Systematic investigation of the oxidative polymerization of linseed oil catalyzed by Co(II), Mn(II), and Fe(II) complexes with chelating nitrogen ligands

Abstract

Several metal catalysts, i.e., cobalt(II) 2‐ethylhexanoate (1), manganese(II) 2‐ethylhexanoate (2) and iron(II) 2‐ethylhexanoate (3), and their complexes with the chelating nitrogen ligands, i.e., 1,10‐phenanthroline (a), 4‐methyl‐1,10′‐phenanthroline (b), and 5,6′‐dimethyl‐1,10′‐phenanthroline (c), were tested for the oxidative polymerization of linseed oil. The stoichiometries of the complexes were determined, and the isolated complexes were characterized by IR spectroscopy to confirm that complexation had occurred. The evolution of the viscosity was evaluated for 18 h, and the results were expressed as apparent kinetic constants calculated from ln(viscosity) versus time. The results indicate that the manganese and iron chelates exhibit higher catalytic efficiencies than their corresponding carboxylates and that their performances are comparable to that of the cobalt carboxylate.Practical applications: The coordination of chelating nitrogen ligands to manganese and iron carboxylates improves their catalytic performance and is a promising strategy for substituting cobalt carboxylates in some applications in the coating industry.Precursors and ligands used to obtain new complexes 1a, 1b, 1c, 2a, 2b, 2c, 3a, 3b, and 3c, investigated in oxidative polymerization process.