Thermal studies of analgesic active 8-aryl-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-diones

This article describes the determination of thermal stability by investigating the thermal degradation of six analgesic active derivatives of 8-aryl-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-dione (8-ATHITD). The compounds under study were characterized by TG-DSC and TG-FTIR analyses. The investigated compounds are stable at room temperature which is important for medical application. Thermogravimetric measurements in air atmosphere showed that the decomposition of compounds proceeds in the two main stages. The first mass loss steps are observed in the temperature ranges of 261-305 A degrees C and occurred together with the melting process for the majority of studied compounds. It was also noted that the para isomers are found to be more thermal stable than their ortho analogues as a consequence of a higher symmetry of compounds. Based on the obtained data from the TG-FTIR analysis, the main gaseous products resulting at thermal degradation are CO2, CO, NH3, HCN, HNCO (and its derivatives), aniline or its derivatives and carbonyl compounds.