Květoslav Růžička

Simultaneous Treatment of Vapor Pressures and Related Thermal Data Between the Triple and Normal Boiling Temperatures for n‐Alkanes C5–C20

Experimental vapor pressures, calorimetric enthalpies of vaporization and differences between the heat capacities of the ideal gas and the liquid for n‐alkanes C5 to C20 between the triple and normal boiling temperatures have been treated simultaneously. Attention was focused particularly on the region of low pressures where vapor pressure data are scarce and subject to important systematic errors. The reliability and consistency of data fro different sources was evaluated and the three parameter Cox equation was used to correlate simultaneously as a function of temperature the selected values of different properties. The recommended vapor pressures and thermal data resulting from this procedure are mutually consistent over the homologous series and present a considerable refinement particularly at lower pressures.

High temperature enthalpy and heat capacity of GaN

The heat capacity and the heat content of gallium nitride were measured by calvet calorimetry (320–570 K) and by drop calorimetry (670–1270 K), respectively. The temperature dependence of the heat capacity in the form Cpm = 49.552+5.440× 10 −3 T − 2.190× 10 6 T −2 + 2.460× 10 8 T −3 was derived by the least squares method. Furthermore, thermodynamic functions calculated on the basis of our experimental results and literature data on the molar entropy and the heat of formation of GaN are given.

Recommended vapour and sublimation pressures and related thermal data for chlorobenzenes

Abstract Recommended data on vapour pressures are presented for all dichlorobenzenes, all trichlorobenzenes, and pentachlorobenzene in the temperature range from the triple point up to the normal boiling point. For some chlorobenzenes where reliable sublimation pressures and solid heat capacities are available (1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,3,5-trichlorobenzene, and pentachlorobenzene), recommended sublimation pressures are also given that cover the range from about −40°C (with the exception of 1,4-dichlorobenzene where there are no experimental sublimation pressures below the phase transition at −1.38°C) up to the triple point temperature. The data were developed by a simultaneous multi-property correlation of vapour or sublimation pressures and the related thermal data (heat capacities in the liquid or the solid phase, heat capacities of the ideal gas, enthalpies of vaporisation or sublimation). The data are presented as parameters of the Cox correlation equation which has an identical form for description of vapour–solid (v–s) and vapour–liquid (v–l) equilibria and are consistent at the triple point. Recommendations are based mostly on new experimental vapour and sublimation pressures obtained recently by the authors. Solid and liquid heat capacities required for the simultaneous correlation were provided by merging new experimental data measured using a C80 Setaram heat conduction calorimeter over approximate temperature range from 30 to 160°C (depending on the compound) with the data critically selected from the literature.

Vapor pressures and thermal data for three high-boiling compounds of petroleum interest: 1-phenyldodecane, (5α)-cholestane, adamantane

Abstract Vapor pressures above liquid and solid phases and enthalpies of vaporization and sublimation were established in a wide temperature range for three hydrocarbons that are among the model compounds for higher boiling petroleum fractions and coal liquids. The recommended values were obtained by combining the data from vapor pressure measurements with the calorimetric measurements of heat capacities and heats of fusion, and with additional data on ideal gas heat capacities. The recommended values are given for both the vapor–solid (v–s) and vapor–liquid (v–l) equilibria in terms of the parameters of the Cox vapor pressure equation allowing calculations from 223 to 623, 533 and 583 K for 1-phenyldodecane, adamantane and (5α)-cholestane, respectively.

Vapor pressure of metal organic precursors

The vapour pressure of four metal organic precursors, diethylzinc, triethylantimony, trimethylgallium and trimethylaluminium, used in the metal organic vapor phase epitaxy processes was measured by a static method in the technologically important temperature range from 238 to 293 K. The experimental data were fitted by the Antoine equation and represent updated values of the present day high-purity materials providing comparison with the previously published data.

