Abraham model enthalpy of solvation correlations for solutes dissolved in dimethyl carbonate and diethyl carbonate

Experimental data have been compiled from the published chemical and engineering literature on the enthalpies of solvation for 80 different inorganic gases and organic vapours in diethyl carbonate and for 57 different gaseous compounds in dimethyl carbonate. The compiled data are used to derive mathematical correlations based on the Abraham solvation parameter model. The derived expressions describe the experimental solvation enthalpies in diethyl carbonate and dimethyl carbonate to within standard deviations of 2.1 and 2.7 kJ mol^?1, respectively.     

Development of Abraham model correlations for predicting enthalpies of solvation of nonionic solutes dissolved in formamide

Experimental enthalpy of solution data for 81 solutes dissolved in formamide have been compiled from the published literature and converted to enthalpies of solvation data using standard thermodynamic relationships. Abraham model correlations were derived from the compiled enthalpy of solvation data. The derived mathematical equations describe the observed experimental to within overall standard deviations of 2.3 kJ mol^?1. A principal component analysis based on the calculated equation coefficients, and the coefficients for water and 23 organic solvents previously determined, shows that formamide is both a hydrogen-bond acid and a hydrogen-bond base. Of the solvents that we have studied thus far, formamide is the closest to water in terms of enthalpies of solvation of dissolved solutes.     

Development of Abraham model correlations for enthalpies of solvation of organic solutes dissolved in 1,3-dioxolane

Published excess enthalpy of mixing data has been assembled from the chemical literature for binary mixtures containing 1,3-dioxalane. The experimental data were converted into partial molar enthalpies of solution and enthalpies of solvation for solutes dissolved in 1,3-dioxolane using standard thermodynamic relationships. The compiled enthalpy of solvation data for 59 different organic solutes was used to derive mathematical correlations based on the Abraham solvation parameter model. The derived correlations describe the experimental enthalpy of solvation data in 1,3-dioxolane to within a standard deviation of 2.0 kJ mol^?1.     

Deferiprone solubility in some non-aqueous mono-solvents at different temperatures: experimental data and thermodynamic modelling

The solubility of deferiprone (DFP) in five organic solvents including ethyl acetate, chloroform, acetonitrile, 1,4-dioxane and dichloromethane was investigated by the flask-shake method under atmospheric pressure at temperatures ranging from 293.15 to 313.15 K. In general, the solubility (mol L^–1) obeyed the following order from high to low in different mono-solvents: dichloromethane > chloroform > acetonitrile > 1,4-dioxane > ethyl acetate. The solubility of DFP in the mono-solvents increased with a rise of temperature. The solubility data were successfully correlated with the van’t Hoff equation. The generated data in this work and the previously published data were used to calculate the thermodynamic parameters of the system using the modified van’t Hoff equation, and the derived thermodynamic properties were correlated using Abraham solvation parameters.     

Development of Abraham model expressions for predicting the enthalpies of solvation of solutes dissolved in acetic acid

Experimental data have been compiled from the published chemical and engineering literature on the enthalpies of solvation for 92 different inorganic gases and organic vapours in acetic acid. The compiled data are used to derive mathematical correlations based on the Abraham solvation parameter model. The derived expressions describe the experimental solvation enthalpies in acetic acid to within a standard deviation (SD) of 2.2 kJ mol^?1. Principal Component Analysis (PCA) on the five equation coefficients from a derived Abraham model correlation shows that acetic acid does not resemble hydroxylic solvents in terms of enthalpic interactions, but is more akin to moderately polar solvents such as ethyl acetate or acetone.     

Updated Abraham model correlations for enthalpies of solvation of organic solutes dissolved in benzene and acetonitrile

A search of the published chemical and engineering literature found enthalpy of solution data for an additional 104 and 49 organic compounds dissolved in benzene and acetonitrile, respectively. Standard thermodynamic relationships were used to convert the experimental enthalpy of solution data, ΔH_solv, to enthalpies of solvation, ΔH_solv. Updated Abraham model correlations were derived for describing gas-to-benzene and gas-to-acetonitrile enthalpies of solvation by combining the 104 and 49 additional values to existing benzene and acetonitrile ΔH_solv databases. The updated Abraham model correlations for benzene and acetonitrile described the observed ΔH_solv values to within overall standard deviations of less than 3.4 kJ mol^?1.     

