Highly Active Cellulose-Supported Poly(hydroxamic acid)-Cu(II) Complex for Ullmann Etherification

Choong Jian Fui; Tang Xin Ting; Mohd Sani Sarjadi; Zarina Amin; Shaheen M Sarkar; Baba Musta; MdLutfor Rahman

doi:10.1021/acsomega.0c05840

Highly Active Cellulose-Supported Poly(hydroxamic acid)-Cu(II) Complex for Ullmann Etherification

ACS Omega. 2021 Mar 5;6(10):6766-6779. doi: 10.1021/acsomega.0c05840. eCollection 2021 Mar 16.

Authors

Choong Jian Fui¹, Tang Xin Ting¹, Mohd Sani Sarjadi¹, Zarina Amin², Shaheen M Sarkar³, Baba Musta¹, MdLutfor Rahman¹

Affiliations

¹ Faculty of Science and Natural Resources, University Malaysia Sabah, 88400 Kota Kinabalu, Sabah, Malaysia.
² Biotechnology Research Institute, University Malaysia Sabah, 88400 Kota Kinabalu, Sabah, Malaysia.
³ Department of Chemical Sciences, Bernal Institute, University of Limerick, Limerick V94 T9PX, Ireland.

Abstract

Highly active natural pandanus-extracted cellulose-supported poly(hydroxamic acid)-Cu(II) complex 4 was synthesized. The surface of pandanus cellulose was modified through graft copolymerization using purified methyl acrylate as a monomer. Then, copolymer methyl acrylate was converted into a bidentate chelating ligand poly(hydroxamic acid) via a Loosen rearrangement in the presence of an aqueous solution of hydroxylamine. Finally, copper species were incorporated into poly(hydroxamic acid) via the adsorption process. Cu(II) complex 4 was fully characterized by Fourier transform infrared (FTIR), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectrometry (ICP-OES), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses. The cellulose-supported Cu(II) complex 4 was successfully applied (0.005 mol %) to the Ullmann etherification of aryl, benzyl halides, and phenacyl bromide with a number of aromatic phenols to provide the corresponding ethers with excellent yield [benzyl halide (70-99%); aryl halide (20-90%)]. Cu(II) complex 4 showed high stability and was easily recovered from the reaction mixture. It could be reused up to seven times without loss of its original catalytic activity. Therefore, Cu(II) complex 4 can be commercially utilized for the preparation of various ethers, and this synthetic technique could be a part in the synthesis of natural products and medicinal compounds.