ABSTRACT

The solubility of theobromine, theophylline, and caffeine in water and five organic solvents including methanol, ethanol, 1-propanol, ethyl acetate, and acetone was determined by a high performance liquid chromatography method at T = (288.15 to 328.15) K and atmospheric pressure. It was found that the solubility of theobromine, theophylline, and caffeine in these solvents increased with increasing temperature. The empirical Apelblat equation and universal quasichemical model were used to correlate the experimental solubility. The results showed that both models can satisfactorily correlate the solubility data. The crystal forms of the solutes in equilibrium with the saturated solution were analyzed using scanning electron microscopy and powder X-ray diffraction.

Compounds

#	Formula	Name
1	C7H8N4O2	1H-purine-2,6-dione, 3,7-dihydro-3,7-dimethyl-
2	C7H8N4O2	3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione
3	C8H10N4O2	caffeine
4	C14H10O2	1,2-diphenylethanedione
5	C2H3N	acetonitrile
6	CH4O	methanol
7	C2H6O	ethanol
8	C3H8O	propan-1-ol
9	C4H8O2	ethyl acetate
10	C3H6O	acetone
11	H2O	water

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	2	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	3	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	4 10	Mole fraction - 4 ; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal - 4	Chromatography	1
POMD	4 5	Mole fraction - 4 ; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal - 4	Chromatography	1
POMD	1 11	Mole fraction - 1 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 1	Chromatography	5
POMD	1 6	Mole fraction - 1 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 1	Chromatography	5
POMD	1 7	Mole fraction - 1 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 1	Chromatography	5
POMD	1 8	Mole fraction - 1 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 1	Chromatography	5
POMD	2 11	Mole fraction - 2 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 1	Chromatography	5
POMD	2 6	Mole fraction - 2 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 2	Chromatography	5
POMD	2 7	Mole fraction - 2 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 2	Chromatography	5
POMD	2 8	Mole fraction - 2 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 2	Chromatography	5
POMD	1 9	Mole fraction - 1 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 1	Chromatography	5
POMD	1 10	Mole fraction - 1 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 1	Chromatography	5
POMD	2 9	Mole fraction - 2 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 2	Chromatography	5
POMD	2 10	Mole fraction - 2 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 2	Chromatography	5
POMD	3 11	Mole fraction - 3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 1	Chromatography	5
POMD	3 7	Mole fraction - 3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 3	Chromatography	5
POMD	3 6	Mole fraction - 3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 3	Chromatography	5
POMD	3 8	Mole fraction - 3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 3	Chromatography	5
POMD	3 9	Mole fraction - 3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 3	Chromatography	5
POMD	3 10	Mole fraction - 3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid Crystal - 3	Chromatography	5

Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

Measurement and Correlation of Solubility of Theobromine, Theophylline, and Caffeine in Water and Organic Solvents at Various Temperatures

Zhong, J.[Jialun], Tang, N.[Ning], Asadzadeh, B.[Behnaz], Yan, W.[Weidong]

ABSTRACT