ABSTRACT

The heat capacities of 4-methylbiphenyl and 4-tert-butylbiphenyl were measured by vacuum adiabatic calorimetry over the temperature range from (8 to 372) K. The temperatures and changes of the enthalpy and entropy of the phase transitions have been determined. The saturation vapour pressures of the biphenyl derivatives were measured by the dynamic transpiration method over the temperature and pressure intervals from (301 to 362) K and (0.09 to 69.5) Pa, respectively. The enthalpies of vaporisation and sublimation at T = 298.15 K were derived. The standard thermodynamic functions (changes of the entropy, enthalpy, and Gibbs free energy) were obtained for the crystal and liquid states for the temperature intervals studied and for the ideal gas state at T = 298.15 K. The ideal gas entropies of the compounds under study were also calculated by the principle of additivity and the correlation equations of TRC data series of NIST. The entropy values derived from the experimental and calculated data agree within (1 to 1.3) % that supports their reliability.

Compounds

#	Formula	Name
1	C13H12	4-methylbiphenyl
2	C16H18	4-(1,1-dimethylethyl)-1,1'-biphenyl

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	Constraint	Phase	Method	#Points
POMD	1	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Gas	Adiabatic calorimetry	1
POMD	1	Triple point temperature, K ; Crystal			Crystal Liquid Gas	Adiabatic calorimetry	1
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Crystal 2	Temperature, K; Crystal 2	Pressure, kPa; Crystal 2	Crystal 2	Vacuum adiabatic calorimetry	315
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Crystal 1	Temperature, K; Crystal 1	Pressure, kPa; Crystal 1	Crystal 1	Vacuum adiabatic calorimetry	33
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	94
POMD	1	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid		Liquid Gas	Transpiration method	14
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Gas	Adiabatic calorimetry	1
POMD	2	Triple point temperature, K ; Crystal			Crystal Liquid Gas	Adiabatic calorimetry	1
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Vacuum adiabatic calorimetry	327
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	54
POMD	2	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal		Crystal Gas	Transpiration method	16
POMD	2	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid		Liquid Gas	Transpiration method	30

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

The heat capacities and thermodynamic functions of 4-methylbiphenyl and 4-tert-butylbiphenyl

Varushchenko, R. M., Efimova, A. A., Druzhinina, A. I., Tkachenko, E. S., Nesterov, I. A., Nesterova, T. N., Verevkin, S. P.

ABSTRACT