Studies On The Organic Synthesis Reactions Catalyzed By Solid Acids

This thesis consists of three chapters.In the first chapter, Zr(S04)2'4H2O/SiO2 is found to be an efficient catalyst. Because of its acidity, inexpensive, noncorrosive and nonpollution, Zr(SO4)2-4H2O has been extensively used in a variety of organic reactions. First part, an efficient and convenient method for the preparation of 1,1-diacetates from aldehydes catalyzed by Zr(SO4)2-4H2O/SiO2 has been presented. The present method is better than conventional counterparts because it has such merits as short reaction time, high yield and easy to control. What must be mentioned is that aldehyde is selectively protected when ketone is present in the reaction. Secondly part, the Zr(SO4)2'4H2O/Si02 is used to catalyze the deprotection of 1,1-diacetates. In this reaction 1,1-diacetates transform into corresponding aldehydes in good to high yield. In convenient method, the reaction was catalyst by H2SO4 or HC1, but the two catalysts both have their drawbacks such as corrosion, effluent pollution, non-recoverable and low yields. With catalyzed by Zr(SO4)2'4H2O/SiO2 we have found this method has the merits of short reaction time, high yields and easy to control.In the second chapter, Solid superacids are used to catalyst the synthesis of N-sulfonylimines. In this reaction aldehydes with P/Toluenesulfonamide or benzene sulfonamide are transformed into corresponding N-sulfonylimines in good to high yield. We mainly study the procedure for synthesis of N-sulfonylimines catalyzed by ZrO2/S2082- under microwave irradiation or by TiO2/SO42- through conventional method. As a result, both methods have the merits of short reaction time, good yields and easy to control.In the third chapter, a rapid and efficient method for the synthesis of coumarins from phenols with ethyl acetoacetate or methyl acetoacetate is described in the presence of zirconium sulfate tetrahydrate-silica gel under microwave irradiation. The work-up of the reaction is very simple, high yields, short reaction times and recyclable and environment-friendly catalyst.