Modified binh thuan bentonite as catalyst for the heck cross-coupling reaction between iodotoluene and styrene

Abstract

Modified Binh Thuan bentonite catalyst was prepared by exchanging with aqueous solution of PdCl₂, giving a catalyst loading of 0.14 mmol of Pd/g (AAS) and surface areas of160.36 m²/g. The Pd²⁺ - exchanged bentonite effectively catalyzed the Heck carbon-carbon cross-coupling reaction between 4-iodotoluene and styrene. The reaction was performed using less than 1 mol% catalyst at 120^oC in dimethylformamide (DMF) in the presence of Na₂CO₃ as a base, affording the cross-coupling products in good conversions (trans-4-methylstilben: 1-phenyl-1-tolylethylene = 7.5 : 1), identified by GC and GC-MS. The catalyst could be facilely separated from the reaction mixture and could be reused in subsequent reaction without significant degradation in activity. It was also observed that the reaction rate was significantly enhanced under microwave irradiation.