Energetic studies of urea derivatives: Standard molar enthalpy of formation of 3,4,4′-trichlorocarbanilide

• Published in: The Journal of chemical thermodynamics 2010-04, Vol.42 (4), p.536-544
• Main Authors: Ribeiro da Silva, Maria das Dores M.C., Ribeiro da Silva, Manuel A.V., Freitas, Vera L.S., Roux, Maria Victoria, Jiménez, Pilar, Dávalos, Juan Z., Cabildo, Pilar, Claramunt, Rosa M., Pinilla, Elena, Rosario Torres, M., Elguero, José
• Format: Article
• Language: English
• Subjects: 3,4,4′-Trichlorocarbanilide; Biological and medical sciences; Calvet microcalorimetry; Chemical thermodynamics; Chemistry; Combustion calorimetry; Elements, mineral and organic compounds; Enthalpy of combustion; Enthalpy of sublimation; Exact sciences and technology; General and physical chemistry; General pharmacology; Heat capacities; Medical sciences; Pharmacology. Drug treatments; Phase transitions; Physicochemical properties. Structure-activity relationships; TCC; Thermodynamic properties; Trichlorocarban; X-ray crystallography
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/j.jct.2009.11.012

Thermochemical and thermophysical studies have been carried out for crystalline 3,4,4′-trichlorocarbanilide. The standard ( p° = 0.1 MPa) molar enthalpy of formation, at T = 298.15 K, for the crystalline 3,4,4′-trichlorocarbanilide (TCC) was experimentally determined using rotating-bomb combustion calorimetry, as −(234.6 ± 8.3) kJ · mol −1. The standard enthalpy of sublimation, at the reference temperature of 298.15 K, was measured by the vacuum drop microcalorimetric technique, using a High Temperature Calvet Microcalorimeter as (182.1 ± 1.7) kJ · mol −1. These two thermochemical parameters yielded the standard molar enthalpy of formation of the studied compound, in the gaseous phase, at T = 298.15 K, as −(52.5 ± 8.5) kJ · mol −1. This parameter was also calculated by computational thermochemistry at M05-2X/6-311++G∗∗ and B3LYP/6-311++G(3df, 2p) levels, with a deviation less than 4.5 kJ · mol −1 from experimental value. Moreover, the thermophysical study was made by differential scanning calorimetry, DSC, over the temperature interval between T = 263 K and its onset fusion temperature, T = (527.5 ± 0.4) K. A solid–solid phase transition was found at T = (428 ± 1) K, with the enthalpy of transition of (6.1 ± 0.1) kJ · mol −1. The X-ray crystal structure of TCC was determined and the three-centred N–H⋯O C hydrogen bonds present analyzed.