Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C-S cross-coupling reaction.

Debasish Sengupta,Basudeb Basu,Koushik Bhowmik,Goutam De

doi:10.3762/bjoc.13.174

Debasish Sengupta, Basudeb Basu + Show 2 more

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https://doi.org/10.3762/bjoc.13.174

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Abstract

The present work demonstrates the C–S cross-coupling reaction between aryl halides and thiols using nickel nanoparticles (Ni NPs) supported on reduced graphene oxide (Ni/RGO) as a heterogeneous catalyst. It is observed that the uniformly dispersed Ni NPs supported on RGO could exhibit excellent catalytic activity in C–S cross-coupling reactions and the catalytic application is generalized with diverse coupling partners. Although the electron-rich planar RGO surface helps in stabilizing the agglomeration-free Ni NPs, the catalytic process is found to occur involving Ni(II) species and the recovered catalyst containing both Ni(0)/Ni(II) species is equally efficient in recycle runs. A correlation of loading of Ni species, size of NPs and the intermediate Ni-related heterostructures formed during the catalytic process has been established for the first time, and found to be best in the C–S cross-coupling reaction for Ni(0) and Ni(II) NPs of the average sizes 11–12 nm and 4 nm, respectively.

Highlights

The formation of a carbon–sulfur bond is an imperative step for the synthesis of many biologically active chemical entities that have significant applications in different therapeutic areas such as HIV, cancer, diabetes, inflammation, Alzheimer’s and Parkinson’s diseases etc. [1,2,3,4]
We have recently shown that uniformly dispersed nickel nanoparticles (Ni NPs) that are free of agglomeration can be embedded in Reduced graphene oxide (RGO) sheets (Ni/RGO)
In the Ni/RGO composite, the electron-rich RGO surface helps in stabilizing the Ni in its zero-valent state

Summary

Introduction

The formation of a carbon–sulfur bond is an imperative step for the synthesis of many biologically active chemical entities that have significant applications in different therapeutic areas such as HIV, cancer, diabetes, inflammation, Alzheimer’s and Parkinson’s diseases etc. [1,2,3,4]. Bare Ni NPs (of an average size ≈10 nm) prepared following the reported procedure [51], gave the corresponding cross-coupled product in 79% yield (Table 1, entry 14).

Results

Conclusion