Thermodynamic parameters for the extraction of some lanthanides with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 and trioctylamine

The synergistic extraction of Pr, Gd and Yb with a mixture of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 and trioctylamine diluted in C₆H₆, CHCl₃ and CCl₄ at 288 K, 298 K, 308 K and 318 K has been investigated. The values of the equilibrium constants as well as of H°, S° and G° have been calculated. The thermodynamic parameters indicate that the adduct formed becomes stable on the account of the enthalpy change which exceeds the antistabilizing effect of the entropy factor. A comparison is made to the extraction of the same elements with thenoyltrifluoroacetone.

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Die thermodynamischen Parameter für die Extraktion einiger Lanthaniden mit 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolon und Trioctylamin

Zusammenfassung Es wurde die synergistische Extraktion von Pr, Gd und Yb mit einer Mischung von 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolon mit Trioctylamin in C₆H₆, CHCl₃ und CCl₄ bei 288 K, 298 K, 308 K und 318 K bestimmt. Die Gleichgewichtskonstanten und die Werte für H°, S° und G° wurden berechnet. Die thermodynamischen Parameter legen den Schluß nahe, daß die Stabilität des gebildeten Addukts in Änderungen der Enthalpie begründet ist, wobei der destabilisierende entropische Effekt übertroffen wird. Die Ergebnisse werden mit der Extraktion mittels Thenoyltrifluoraceton verglichen.

     

Numerische Auswertung von Enzymanalysen

Zusammenfassung Für eine numerische Auswertung von Enzymanalysen erscheint es zunächst naheliegend, in die Meßpunkte eine Ausgleichsgerade einzupassen und deren Steigung als Schätzwert für die gesuchte Anfangsgeschwindigkeit E/t ₀ zu nehmen. Die Steigung der Ausgleichsgeraden liefert aber die mittlere Reaktionsgeschwindigkeit über die gesamte Meßzeit und unterschätzt E/t ₀ immer dann, wenn die Reaktion gegen Ende der Meßzeit etwas langsamer läuft. Bei automatischen Geräten muß das Auswerteverfahren auch in solchen Fällen E/t ₀ richtig schätzen. In der vorliegenden Arbeit wird eine einfache Möglichkeit, die zu diesem Ziel führt, diskutiert, nämlich die Schätzung von E/t ₀ mit einer Ausgleichsparabel, die dem Reaktionsverlauf folgen kann.

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Numerical evaluation of enzyme analyses

To calculate enzyme concentrations numerically, it seems obvious to fit a straight line into the data points and take the slope as an estimate for the starting velocity E/t ₀. This slope, however, is proportional to the average reaction rate over the total measurement interval and always underestimates E/t ₀ when the reaction is slowing down towards the end. Automatic analyzers must correctly estimate E/t ₀ even in such cases. As discussed in this article, this can be achieved by fitting a second order parabola, that can follow the reaction, into the data points.

     

Determination of enthalpy of ionization of water from 250 to 350° C

The enthalpy changes at zero ionic strength (H°) for the ionization of water (H₂O=H⁺+OH^–) were determined by flow calorimetry from the heats of mixing of aqueous NaOH and HCl solutions in the temperature range 250 to 350°C. Pitzer ion-interaction models developed by other workers were used to calculate enthalpies of dilution of aqueous NaOH, HCl, and NaCl solutions for the extrapolation of H values from the conditions of the experiment to infinite dilution. Equations are derived for thermodynamic quantities (log K, H°, S°, C _p ^° and V°) for the ionization of water using the H° values determined in this study from 250 to 350°C and literature log K and H° values from 0 to 225°C. Smoothed values of log K, H°, S°, C _p ^° , and V° are presented at rounded temperatures from 0 to 350°C and at the saturation pressure of water for each temperature. The equations in the present study provide a better representation of experimental thermodynamic data from 0 to 350°C than the Marshall-Franck equation.     

