Morphology and crystallinity of the two diastereomer racemates of triglycidyl isocyanurate (TGIC)

Triglycidyl isocyanurate [2451-62-9] is a trifunctional monomer containing epoxy groups, and is presently used mainly for cross-linking carboxyl-functional polyester resins in powder coatings. There are three chiral carbon atoms in its molecule, and due to its symmetrical structure four antipodes exist according to the configuration of the chiral carbon atoms; namely RRR, SSS, RRS and SSR. Therefore the synthesized or commercially available TGIC is a physical mixture of two diastereomer racemates, i.e. beta-TGIC or RRR/SSS and alpha-TGIC or RRS/SSR. The physical and chemical properties of the two diastereomer racemates of TGIC are different. Their morphology and crystalline structure have been determined by polarizing microscopy and X-ray diffraction analysis. Beta-TGIC has hexagonal symmetry and belongs to the space group R3 or R3m. The cell parameters are: a₀ = 14.037 Å, c₀ = 11.55 Å, and cell volume: V₀ = 1970.88 Å³. Alpha-TGIC has orthorhombic crystallinity and belongs to the space group Pna2₁. Its cell parameters are: a₀ = 9.29 Å, b₀ = 9.48 Å, c₀ = 15.66 Å and cell volume: V₀ = 1379.16 Å³.     

Diastereomeric 2-aminomethyl-1,4-benzodioxane mandelates: phase diagrams and resolution

The diastereomeric salts of (R)- and (S)-2-aminomethyl-1,4-benzodioxane with unichiral mandelic acid form a simple eutectic, whose binary phase melting point diagram shows the unique eutectic at 0.35 M ratio of the less soluble diastereomer. Such an eutectic composition, near to 0.5, is consistent with the modest efficiency previously reported for their separation via crystallization from ethanol/ethyl acetate. However, the ternary solubility phase diagram, obtained from solubility measurements in methanol, shifts the eutectic to a lower molar ratio (0.10) of the less soluble diastereomer, thus indicating an optimal resolvability of the diastereomeric mandelates. This was confirmed by the highly efficient resolution of racemic 2-aminomethyl-1,4-benzodioxane with (R)-mandelic acid via a single crystallization from methanol. The ready availability of both the racemic substrate and the resolving acid makes this simple and efficient resolution procedure very attractive to obtain the enantiomers of 2-aminomethyl-1,4-benzodioxane, which are important synthetic intermediates.     

Solubility of AlPO4 in cryolite melts

The solubility of aluminium orthophosphate in cryolite melts was determined. Part of the binary phase diagram of the system Na₃AlF₆-AlPO₄ was investigated. The eutectic point was determined to be at 43.7 mass% (or 57.2 mol%) AlPO₄ and (696 ± 1) °C. It is suggested that in pure molten cryolite melts the orthophosphate ion dissociates partly into a metaphosphate ion and an oxide ion.     

High pressure phase equilibria in methane + waxy systems. 2. Methane + waxy ternary mixture

Liquid–vapour and fluid–solid phase transitions were experimentally determined under pressure on the system methane + a ternary waxy mixture using a full visibility cell. The wax was an approximately equimolar mixture of n-C₁₆, n-C₁₇ and n-C₁₈, the composition being chosen to obtain a mixture with an average molecular weight similar to heptadecane. Measurements were performed according to the synthetic method on different mixtures ranging from 0 to 99.5 mol% of methane. The liquid–solid phase transitions were investigated up to 100 MPa and fluid phase boundary was studied in the temperature domain from 293 to 373 K. Measurements performed on this pseudo-binary system were compared to the phase diagram of the binary system methane + heptadecane.     

