Origin of Substituent Effect on Tautomeric Behavior of 1,2,4-Triazole Derivatives: Combined Spectroscopic and Theoretical Study.

The reaction of 2-aryl-[1,2,4]triazolo[1,5-c]quinazolines with nucleophilic reagents (hydrazine hydrate, sodium hydroxide, sodium methoxide, hydrochloric acid) under acidic conditions leads to formation of compounds that tend to tautomerize. The products of the transformation are distinguished by the position (ortho-, meta-, para-) of the OCH group in the aryl moiety. To assign their structures we used the combined approach: experiment and theoretical modeling.