ABSTRACT

The standard molar enthalpies of vaporization of alkyl-pyrazoles were derived from their vapor pressure-temperature dependence measured by the transpiration method as well as indirectly using solution calorimetry. Thermodynamic data on vaporization processes available in the literature were collected, evaluated, and combined with our own experimental results. Additional combustion experiments on the highly pure 1-methyl-pyrazoles helped to resolve ambiguity in the enthalpy of formation for this compound. We have evaluated and recommended a set of vaporization and formation enthalpies for the alkyl-pyrazoles at 298.15 K as the reliable benchmark properties for further thermochemical calculations. Gas phase molar enthalpies of formation of alkyl-pyrazoles calculated by the high-level quantum-chemical G4 and G3MP2 methods were in an excellent agreement with the recommended experimental data. The hydrogenation/dehydrogenation reaction enthalpies of alkyl-pyrazoles were calculated and compared with the data for other potential liquid organic hydrogen carriers.

Compounds

#	Formula	Name
1	CO2	carbon dioxide
2	N2	nitrogen
3	H2O	water
4	O2	oxygen
5	C3H4N2	1H-pyrazole
6	C4H6N2	1-methyl-1H-pyrazole
7	C5H8N2	1-ethylpyrazole
8	C4H6N2	3-methylpyrazole
9	C4H6N2	4-methylpyrazole
10	C5H8N2	3,5-dimethylpyrazole
11	C6H10N2	1,3,5-trimethylpyrazole
12	C10H10N2	1-benzylpyrazole
13	C9H8N2	1-phenylpyrazole
14	C7H6N2	1,2-diazaindene
15	C4H8O	tetrahydrofuran

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Phase	Method	#Points
POMD	5	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Transpiration method	11
POMD	6	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Transpiration method	22
POMD	7	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Transpiration method	18
POMD	7	Boiling temperature at pressure P, K ; Liquid	Pressure, kPa; Liquid	Liquid Gas	Distillation	1
POMD	8	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Transpiration method	11
POMD	9	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Transpiration method	10
POMD	10	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	10	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	10	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Transpiration method	17
POMD	11	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	11	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	11	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Transpiration method	14
POMD	11	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Transpiration method	13
POMD	12	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Transpiration method	15
POMD	12	Boiling temperature at pressure P, K ; Liquid	Pressure, kPa; Liquid	Liquid Gas	Distillation	1
POMD	13	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Transpiration method	14
POMD	14	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Transpiration method	17
POMD	15 5	Molar enthalpy of solution, kJ/mol ; Liquid	Mole fraction - 5; Liquid Temperature, K; Liquid Pressure, kPa; Liquid	Liquid	Power-compensation calorimetry	1
POMD	15 6	Molar enthalpy of solution, kJ/mol ; Liquid	Mole fraction - 6; Liquid Temperature, K; Liquid Pressure, kPa; Liquid	Liquid	Titration calorimetry	1
POMD	15 8	Molar enthalpy of solution, kJ/mol ; Liquid	Mole fraction - 8; Liquid Temperature, K; Liquid Pressure, kPa; Liquid	Liquid	Titration calorimetry	1
POMD	15 10	Molar enthalpy of solution, kJ/mol ; Liquid	Mole fraction - 10; Liquid Temperature, K; Liquid Pressure, kPa; Liquid	Liquid	Power-compensation calorimetry	1
POMD	15 11	Molar enthalpy of solution, kJ/mol ; Liquid	Mole fraction - 11; Liquid Temperature, K; Liquid Pressure, kPa; Liquid	Liquid	Power-compensation calorimetry	1
RXND	6 1 2 3 4	Specific internal energy of reaction at constant volume, J/g			Static bomb calorimetry	1

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Benchmark properties of pyrazole derivatives as a potential liquid organic hydrogen carrier: Evaluation of thermochemical data with complementary experimental and computational methods

Safronov, Sergey P., Nagrimanov, Ruslan N., Samatov, Aizat A., Emel'yanenko, Vladimir N., Zaitsau, Dzmitry H., Pimerzin, Andrey A., Skrzypczak, Andrzej, Verevkin, Sergey P.

ABSTRACT