Studies On The Organic Synthesis Reactions Catalyzed By Solid Acids And Structural Analysis

This thesis consists of three parts.In the first part, solid superacid ZrO2/SO42- is found to be cheap solid acidic catalyst for many organic reactions, it has much more efficient behavior in catalysis and work-up than conventional counterparts. An efficient and convenient method for preparation of 2,2-disubstituted and 2-monosubstituted 1,3-benzodioxoles from ketones and aldehydes with catechol catalysed by ZrO2/SO42- has been presented. The present methods have the additional advantages of non-corrosivity, mild reaction conditions, high yield and selectivity, easy of set-up and work-up over the classical methods.In the second part, dihydropyrimidines are prepared by a one-pot cyclocondensation of aldehydes, p-ketoesters and urea with aminosulfonic acid and p-toluenesulfonic acid-catalyzed condensation reaction. They have been the focus of considerable due to their therapeutic and pharmacological properties. Excellent yields with short reaction time, non-side reaction, non-corrosive and easy experimental and product isolation procedures make this an important alternation to traditional Biginelli catalyst.In the third part, transesterification of β-ketoesters with alcohols catalyzed by Montmorillonite K-10 in good yields. β-Ketoesters are of interest as chemical intermediates in the pharmaceutical, agrichemical, chemical and polymer industries, it is well known that traditional acidic catalysts such as sulfuric acid, phosphoric acid and hydrochloric acid can cause severe environmental problems. The obvious advantages of the catalyst are easy and simple operation in the workup, inexpensive, non-toxic, non-corrosive, recyclable, more economical and environmental.