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The solid-liquid equilibrium of the phenanthrene-fluorene system was investigated by differential thermal analysis. Supplementary measurements were applied too: crystal decay temperature examination and melting point examination with a Boetius microscope. The investigated system forms a stable solution with a minimum at 58 mole% of phenanthrene and a temperature of 95.5°.

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. Rai , RN , Rai , US . Solid–liquid equilibrium and thermochemical properties of organic eutectic in a monotectic system . Thermochim Acta . 2000 ; 363 : 23 – 28 . 10.1016/S0040-6031(00)00625-0 . 21

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Abstract  

We have studied the solid-liquid equilibrium of the system Sr1–yBayFCl1–xBrx using DTA and X-ray diffraction techniques. The entire composition range in this system yields solid solutions which crystallize in the PbFCl (Matlockite) structure type. The melting points of the entire composition range have been parametrized (within 5°C rms error) using a biquadratic fit of the available data obtained by experiment and from the literature.

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The equilibria of the naphthalene-picric acid and the 2,3- and 2,6-dimethylnaphthalene-picric acid systems were subjected to thermal investigation.

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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  

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 intersection of the two lines gives the solubility limit and the corresponding enthalpy of dissolution of the solute in the solvent. Phase diagrams have been established at 303.15 K in binary mixed solvents ethanol-water over the whole concentration range for four components of pharmaceutical interest, namely: caffeine, nicotinamide, nicotinic acid and salicylic acid.

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Abstract  

Isothermal titration calorimetry (ITC) and reaction calorimetry (RC) have been used to construct the solid-liquid equilibrium line in ternary systems containing the solute to precipitate and an aqueous mixed solvent, and to study polymerization reactions under real process conditions, respectively. Phase diagrams have been established over the whole concentration range for some benzene substituted derivatives, including o-anisaldehyde, 1,3,5-trimethoxybenzene and vanillin, in {water + alcohol}mixtures at different temperatures. Acrylamide polymerization in aqueous solution using potassium permanganate/acid oxalic redox system as initiator was investigated on a homemade calorimeter, which works according to the isoperibolic mode. A Calvet type differential RC was used to illustrate the applicability of temperature oscillation calorimetry (TOC) for the evaluation of the heat transfer coefficient during the course of reaction.

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Abstract  

Diamines are an important group of compounds in different fields of industry and particularly in the synthesis of a number of polymers. In this work, study of binary solid-liquid equilibriums SLE for (biphenyl+4,4’diaminodiphenylmethane), and (naphthalene+ 4,4’diaminodiphenylmethane) systems is done by differential scanning calorimetry.> Results obtained with this technique are compared with those predicted by modified UNIFAC (Larsen and Gmehling) models. It was found out that all the systems are eutectic and globally good agreement is obtained between experimental and predicted SLE.

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Abstract  

Trichlorofluoromethane (CCl3F) and water form clathrate hydrate which melts at 8.5 °C under atmospheric pressure. By DSC and X rays analysis we could distinguish between hydrate and ice formed in emulsion containing NaCl and show that quantity of hydrate formed and its dissociation temperature are dependent on solution concentration. The equilibrium curve hydrate-NaCl solution is displaced towards higher temperatures with respect to corresponding ice curve. Consequently solid–liquid equilibrium can not be established in presence of both solids. Growth of hydrate crystals at the expense of ice was evidenced. Role of salt in hydrate growth and ice melting is examined.

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