ABSTRACT

The solubility values of pyrazinamide, isoniazid, and p-aminobenzoic acid in buffers (pH 2.0 and 7.4) and octanol were measured in the temperature range of 293.15 to 313.15 K. The dissolution Gibbs energy, enthalpy, and entropy were calculated. The dissolving process was endothermic and enthalpydetermined. The activity coefficients of the compounds at infinite dilution were determined based on the solubility data and thermophysical parameters. A positive deviation from the ideality was observed in all the solutions. A common tendency of the solubility increase with a decrease in the activity coefficients at T = 298.15 K was revealed for the investigated solute-solvent systems. The excess thermodynamic solubility functions were calculated from the temperature dependences of the activity coefficients. The solvation processes were found to have a considerable influence on the solubility of the substances in solutions studied.

Compounds

#	Formula	Name
1	C5H5N3O	pyrazinecarboxamide
2	C6H7N3O	isonicotinic acid hydrazide
3	C7H7NO2	4-aminobenzoic acid
4	C8H18O	octan-1-ol

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 Air at 1 atmosphere	DSC	1
POMD	1	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	2	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	3	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	3	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	1 4	Mole fraction - 1 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 1	Spectrophotometer	5
POMD	2 4	Mole fraction - 2 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 2	Spectrophotometer	5
POMD	4 3	Mole fraction - 3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 3	Spectrophotometer	5

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Solution thermodynamics of pyrazinamide, isoniazid, and p-aminobenzoic acid in buffers and octanol

Blokhina, S. V.[Svetlana V.], Olkhovich, M. V.[Marina V.], Sharapova, A. V.[Angelica V.], Volkova, T. V.[Tatyana V.], Perlovich, G. L.[German L.]

ABSTRACT