Synthesis and Tautomeric Structure of 3,6-bis(arylazo)pyrazolo [1,5-a]pyrimidine-5,7(4H,6H)-diones

Abstract

Two series of 3,6- bis(arylazo)pyrazolo[1,5- a]pyrimidine-5,7-diones were prepared, and their acid dissociation constant pKas were determined and correlated with the Hammett equation. The results of these correlations, together with the spectroscopic data, indicated that the title compounds exist predominantly in the 3-arylazo-6-arylhydrazonopyrazolo[1,5- a]pyrimidine-5,7-dione tautomeric form, both in the solid and solution phases.