Studies on the application of modified phase transfer catalysts in organic synthesis

Abstract

INTRODUCTION This thesis reports the studies carried out in the development of new reagents with wide applicability in synthetic organic synthesis. Phase transfer catalysts are usually the quaternary ammonium, phosphonium, arsonium salts with a wide variety of solubility characteristics. Phase transfer catalysts have been used extensively for the carrying out reactions in biphasic conditions. The use of phase transfer catalysts in organic synthesis has been elaborately discussed in several research manuscripts and text books. Another aspect of the phase transfer catalysts is the ease with which the anions can be either exchanged or modified. The modified phase transfer catalysts or rather the modified quaternary ammonium compounds have been extensively studied for their use as the reagents themselves for carrying out a variety of organic transformations especially oxidation, reduction and hydrolytic reactions. In this thesis a report on a unique procedure for the chemical modification of the easily available quaternary ammonium bromides to the bromates is reported and experiments have been carried out using these bromates as mild and efficient oxidizing agents. Metal bromates are known to have good oxidizing characteristic as bourne out by the oxidation potential of several bromates in aqueous medium. However these metal bromates are seldom used as oxidizing agents because of two important reasons. They are insoluble in most organic solvents which is necessary for carrying out organic transformations and because their explosive proclivities. In this thesis is reported a simple procedure for transforming several tetraalkylammonium bromides to the apparently more useful bromates. The quaternary ammonium bromates have the two fold advantage of being soluble in water as well as in organic solvents further the reported explosive nature of the bromates have not been observed. This thesis is consists of six chapters and the abstract of each chapter is given as under. CHAPTER I In this chapter, a review of the various...