Pd on thermo-responsive composite of silica-coated carbon nanotube and 1-vinyl-3-butylimidazolium-based ionic liquid copolymers as an efficient catalyst for hydrogenation of nitro compounds

Samahe Sadjadi,Majid M Heravi,Neda Abedian-Dehaghani

doi:10.1038/s41598-022-07708-0

Samahe Sadjadi, Majid M Heravi + Show 1 more

Open Access

https://doi.org/10.1038/s41598-022-07708-0

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Abstract

In this work, an ionic liquid-containing thermo-responsive heterogeneous catalyst with utility for promoting hydrogenation of nitro-compounds in aqueous media is developed. To prepare the catalyst, silica-coated carbon nanotubes were synthesized and vinyl-functionalized. The resulted compound was then polymerized with 1-viny-3-butylimidazolium bromide and N-isopropylacrylamide. The obtained ionic liquid-containing thermo-responsive composite was palladated via wet-impregnation method to give the final catalyst. Study of the performance of the catalyst confirmed high catalytic activity of the catalyst at temperature above the lower critical solution temperature. Furthermore, the catalyst was highly recyclable and showed negligible Pd leaching upon recycling. Broad substrate scope and selectivity of the catalyst towards reduction of nitro functionality were also confirmed. Furthermore, hot filtration test implied the heterogeneous nature of the catalysis. The comparison of the activity of Pd/CNT-P with some control catalysts approved the importance of hybridization of P and CNT and the presence of ionic liquid for the catalytic activity.

Highlights

Smart polymers are polymeric c ompounds[1–3] that respond to the external stimuli, such as mechanical force, light4, temperature5,6, pH7 etc
Reduction of nitro functionality to amino group is a key chemical transformation that can be extensively utilized for the synthesis of complex chemicals and drugs[20–22]
To study the morphology of Pd/CNT-P, it was analyzed via transmission electron microscopy (TEM)

Summary

Introduction

Smart polymers are polymeric c ompounds[1–3] that respond to the external stimuli, such as mechanical force, light4, temperature5,6, pH7 etc. Carbon n anotubes[12–14], CNTs, have received significant attention These compounds benefit from some excellent properties, such as inertness, high surface area, thermal and chemical stability, electric conductivity and tune-ability. These features attracted many scientists to utilize CNTs in various research fields, such as catalysis. Reduction of nitro functionality to amino group is a key chemical transformation that can be extensively utilized for the synthesis of complex chemicals and drugs[20–22] This reduction reaction can be exploited for de-colorization of dyes and waste water treatment. Supporting materials are modified by introduction of functional groups on their surface This can be conducted through covalent or non-covalent approaches[26]. To date various IL-based catalysts have been developed for various chemical transformations[34–39]

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