| Summary: | A catalyst-free highly efficient synthesis of 3(5)-amino-5(3)-(het)aryl-1,2,4-triazoles in aqueous mediumwas performed using conventional heating and microwave irradiation. The tautomerism in the productswas investigated using NMR spectroscopy and X-ray crystallography. The effects of the substitution, temperature, solvents, and concentration on the tautomerism were studied. The triazoles were found to exist in 1H-forms, the 4H-form was not observed either in solid state or in solution. In general, 5-amino-1,2,4-triazoles were electronically preferred in the tautomeric equilibrium, but some exceptions from theestablished relationship were also identified.
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