La solubilité mutuelle des liquides sous pression variable

Timmermans, Jean

doi:10.1051/jcp/1922200491

Cited by 50 publications

(10 citation statements)

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“…Since it turns out that the singular part of ap.x, of the system isobutyric acid/water is negative (ap,xc --(T -T,)-"; 0 5 a 5 0.1) [19] it can be predicted that dP/dTJcRs should be negative for this system. This prediction is in agreement with experiments of Timmennans [20] (s. Table 6). The critical temperature of the system isobutyric acid/water is lowered with increasing pressure.…”

Section: Temperature Dependence Of Coefffcid Of Thermal Expansion Neasupporting

confidence: 92%

Specific heat of binary liquid mixtures near the critical mixing point

Klein

Woermann

1975

Ber Bunsenges Phys Chem

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The temperature dependence of specific heat cp,,, at constant pressure P of mixtures of critical composition x, of the systems methanol/ n-heptan and isobutyric acid/water is measured in an isothermal Calvet calorimeter. Near the critical mixing temperature T,(T > T,) the temperature dependence of cp.,, of both systems can be represented by a logarithmic singularity to a good approximation, i.e. cP,,=t i -" ; I: = ( T -TJT; 0 I a I 0.1. The values of excess specific heat near T, calculated from the Fixman theory are in satisfactory agreement with the experimental data.Measurements of the temperature dependence of coefficient of thermal expansion aP,,-of the system isobutyric acidjwater show that diverges weakly. The critical exponent of ap,,c has the same value as that of specific heat within the accuracy of the experiments (0 I a I 0.1 ). This is in agreement with postulates of Griffiths and Wheeler. The singular part of ap,,c of the system isobutyric acid/water is negative (a,,,rc --c -" ) . From this observation and theoretical considerations of Griffiths and Wheeler it can be predicted that the critical temperature of the system isobutyric acid/water should decrease with increasing pressure. This is in agreement with experimental data reported in the literature. Die Temperaturabhingigkeit der spezifischen Warme von Mischungen kritischer Zusammensetzung xe bei konstantem Druck P der Systeme Methanol/n-Heptan und Isobuttersaure/Wasser werden in einem isothermen Calvet-Kalorimeter untersucht. In der Nahe dcr kritischen Entmischungstemperatur T,(T > T,) la& sich die Temperaturabhangigkeit von cp,xc beider Systeme in guter Niherung durch eine logarithmische Singularitat beschreiben, das heiOt cP,,=c-"; c = (T -T,)/T,; 0 I a < 0.1. Die Werte der Zusatz-spezifischen Warme in der Nihe von x, die nach der Theorie von Fixman berechnet werden, sind in befriedigender ubereinstimmung mit den experimentellen Daten. Messungen der Temperaturabhangigkeit des thermischen Ausdehnungskoeffizienten aP,*< des Systems Isobutterslure/Wasser zeigen, daD up schwach divergiert. Der kritische Exponent von ap,,, hat innerhalb der MeDgenauigkeit den gleichen Wert wie der der spezifischen Wirme (0 I a I 0.1). Das ist in Ubereinstimmung mit Postulaten von Grilfiths und Wheeler. Der singulare Anteil von ap,,, des Systems J. H. Hildebrand (1953) r31 J. H. Hildebrand (1953) r31 J. H. Hildebrand (1959) r41 ( 1969) r 51 C. J. Pings (1972) [71 R. D. Gambhir, B. Viswanathan. 0 I a I 0.1 and E. S. R. Gopal (1971) [61 K. Govindarajan, and E. S. R. Gopal (1973) P I 0 = critical exponent.

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Section: Temperature Dependence Of Coefffcid Of Thermal Expansion Neasupporting

confidence: 92%

Specific heat of binary liquid mixtures near the critical mixing point

Klein

Woermann

1975

Ber Bunsenges Phys Chem

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“…Acrolein (C 3 H 4 O), or 2-propenal, was chosen as the blind test target for category (1). Acrolein melts at $186 K (Timmermans, 1922), so crystal growth was performed at 178 K in situ by laser-assisted zone refinement Summary of conformational treatment of molecule (XIV) and approach taken for generating cocrystal structures for (XV).…”

Section: Experimental Structuresmentioning

confidence: 99%

Significant progress in predicting the crystal structures of small organic molecules – a report on the fourth blind test

Day

Cooper

Cruz‐Cabeza

et al. 2009

Acta Crystallogr B Struct Sci

396

319

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We report on the organization and outcome of the fourth blind test of crystal structure prediction, an international collaborative project organized to evaluate the present state in computational methods of predicting the crystal structures of small organic molecules. There were 14 research groups which took part, using a variety of methods to generate and rank the most likely crystal structures for four target systems: three single-component crystal structures and a 1:1 cocrystal. Participants were challenged to predict the crystal structures of the four systems, given only their molecular diagrams, while the recently determined but as-yet unpublished crystal structures were withheld by an independent referee. Three predictions were allowed for each system. The results demonstrate a dramatic improvement in rates of success over previous blind tests; in total, there were 13 successful predictions and, for each of the four targets, at least two groups correctly predicted the observed crystal structure. The successes include one participating group who correctly predicted all four crystal structures as their first ranked choice, albeit at a considerable computational expense. The results reflect important improvements in modelling methods and suggest that, at least for the small and fairly rigid types of molecules included in this blind test, such calculations can be constructively applied to help understand crystallization and polymorphism of organic molecules.

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“…The name "piezometric" was proposed by TIMMERMANS [4] to describe the method for the determination of phase equilibria in which the substance is maintaiiied at a constant temperature while the volume of the system is slowly increased and the resulting pressures are observed. During a phase transition the pressure remains constant because the change in volume of the substance compensates Tor the change in volume in the system.…”

Section: Piezometrjc Methodsmentioning

confidence: 99%

“…(3) Honorary Professor of Physical Chemistly and Director of the Bureau des Etalons, Universite Libre de Bruxelles. (4) Numbers in brackets refer to literature references at the end o f this paper. dichloroacetic acids were studied at pressures to 5000 atmospheres.…”

Section: Introductionmentioning

confidence: 99%

Polymorphism in Monobromoacetic Acid and the Diagram of State of Dichloroacetic Acid at Elevated Pressures

Glasgow

Timmermans

1961

Bulletin des Soc Chimique

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Piezometric measurements to 5000 atmospheres have shown that dichloroacetic acid occurs in only one crystalline form; monobromoacetic acid exists in three forms with triple points at about 50.5OC and 120 kg/cm2 (liq, C I, C If) and 53OC and 260 kg/cni2 (liq, C 11, C 111). The transitions C I to C I T and C II to C I11 have negative temperature-pressure coefficients (dT,/dP) and occur only at elevated pressures. No example h a been previously reported of an organic compound which has two successive solid transitions with negative dTjdP coefficients such as were observed for monbromoacetic acid.Values of dTidP, AH, and AS, calculated from the piezometric data are given for the fusion of dichloroacetic acid and for the two solid transitions and the fusion (C TI[, liq) of monobronioacetic acid. An evaluation of purity of the acids from time-pressure data is discussed.

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La solubilité mutuelle des liquides sous pression variable

Cited by 50 publications

References 2 publications

Specific heat of binary liquid mixtures near the critical mixing point

Specific heat of binary liquid mixtures near the critical mixing point

Significant progress in predicting the crystal structures of small organic molecules – a report on the fourth blind test

Polymorphism in Monobromoacetic Acid and the Diagram of State of Dichloroacetic Acid at Elevated Pressures

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