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Abstract  

Literature data of solubility of MgSO3 in water and in aqueous solutions of MgSO4 have been correlated. Magnesium sulfite forms hexahydrate (stable below 40C) and trihydrate (above 40C), nevertheless, metastable hexahydrate can precipitate at temperatures significantly higher than this transition temperature. Magnesium sulfate increases the solubility of the sulfite.

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Abstract  

The solubilities of lanthanum oxide in LiF, NaF, KF and eutectic melt LiF-NaF-KF (46.5 mole% LiF; 11.5 mole% NaF and 42.0 mole% KF) were measured in order to find the suitable electrolyte for electrodeposition of lanthanum. Solidus-liquidus lines were obtained by the method of thermal analysis. The solubility of lanthanum oxide in alkali fluorides is rather low and decreases in the order LiF>NaF>KF. It was found that lanthanum oxide reacts with the components of the melt. LaOF and alkali metal oxide are formed during dissolution of La2O3 in the melt.

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Abstract  

The enthalpies of absorption and solubility at T=298.15 K of carbon dioxide in aqueous solutions of bis-(3-dimethylaminopropyl)amine (CAS RN: [6711-48-4]) are reported in this paper. It was observed that the saturation loading of the CO2 is α=2.9 mol CO2/mol TMBPA, which is close to the theoretical value, α0=3 mol CO2/mol TMBPA. The molar heat of absorption of CO2 is independent of the polyamine concentration of the solutions and the amount of CO2 absorbed and was calculated to be Δabs H m=–44 (2) kJ mol–1 CO2.

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Solubility diagrams in solvent-antisolvent systems by titration calorimetry

Application to some pharmaceutical compounds in water-ethanol mixtures

Journal of Thermal Analysis and Calorimetry
Authors: M. Hamedi and J. Grolier

Abstract  

Isothermal titration calorimetry (ITC) has been used to develop a method to construct the solid-liquid equilibrium line in ternary systems containing the solute to precipitate and an aqueous mixed solvent. The method consists in measuring the heat of dissolution of a solid component (the solute) during successive additions of the liquid solvent. The cumulated heat, resulting from the successive heat peaks obtained for the different injections of known volumes of solvent, plotted vs. the ratio of the numbers of moles n solvent/n solute is represented by two nearly straight lines. The intercept of the two lines gives the solubility limit and the corresponding enthalpy of dissolution of the solute in the solvent. Solubility diagrams have been established at 303.15 K in binary mixed solvents ethanol-water over the whole concentration range for seven compounds of pharmaceutical interest, namely: urea, phenylurea, l-valine, dl-valine, l-valine ethyl ester hydrochloride, tris(hydroxymethyl)amino methane.

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Abstract  

The solubility of two n-alkanes in commercial organic liquids, such as diesel fuel and jet fuel represent a problem to industry, because they precipitate in an unpredictable fashion. First we calculated the metastable enthalpy and entropy of fusion of the low temperature forms of the n-alkanes. We analyzed the solubility of alkanes n-C22H46, n-C23H48, n-C24H50 and n-C28H58 in ethylbenzene, m-xylene, n-heptane and gas oil. All systems seem to be close ideal, possibly with a slight positive deviation. We analyzed the solubility at constant temperature of the ternary system solvent C22H46-C24H50, C23H48-C24H50, C13H28-C16H34, C20H42-C22H46, C20H42-C24H50 and C20H42-C28H58, and looked at cloud points in various ternary systems. When the difference in the number of carbon atoms in the two alkanes is small, four or less, a metastable solid solution precipitates from the solvent. If the difference in the number of carbon atoms is six or more, the ‘equilibrium’ phases, or at least phases with low solubility precipitate.

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Abstract  

The solubility isotherm of the system La2O3—SeO2—H2O at 100°C was studied. The compounds of the three-component system were identified by the Schreinemakers method as well as by chemical and X-ray phase analyses. Simultaneous TG and DTA analyses of all compounds of the system were made by using a derivatograph. The mechanism of thermal decomposition was described.

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Abstract  

Temperature dependences of solubility, saturated vapour pressure and crystal heat capacity of [4-(Benzyloxy)phenyl]acetic acid were determined. The solubility of this compound was investigated in n-hexane, buffered water solutions with pH 2.0 and 7.4 and n-octanol. The enthalpy of sublimation and vaporization as well as the fusion temperature were determined. Solvation and solubility processes have been analyzed. The thermodynamics of transfer processes from one buffer to another (protonation process), from buffers to 1-octanol (partitioning process), and from n-hexane to the applied solvents (specific interaction) have been calculated and compared to those of other NSAIDs. The relevant shares of specific and non-specific interactions in the process of solvation have been investigated and discussed.

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Abstract  

The solubility of magnesium-ammonium-phosphate (struvite) has been studied employing radioisotope32P as tracer. The amount of sample in solution is determined by measuring the Cherenkov radiation due to the fast -particles emitted from this radionuclide. The themodynamic solubility product is determined at various temperatures and compared with former results.

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taurine and 10 water-soluble vitamins in multivitamin tablets. Anal. chim. Acta , 569 , 169–175. Yao S.Z. High-performance liquid chromatography/electrospray ionization

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82 125 132 Doerk, K. and Hawkes, T. , Finite Soluble Groups , Walter de Gruyter, Berlin-New York, 1992

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