Enthalpy of formation of guanidine and its amino and nitro derivatives

Дорофеева, О. В.; Ryzhova, Oxana N.; Sinditskii, Valery P.

doi:10.1007/s11224-015-0648-y

Cited by 14 publications

(4 citation statements)

References 63 publications

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“…To calculate the gas-phase enthalpies of formation, we use the composite quantum chemical G4 method in combination with isodesmic reactions approach . In our recent publications, we have shown that the G4 method applied to atomization reaction could resulted in large errors for nitrogen containing compounds, − whereas the use of isodesmic reactions allowed us to achieve an accuracy comparable with that obtained from the experimental measurements. The same picture is observed for other composite methods: the average of CBS-QB3, CBS-APNO, G3, and G4 methods obtained for hydrazine using isodesmic reactions (97.7 ± 2.0 kJ/mol) is in close agreement with results of high-level W4, CCSD(T)-F12b, and W3X-L calculations (97.3, 97.4, and 97.5 kJ/mol, respectively), − whereas the average value calculated using atomization reactions (100.8 ± 2.0 kJ/mol) is substantially higher.…”

Section: Introductionsupporting

confidence: 77%

“…Two thiocarbohydrazides (26,27) are presented in Table 2. Two experimental values of Δ f H 298 °(cr) for 26 differ by about 20 kJ/mol.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Such differences are observed for compounds with nitro groups (17,18,33,36) and aromatic compounds containing three and four phenyl rings (20,21). As shown earlier, 26 this difference also depends on the number of NH 2 groups, and the addition of NH 2 groups somewhat compensates for the effect of NO 2 groups. Because of this, it is difficult to predict in advance how large the difference will be for different nitrogen containing compounds.…”

Section: ■ Conclusionmentioning

confidence: 99%

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Enthalpies of Formation of Hydrazine and Its Derivatives

2017

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Enthalpies of formation, ΔH, in both the gas and condensed phase, and enthalpies of sublimation or vaporization have been estimated for hydrazine, NHNH, and its 36 various derivatives using quantum chemical calculations. The composite G4 method has been used along with isodesmic reaction schemes to derive a set of self-consistent high-accuracy gas-phase enthalpies of formation. To estimate the enthalpies of sublimation and vaporization with reasonable accuracy (5-20 kJ/mol), the method of molecular electrostatic potential (MEP) has been used. The value of ΔH(NHNH,g) = 97.0 ± 3.0 kJ/mol was determined from 75 isogyric reactions involving about 50 reference species; for most of these species, the accurate ΔH(g) values are available in Active Thermochemical Tables (ATcT). The calculated value is in excellent agreement with the reported results of the most accurate models based on coupled cluster theory (97.3 kJ/mol, the average of six calculations). Thus, the difference between the values predicted by high-level theoretical calculations and the experimental value of ΔH(NHNH,g) = 95.55 ± 0.19 kJ/mol recommended in the ATcT and other comprehensive reference sources is sufficiently large and requires further investigation. Different hydrazine derivatives have been also considered in this work. For some of them, both the enthalpy of formation in the condensed phase and the enthalpy of sublimation or vaporization are available; for other compounds, experimental data for only one of these properties exist. Evidence of accuracy of experimental data for the first group of compounds was provided by the agreement with theoretical ΔH(g) value. The unknown property for the second group of compounds was predicted using the MEP model. This paper presents a systematic comparison of experimentally determined enthalpies of formation and enthalpies of sublimation or vaporization with the results of calculations. Because of relatively large uncertainty in the estimated enthalpies of sublimation, it was not always possible to evaluate the accuracy of the experimental values; however, this model allowed us to detect large errors in the experimental data, as in the case of 5,5'-hydrazinebistetrazole. The enthalpies of formation and enthalpies of sublimation or vaporization have been predicted for the first time for ten hydrazine derivatives with no experimental data. A recommended set of self-consistent experimental and calculated gas-phase enthalpies of formation of hydrazine derivatives can be used as reference ΔH(g) values to predict the enthalpies of formation of various hydrazines by means of isodesmic reactions.

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Section: Introductionsupporting

confidence: 77%

“…Two thiocarbohydrazides (26,27) are presented in Table 2. Two experimental values of Δ f H 298 °(cr) for 26 differ by about 20 kJ/mol.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Conclusionmentioning

confidence: 99%

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Enthalpies of Formation of Hydrazine and Its Derivatives

2017

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“…• (s) of guanidinium nitrate (−386.9 kJ•mol −1 ) [37], guanidine (−56.1 kJ•mol −1 ) [37], and liquid nitric acid (−174.10 kJ•mol −1 ) [24] are available in the literature. The value for ∆ r H can then be obtained from Equations ( 10) and (11).…”

Section: Computational Results For Gztmentioning

confidence: 99%

Enthalpy of Formation of the Nitrogen-Rich Salt Guanidinium 5,5′-Azotetrazolate (GZT) and a Simple Approach for Estimating the Enthalpy of Formation of Energetic C, H, N, O Salts

Silva,

León,

Ribeiro da Silva

et al. 2023

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The discrepancy between the calculated (CBS-4M/Jenkins) and experimentally determined enthalpies of formation recently reported for the 2:1 salt TKX-50 raised the important question of whether the enthalpies of formation of other 2:1 C, H, N, O salts calculated using the CBS-4M/Jenkins method are reliable values. The standard (p° = 0.1 MPa) enthalpy of formation of crystalline guanidinium 5,5′-azotetrazolate (GZT) (453.6 ± 3.2 kJ/mol) was determined experimentally using static-bomb combustion calorimetry and was found to be in good agreement with the literature’s values. However, using the CBS-4M/Jenkins method, the calculated enthalpy of formation of GZT was again in poor agreement with the experimentally determined value. The method we used recently to calculate the enthalpy of formation of TKX-50, based on the calculation of the heat of formation of the salt and of the corresponding neutral adduct, was then applied to GZT and provided excellent agreement with the experimentally determined value. Finally, in order to validate the findings, this method was also applied to predict the enthalpy of formation of a range of 1:1 and 2:1 salts (M+X− and (M+)2X2− salts, respectively), and the values obtained were comparable to experimentally determined values. The agreement using this approach was generally very good for both 1:1 and 2:1 salts; therefore, this approach provides a simple and reliable method which can be applied to calculate the enthalpy of formation of energetic C, H, N, O salts with much greater accuracy than the current, commonly used method.

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