Synthesis of and complexation studies with polyaminopolycarboxylic acid crown ethers

Abstract

This thesis deals with the synthesis of and complexation studies withpolyamino polycarboxylic acid crown ethers, the crown diamine 71, the crown tetraamine 78, the crown diaminetetraacetic acid 79 and the crown tetraaminehexaacetic acid 82. The thesis consists of three sections, namely, introduction, results and discussion and experimental The results and discussion is divided into two parts Part-1 deals with the synthesis of the ligands 71, 78, 79 and 82. Part-2 deals with the determination of the dissociation constants of 71, 79 and 82 and the stability constants of these ligands with different metal ions. The introductory chapter is divided into two sections. The first section presents a brief survey of some of the salient features of crown ether chemistry. In the second section the synthesis of polyaminopolycarboxylic acid chelating agents of medicinal interest, both diagnostic and therapeutic, are covered. A brief survey of their utility in medicine is also included Multidentate polyamino crown ethers 71 and 78 were synthesized in high yields starting from easily available pentaerythritol 2. Utilising the compounds 71 and 78, we prepared the target crown diaminetetraacetic acid 79 and the crown tetraaminehexaacetic acid 82. The general methods of Nalkylation of 71 and 78 with bromoacetic acid as well as with ethyl bromoacetate followed by hydrolysis of the respective ethyl esters 80 and 83 to obtain 79 and 82 in pure form were unsuccessful Finally, the polyaminopolycarboxylic acid crown ethers 79 and 82 were obtained in pure form, by alkylating 71 and 78 with benzyl bromoacetate followed by hydrogenolysis of the respective benzyl esters 81 and 84. Attempts at the synthesis of multiloop spiro crown ethers 85, 87 and 89 were however unsuccessful.