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Nanocomposite‐based inorganic‐organocatalyst Cu(II) complex and SiO 2 ‐ and Fe 3 O 4 nanoparticles as low‐cost and efficient catalysts for aniline and 2‐aminopyridine oxidation
Author(s) -
Adam Mohamed Shaker S.,
AlOmair Mohammed A.
Publication year - 2020
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.5999
Subject(s) - chemistry , catalysis , aniline , inorganic chemistry , heterogeneous catalysis , acetonitrile , adsorption , nuclear chemistry , organic chemistry
Bis ‐imino Cu(II) complex (CuLAn 2 ), in which the imine ligand (HLAn) acts as a bidentate chelating ligand, was synthesized. The catalytic potential of the inorganic‐organocatalyst was studied homogeneously and heterogeneously in the oxidation of aniline and 2‐aminopyridine by H 2 O 2 or t BuOOH. Two heterogeneous inorganic‐organocatalysts, CuLAn 2 @Fe 3 O 4 and CuLAn 2 @SiO 2 @Fe 3 O 4 , were synthesized by the successful immobilization of CuLAn 2 on the Fe 3 O 4 surface and the composited Fe 3 O 4 with SiO 2 , respectively. The heterogeneous structure of those inorganic‐organocatalysts was confirmed using Fourier‐transform infrared, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, transmission electron microscopy, and magnetic properties. The adsorption–desorption isotherms revealed respectable adsorption parameters ( S BET , V p , and r p ). All catalysts exhibited high potential in the oxidation of aniline (with phenylhydroxylamine as the main product) and good potential in the oxidation of 2‐aminopyridine, in the first attempt (with 2‐nitropyridine‐ N ‐oxide and 2‐nitrosopyridine‐ N ‐oxide as main products), at room temperature. Acetonitrile was found to be the best solvent compared to ethanol, dimethyl sulfoxide, chloroform, and water. The homogeneous catalyst exhibited reusability for three times. The heterogeneous catalysts, CuLAn 2 @Fe 3 O 4 and CuLAn 2 @SiO 2 @Fe 3 O 4 , were active for five and seven times, respectively. A mechanism was proposed within electron and oxygen transfer processes.