Thermal behaviour of 1,2,4-triazole and 1,2,4-triazine derivatives

Process of thermal decomposition and stability of the methyl esters of 3-(2-pyridyl)-4-phenyl-1,2,4-triazol-5-carboxylic acid (I), 3-(2-pyridyl)-4-(4-methyl-phenyl)-1,2,4-triazol-5-carboxylic acid (II), 3-(2-pyridyl)-4-(4-methyl-phenyl)-5-oxo-1,2,4-triazine-6-acetic acid (III) and 3-(2-pyridyl)-4-phenyl-5-oxo-1,2,4-triazine-6-acetic acid (IV) were studied. The compounds are stable up to fusion point. Next they decompose in several overlapping stages. Among the decomposition products CO2, H2O, NH3 and CH3OH molecules are presented. When kept in air under atmospheric pressure at temperature over the range of 20-80 degrees C and relative humidity over the range of 50-90% the esters do not change their structure and composition.