The synthesis and characterization of oligo-N-4-aminopyridine, oligo-2-[(pyridine-4-yl-imino) methyl] phenol and its some oligomer–metal complexes

• Published in: Polymer (Guilford) 2003-11, Vol.44 (24), p.7299-7309
• Main Authors: Kaya, İsmet, Koyuncu, Sermet
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Oligo-2-[(pyridine-4-yl-imino) methyl] phenol; Oligo-N-4-aminopyridine; Organic polymers; Oxidative polycondensation; Physicochemistry of polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2003.09.011

The product and the oxidative polycondensation reaction conditions of oligo-4-aminopyridine were studied by using NaOCl as oxidant. Oligo-4-aminopyridine (4-OAP) was synthesized from the oxidative polycondensation of 4-aminopyridine (4-AP) in an aqueous solution medium acidic and neutral between 25 and 60 °C by using NaOCl as oxidant. About 85% of 4-AP was converted to 4-OAP. The number average molecular weight, ( M n) mass average molecular weight ( M w) and polydispersity index (PDI) values of 4-OAP synthesized were found to be 270, 850 g mol −1 and 3.15, respectively, using NaOCl. The respective values of the Schiff base were 1721, 2256 g mol −1 and 1.31, respectively, using air oxygen and 2173, 2372 g mol −1 and 1.09, respectively, using NaOCl and 2749, 6432 g mol −1 and 2.33, respectively, using H 2O 2. At the optimum reaction conditions, the yield of oligo-2-[(pyridine-4-yl-imino) methyl] phenol (OPMP) were found to be 86% (H 2O 2) and 89% (NaOCl) and 95% (air oxygen). The 4-OAP and OPMP were characterized by 1H NMR, FT-IR, UV–Vis and elemental analysis. TG analysis showed to be stable of 4-OAP against thermo-oxidative decomposition. The weight loss of 4-OAP and its Schiff base oligomer was found to be 50, 86.39 and 71.78% at 525, 625 and 1000 °C, respectively. Also, new oligomeric Schiff base was synthesized from condensation of 4-AP with salicylaldehyde and their structures and properties were determined. During polycondensation reaction, a part of the azomethine (–CHN–) groups oxidized to carboxylic (–COOH) group. Thus, soluble fraction in water of oligo-2-[(pyridine-4-yl-imino) methyl] phenol involved in carboxylic (–COOH) (11%) group. Besides, the structure and properties of oligomer–metal complexes of oligo-2-[(pyridine-4-yl-imino) methyl] phenol (OPMP) with Cu(II), Ni(II) and Co(II) were studied.