Catalytic evaluation of copper (II) N‐salicylidene‐amino acid Schiff base in the various catalytic processes

• Published in: Applied organometallic chemistry 2020-06, Vol.34 (6), p.n/a
• Main Authors: Al‐Hussein, Maryam F.I., Adam, Mohamed Shaker S.
• Format: Article
• Language: English
• Subjects: Acetonitrile; Aqueous solutions; Benzyl alcohol; Catalysts; Chelation; Chemistry; Copper; copper (II); Electron microscopy; Fe3O4; heterogeneous; homogeneous; Imines; Iron oxides; Ligands; Magnetism; Microscopy; Nanoparticles; Oxidation; Oxidizing agents; Silicon dioxide; SiO2; Tyrosine
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.5598

N‐Salicylidene amino acid Schiff base sodium sulfonate salt, as a tridentate dibasic chelating ligand, was obtained from the common condensation of salicylaldehyde‐5‐sodium sulfonate with tyrosine (HPST). The internal formed ligand coordinated to Cu2+ ion in an aqueous media affording new Cu (II)‐complex (Cu‐PST), which characterized by various physico‐chemicals spectral tools. The mononuclear complex was evaluated as a homogeneous and heterogeneous catalyst in the (ep)oxidation protocols of 1,2‐cyclooctene and benzyl alcohol. Heterogeneously, Cu‐PST was immobilized on Fe3O4‐SiO2, as nanoparticles. The heterogeneous catalyst was characterized by infrared, X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, energy‐dispersive spectroscopy, Brunauer−Emmett−Teller and magnetism. Homogeneously, the temperature, solvent and oxidant influences were examined in the catalytic reactions to realize the best reaction conditions. Cu‐catalyst exhibited better catalytic performance in the (ep)oxidation processes homogeneously than that in the heterogeneous phase at 80°C for 2 hr in acetonitrile. Reusability of the homogeneous catalyst was for a maximum of three times in the (ep)oxidation reaction, whereas the heterogeneous catalyst was active for six times. A mechanistic pathway was proposed for both catalysts, comparatively. Cu (II) complex of N‐salicylidene‐amino acid Schiff base‐5‐sodium sulfonate salt (Cu‐PST) was synthesized and characterized Cu‐PST was evaluated as a homogeneous and heterogeneous catalyst in the (ep)oxidation protocols of 1,2‐cyclooctene and benzyl alcohol. Heterogeneously, Cu‐PST was immobilized on Fe3O4‐SiO2. Cu‐catalyst exhibited better catalytic performance homogeneously than that in the heterogeneous phase. Reusability of the homogeneous catalyst was for three times, whereas the heterogeneous catalyst was active for six times.