Evaluation of sublimation enthalpy by thermogravimetry: Analysis of the diffusion effects in the case of methyl and phenyl substituted hydantoins

Ramos, Fernando M.; Ledo, J. Manuel; Flores, Henoc; Camarillo, E. Adriana; Carvente, Jaime; Amador, M. Patricia

doi:10.1016/j.tca.2017.06.024

Cited by 40 publications

(42 citation statements)

References 95 publications

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“…In each experiment, a sample (10-15) mg of 1MH was used, which was subjected to a heating of 10 K•min −1 from room temperature to 500 K with a gas nitrogen flow of 100 K•min −1 . The usefulness and practicality of this technique to calculate enthalpies of vaporization was reported in a previous work [19].…”

Section: Thermogravimetric Analysismentioning

confidence: 87%

“…The description of the technique, as well as its practical applicability, are widely described in our previous work [19]. Table 2 compiles the physicochemical properties obtained by DSC from four experiments, where the uncertainty corresponds to the expanded one, which was calculated considering a t-student distribution with a coverage factor of k = 2.45 and a confidence level of 0.95.…”

Section: Physicochemical Properties By Dscmentioning

confidence: 99%

“…For example, El-Sayed [16] reported the enthalpies of combustion and formation of hydantoin; Silva et al [17] described a comprehensive computational and experimental energy study on hydantoin and 2-thiohydantoin. Recently, our research group has carried out thermochemical studies on the enthalpies of sublimation and enthalpies of formation in the condensed and gas phase of 5-methylhydantoin, 5-methyl-5-phenylhydantoin, and 5,5-diphenylhydantoin [18,19]. Nogueira et al [20] conducted a study on the spectroscopic characterization and thermal behavior of 1-methylhydantoin.…”

Section: Introductionmentioning

confidence: 99%

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Thermochemical Study of 1-Methylhydantoin

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Using static bomb combustion calorimetry, the combustion energy of 1-methylhydantoin was obtained, from which the standard molar enthalpy of formation of the crystalline phase at T = 298.15 K of the compound studied was calculated. Through thermogravimetry, mass loss rates were measured as a function of temperature, from which the enthalpy of vaporization was calculated. Additionally, some properties of fusion were determined by differential scanning calorimetry, such as enthalpy and temperature. Adding the enthalpy of fusion to the enthalpy of vaporization, the enthalpy of sublimation of the compound was obtained at T = 298.15 K. By combining the enthalpy of formation of the compound in crystalline phase with its enthalpy of sublimation, the respective standard molar enthalpy of formation in the gas phase was calculated. On the other hand, the results obtained in the present work were compared with those of other derivatives of hydantoin, with which the effect of the change of some substituents in the base heterocyclic ring was evaluated.

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Section: Thermogravimetric Analysismentioning

confidence: 87%

Section: Physicochemical Properties By Dscmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermochemical Study of 1-Methylhydantoin

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“…By combining the Clausius-Clapeyron equation with the Langmuir equation, it is possible to calculate the standard molar enthalpy of vaporization/sublimation, using Equation (5) given above. In the Equation ( 5), B = ln(DMS/R) + C, where the diffusion phenomena were considered [50,51]. This equation is used to realize both, isothermal and dynamic experiments and it is not necessary to determine the vapour pressure directly, only a thermogravimetric device is needed to measure with accuracy and precision the mass loss rate as a function of the temperature of the study compounds.…”

Section: Thermogravimetrymentioning

confidence: 99%

“…(2) The recovered substance was analysed by DSC and in both cases, for each compound (NCB and DAB) there was no difference in the melting thermograms. Details about the device, calibrations, and testing were recently reported [51].…”

Section: Thermogravimetrymentioning

confidence: 99%

A Promising Thermodynamic Study of Hole Transport Materials to Develop Solar Cells: 1,3-Bis(N-carbazolyl)benzene and 1,4-Bis(diphenylamino)benzene

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The thermochemical study of the 1,3-bis(N-carbazolyl)benzene (NCB) and 1,4-bis(diphenylamino)benzene (DAB) involved the combination of combustion calorimetric (CC) and thermogravimetric techniques. The molar heat capacities over the temperature range of (274.15 to 332.15) K, as well as the melting temperatures and enthalpies of fusion were measured for both compounds by differential scanning calorimetry (DSC). The standard molar enthalpies of formation in the crystalline phase were calculated from the values of combustion energy, which in turn were measured using a semi-micro combustion calorimeter. From the thermogravimetric analysis (TGA), the rate of mass loss as a function of the temperature was measured, which was then correlated with Langmuir’s equation to derive the vaporization enthalpies for both compounds. From the combination of experimental thermodynamic parameters, it was possible to derive the enthalpy of formation in the gaseous state of each of the title compounds. This parameter was also estimated from computational studies using the G3MP2B3 composite method. To prove the identity of the compounds, the 1H and 13C spectra were determined by nuclear magnetic resonance (NMR), and the Raman spectra of the study compounds of this work were obtained.

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