Thermodynamics of protonation of amino acid carboxylate groups from 50 to 125°C

Flow calorimetry has been used to study the interaction of glycine, DL--alanine, DL-2-aminobutyric acid, -alanine, 4-aminobutyric acid, and 6-aminocaproic acid with protons in aqueous solutions from 323.15 K to 398.15 K and at 1.52 MPa. LogK, H°, S°, and C _p ^° for the protonation of the carboxylate groups of these amino acids have been obtained at each temperature studied. Equations are given expressing these values as functions of temperature. The protonation reactions are exothermic at lower temperatures and become endothermic as temperature increases. The logK, H°, and S° values are close together over the temperature range studied for the protonation of -amino acids, i.e., glycine, DL--alanine, and 2-aminobutyric acid. At each temperature, the magnitudes of these thermodynamic quantities increase as the number of methylene groups between the amino group and the carboxylate group increases. The C _p ^° value for the protonation of the carboxyl group is found to lie between those of an isocoulombic reaction and a charge reduction reaction. At 323.15 K, the protonation reactions of the carboxylate groups have larger C _p ^° values which approach those associated with charge reduction reactions. As the temperature increases, C _p ^° decreases and approaches those found for isocoulombic reactions. This result is explained by considering long-range and short-range solvent effects. The trend in H° and S° with temperature and with charge separation in the zwitterions is interpreted in terms of solvent-solute interactions and the electrostatic interaction of the two oppositely charged groups within the molecule.     

Etats de valence 2Π et 2Δ des molécules isoélectroniques N 2 + , CN et CO+

Résumé On a calculé les courbes d'énergie potentielle de plusieurs états excités de N₂ ⁺, CN et CO⁺, en utilisant les fonctions d'onde LCAO MO SCF. Les valeurs calculées des constantes spectroscopiques et spin orbite sont en bon accord avec l'expérience. Notre calcul prévoit qu'on ne peut pas observer de transition ² -A ² dans CO⁺, et confirme que l'état supérieur de la transition récemment observée est un état ² et non ² .

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Potential energy curves have been calculated for several excited states of N₂ ⁺, CN and CO⁺, using LCAO MO SCF functions. Good agreement with experiment has been obtained for spectroscopic and spin orbit constants. From our calculation, ² -A ² transition in CO⁺ is predicted to be non observable, but we confirm that the upper state of the experimentally observed transition is ² _r and not ² .

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Zusammenfassung Für verschiedene angeregte Zustände der iso-elektronischen Moleküle N₂ ⁺, CN und CO⁺ wurden unter Verwendung von LCAO-MO-SCF-Funktionen die Potentialkurven berechnet. Für die spektroskopischen und die Spin-Bahn-Kopplungskonstanten wurde gute Übereinstimmung mit dem experimentellen Befund erreicht. Unseren Berechnungen nach sollte der ² -A ² -Übergang in CO⁺ nicht beobachtbar sein, während die Rechnung bestätigt, daß der obere Zustand des experimentell beobachteten Überganges ein ² _r -Zustand und nicht ein ² -Zustand ist.

     

Enthalpy of dissociation of water at 325°C and LogK, ΔH, ΔS,and ΔC p values for the formation of NaOH(aq) from 250 to 325°C

The aqueous reactions H⁺+OH^–=H₂O at 325°C and Na⁺+OH^–= NaOH(aq) at 250–325°C, were studied using a flow calorimeter. Heats of mixing of aqueous NaOH and HCl solutions were measured at 325°C. The enthalpy of water formation (H=95.9 kJ-mol^–1, valid at 12.4 MPa and infinite dilution) was obtained at this temperature from the heat of mixing data but differs significantly from that calculated from the Marshall-Franck equation. This calorimetric H at 325°C was used in combination with literaturelog K and H values at lower temperatures to derive equations representinglog K, H, S, and C_p for the formation of water from 250 to 325°C. Heats of dilution of aqueous NaOH solutions were measured at 250, 275, 300, and 325°C. Log K, H, and S for the formation of NaOH(aq) were determined at these temperatures from the fits of the calculated and measured heats while C_p values were calculated from the variation of H with temperature. No previous experimental results have been reported for the formation of NaOH(aq). The isocoulombic reaction principle is tested using thelog K values obtained in this study. The plot oflog K vs. 1/T for the isocoulombic reaction NaOH(aq) +H⁺=H₂O+Na⁺ is approximately linear.Presented at the Second International Symposium on Chemistry in High Temperature Water, Provo, UT, August 1991.Taken in part from the Ph.D. Dissertation of Xuemin Chen, Brigham Young University, 1991.     

