Cross-Linked Chitosan/Multi-Walled Carbon Nanotubes Composite as Ecofriendly Biocatalyst for Synthesis of Some Novel Benzil Bis-Thiazoles

• Main Authors: Latifah A. Alshabanah, Sobhi M. Gomha, Laila A. Al-Mutabagani, Tariq Z. Abolibda, Nahed A. Abd El-Ghany, Waleed A. M. A. El-Enany, Ahmed K. El-Ziaty, Rania S. Ali, Nadia A. Mohamed
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Polymers
• Subjects: thiosemicarazones; hydrazonoyl halides; bis-thiazoles; cross-linked chitosan; multiwalled carbon nanotubes/cross-linked chitosan composite
• Online Access: https://www.mdpi.com/2073-4360/13/11/1728

Aminohydrazide cross-linked chitosan (CLCS) and its MWCNTs (CLCS/MWCNTs) were formulated and utilized as a potent ecofriendly basic heterogeneous biocatalyst under ultrasonic irradiation for synthesis of two novel series of benzil bis-aryldiazenylthiazoles and benzil bis-arylhydrazonothiazolones from the reaction of benzil bis-thiosemicarbazone with 2-oxo-<i>N</i>′-arylpropanehydrazonoyl chlorides and ethyl 2-chloro-2-(2-phenylhydrazono) acetates, respectively. The chemical structures of the newly synthesized derivatives were elucidated by spectral data and alternative methods, where available. Additionally, their yield % was estimated using a traditional catalyst as TEA and green recyclable catalysts as CLCS and CLCS/MWCNTs composite in a comparative study. We observed that, under the same reaction conditions, the yield % of the desired products increased by changing TEA to CLCS then to CLCS/MWCNT from 72–78% to 79–83% to 84–87%, respectively. The thermal stability of the investigated samples could be arranged as CLCS/MWCNTs composite > CLCS > chitosan, where the weight losses of chitosan, CLCS and CLCS/MWCNTs composite at 500 °C were 65.46%, 57.95% and 53.29%, respectively.