| Popis: |
Preparation and characterization of strong neutral organic bases has been a subject matter of considerable interest in recent years. This is not surprising, since strong neutral bases have some important advantages over their ionic counterparts. They require milder reaction conditions and enable reactions to be carried out in homogeneous environment. Special attention in these studies has been devoted to acyclic and cyclic guanidines, biguanidines, vinamidines and phosphazenes. In this talk an overview of our recent studies in guanidine chemistry aiming at developing potent basic catalysts, will be presented. The following issues will be addressed:(a) synthesis and structure elucidation of guanidine bases capable of forming multiple intramolecular hydrogen bonds ; (b) exploration of catalytic activity of some of these bases in selected reactions, like transesterification, Knoevenagel and nitroaldol reaction and (c) synthesis and structure elucidation of new triguanide derivatives. Experimental data will be complemented by calculation of the gas phase proton affinities and pKa values in acetonitrile. |