Prediction and experimental determination of the binary and ternary phase diagrams of (±)medetomidine hydrochloride

The binary phase diagram of medetomidine hydrochloride was determined based on thermogravimetric differential thermal (TGA/DTA) measurements. The binary phase diagram presented a eutectic point in the 19:81 [(R)/(S)] composition and the ternary phase diagram in the presence of 2-propanol showed a eutectic point in the 75:25 [(S)/(R)] composition, both characterizing the product as a racemic compound forming system. The solubility of enantiomeric mixtures in 2-propanol was measured at 10, 20 and 30 °C. The ideal solubility curves of the mixtures were calculated and the activity coefficients derived. A semi-empirical thermodynamic model UNIversal QUAsi-Chemical (UNIQUAC) was used to predict the solubility of various compositions of enantiomers at different temperatures. There was good agreement between the experimental solubility data of medetomidine hydrochloride and the results obtained from the UNIQUAC equation.     

Revised Phase Diagram of the System NaF–NaBF4

Summary. The phase diagram of the binary system NaF–NaBF₄ was determined using the thermal analysis method. Subsequent coupled analysis of the thermodynamic and phase diagram data was carried out to calculate the thermodynamically consistent phase diagram. The system NaF–NaBF₄ forms a simple eutectic phase diagram with the calculated coordinates of the eutectic point: 8.1 mol% NaF, 91.9 mol% NaBF₄, and 385.7°C. The probable inaccuracy in the calculated binary phase diagram is 9°C.     

The solid-liquid phase diagrams of binary mixtures of even saturated fatty alcohols

This study is part of a work developed in the author's research group on the solid-liquid equilibrium of fatty substances. The phase diagrams of the following fatty alcohol systems were determined by differential scanning calorimetry (DSC): 1-octanol + 1-dodecanol, 1-octanol + 1-tetradecanol, 1-decanol + 1-tetradecanol, 1-decanol + 1-hexadecanol and 1-dodecanol + 1-octadecanol. The liquidus lines of three of these systems were previously reported in the literature but the other two systems were never published. Moreover other transitions, in addition to the eutectic temperature, were also detected in all the systems. A region of solid solution at the extreme left of the phase diagrams was observed for all the binary mixtures. Polarized light microscopy was used to complement the characterization of the systems for a full grasp of the phase diagrams. The solid-liquid equilibrium was modeled using the Margules 2-suffix, Margules 3-suffix, NRTL and UNIFAC Dortmund equations.     

Solid-liquid interfacial energy for solid succinonitrile in equilibrium with succinonitrile dichlorobenzene eutectic liquid

The equilibrated grain boundary groove shapes for solid succinonitrile (SCN) in equilibrium with the succinonitrile (SCN) dichlorobenzene (DCB) eutectic liquid were directly observed. From the observed grain boundary groove shapes, the Gibbs-Thomson coefficient and solid-liquid interfacial energy for solid SCN in equilibrium with the SCN DCB eutectic liquid have been determined to be (5.43 ± 0.27) × 10⁻⁸ K m and (7.95 ± 0.80) × 10⁻³ J m⁻² with present numerical method and Gibbs-Thomson equation, respectively. The grain boundary energy of SCN rich phase of the SCN DCB eutectic system has been determined to be (14.77 ± 1.77) × 10⁻³ J m⁻² from the observed grain boundary groove shapes. Thermal conductivity of eutectic solid phase and eutectic liquid phase at the eutectic melting temperature have also been measured to be 0.269 and 0.231 W/K m, respectively.     

Solid–liquid equilibria of acenaphthene with o-, m-, or p-dichlorobenzene

A differential scanning calorimetry (DSC) was used to determine binary solid–liquid equilibria (SLE) for acenaphthene  + o-dichlorobenzene, +m-dichlorobenzene, and +p-dichlorobenzene over the whole concentration range. It was found that all systems are simple eutectic systems. The eutectic point of the (acenaphthene + o-dichlorobenzene) system is at 254.95 K and 0.0334 mole fraction of acenaphthene, that of the (acenaphthene + m-dichlorobenzene) system at 246.15 K and 0.0460 mole fraction of acenaphthene and that of the (acenaphthene + p-dichlorobenzene) system at 307.75 K and 0.2940 mole fraction of acenaphthene. Furthermore, the activity coefficients of the components in the binary mixtures have been correlated by the Scatchard–Hildebrand expression with one adjustable parameter. This approach offers a useful procedure for estimating with good accuracy.     