Dibenzofuran and methyldibenzofuran derivatives: assessment of thermochemical data

Thermochemical data of dibenzofuran, a compound of considerable industrial and environmental significance, obtained from experimental calorimetric and computational techniques are reported in this work. The enthalpy of fusion, (19.4 ± 1.0) kJ mol^?1, at the temperature of fusion, (355.52 ± 0.02) K, was determined by differential scanning calorimetry measurements of dibenzofuran. From the standard (p° = 0.1 MPa) molar enthalpies of formation of crystalline dibenzofuran, (?29.2 ± 3.8) kJ mol^?1, and of sublimation, (84.5 ± 1.0) kJ mol^?1, determined at T = 298.15 K by static bomb combustion calorimetry and by vacuum drop microcalorimetry, respectively, it was possible to calculate the enthalpy of formation of the gaseous compound, (55.0 ± 3.9) kJ mol^?1, at the same temperature. The enthalpy of formation in the gaseous phase was also determined from G3(MP2)//B3LYP calculations. The same computational strategy was employed in the calculation of the standard molar enthalpies of formation, at T = 298.15 K, in the gas-phase, of single methylated derivatives of benzofuran and dibenzofuran.     

Thermochemical and structural properties of anthraquinones

We have investigated the energetic, structural, and other physical–chemical properties (aromaticity, intrinsic strain, hydrogen bond interaction) of 1,4-anthraquinone (1), its better known isomer 9,10-anthraquinone (2) and the derivatives 9-hydroxy-1,4-anthraquinone (3) and 9-methoxy-1,4-anthraquinone (4). In particular, the standard enthalpy of formation in the gas phase at 298.15 K of 1,4-anthraquinone was determined [ $\Updelta_{\text{f}}^{{}} H_{\text{m}}^{\text{o}} \left( {{\text{g}},{\mathbf{1}}} \right) \, = \, - 4 4. 9 { } \pm { 5}. 7\;{\text{kJ}}\;{\text{mol}}^{ - 1} ]$ . Using isodesmic/homodesmotic reaction schemes, we have experimentally estimated: (i) the stabilization energy of 1 (162.2 ± 7.2 kJ mol^?1) and 2 (193.2 ± 5.2 kJ mol^?1), (ii) strength of intramolecular hydrogen bonding in 3 (HB = 79.8 ± 10.8 kJ mol^?1), and (iii) additional strain energy due to peri-oxygen interaction in 4 (?34.2 ± 7.6 kJ mol^?1). A computational study of these species, at the B3LYP/6-311++G(3df,2p) level, sheds light on structural, aromatic, intrinsic strain, or hydrogen bond effects and further confirmed the consistency of the experimental results.     

Kinetic and thermodynamic parameters of volatilization of biodiesel from babassu, palm oil and mineral diesel by thermogravimetric analysis (TG)

The boiling point and volatility are important properties for fuels, as it is for quality control of the industry of petroleum diesel and biofuels. In addition, through the volatility is possible to predict properties, such as vapor pressure, density, latent heat, heat of vaporization, viscosity, and surface tension of biodiesel. From thermogravimetry analysis it is possible to find the kinetic parameters (activation energy, pre-exponential factor, and reaction order), of thermally simulated processes, like volatilization. With the kinetic parameters, it is possible to obtain the thermodynamic parameters by mathematical formula. For the kinetic parameters, the minor values of activation energy were found for mineral diesel (E = 49.38 kJ mol^?1), followed by babassu biodiesel (E = 76.37 kJ mol^?1), and palm biodiesel (E = 87.00 kJ mol^?1). Between the two biofuels studied, the babassu biodiesel has the higher minor value of activation energy. The thermodynamics parameters of babassu biodiesel are, ΔS = ?129.12 J mol^?1 K^?1, ΔH = +80.38 kJ mol^?1 and ΔG = +142.74 kJ mol^?1. For palm biodiesel ΔS = ?119.26 J mol^?1 K^?1, ΔH = + 90.53 kJ mol^?1 and ΔG = +141.21 kJ mol^?1, and for diesel ΔS = ?131.3 J mol^?1 K^?1, ΔH = +53.29 kJ mol^?1 and ΔG = +115.13 kJ mol^?1. The kinetic thermal analysis shows that all E, ΔH, and ΔG values are positive and ΔS values are negative, consequently, all thermodynamic parameters indicate non-spontaneous processes of volatilization for all the fuels studied.     

Abraham model expressions for describing water-to-organic solvent and gas-to-organic solvent partition coefficients for solute transfer into anhydrous poly(ethylene glycol) dialkyl ether solvents at 298.15 K

Henry’s law constants and infinite dilution activity coefficients were compiled from the published chemical and engineering literature for gaseous solutes and organic liquids in butyl diglyme, butyl triglyme and tetraglyme. The published literature values were converted into water-to-liquid and gas-to-liquid partition coefficients using standard thermodynamic relationships. The calculated partition coefficients were correlated mathematically with the Abraham solvation parameter model. The derived Abraham model correlations can be used to predict the partitioning behaviour of additional solutes into dry, anhydrous butyl diglyme, butyl triglyme and tetraglyme.     

