Study On Property Of Salicylaldehyde Schiff Base Metal Complexes For Catalytic Oxidation Of Model Sulfides

Seven kinds of Schiff base metal complexes (C1-C7) were synthesized by the reaction of substituted salicylaldehyde Schiff base with cobalt nitrate, nickel nitrate, and copper nitrate, respectively. The oxygen carrying performance, and the catalytic property of complexes for the oxidation of model sulfides 1-hexanethiol, dibutyl sulfide, and 2-methylthiophene along with their influencing factors were explored, while the oxidized products of the model sulfides were also analyzed and characterized. The results show that the catalytic oxidation property of the complexes is determined by their oxygen carrying performance and solubility in n-octane. The oxygen carrying performance of the complexes is mainly affected by the central ion species, the electronic effects, and the spatial effects of the substituents as well as the degree of conjugation. More specifically, the oxygen carrying performance can be improved by enhancing the oxygenation capacity of the central metal ions, increasing the electron donating ability of the ligand substituent, and diminishing the steric hindrance as well as extending the conjugated chain. Complexes C7 were found to be with high oxygen carrying capacity and high solubility in n-octane, which shows the best catalytic oxidation property, and the oxidation conversion rates for 1-hexylthiol, dibutyl sulfide, and 2-methylthiophene are 74.2%, 65.1%, and 22.7%, respectively. Upon using the oxidation catalyst of Schiff base metal complexes, three sulfides can be oxidized by oxygen to form sulfones and sulfoxides. 1-Hexanethiol and dibutyl sulfide will continue to be oxidized to form sulfates and sulfites.