Synthesis, characterization, and optimum reaction conditions of oligo-3-aminopyridine and its Schiff base oligomer

The products and the oxidative polycondensation reaction conditions of oligo-3-aminopyridine with H2O2 and NaOCl were studied. In this reaction, NaOCl was observed to be more active than H2O2 and optimum reaction conditions were determined. Oligo-3-aminopyridine (OAP) was synthesized from the oxidative polycondensation of 3-aminopyridine (AP) with NaOCl and H2O2 in an aqueous acidic medium at 25 degrees-90 degrees C. The products were characterized by H-1 NMR, FT-IR, UV-Vis, and elemental analysis. The number-average molecular weight, weight-average molecular weight, and polydispersity index values of OAP synthesized were found to be 250, 800g mol(-1), and 3.20, respectively, using NaOCl, and 240, 840g mol(-1), and 3.50, respectively, using H2O2. The respective values of the Schiff base were 1140, 5190g mol(-1), and 4.55. At optimum reaction conditions, yields of the reaction products were 80.1% (H2O2) and 82.0% (NaOCl). About 90% AP was converted into OAP. TG analyses showed that OAP was stable towards thermo-oxidative decomposition. The weight loss of OAP was found to be 5, 50, and 92 at 125 degrees, 617 degrees, and 1000 degrees C, respectively. The weight loss of oligo-aminopyridinylazomethinephenol (OAPAP) was found to be 5, 50, and 80.50 at 175 degrees, 660 degrees, and 1000 degrees C, respectively. Also, a new oligomeric Schiff base was synthesized from the condensation of OAP with salicylaidehyde and their structures and properties were determined.