Zur Berechnung der freien Mischungsenthalpie und der Aktivitätskoeffizienten beschränkt mischbarer Systeme aus der Löslichkeitskurve

Zusammenfassung Die in dieser Arbeit vorgeschlagene Methode gestattet, die Änderungen der freien Zusatzenthalpie mit der Konzentration bei der kritischen Lösungstemperatur auf Grund der Löslichkeitskurve beschränkt mischbarer Systeme innerhalb des Konzentrationsbereiches der Mischungslücke zu berechnen, soferne Daten für die Zusatzentropie S _z und für die Zusatzwerte zu den Molwärmen C _p,z bekannt sind. Durch numerische Integration von erhält man die Werte für die freie Zusatzenthalpie G _z bei der kritischen Lösungstemperatur.Die Methode wird zur Berechnung von G _z der Systeme n-Pentan-Aceton und Nickel-Gold herangezogen. An diesen Beispielen wird der Einfluß der näherungsweisen Vernachlässigung von S _z und C _p,z untersucht.Bei dem System n-Pentan-Aceton stimmen die nach dieser Methode erhaltenen Werte mit den aus Dampfdruckmessungen gewonnenen innerhalb der Fehlergrenzen vollkommen überein. Die Vernachlässigung von S _z bzw. C _p,z führt hier lediglich zu einem Fehler von weniger als 2%.Die für das System Nickel-Gold erhaltenen G _z-Werte sind niedriger als die vonSeigle, Cohen undAverbach auf Grund elektromotorischer Kräfte berechneten. Die Vernachlässigung von S _z und C _p,z bedingt hier einen Fehler von etwa 10%.Mit 7 Abbildungen     

Influence of the temperature on the extraction of some lanthanides with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5

The extraction of Pr, Gd and Yb with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) diluted in CHCl₃, C₆H₆, and CCl₄ at 288 K, 298 K, 308 K, and 318 K has been investigated. A compound of the typeMe(PMBP)₃HPMBP is formed in the organic phase. The values of the thermodynamic constants as well as of the parameters H°, S° and G° have been determined.

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Der Temperatureinfluß auf die Extraktion einiger Lanthaniden mit 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolon

Zusammenfassung Es wurde die Extraktion von Pr, Gd und Yb mit 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolon (HPMBP) in CHCl₃, C₆H₆ oder CCl₄ als verdünnendes Lösungsmittel bei 288 K, 298 K, 308 K und 318 K untersucht. Es wird eine Verbindung des TypsMe(PMBP)₃HPMBP in der organischen Phase gebildet. Die thermodynamischen Konstanten und auch die Parameter H°, S° und G° wurden bestimmt.

     

NMR Study of Non-freezing Water in Protein-Modified Carbon Adsorbents

Temperature dependences of ¹H NMR spin–spin relaxation were studied for the non-freezing water at the surface of carbon matrices modified with proteins (human serum albumin (HSA) and mouse immunoglobulin (MIG)) in the presence of water-soluble carbodiimide. The entropy, S , and enthalpy, H , values characterizing molecular mobility in non-freezing water were estimated. The compensation effect was observed for all modified samples, which is well approximated by the linear dependence of the type H = T ₀S + H ₀. The compensation temperature T ₀ = 231 ± 33 corresponds to such a state of non-freezing water, when the effect of modifying additives on the isobaric potential of molecular mobility activation in the non-freezing water, G , is minimal. The G has approximately constant value equal to H ₀ = 24.2 ± 0.5 kJ/mol. Modification of the base carbon matrix with MIG protein results in higher structurization of the non-freezing water, whereas HSA reduces this structurization. The observed effects are explained in terms of the hydration of modifying agents and also by the peculiarities of their location on the surface of carbon adsorbent.     

Konformations-Enatiomerie, 3. Mitt.: Kinetik und thermodynamische Daten der Racemisierung von optisch aktivem 4,5-6,7-Dibenzo-1,2-dithia-cyclooctadien

Zusammenfassung Die Racemisierung der im Titel genannten, in Konformations-Enantiomere gespaltenen Verbindung (I) wird kinetisch untersucht. Aus der Temperaturabhängigkeit der Geschwindigkeitskonstanten werden die Aktivierungsparameter:E =27,3±±0,6, H=26,6±0,6, G=28,8±0,2 kcal/Mol und S=–6,0±2,2 kcal/Mol·Grad bestimmt. Die Konformationen und die Ursachen für ihre hohe Stabilität werden diskutiert.Mit 5 AbbildungenHerrn Prof. Dr.F. Wessely zum 70. Geburtstag gewidmet.2. Mitt.:A. Lüttringhaus undK. C. Peters, Angew. Chem.78, 603 (1966).     

