Synthesis, characterisation, theoretical nmr calculations and crystal structure of the 3-methyl-1h-1,2,44-triazole-5-amine acetate

Abstract

A reação de condensação entre bicarbonato de aminoguanidina com ácidos carboxílicos levou à formação de 3-metil-1S-1,2,4-triazol-5-amine (mta), 3-metil-1H-1,2,44-triazole-5-amine acetato (Hmta) e 3-fenil-1H-1,2,4-triazole-5-amine (pta). O composto N-(3-metil-1S-1,2,4-triazole-5-yl)propan-2-imine (mpta) foi obtido reagindo a mta com acetona, após uma tentativa de purificar mta neste solvente. O excesso de ácido acético obteve o Hmta durante a preparação do mta. Esses compostos foram caracterizados por espectroscopia infravermelha e multinuclear de NMR (1H e 13C), microanálise e ponto de fusão. Para investigar a formação de possíveis conformações tautoméricas de mta, pta e mpta em solução, utilizou-se uma abordagem teórica para calcular as mudanças químicas do carbono 13, com base nos valores do tensor de blindagem magnética (NMR) pelos métodos MPn e DFT. O ensaio biológico dos triazoles mta, pta e mpta contra Staphylococcus aureus, Bacillus subtilis, Escherichia colie Salmonella typhimuriumnão mostrou atividade na maior concentração utilizada no experimento.

The condensation reaction between aminoguanidine bicarbonate with carboxylic acids led to the formation of 3-methyl-1H-1,2,4-triazole-5-amine (mta), 3-methyl-1H-1,2,4l4-triazole-5-amine acetate (Hmta) and 3-phenyl-1H-1,2,4-triazole-5-amine (pta). The compound N-(3-methyl-1H-1,2,4-triazole-5-yl)propan-2-imine (mpta) was obtained by reacting the mta with acetone, upon an attempt of purifying mta in this solvent. The excess of acetic acid obtained the Hmta during the preparation of mta. These compounds were characterised by infrared and multinuclear NMR (1H and 13C) spectroscopy, microanalysis, and melting point. To investigate the formation of possible tautomeric conformations of mta, pta and mpta in solution, a theoretical approach was used to calculate the chemical shifts of carbon 13, based on the values of magnetic shielding tensor (NMR) by MPn and DFT methods. The biological assay of the triazoles mta, pta and mpta against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhimurium showed no activity at the highest concentration used in the experiment.