Study of the basicity of some 1,2-diazinium ylids

In this paper we present a study concerning the basicity of some new carban ion monosubstituted pyridazinium, 3-methyl-pyridazinium, 3-(p-halogenopheny l)-pyridazinium and phtalazinium ylids. The pk, values of the conjugated ac ids (salts) of ylids have been experimentaly determinated. Consequently, we have evaluated their basicity (kb) using the titration curves. The basicit y depends mainly on the structure of the ylids carbanion itself, however th e heterocycle's structures also has some influence on bacisity. Having in v iew the basicity, we have established certain correlations between basicity , structure and stability of the analised ylids.