alkenes with high stability. The anchored solid catalysts can be recycled effectively and reused several times without major loss in activity.