Heat capacities of some phthalate esters

Isobaric heat capacities Cp in the liquid phase of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, bis(2-ethylhexyl) phthalate, and benzyl butyl phthalate were measured by commercial SETARAM heat conduction calorimeters. Results obtained cover the following temperature range: dimethyl phthalate 283 to 323 K, diethyl phthalate 306 to 370 K, dibutyl phthalate 313 to 447 K, bis(2-ethylhexyl) phthalate from 313 to 462 K, benzyl butyl phthalate from 313 to 383 K. The heat capacity data obtained in this work were merged with available experimental data from literature, critically assessed and sets of recommended data were developed by correlating selected data as a function of temperature.

CCSD(T)/CBS fragment-based calculations of lattice energy of molecular crystals.

A comparative study of the lattice energy calculations for a data set of 25 molecular crystals is performed using an additive scheme based on the individual energies of up to four-body interactions calculated using the coupled clusters with iterative treatment of single and double excitations and perturbative triples correction (CCSD(T)) with an estimated complete basis set (CBS) description. The CCSD(T)/CBS values on lattice energies are used to estimate sublimation enthalpies which are compared with critically assessed and thermodynamically consistent experimental values. The average absolute percentage deviation of calculated sublimation enthalpies from experimental values amounts to 13% (corresponding to 4.8 kJ mol(-1) on absolute scale) with unbiased distribution of positive to negative deviations. As pair interaction energies present a dominant contribution to the lattice energy and CCSD(T)/CBS calculations still remain computationally costly, benchmark calculations of pair interaction energies defined by crystal parameters involving 17 levels of theory, including recently developed methods with local and explicit treatment of electronic correlation, such as LCC and LCC-F12, are also presented. Locally and explicitly correlated methods are found to be computationally effective and reliable methods enabling the application of fragment-based methods for larger systems.

Intramolecularly coordinated gallium sulfides: Suitable single source precursors for GaS thin films

Our studies have been focused on the synthesis of N→Ga coordinated organogallium sulfides [L1 Ga(μ-S)]3 (1) and [L2 Ga(μ-S)]2 (2) containing either N,C,N- or C,N-chelating ligands L1 or L2 (L1 is {2,6-(Me2 NCH2 )2 C6 H3 }- and L2 is {2-(Et2 NCH2 )-4,6-tBu2 -C6 H2 }- ). As the result of the different ligands, compounds 1 and 2 differ mutually in their structure. To change the Ga/S ratio, unusually N→Ga coordinated organogallium tetrasulfide L1 Ga(κ2 -S4 ) (3) was prepared and the unprecedented complex [{2-[CH{(CH2 )3 CH3 }(μ-OH)]-6-CH2 NMe2 }C6 H3 ]GaS (4) was also isolated as the minor by-product of the reaction. Compounds 1-3 were further studied as potential single-source precursors for amorphous GaS thin film deposition by spin-coating.

Single‐Crystal‐to‐Single‐Crystal Transition in an Enantiopure [7]Helquat Salt: The First Observation of a Reversible Phase Transition in a Helicene‐Like Compound

Here it is reported that crystals of an enantiopure [7]helquat salt undergo reversible thermal solid-solid phase transition at 404 K. Differential scanning calorimetry (DSC), capillary electrophoresis (CE), and X-ray diffraction analysis were used to unravel the mechanistic details of this process. The single-crystal-to-single-crystal course enabled direct monitoring of the structural changes by in situ variable-temperature X-ray diffraction, thus providing the first direct evidence of a solid phase transition in a helicene-like compound.

CHAPTER 17:Calculation of Thermodynamic Functions from Volumetric Properties

Volumetric properties are key inputs in calculations of thermodynamic properties of real fluids as they give information about the variation of the thermodynamic properties with pressure or density at constant temperature. In this chapter, a rational way of calculating thermodynamic quantities, including partial molar quantities based on volumetric properties, is presented. Finally, empirical rules are discussed which enable one to use state-of-the-art equations of state for each component of a given mixture. Some of these rules have rarely been reported in the literature.