Heterogeneous Hybrid Nanocomposite Based on Chitosan/Magnesia Hybrid Films: Ecofriendly and Recyclable Solid Catalysts for Organic Reactions.

Metwally Madkour,Khaled D Khalil,Fakhreia A Al-Sagheer

doi:10.3390/polym13203583

Metwally Madkour, Khaled D Khalil + Show 1 more

Open Access

https://doi.org/10.3390/polym13203583

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Journal: Polymers	Publication Date: Oct 17, 2021
Citations: 8	License type: CC BY 4.0

Affiliation: Kuwait University, Cairo University, Taibah University

Abstract

Chitosan/magnesia hybrid films (CS-Mg) have been prepared via sol-gel process and employed as heterogeneous catalysts. An in situ generation of a magnesia network in the chitosan matrix was performed through hydrolysis/condensation reactions of magnesium ethoxide. The synthesized hybrid films were characterized using various analytical techniques, such as X-ray photo-electron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The hybrid films display excellent catalytic activities in Michael and Knoevenagel reactions via one pot or solvent-free approaches under microwave irradiation conditions. Chitosan/magnesia hybrid films, catalysed pyrimidine, benzochromene, coumarin and arylidene-malononitriles derivatives formation reactions occurred with highly efficient yields of 97%, 92%, 86% and 95% respectively. Due to the fact that the films are durable and insoluble in common organic solvents, they were easily separated and can be recycled up to five times without a considerable loss of their catalytic activity.

Highlights

Over the past several decades, increasing attention has been directed toward the development of cleaner/greener synthetic methods, including processes that produce maximum yields of products, have minimum costs, avoid the use of toxic reagents and solvents, and proceed by synthetic routes that avoid the need for isolation of intermediates [1,2,3,4]
We uncovered an efficient protocol for catalyzing Michael addition reactions that rely on the use of modified and non-modified chitosan as heterogeneous recyclable catalysts [4,5]
The results show that the hybrid films are more thermally stable than the pure polymer because of the presence of magnesium oxide

Summary

Introduction

Over the past several decades, increasing attention has been directed toward the development of cleaner/greener synthetic methods, including processes that produce maximum yields of products, have minimum costs, avoid the use of toxic reagents and solvents, and proceed by synthetic routes that avoid the need for isolation of intermediates [1,2,3,4]. In this context, heterogeneous catalysts have advantages over their homogeneous counterparts because they can be isolated from reaction mixtures using simple filtration and can be reused. We uncovered an efficient protocol for catalyzing Michael addition reactions that rely on the use of modified and non-modified chitosan as heterogeneous recyclable catalysts [4,5]

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Results

Conclusion