As. Shawali et al., Synthesis, acidity constants and tautomeric structure of 7-arylhydrazono[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines in ground and excited states, J CHIN CHEM, 48(1), 2001, pp. 65-72
7-Arylhydrazono[1,2,4]triazolo[3,4-b] [1,3,4]thiadiazines 4 were synthesize
d from the reactions of 4-amino-5-phenyl-4H-[1,2,4]triazole-3-thiol 2 and 2
-(2-naphthyl)-2-oxoethanehydrazonoyl bromides 1 and their acid dissociation
constants pK and pK*, in the ground and excited states, respectively, were
determined. Both pK and pK* constants were correlated by Hammett equation.
The pK and the spectral data presented indicate that the title compounds e
xist predominantly in the hydrazone tautomeric form.