Solid–liquid equilibrium, thermal and physicochemical studies of organic eutectics (original) (raw)
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Solid-Liquid Equilibrium and Phase Diagram of Organic System Forming Simple Eutectic
Butwal Campus Journal
The study of phase diagram guided with solid-liquid equilibrium (SLE) data at different molar composition in two component systems serve as a basic roadmap for the material synthesis, and also provide in-depth study of physicochemical and thermochemical properties of synthesized materials. The solid-liquid equilibrium data of binary organic system, acetanilide – acetamide (ACN-ACT) is determined by thaw melt method. The system exhibits simple eutectic type phase diagram at 0.20 molar composition of ACN with congruent melting temperature 52oC.
Thermoanalysis of binary condensed eutectic phases evincing molecular interactions
Journal of Thermal Analysis and Calorimetry, 2011
This article discusses the thermoanalytical model developed in the current work to study the influence of the molecular interactions between binary condensed eutectic phases in terms of excess thermodynamic functions that exhort the ability of providing quantitative idea of the interactions. Non-ideality of binary eutectic systems over the entire range of mole fraction composition is ascertained by subjecting the experimentally determined solidus-liquidus equilibrium data to thermodynamic analysis and thereby, apprehending quantitative idea about the nature of molecular interactions. The estimation of molecular interactions model of binary naphthalene-o-nitrophenol, a-naphthol-naphthalene, diphenylamine-a-naphthol, benzil-diphenyl, acenaphthene-antimonytrichloride and cadmium-bismuth eutectic systems authenticates the reliability of the excess functions, since the mixing of the eutectic phases either side of solidusliquidus equilibrium curves of the systems is found to follow the criteria of spontaneity and Planck formulation S = klnw; where S, k and w, respectively, are the configurational entropy, Boltzmann constant and complexion number of constituent phase molecules. Moreover, the Guggenheim lattice theory applied to solidus mixtures at their liquidus temperatures offers supporting evidence to the essence of the excess functions and hence the thermomolecular interactions model.
Materials Letters, 1999
The phase-diagram of the 1,2,4,5-tetrachlorobenzene-m-aminophenol system studied by the thaw-melt method shows Ž . Ž the formation of a eutectic at 120.08C 0.946 mole fraction of m-aminophenol and a monotectic at 136.08C 0.094 mole . fraction of m-aminophenol with a consolute temperature at 177.08C. The growth kinetic studies at different undercoolings Ž . DT by the capillary method give straight lines for the plots between log Õ and log DT where Õ is the rate of movement of solid-liquid interface. From the enthalpy of fusion of the pure components, the eutectic and the monotectic determined by the DSC method, different thermodynamic parameters such as enthalpy of mixing, excess thermodynamic functions and entropy of fusion were calculated. While the microstructure of the pure components give their faceted growth, the eutectic and the monotectic show their characteristic features. q
2014
Phase diagrams of the binary systems of Nicotinamid e (NA) with o-Nitroaniline (oNA), Cinnamic acid (CA ) and 2Methylimidazole (MIm) have been studied by thaw mel t method. The result infers that all these mixtures are simple eutectic in nature. Eutectics (E) of NA-oNA, NA-CA and NA-MIm are formed at 65 °C, 100 °C and 102 °C melting temperature, respectively and 0.780, 0.502 and 0.54 9 mole fraction of oNA, CA and MIm respectively. He at of fusion (∆H) of all the alloys and eutectics are also calcula ted with the help of mixture law. Thermodynamic sta bility in form of excess stability and ideal stability of the alloys of all systems are discussed in the pres ent work. It gives an idea about the stability of eutectics and non-eutec tics alloys of the systems. Interface morphology of the alloys predicts the faceted growth (α > 2) in all the cases in the light of Jackson’s surface roughness ( α) theory. The microstructures of pure components of taken binary systems having high entr...