Phase Diagram of the NaNO<Subscript>2</Subscript>—KNO<Subscript>3</Subscript> System in the 0 to 1 Molar Fraction Range of Concentrations of KNO<Subscript>3</Subscript>

The temperature dependence of the phase composition of KNO₃—NaNO₂ mixtures in the 0 to 1 molar fraction range of concentrations of KNO₃ is investigated. A phase diagram of the KNO₃—NaNO₂ binary system in the range of concentrations from 0 to 1 molar fractions of KNO₃ is drawn on the basis of DTA results. The composition of the eutectic mixture and its melting temperature is determined experimentally.     

Attempts to explain the self-disproportionation observed in the partial sublimation of enantiomerically enriched carboxylic acids

The partial sublimation of two carboxylic acids, the mandelic acid and ibuprofen has been studied. Many (RS) + (S) samples with various enantiomeric excesses (ee) have been slowly and partially sublimed at a low temperature and the sublimates have been condensed before analysis. About 1% of the starting material was sublimed in each experiment. The results are reproducible showing that the sublimation is under control. The ee of sublimates are comparable to the ee of the eutectic but also to those obtained by mixing the sublimates of two apparatuses used to sublime separately the racemate and the enantiomer. Thus, the sublimations of both carboxylic acids could be controlled by the saturated vapor pressure of the components ((RS) and (S)) or, as usually proposed, by the formation of a gas phase with a eutectic composition. In the case of mandelic acid, a definitive answer has been given by the partial sublimation of (S) + (R) solid mixtures where sublimates with a eutectic composition have been obtained and without any indication of the sublimation of a “kinetic conglomerate”. This study paves the way for future investigations on the slow and partial sublimation of enantioenriched compounds to determine how this latter occurs.     

Thermodynamic studies of mixtures for topical anesthesia: Lidocaine–salol binary phase diagram

The lidocaine–salol binary system has been investigated by differential scanning calorimetry, direct visual observations, and X-ray powder diffraction, resulting in a temperature-composition phase diagram with a eutectic equilibrium. The eutectic mixture, found at 0.423 ± 0.007 lidocaine mole-fraction, melts at 18.2 ± 0.5 °C with an enthalpy of 17.3 ± 0.5 kJ mol^?1. This indicates that the liquid phase around the eutectic composition is stable at room temperature. Moreover, the undercooled liquid mixture does not easily crystallize. The present binary mixture exhibits eutectic behavior similar to the prilocaine–lidocaine mixture in the widely used EMLA^® topical anesthetic preparation.     

Influence of size and shape effects on the high-pressure solubility of n-alkanes: Experimental data, correlation and prediction

(Solid + liquid) phase equilibria (SLE) of (n-hexadecane, or n-octadecane + 3-methylpentane, or 2,2-dimethylbutane, or benzene) at very high pressures up to about 1.0 GPa have been investigated at the temperature range from T = (293 to 353) K. The thermostated apparatus for the measurements of transition pressures from the liquid to the solid state in two component isothermal solutions was used. The pressure-temperature-composition relation of the high pressure (solid + liquid) phase equilibria, polynomial based on the general solubility equation at atmospheric pressure was satisfactorily used. Additionally, the SLE of binary systems (n-hexadecane, or n-octadecane + 3-methylpentane, or 2,2-dimethylbutane, or benzene, or n-hexane or cyclohexane) at normal pressure was discussed. The results at high pressures were compared for every system to these at normal pressure. The influence of the size and shape effects on the solubility at 0.1 MPa and high pressure up to 600 MPa was discussed.The main aim of this work was to predict the mixture behaviour using only pure components data and cubic equation of state in the wide range of pressures, far above the pressure range which cubic equations of state are normally applied to. The fluid phase behaviour is described by the corrected SRK-EOS and the van der Waals one fluid mixing rules.     