Strain Energies of α-Alkylsubstituted Styrenes, 1,1-Di-phenyl-ethene,Tri-, and Tetra-phenyl-ethene

The standard (p° = 0.1 MPa) molar enthalpies of formation _fH°_m (1 or cr) at the temperature T = 298.15 K were determined by using combustion calorimetry for -ethyl-styrene (A), -iso-propyl-styrene (B), -tert-butyl-styrene (C), 1,1-di-phenyl-ethene (D), tri-phenyl-ethene (E), and tetra-phenyl-ethene (F). The standard molar enthalpies of vaporization _l ^g H°_m or sublimation _cr ^g H°_m of compounds A to F were obtained from the temperature variation of the vapor pressure measured in a flow system. Molar enthalpies of fusion _cr ^l H°_m of solid compounds were measured by d.s.c. Resulting values of _fH°_m (g) were obtained at the temperature T = 298.15 K and used to derive strain enthalpies of phenylalkenes. The interactions of the substituents are discussed in terms of deviations of _fH°_m (g)from the group additivity rules. These values provide a further improvement on the group-contribution methodology for estimation of the thermodynamic properties of organic compounds.     

Effects of alkyl chain length on surface and micellar properties of octaethyleneglycol-n alkyl ethers

Summary Surface and micellar properties of a homologous series of Octaethylene glycol-n-alkyl ethers (C _n E₈;n = 9 to 15) have been studied in aqueous solutions by the surface tension measurements. The effects of the alkyl chain length comprising even and carbon numbers have been examined in order to evaluate the surface free energy G _A-W and the standard free energy G _m for the micellization obtained from their surface tension data. The areas per molecule and the equilibrium surface tension values at the CMC decreased with an increasing carbon number and they showed zigzag curves by the difference in even and odd carbon numbers.These findings may be attributed to the differences in the molecular orientation between the molecules with even carbon number and ones with odd carbon number on the air-water interface at CMC. G _A-W values decreased linearly with an increasing alkyl chain length but did not show a zigzag line by the differences in even and odd carbon numbers. This suggests that the molecular orientation is not influenced by the difference between their even and odd carbon numbers in the alkyl chain on the surface of the very diluted solution, and their molecules form some stable adsorbed films with an increase of the alkyl chain length. A division of G _A-W into the contribution made both by the hydrophilic group G _A-W (-W) and by the hydrophobic group G _A-W (-CH₂-) was attempted as follows; G _A-W (-CH₂-) = – 0.80 kcal/mol and G _a-W (-W) = + 0.15 kcal/mol.The free energy changes G _m of micellization were discussed on the basis of the CMC data obtained from the surface tension measurements by treating the formation of micelles as analogous to phase separation, and the contribution from the each moieties in the molecule were calculated as follows; G _m (-CH₂-) = – 0.68 kcal/mol and G _m (-W) = + 1.54 kcal/mol. The difference between G _A-W and G _m is discussed using their data.     

Circulardichroismus. XXX

Zusammenfassung Es wird eine einfache Anordnung beschrieben, die es gestattet, auf einem Zweitschreiber zum Roussel-Jouan-Dichrographen wahlweise direkt oder / aufzuzeichnen. Integration der letzteren Kurve mit einem Planimeter gibt (unter Berücksichtigung der entsprechenden Faktoren) dann die Rotationsstärke der betrachteten CD-Bande, auch wenn diese starke Peinstruktur zeigt.

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Circular dichroism XXX. On the direct determination of the rotatory strength by the roussel-jouan dichrograph

A simple device is described which can be used with the Roussel-Jouan Dichrograph to give direct readings of s and /, resp. Integration of the latter curve with a planimeter yields the rotatory strength of any partial CD-band.

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Der Deutschen Forschungsgemeinschaft danken wir sehr für die großzügige Unterstützung unserer Arbeiten.

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XXIX. Mitteilung: Snatzke, G., u. K. Schaffner [10].

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Herrn Prof. Dr. E. Asmus zum 60. Geburtstag gewidmet.     

First and second thermodynamic mixing properties of ethylbenzene +n-alkanes: Experimental and theory

Isobaric expansibilities _P and isothermal compressibilities _T have been determined at 25 and 45°C for binary mixtures of ethylbenzene + n-tetradecane and + n-hexadecane and the corresponding excess functions (V ^E /T)_P and (V ^E /P)_T have also been obtained. With these data and supplementary literature values, the following second order mixing properties are also reported at 25°C: _S ^E , (V ^E /P)_T, C_V and (VT). All mixing quantities have been compared with the results obtained at 25°C by using the Prigogine-Flory-Patterson theory of liquid mixtures. The predicted values suggest that the ability of ethylbenzene as a breaker of the pure n-C_n orientations is similar to what we found for toluene and higher than for p-xylene.     

