Hybrid Cobalt Doped-Cerium Oxide as a Multifunctional Nanocatalyst for Various Organic Transformations

Abstract

Development of a low-cost, environmentally benign and robust catalyst for multipurpose industrially relevant organic transformations is highly desirable for the sustainable future of chemical industries. A hybrid cobalt doped-cerium oxide nanocatalyst (Co@CeO2NC) was prepared via simple coprecipitation method using water as the solvent. The characterization of Co@CeO2NC was performed using different techniques such as XRD, TGA, FE-SEM, HR-TEM, EDAX-mapping, BET, and XPS analysis. The structural characterization of the prepared sample by XRD and XPS analysis revealed the presence of the mixed phase of cobalt oxide and cobalt doped-cerium oxide as a hybrid (Co@CeO2NC). Industrially relevant organic transformations such as (i) nitrile formation using aldehyde with hydroxylamine hydrochloride, (ii) reductive amination of aldehydes to form tertiary N,N-dimethyl amines, and (iii) direct acetylation of alcohols/amines with acetic acid were achieved in an excellent manner using Co@CeO2NC hybrid as the multifunctional catalyst. Excellent catalytic activity of Co@CeO2NC was noticed for the conversion of 4-chlorobenzaldehyde to 4-chlorobenzonitrile with 99% conversion and 99% selectivity and 100% conversion of benzaldehyde to N,N-dimethylbenzylamine using DMF as NMe2 source, reductant, and solvent. Moreover, acetylation of 4-methoxybenzyl alcohol and 2-methyl aniline gave excellent conversion and selectivity toward the formation of -O and -N acetyl. The scope of the Co@CeO2NC was further evaluated for other aldehydes, alcohols, and amines with an excellent conversion and high selectivity. Copyright © 2019 American Chemical Society.