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The third chapter summarizes the investigation of acid-catalyzed reactions of epoxides to form carbonyl compounds using different acidic zeolites. Initial reaction involved styrene oxide as a model example, which had been reported to be converted to phenylacetaldeyhyde over HZSM-5 zeolite at 90°C, under nitrogen, in the presence of toluene as solvent. The investigation began with changing the reaction conditions for this reaction, such as temperature, solvent, and silica to alumina ratio of the zeolite, in order to show the effect of each factor on the percentage yield of phenylacetaldehyde obtained, and the conclusion of this study was to define the optimum conditions for rearrangement of styrene oxide by H-zeolite catalysts. The methodology was then tested on a number of para-subtituted styrene oxides to show the effect of different groups on the rearrangement process. The effect of re-using the HZSM-5 catalyst, after calcination, was tested in the rearrangement of styrene oxide, and provided excellent results. Secondly, the methodology was tested on aliphhatic epoxides, such as 1,2-epoxyoctane, and cycloepoxides such as cyclohexene oxide. Finally the effects of large pore zolites such as zeolite beta on disubtituted epoxides such as trans and cis-stilbene oxides and diphenylethene oxide were tested. Chapter four summarizes studies of the base-catalyzed reaction of epoxides to form allylic alcohols as main products using different catalysts. First, solid supports such as γ-alumina were used to support the reagent such as KNO3 or NaOH/Na in order to get solid catalyst which has high basic strength (H. higher then 26.5). These prepared catalysts were tested as superbases for the rearrangement of epoxides to give the corresponding allylic alcohols, but from this piece of work the results were unsuccessful under various conditions. According to the literature the conversion of epoxides to allylic alcohols can be achieved with lithium amide reagents. In this study lithium amide reagents attached to Merrifield's resin were produced and then reacted with epoxides in solvents such as terahydrofuran (THF). The reactions of such lithium amide polymers with epoxides in THF provided excellent results. |