Experimental and theoretical evidence suggests carbamate intermediates play a key role in CO2 sequestration catalysed by sterically hindered amines

The chemisorption of CO₂ by aqueous-hindered amines has been investigated experimentally and theoretically. Negative-ion ESI–MS analysis of solutions containing a sterically hindered amine and a source of ¹³CO₂ reveals peaks corresponding to [M–H + 45]^?. These ions readily lose 45 Da when subjected to collisional activation, and together with other key fragments confirms the generation of the ¹³C-labelled carbamate derivatives. The thermochemistry of the two key capture reactions: $$2.{\text{amine }} + {\text{ CO}}_{ 2} { \leftrightarrows }{\text{amine}} - {\text{CO}}_{ 2}^{ - } + {\text{ amine}} - {\text{H}}^{ + } {\kern 1pt} \quad 1:{\text{carbam}}$$ $${\text{amine }} + {\text{ CO}}_{ 2} + {\text{ H}}_{ 2} {\text{O}}{ \leftrightarrows }{\text{HCO}}_{ 3}^{ - } + {\text{ amine}} - {\text{H}}^{ + } \quad 2:{\text{ bicarb}}$$ at 298 K was modelled using composite chemistry methods, CCSD(T), DFT, and SM8 free energies of solvation. The aqueous reaction free energies (ΔG ₂₉₈) for reaction 1 are predicted to be more negative than ΔG ₂₉₈ for reaction 2 when amine = ammonia, 2-aminoethanol (MEA), 2-amino-2-methyl-1-propanol (AMP), 2-amino-2-hydroxymethyl-propane-1,3-diol (tris), and 2-piperidinemethanol (2-PM). For AMP, tris, and 2-PM, activation free energies ΔG ₂₉₈ ^? for reaction 1 (SM8 + CCSD(T)/6-311 ++G(d,p)//M08-HX/MG3S: 38–67 kJ mol^?1) are smaller than the corresponding values for 2 (109–113 kJ mol^?1). For 2-PM, the computed carbamate ΔG ₂₉₈ ^? (38 kJ mol^?1) is comparable to the MEA value (45 kJ mol^?1), whereas the primary amines with tertiary alpha carbons have slightly larger values (60–70 kJ mol^?1). The organic amine values are much lower than the value for ammonia (93 kJ mol^?1). The results indicate CO₂ chemisorption proceeds via a carbamate intermediate for all aqueous primary and secondary amines. Hindered carbamates are susceptible to further chemical transformations following their formation.     

Using only the very accurately known experimental enthalpy of hydrogenation of ethylene as a reference standard in the atomization method

Theoretical Gn model chemistries yield slightly different values for the enthalpy of formation of the hydrogen molecule from the constituent protons and electrons. For example, the G3 model yields ?1.92 kJ mol^?1 at 298 K, which differs from zero by an acceptably small amount. However, using this G3 value for a stepwise series of hydrogenations of polyunsaturated molecules multiplies the error, e.g., by five times for the hydrogenation of naphthalene. For polyunsaturates, this can produce errors considerably greater than experimental uncertainties. We calculate enthalpies of hydrogenation by referring the calculated values to the accurately known experimental enthalpy of hydrogenation of ethylene. This approach is simpler than the atomization method that depends on several experimental enthalpies of formation of the constituent atoms of the target molecules. This method yields enthalpies of hydrogenation and of formation in excellent agreement with experiment for many polyunsaturated compounds and lends confidence to results obtained for others, for which no accurate experimental values exist or are disparate, for example azulene. Some new and surprising results are that the formally conjugated triple bonds of cyanoacetylene do not lead to stabilization, but to destabilization by 10.2 kJ mol^?1. The conjugated triple bonds of cyanogen cause thermodynamic destabilization by 47.5 kJ mol^?1. Stabilization by conjugation in acrylonitrile is near zero. The remarkable endothermic monohydrogenation of benzene (25 kJ mol^?1), first noted by Kistiakowsky, is also found in toluene and naphthalene, leading to stability of the reactant relative to the product of ~30 and 22 kJ mol^?1, respectively.     

Experimental and computational study of the thermal decomposition of 3-buten-1-ol in m-xylene solution

An experimental study of the thermal decomposition of a β-hydroxy alkene, 3-buten-1-ol, in m-xylene solution, has been carried out at three different temperatures: 553.15, 573.15, and 593.15 K. The temperature dependence of the rate constants for the decomposition of this compound in the corresponding Arrhenius equation is given by ln k (s^?1) = (27.34 ± 1.24)–(19,328 ± 712) (kJ mol^?1) T ^?1. A computational study has been performed at the MP2/6-31+G(d) level of theory to calculate the rate constants and the activation parameters by the classical transition state theory. The Arrhenius equation obtained theoretically, ln k (s^?1) = (28.252 ± 0.025)–(19,738.0 ± 14.4) (kJ mol^?1) T ^?1, agrees very satisfactorily with the experimental one. The bonding characteristics of reactant, transition state, and products have been investigated by the natural bond orbital analysis which provides the natural atomic charges and the Wiberg bond indices used to follow the progress of the reaction. The enthalpy of the reaction has been calculated using experimental values taken from literature and theoretic calculations. The agreement between both values is satisfactory.     

