Synthesis and Identification of Heterocyclic Compounds (Oxazepine, Tetrazole) Derived from Benzidine as Photostabilizing for Poly vinyl chloride

This research describes preparation of new four compounds (A2-A5) having 1,3-oxazepine and Tetrazole rings. The first step involves reaction of benzidine (A1) with aromatic aldehyde (cinnamaldehyde) in ethanol as a solvent in the presence of acid as catalyst to yield the Schiff base (A2), Schiff base (A2) was condensed with maleic anhydride and phthalic anhydride in dry benzene to give a seven-membered heterocyclic ring derivative (A3, A4), In addition, we synthesis novel tetrazole derivative (A5) from the reaction of Schiff base (A2) with sodium azide in tetrahydrofuran. The structure of synthesized compounds were identified by spectral methods [FTIR, ¹H-NMR, and ¹³C-NMR] and measurement physical properties. The photo stabilization of poly (vinyl chloride) films by compounds (A1-A5) was studied. The Photostabilization activities of these compounds were determined by monitoring the carbonyl and hydroxyl indexes values with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were studied by using tetrahydrofuran as a solvent. The influence of concentrations additives (range 0.1-0.5wt) on the rate of photodegradation and Photostabilization course was studied. Therefore, we found that was an increase Photostabilization rates with increasing concentrations of additives. In addition, Studying the effect of film thickness and the results showed that an increase in film thickness would reduce the rate of photolysis. The results indicated that Photostabilisation proportion of plastic in the presence of additives follow the trend: (PVC blank) > PVC+A1> PVC+A2 > PVC+A5> PVC+A4> PVC+A3. According to the results obtained, it proposed mechanisms depending on the structure of the additive.