Synthesis and Investigation of Ring-chain Isomerism of the Derivatives of N-Amino-5-hydroxy-1,2,3-triazole-4-carboxylic Acid

Abstract

A series of sodium salts of 4-substituted 1-amino-5-hydroxy-1,2,3-triazoles was obtained by the “diazo transfer” reaction to arylmethylene-protected α-ethoxycarbonyl- and α-(methylcarbamoyl)-acetohydrazides. In DMSO solution the corresponding neutral hydroxytriazoles exist in equilibrium with the isomeric diazo compounds with an open chain. Electron-donating substituents stabilize the cyclic form. A good correlation was obtained between the equilibrium constants and the Hammett σ-constants. During the diazotization of benzaldehyde α-amino-α-cyanoacetylhydrazone the initially formed diazo compound undergoes spontaneous cyclization in solution to hydroxytriazole. Removal of the arylmethylene protection leads to N-unsubstituted sodium salts of 1-amino-5-hydroxytriazoles, but acidification of the latter leads to diazoacetohydrazides with an open chain.