Materials Letters, 2004
The phase diagram of p-dibromobenzene-m-aminophenol system, determined by the thaw -melt method, shows the formation of a eutectic at 86.8 jC and a monotectic at 120.0 jC at 0.9899 and 0.0496 mole fractions of p-dibromobenzene, respectively. Growth data for the pure components, the eutectic and the monotectic, determined by measuring the rate of movement of solid -liquid interface in a capillary at different undercoolings (DT) suggest the applicability of Hillig -Turnbull equation, v=u (DT) n , where u and n are constants depending on the nature of materials involved. The values of enthalpy of fusion of the pure components, the eutectic and the monotectic were determined and from these values, the enthalpy of mixing, entropy of fusion, Jackson's roughness parameter and excess thermodynamic functions were calculated. Optical microphotographs of the pure and binary materials show their characteristic features. D 2004 Published by Elsevier B.V.
Materials, 2021
Nimesulide, salicylic acid and their binary mixtures were studied by differential scanning calorimetry (DSC) and Fourier Transform Infrared spectroscopy (FTIR). The study of such systems is a promising and viable approach for solving the problem of poor solubility of materials in general and drug systems in particular. All areas of human activity are inextricably linked to materials, and thus, the study presented in the paper and not reported in the literature is very important and provides useful data for those working in various fields. The eutectic mixtures were obtained by mechanosynthesis and by recrystallization from ethanol over the entire 0–1 range of molar fractions. For both situations at the molar fraction of nimesulide 0.5, the mixture has a eutectic that suggests an increase in solubility at this composition. The interactions that take place between the components were determined with the help of the excess thermodynamic functions (GE, SE, µE), which highlight the devia...
Properties and thermal behavior of natural deep eutectic solvents
Journal of Molecular Liquids, 2016
Natural deep eutectic solvents (NADES) have shown to be promising sustainable media for a wide range of applications. Nonetheless, very limited data is available on the properties of these solvents. A more comprehensive body of data on NADES is required for a deeper understanding of these solvents at molecular level, which will undoubtedly foster the development of new applications. NADES based on choline chloride, organic acids, amino acids and sugars were prepared, and their density, thermal behavior, conductivity and polarity were assessed, for different NADES compositions. The NADES studied can be stable up to 170°C, depending on their composition. The thermal characterization revealed that all the NADES are glass formers and some, after water removal, exhibit crystallinity. The morphological characterization of the crystallizable materials was performed using polarized optical microscopy which also provided evidence of homogeneity/phase separation. The conductivity of the NADES was also assessed from 0 to 40°C. The more polar, organic acidbased NADES presented the highest conductivities. The conductivity dependence on temperature was well described by the Vogel-Fulcher-Tammann equation for some of the NADES studied.
Journal of Crystal Growth, 2000
The phase-diagram of durene±pyrogallol system, determined by the thaw-melt method, shows the formation of a eutectic at 79.68C and a monotectic at 127.78C containing 0.95 and 0.05 mol fractions of durene, respectively. Growth data for the pure components, the eutectic and the monotectic, determined by measuring the rate of movement of solid±liquid interface in a capillary at different undercoolings (DT) suggest the applicability of Hillig±Turnbull equation, v uDT n , where u and n are constants depending on the nature of materials involved. The values of enthalpy of fusion of the pure components, the eutectic and the monotectic were determined and from these values, the enthalpy of mixing, size of the critical nucleus, interfacial energy and excess thermodynamic functions were calculated. While optical microphotographs of the pure components showed a faceted microstructure, those of eutectic and monotectic show their characteristic features. #
THERMAL STABILITY OF SELECTEDDEEP EUTECTIC SOLVENTS
In this study, a new type of " green solvents " named deep eutectic solvents (DESs) has been synthesized combining hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). Choline chloride (ChCl) was chosen as typical HBA, and lactic acid, tartaric acid, citric acid and oxalic acid were chosen as HBDs. The thermal stability of deep eutectic solvents is an important parameter for their application and limits the maximum operation temperature. The thermal stability of DESs such as lactic, tartaric, citric and oxalic acid with choline chloride showed wide range of application (134.8 – 197.8°C). All DESs were observed in temperature range 25 – 400°C.