Synthesis of palladium supported on mesoporous hydroxyapatite from oyster shells for use as efficient, green, and recyclable catalyst for Heck reactions

Abstract

catalyst was synthesized by the immobilization of Pd on hydroxyapatite obtained by the hydrothermal method using naturally abundant oyster shells as the calcium source, ammonium dibasic phosphate as the phosphorus source, and cetyltrimethylammonium bromide as the porogen. The synthesized heterogeneous catalyst was characterized using N 2 -physisorption (adsorptiondesorption) measurements, X-ray diffraction analysis, X-ray photoelectron spectroscopy, inductively coupled plasma mass spectrometry, transmission electron microscopy, and temperature-programmed reduction and desorption measurements. The Pd/HAP catalyst shows high catalytic activity for the cross-coupling reaction between iodobenzene and olefins, resulting in yields greater than 67%. Moreover, the Pd/HAP catalyst could be recycled and reused six times with slight reduction in the yield, and thus, is highly stable and recyclable. In addition, it is suitable for use in Heck cross-coupling reactions between various aryl halides and alkenes. Thus, the synthesized catalyst should find extensive use in synthetic chemistry.