Ternary systems phase diagrams

Ternary System Phase Diagram Determinations Concerning Potassium Electrolyte Influence on Aqueous Solutions of Dioxane or T etrahy drof uran... 

Figure 11.2-11/, for the liquid-liquid phase equilibrium behavior of liquid carbon dioxide with pairs of other liquids, has been included to illustrate the variety of types of ternary system phase diagrams the chemist and engineer may encounter. Complete discussions of these different types of phase diagrams are given in numerous places (including A. W. Francis, Liquid-Liquid Equilibriums, John V Tley Sons, New York, 1963). 

Effenberg, G. and Ilyenko, S. (ed.) (2004) Landolt-Bornstein, Numerical Data and Functional Relationships in Science and Technology, Physical-Chemistry. Ternary Alloy Systems Phase Diagrams, Crystallographic and Thermodynamic Data. Critically evaluated byMSIT (Springer Verlag, Berlin). 

More complex situations were shown in Figs. 2.26 and 2.27, where some typical examples of isobarothermal sections of ternary alloy phase diagrams were presented. In the case of ternary systems, several binary and ternary stoichiometric (Fig. 2.28) phases and/or different types of variable composition phases (Fig. 2.29) may be found. We may differentiate between these phases by using terms such as point compounds (or point phases, that is, phases represented in the composition triangle, or more generally in the composition simplex by points), Tine phases , field phases , etc. 

To understand why solution experiments sometimes fail to produce cocrystal products, and why solvent-drop grinding experiments can work when performed on the same system, the 1 1 cocrystal formed by nicotinamide and frans-cinnamic acid (frans-(2E)-3-phenylacrylic acid) has been studied [56]. In this work ternary isothermal phase diagrams of the cocrystal system was used to understand the crystallization phenomena, and to deduce methodologies and for the experimental design of cocrystal preparation. Cocrystals are most likely to form from solutions in which the two reactants have similar degrees of solubility, and the success of solvent-drop grinding was explained in that crystallization took place in the region of low solvent mole fractions where the cocrystal would be more stable relative to the separated reactants. 

Figure 2-34. Calculated ternary CVD phase diagram for the Y-Ba-Cu-C-O-H system at a temperature of 877 °C, a total pressure of 760Torr, and an oxygen partial pressure of 750Torr. The contours represent iso-yields of the tetragonal 123 phase with the numerical legends given as molar percentages 123 versus other phases. (From Vahlas and Besmann [213].)...

Rag] Raghavan, V., The C-Fe-P (Carbon-Iron-Phosphorous) System , Phase Diagrams of Ternary Iron Alloys. Part 3 Ternary Systems Containing Iron and Phosphorous, Indian Institute of Metals, 3, 33-44 (1988) (Phase Diagram, Phase Relations, Review, 22)... 

Here there is shown a typical ternary liquid-phase diagram for a Type 1 system, with an heterogeneous area MKPLN and a typical tie line KL,... 

For a ternary system, the diagram is one-dimensional with a triple criticed (tricritical) point which separates the three-phase region from the two-phzise ones with double criticed points (Figure 3.100a see also Figures 3.93 and 3.94). The location of the tricritical point r2,tc = r (pi) depends on pi, varying from r 15.645 for p = 1 to r 9.899 for pi oo (Tompa, 1949 Sole et al., 1984). 

A. Bondar, 2006. Boron-Chromium-Nickel, in G. Effenberg, ve S. Ilyenko (Eds.), Ternary Alloy System Phase Diagrams, Crystallographic and Thermodynamic Data VolllDl, 320-343. 

However, often the phase diagrams required are not known in particular for new substances in the fine chemical and pharmaceutical fields. Even more hard to find are ternary solubility phase diagrams that describe equilibria of two substances in a solvent such as the target compound and an impurity in a solvent of choice or the two enantiomers of a chiral system in a solvent. Often one faces a lack of consistent solubility data for the substance of interest. Experimental determination of solubilities is a tedious and time-consuming work and requires a sufficient amount of substance that is often not available in an early stage of development. Also, usually a combination of different analytical techniques is necessary to obtain both the solubility and the identity of the solid phase in equilibrium. 

Impurities can also affect the solubility of a solute of interest. Here, both a solubility enhancement and a solubility decrease occur. When electrolytes are involved, the terms salting-in and salting-out apply. Small impurity contents might be evaluated together with the solvent. In presence of higher impurity contents or in cases where the impurity is readily available in sufficient amounts, it should be considered as a third component in the system. Then, SLE data in the ternary system of the target compound, the impurity, and the solvent/solvent mixture have to be measured and instead of a binary a ternary (solubility) phase diagram applies. The representation and application of ternary SLE will be addressed in Section 3.3.7 on the example of enantiomers. 

Figure 3.29 presents the relation between the binary melt phase diagrams and an isothermal slice of the ternary solubility phase diagrams (introduced in Section 3.1.4). Since the two enantiomers of a chiral system have same melting points and melting enthalpies, their melt phase diagrams are symmetrical to the 1 1 (i.e., racemic) composition. The same applies to the solubility diagrams of the enantiomers as shown in Figure 3.29. Therefore, in general only one haF of the phase diagram has to be measured.

What is not considered here is partial miscibility in solid state also occurring in chiral systems. How this is represented in a ternary solubility phase diagram is shown in Section 7.2. 

Figure 3.30 Ternary solubility phase diagrams solubilities in the threonine/water system, only of the threonine and mandelic acid (MA) the upper part of the phase diagram is depicted...

Boon, J.A., Carlin, R.T., Elias, A.M. and V lkes, J.S., Dialkylimidazolium-sodium chloroaluminate ternary salt system - phase-diagram and crystal-structure, J. Chem. Crystallogr. 25 (2), 57-62 (1995). 

However, in many ternary systems, all compounds have a degree of solubility in both phases (Figure 3.3.35). Typically, such ternary triangular phase diagrams are characterized by two liquid pairs that are completely miscible in all proportions, for example, water-ethanol and ethanol-benzene (Figure 3.3.35a), or by two pairs that are only partially miscible, for example, heptane-aniline and aniline-methylcyclo-hexane (Figure 3.3.35b). 

The ternary solubility phase diagram of (S) - and (R) - propranolol hydrochloride in a mixed solvent of methanol and acetone was measured by isothermal method [25]. For isothermal method, enough amount of powder, namely lOfttO.lmg, was dissolved in the solvent of methanol in a test tube. Saturated solution samples were carefully withdrawn and filtered, and the concentration of which were analyzed by the HPLC system with employment of above-mentioned self-packed column. 

FIGURE 56.15. Ternary solubility phase diagram of racemic-compound-forming system. 

FIGURE 56.18. Ternary solubility phase diagrams of racemic compound-forming systems (a) racemic compound forms solvate, (b) enantiomers form solvate, and (c) both enantiomers and racemic compound form solvates. 

Crystallization is widely used for chiral purification. Development of such a crystallization method involves determination of racemate type, solvent screening, temperature selection, and definition of system composition. Construction of a ternary solubility phase diagram is instrumental during this process. However, constmcting phase diagrams in different solvents at various temperatures is time consuming and requires a large quantity of compound. Perhaps... 

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