Synthesis, characterization, and thermal stability of azomethine oligomer and its metal complexes

Abstract

AbstractThe oxidative polycondensation reaction conditions of N,N′‐bis[(2‐hydroxy‐1‐naphthyl)methylene]urea (2‐HNMU) has been accomplished using NaOCl, H2O2, and air O2 oxidants in an aqueous alkaline medium. The structures of the obtained monomer and oligomer were confirmed by FTIR, UV–vis, 1H NMR, 13C NMR, and elemental analysis. The characterization was made by TG‐DTA, size exclusion chromatography (SEC), and solubility tests. At the optimum reaction conditions, the yield of oligo‐N,N′‐bis[(2‐hydroxy‐1‐naphthyl)methylene]urea (O‐2‐HNMU) was found to be 95% (for air O2 oxidant), 51% (for H2O2 oxidant), 96% (for NaOCl oxidant). According to the SEC analysis, the number‐average molecular weight (Mn), weight‐average molecular weight (Mw), and polydispersity index values of O‐2‐HNMU was found to be 1036, 1225 g/mol, and 1.182, respectively, using H2O2, and 765, 1080 g/mol, and 1.412, respectively, using air O2, and 857, 1105 g/mol, and 1.289, respectively, using NaOCl. TG‐DTA analyses showed that O‐2‐HNMU was more stable than 2‐HNMU. According to TG analyses, the carbonaceous residue of 2‐HNMU and O‐2‐HNMU was found to be 0.49% and 2.11% at 1000°C, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007