Thermodynamic properties of benzotriazole derivatives: An experimental and computational study

• Published in: The Journal of chemical thermodynamics 2023-11, Vol.186, p.107140, Article 107140
• Main Authors: Silva, Ana L.R., Lima, Ana C.M.O., Ribeiro da Silva, Maria D.M.C.
• Format: Article
• Language: English
• Subjects: Benzotriazole derivatives; Enthalpic increment; Enthalpy of formation; Enthalpy of sublimation; G3(MP2)//B3LYP method; Gibbs energy of formation; Vapour pressures
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/j.jct.2023.107140

[Display omitted] •Combustion enthalpy of methyl-benzotriazoles derived by combustion calorimetry.•Sublimation study by Calvet microcalorimetry and Knudsen effusion method.•Thermodynamic stability studied in the crystalline and gaseous phases.•Energetic effects associated with the presence of a methyl group were assessed.•Gas enthalpies and entropies of formation were obtained by computational chemistry. A thermochemical study of 5-methyl-1H-benzotriazole and 5,6-dimethyl-1H-benzotriazole was carried out experimentally using calorimetric techniques and an effusion method. Parallel to that, a computational methodology was also applied. The massic energies of combustion and the enthalpies of sublimation were determined from static bomb combustion calorimetry and Knudsen mass-loss effusion method and/or high-temperature Calvet microcalorimetry, respectively. From these experimental data, the standard molar enthalpies of formation of the two benzotriazoles in the gaseous phase were derived. Additionally, the gas-phase enthalpies of formation of these benzotriazoles and other two methylated derivatives were calculated using the G3(MP2)//B3LYP level of theory. The data obtained allowed the study of the energetic effects associated with the presence of a methyl group in the benzotriazole structure and their comparison with identical effects in homocyclic molecules, namely benzene and naphthalene. The Gibbs energies of formation of the compounds in the crystalline and gaseous phases were also determined to assess their thermodynamic stability.