Solution thermodynamics and preferential solvation of triclocarban in {1,4-dioxane (1) + water (2)} mixtures at 298.15 K

The equilibrium solubility and preferential solvation of triclocarban in {1,4-dioxane (1) + water (2)} mixtures at 298.15 K was reported. Mole fraction solubility varies continuously from 2.85 × 10^–9 in neat water to 2.39 × 10^–3 in neat 1,4-dioxane. Solubility behaviour was adequately correlated by means of the Jouyban-Acree model. Based on the inverse Kirkwood-Buff integrals, preferential solvation parameters were calculated. Triclocarban is preferentially solvated by water in water-rich mixtures (0.00 < x₁ < 0.18) and also in 1,4-dioxane-rich mixtures (0.78 < x₁ < 1.00) but preferentially solvated by 1,4-dioxane in mixtures with similar solvent compositions.     

Determination of adsorption heats of individual adsorption complex by combination of microcalorimetry and FTIR spectroscopy

Adsorption of CO as a probe molecule on K-FER zeolites differing in Si/Al ratio was investigated. Successful determination of adsorption heats of individual adsorption complexes formed upon adsorption of CO molecules on K-FER zeolites at 300 K by combination of IR spectroscopy with adsorption microcalorimetry is reported. Adsorption heat of bridged carbonyl complexes, where CO molecule interacts with two nearby extraframework K⁺ cations, was experimentally determined for the first time. It was found that bridged complexes on dual cationic sites exhibit adsorption heat of 34.8 kJ mol^?1, whereas monodentate carbonyls on single isolated K⁺ cation exhibit adsorption heat of only 26.2 kJ mol^?1 and adsorption heat of isocarbonyls was 21.5 kJ mol^?1.     

Thermogravimetric analysis of lignocellulosic and microalgae biomasses and their blends during combustion

Thermogravimetric analysis was used to study and compare the combustion of different blends of corn bioresidues with sunflower, rape and algae bioresidues. Non-isothermal thermogravimetric data were used to obtain the combustion kinetics of these bioresidues. This paper reports on the application of the Vyazovkin and Ozawa–Flynn–Wall isoconversional methods for the evaluation of kinetic parameters (energy activation, pre-exponential factor and order of reaction) for the combustion of the biomasses studied. Differences were found in the TG curves in accordance with the proximate analysis results for the cellulose, hemicellulose and lignin content of biomasses. The activation energy obtained from combustion (E ~ 151.6 kJ mol^?1) was lower than that from the blends (similar values were obtained for corn–sunflower, E ~ 160.5 kJ mol^?1 and corn–rape, E ~ 156.9 kJ mol^?1) whereas the activation energy obtained from the microalgae was higher (E ~ 171.5 kJ mol^?1). Both the Vyazovkin and Ozawa–Flynn–Wall methods yielded similar results.     

Immobilisation of lead(II) ions from aqueous solutions on natural coal

The immobilisation of lead(II) ions from aqueous solutions on natural coal was investigated to compare calculated and measured adsorption enthalpies. For this purpose, adsorption isotherms were measured at temperatures of 303, 333 and 353 K. Adsorption enthalpy ΔH was evaluated from temperature dependence of the equilibrium constant of adsorption using the van‘t Hoff equation. Thus, the value of ΔH = 27 kJ mol^?1 was obtained manifesting endothermic effect of lead(II) immobilisation on the coal. However, based on the flow and immersion calorimetric measurements, the exothermic character of lead(II) adsorption on the studied coal was proven with a value of about ?7 kJ mol^?1.     

Effect of temperature on frying oils: infrared spectroscopic studies

Frying oils were studied by Fourier-transform infrared (FT-IR) spectroscopy, in the range 4,000–200 cm^?1, at different temperatures, in the liquid and solid states. The infrared spectrum at 15 °C was similar to that at 200 °C. The band at 730 cm^?1 which was assigned to the rocking mode of (–CH₂) disappeared at higher temperature because of the rotational isomerism which occurred in the oil structure. The activation energy (E _a) of the disappearing (–CH₂) band, calculated by use of the chemical dynamic method using the Arrhenius equation, is 8.45 kJ mol^?1. The enthalpy difference (ΔH) between the two rotational isomer bands of the conformational structures of the oil at 730 and 1,790 cm^?1, at different high temperatures, was also calculated, by use of the Van’t Hoff equation; the value obtained was ?10.85 kJ mol^?1.