Synthesis, Characterization, and Kinetic of Thermal Degradation of Oligo-2-[(4-bromophenylimino)methyl]phenol and Oligomer-Metal Complexes

摘要

Oligo-2-[(4-bromophenylimino)methyl]phenol (OBPIMP) was synthesized from the oxidative poly-condensation reaction of 2-[(4-bromophenylimino)methyl] phenol (BPIMP) with air and NaOCl oxidants in an aqueous alkaline medium between 50 and 90 degrees C. The yield of OBPIMP was found to be 67 and 88% for air and NaOCl oxidants, respectively. Their structures were confirmed by elemental and spectral such as IR, ultra violet-visible spectrophotometer (UV-vis), H-1-NMR, and C-13-NMR analyses. The characterization was made by TG-DTA, size exclusion chromatography, and solubility tests. The resulting complexes were characterized by electronic and IR spectral measurements, elemental analysis, AAS, and thermal studies. According to TG analyses, the weight losses of OBPIMP, and oligomer-metal complexes with Co+2, Ni+2, and Cu+2 ions were found to be 93.04%, 59.80%, 74.23%, and 59.30%, respectively, at 1000 degrees C. Kinetic and thermodynamic parameters of these compounds investigated by Coats-Redfern, MacCallum-Tanner, and van Krevelen methods. The values of the apparent activation energies of thermal decomposition (E-a), the reaction order (n), preexponential factor (A), the entropy change (Delta S*), enthalpy change (Delta H*), and free energy change (Delta G*) obtained by earlier-mentioned methods were all good in agreement with each other. It was found that the thermal stabilities of the complexes follow the order Cu(II) > Co(II) > Ni(II).