Phase equilibria involved in extractive distillation of dipropyl ether + 1-propyl alcohol using 2-ethoxyethanol as entrainer

Consistent vapour–liquid equilibrium data at 101.3 kPa have been determined for the ternary system dipropyl ether + 1-propyl alcohol + 2-ethoxyethanol and two constituent binary systems: dipropyl ether + 2-ethoxyethanol and 1-propyl alcohol + 2-ethoxyethanol. The dipropyl ether + 2-ethoxyethanol system shows positive deviations from ideal behaviour and 1-propyl alcohol + 2-ethoxyethanol system exhibits no deviation from ideal behaviour. The activity coefficients and the boiling points were correlated with their compositions by the Wilson, NRTL and UNIQUAC equations. It is shown that the models allow a very good prediction of the phase equilibria of the ternary system using the pertinent parameters of the binary systems. The parameters obtained from binary data were utilized to predict the phase behaviour of the ternary system. The results showed a good agreement with the experimental values. Moreover, the entrainer capabilities of 2-ethoxyethanol were compared with 1-pentanol, butyl propionate and N,N-dimethylformamide, concluding that N,N-dimethylformamide is the best entrainer.     

Study on the effect of increasing the chain length of the alkanol in excess molar enthalpies of mixtures containing 2-methoxy-2-methylpropane, 1-alkanol,decane

Excess molar enthalpies for the ternary system {x₁ 2-methoxy-2-methylpropane + x₂ ethanol + (1 − x₁ − x₂) decane} and the involved binary mixture {x ethanol + (1 − x) decane} have been measured at the temperature of 298.15 K and atmospheric pressure, over the whole composition range. No experimental excess enthalpy values were found in the currently available literature for the ternary mixture under study. The results were fitted by means of different variable-degree polynomials. Smooth representations of the results are presented and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. The excess molar enthalpies for the binary and ternary system are positive over the whole range of composition. The binary mixture {x ethanol + (1 − x) decane} is asymmetric, with its maximum displace toward a high mole fraction of decane. The ternary contribution is also positive, and the representation is asymmetric.     

Modeling the thermodynamic and transport properties of decahydronaphthalene/propane mixtures: Phase equilibria, density, and viscosity

The density and viscosity of propane mixed with 66/34 trans/cis-decahydronaphthalene were measured over a wide range of temperatures (323-423 K), pressures (2.5-208 bar), and compositions (0-65 mol% propane). For conditions giving two phases, the composition of the dense phase was measured in addition to the density and viscosity. The modified Sanchez-Lacombe Equation of State (MSLEOS) was used with a single linearly temperature-dependent pseudo-binary interaction parameter to correlate the phase compositions and densities. The compositions and densities of the mixtures were captured well with absolute average deviations between the model and the data of 5.3% and 2.3%, respectively. The mixture viscosities were computed from a free volume model (FVM) by using a single constant binary interaction parameter. Density predictions from the MSLEOS were used as input mixture density values required for the FVM. The FVM was found to correlate well with the mixture viscosity data with an absolute average deviation between the model and the data of 5.7%.     

Phase equilibria in the CdI2-Ag2Se system

The phase diagram of the system CdI₂-Ag₂Se is studied by means of X-ray diffraction, differential thermal analysis and measurements of the density of the material. The unit cell parameters of the intermediate phase 2CdI₂·3Ag₂Se were determined a = 0.6387 Å, b = 4.311 Å, c = 4.044 Å; α = 113.72°, β = 90.27° and γ = 94.85°. The intermediate phase 2CdI₂·3Ag₂Se has a polymorphic transition at 125 °C. It melts incongruently at 660 °C.     

Thermal analysis of binary liquid crystals eutectic system cholesteril p-phenoxi phenyl carbamate–cholesteril p-biphenyl carbamate

For a binary mixture of two liquid crystals, cholesteril p-phenoxi phenyl carbamate and cholesteril p-biphenyl carbamate, the solidus?Cliquidus equilibrium was investigated using differential scanning calorimetry (DSC) and the thermodynamic parameters were obtained. Simple eutectic point was observed for this system, situated approximately at the same temperature for all the studied compositions. This behavior is favored by grinding and is more evident in the composition 50:50. The excess functions G ^E and S ^E for the pre-, post-, and eutectic composition have been calculated using the phase diagram data. Comparing the experimental data with the existing theoretical data, the system deviation from the ideal behavior is observed. The structure of pure compounds was elucidated using FT-IR and hot-stage polarizing microscopy.