Highly active and cost-effective CuO-based carbon nanocomposite with unique morphology for catalytic synthesis of imines under solvent-free conditions

• Published in: Journal of the Taiwan Institute of Chemical Engineers 2017-12, Vol.81, p.455-464
• Main Authors: Gopiraman, M., Chung, I.-M.
• Format: Article
• Language: English
• Subjects: Carbon nanocomposites; CuO nanoparticles; Heterogeneity; Imine synthesis; Nanocatalysts; Reusability
• ISSN: 1876-1070; 1876-1089
• DOI: 10.1016/j.jtice.2017.08.021

•A cheap CuO/carbon nanocomposite (CuO/CNP) with unique morphology was prepared.•Influence of ‘mix and heat’ method on the surface area of CuO/CNP was studied.•CuO/CNP demonstrated excellent catalytic activity toward the synthesis of imines.•CuO/CNP was found to be highly suitable for the cross-coupling reactions as well.•Heterogeneity, stability and reusability of CuO/CNP were found to be good. Herein, we report a highly efficient and cost-effective copper-oxide/carbon-nanoparticles catalyst (CuO/CNP) prepared by a simple ‘mix and heating’ method for the self-coupling of amines. Homogenous dispersion of CuO nanoparticles on the surface of CNP, +2 chemical state of Cu in CuO/CNP, 6.1 wt% of Cu in CuO/CNP, and specific surface area of CuO/CNP (56.4 m2/g) were found out by means of various spectroscopic and microscopic techniques. Presence of defective sites in CuO/CNP was analyzed by Raman analysis. X-ray diffraction results were referred to confirm the crystalline/amorphous nature of CuO/CNP. The CuO/CNP demonstrated excellent catalytic activity for the self-coupling of amines under the optimal reaction conditions involving 12 h of reaction time, 25 mg of catalyst, air atmosphere and 110 °C. The scope of the catalytic systems was extended with a wide range of amines (aromatic, alicyclic and heterocyclic amines). The CuO/CNP was found to be effective for the self-coupling of less reactive amines (aliphatic amines and aromatic amines) as well. Cross-coupling of primary amines with aniline catalyzed by CuO/CNP was also demonstrated. Heterogeneity, stability and reusability of CuO/CNP were tested. Mechanism was proposed for the self-coupling of primary amines catalyzed by CuO/CNP. [Display omitted]