Synthesis, Characterization and Optimum Reaction Conditions of Oligo-N-Salicylidenephenylhydrazone via Oxidative Polymerization

Abstract

The oxidative polycondensation reaction conditions and optimum parameters of N-salicylidenephenylhydrazone (SPH) were determined using air, H2O2 and NaOCl as oxidants at a temperature range between 50 °C and 95 °C in an aqueous alkaline medium. The molecular structures of the obtained monomer and oligomer were confirmed by FT-IR, UV-Vis, 1H-NMR and elemental analyses. The characterization was fulfilled by TG-DTA, size exclusion chromatography (SEC) and solubility tests. The conversion of N-salicylidenephenylhydrazone into oligomer was performed using air, H2O2 and NaOCl as oxidants in an aqueous alkaline medium. According to SEC analysis, the number-average molecular weight (Mn), weight-average molecular weight (Mw) and polydispersity index (PDI) values of oligo-N-salicylidenephenylhydrazone (OSPH) obtained using NaOCl oxidant were found to be 1436 g mol-1, 1631 g mol-1 and 1.14, respectively. The conversion yield of N-salicylidenephenylhydrazone into oligo-N-salicylidenephenylhydrazone was 100% at optimum reaction conditions such as [SPH]0 = [KOH]0 = [H2O2]0 =0.06, mol/L and at 90 °C for 10 h. Also, according to TG-DTA analysis, oligo-N-salicylidenephenylhydrazone was shown to be thermally stable and resistant to thermo-oxidative decomposition. The weight loss of OSPH was found to be 20, 50 and 92.56% at 275°, 597° and 1000 °C, respectively.