چكيده فارسي :
Heteropolyacids due to high variations in charge, size and chemical nature, have unique features. Some of these features include thermal resistance, high acidity, solubility and redox noted Properties. Thermal resistance of heteropolyacids is of great importance especially in cases where they are used as a heterogeneous catalyst [1].
Epoxidation of alkenes is one of the most important chemical processes, the products of this reaction are used as a precursor for the synthesis of many chemicals and pharmaceuticals as well as for the production of many valuable materials including epoxy resins, paints and surfactants [2].
Polyaniline (PANI) is one of the oldest artificial conductive polymers that its high electrical conductivity has attracted a lot of attention. Easy synthesis and high surface area are its other features that can be noted. PANI was prepared by dissolvingdistilled aniline and ammoniumproxydisolfatin 1MHClaccording to the reported procedures [3].
HPAs(H3[PMo12O40]and H4[SiMo12O40]) also were prepared according to the reported procedures [1] and then they were supported on PANI by refluxing in ethanolfor 3 hours.
In this work, the epoxidation of cyclo-octene as a model reaction have been investigated withH3[PMo12O40]and H4[SiMo12O40]supported on PANI. The various parameters such as type of solvent (1,2-dicholoroethane , chloroform, carbon tetrachloride, acetonitrile and methanol), type ofoxidant (hydrogen peroxide, t-butyl-hydro-peroxide and hydrogen peroxide/urea), amount ofoxidant (0.1, 0.2, 0.3 and 0.4ml t-butyl-hydro-peroxide) and amount of catalyst (5, 10, 15 and 20 mg) were optimized for this reaction. The progress ofthese reactionswas analyzedusinggas chromatography (GC) during 30-180 minutes.The optimum conditions were found carbon tetrachlorideas a solvent, 1mmol TBHP as oxidant, 20 mg catalyst for 0.5 mmolcyclo-octene at reflux temperature. At these conditions, H3[PMo12O40]and H4[SiMo12O40]reached near complete conversion during 90minutes.