Zur Konstitution der von E. Fischer dargestellten Δ3-Pyrrolincarbonsäure-(2)

Zusammenfassung Es wird durch verschiedene unabhängige Reaktionen gezeigt, daß es sich bei einer seinerzeit vonE. Fischer dargestellten verbindung nicht um die ³-Pyrrolincarbonsäure-(2) (I), sondern um die ¹-Pyrrolincarbonsäure-(5) (III) handelt.     

Multiphoton Dissociation of Sulfur Hexafluoride in a Vibrationally Cooled Compression Shock

Multiphoton IR dissociation of SF₆ (in a mixture with CH₄) under nonequilibrium conditions of a compression shock formed by an intense, gas dynamically cooled, pulsed molecular beam impacting a solid surface was studied using the HF* luminescence detection ( 2.5 m) technique. The dependences of the HF* luminescence intensity on the distance x between the region in which molecules were excited and the surface and on the laser radiation frequency at different values of x were obtained. It was shown that, as the distance x decreased from 4 to 1.5 mm, the HF* luminescence intensity increased by more than an order of magnitude as compared to the case of excitation of molecules in an undisturbed flow, whereas the frequency dependences of luminescence intensity (SF₆ dissociation yield) were broadened only insignificantly.     

Gibbs Energy and Entropy of Mixing in the NaNO2-KNO3 System

The activity and activity coefficients of the components of the NaNO₂-KNO₃ system, determined from the experimental data on the saturated vapor pressure at 798, 823, and 848 K, are used to calculate the relative and excess partial molar Gibbs energies (G _i and G _i ^{e x c}), entropies (S _i and S _i ^{e x c}), and integral relative and excess thermodynamic functions (G, G ^{e x c}, S, and S ^{e x c}) of the system.     

Anionenaustausch — Selektivitätssequenzen in homologen Reihen hydrophober Ionen

Zusammenfassung Die Gleichgewichtsselektivitätskoeffizienten wurden als Funktion der Temperatur für den Austausch von n-Alkylsulfaten ROSO₃(Na) mit der Chloridform des stark basischen Anionenaustauscherharzes AG-IX8 bestimmt. Selektivitätskoeffizienten und thermodynamische Größen (G, H, S) wurden für die Austausche in den homologen Reihen der Anionen ROSO₃ ^– und RSO₃ ^– verglichen. Die Austauschentropien nahmen mit zunehmender Kettenlänge für beide Ionenfamilien in ähnlicher Weise zu; das Bestehen eines allgemeinen hydrophoben Selektivitätseffektes — wirksam für alle gelösten Ionen, die gesättigte Kohlenwasserstoffketten enthalten — wurde festgestellt.

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Anion exchange selectivity sequences in homologous series of hydrophobic ions

The equilibrium selectivity coefficients as a function of temperature were determined for the exchange of n-alkylsulfates ROSO₃(Na) with the chloride form of the strongly basic anion exchange resin AG-IX8. Selectivity coefficients and thermodynamic quantities (G, H, S) were compared for the exchanges involving the homologous series of ROSO₃ ^– and RSO₃ ^– anions. The entropies of exchange increased with increasing chain length in a similar fashion for both families of ions and the existence of a general hydrophobic selectivity effect active for all ionic solutes containing saturated hydrocarbon chains was established.

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Mit 3 Abbildungen

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Herrn Professor Dr.H. Nowotny gewidmet.     

Thermodynamic study of solvent extraction of monovalent metal picrates with benzo-18-crown-6 into chloroform

Thermodynamic parameters (H _ex ⁰ and S _ex ⁰ ) for the overall extractions of monovalent metal (Na, K, Rb, and Tl) picrates with benzo-18-crown-6 (B18C6), and those (H _D,L ⁰ and S _D,L ⁰ ) for the distribution of B18C6 were determined between chloroform and water. All the extracted B18C6 complexes were l:1:1 complexes (B18C6:metal ion: picrate anion). The H _ex ⁰ and S _ex ⁰ values for all the metals are negative. Every extraction of the metal picrate with B18C6 is completely enthalpy driven. The H _D,L ⁰ and S _D,L ⁰ values of B18C6 are both positive, and the partition of B18C6 is entirely entropy driven. Enthalpy (H _ex,ip ⁰ ) and entropy changes (S _ex,ip ⁰ ) for ion-pair extractions of B18C6-metal ion complexes with picrate anions were calculated. All the H _ex,ip ⁰ and S _ex,ip ⁰ values are negative, and the ion-pair extractions are completely enthalpy driven.