Study On Organic Synthesis Reactions Catalyzed By Silica Sulfuric Acid

Solid acid catalysts have found wide applications in organicsynthesis. On the one hand, they have many distinct features, such asinvolatility, low toxicity, tasteless, low corrosion and pollution, easyrecovery and reusability. On the other hand, there are the mild reactionconditions, high yields and selectivity, simple work-up procedures ofthese reactions catalyzed by solid acid catalysts, which cannot be replacedby liquid catalysts. Solid silica sulfuric acid (SSA) catalysts have wideapplication prospects, due to their unique acidity, convenient preparationand simple work-up procedures.In this thesis, the main results obtained are as follows:(1) This paper described the Michael reaction of the amine andthiophenol with acrylate catalyzed by SSA catalyst. The effect of catalystsand their loadings, solvent and temperature on the results has beeninvestigated. After optimization of the reaction conditions, twentycompounds have been synthsized by using fatty amines, aromatic aminesand thiophenol as Nucleophilic reagents. Besides imidazole, thesereactions can give80%96%yields. The catalyst can be recycled six times and the catalytic capability of did not decrease obviously.(2) SSA-catalyzed the multi-component Hantzsch reactions havebeen developed. We explored the conditions of these reactions. Thereactions of aryl aldehyde,1,3-dicarbonyl conpounds with ammoniumacetate in EtOH can afford a series of symmetric and asymmetric1,4-dihydropyridines with83%96%yields.(3) The condensation reaction of4-(phenylthio)benzaldehyde withcyclohexane-1,3-dione catalyzed by SSA has also been developed. Thebest results have been obtained in EtOH with25mol%Solid silicasulfuric acid at600C. A series of1,8-dioxo-octahydroxanthenederivatives has been synthesized with86%96%yields. This methodhas several advantages, such as simple work-up procedure, shorterreaction time along with high yields, inexpensive, available and reusablecatalyst.