Liquid–Liquid Equilibria of Linalool + Ethanol + Water, Water + Ethanol + Limonene, and Limonene + Linalool + Water Systems

The present work was undertaken to determine liquid–liquid equilibria for ternary systems involved in the citrus essential oil terpeneless using dilute alcohol. Tie-line data have been determined for the linalool + ethanol + water, water + ethanol + limonene, and limonene + linalool + water ternary systems at 298.15 K. The experimental data were satisfactorily correlated using the UNIQUAC and NRTL equations, and the obtained binary interaction parameters are reported. The UNIFAC group-contribution method did not allow adequate predictions of liquid–liquid equilibria involved in this study.     

A nonadiabatic lower bound calculation of H 2 + and D 2 +

Accurate nonadiabatic lower and upper bounds for groundstate energies of H ₂ ⁺ and D ₂ ⁺ are calculated with the linearized method of variance minimization. The results in a.u. are –0.59713906₃<E ₀(H ₂ ⁺ )<–0.59713899₄ –0.59878877₅<E ₀(D ₂ ⁺ )<–0.59877873₈ i.e. the values are determined with an absolute error smaller than 0.02 cm^–1 for H ₂ ⁺ and 0.01 cm^–1 for D ₂ ⁺ .     

Theoretical study of the structurally nonrigid ions LiP 2 + , HP 2 + , and H3P 2 +

New Chemical Problems Institute, USSR Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 4, pp. 164–167, July–August, 1989.     

Investigations of TsVM zeolite acidities with different degrees of exchange of Na+ by H+

The method of programmed thermal desorption of ammonia has been used to establish that on the surface of the sodium form of type TsVM zeolite having a modulus SiO₂/Al₂O₃= 34.5 there are two types of acidic centers having ammonia desorption activation energies E_d equal to 40–45 and 80–100 kJ/mole. Replacement of Na⁺ by H⁺ leads to the appearance of a third type of center with a value E_D=130–150 kJ/mole. In this case in the IR spectra of specimens saturated with ammonia a band appears at 1410 cm_–1, which is evidence for the presence of NH ₄ ⁺ ions. Increasing the degree of Na⁺ replacement by H⁺ leads to a nonproportional rapid increase in the concentration of highly energetic centers, which may be explained by the partial transfer of aluminum into cationic positions with the formation of additional acidic centers.Translated from Teoreticheskie i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 752–755, November–December, 1986.     

Structural and dynamic investigations of aqueous clusters of Na+ and K+

Using computer modeling, we have studied Na⁺–24H₂O and K⁺–24H₂O clusters. We propose ion-water interaction potentials. We obtain structural, energy, and dynamic characteristics of the studied clusters. We show different mechanisms for exchange of water molecules surrounding the Na⁺ and K⁺ ions: single-particle in the case of Na⁺, and close to K⁺, along with single-particle exchange, a large percentage of multiparticle cooperative exchange of water molecules. This difference is explained by the different degrees of orientation of the water molecules surrounding these ions, by the presence of a unified deformed network of H bonds in the K⁺ cluster and its absence in the Na⁺ cluster. We propose a negative hydration mechanism for the K⁺ ion.Institute of General and Inorganic Chemistry, Russian Academy of Sciences. Institute of Physical Chemistry, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 96–104, March–April, 1993.     

Contribution from the aqueous phase to stability of Cs+ and Na+ cryptand[2.2.2] complexes

Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 6, pp. 757–758, November–December, 1989.     

Study of weak Mn2+ and Cu2+ complexes by a nuclear magnetic resonance method

An NMR method is described and applied, which allows the investigation of the first coordination sphere of certain transition metal ions. It is based on the measurement of the solvent proton nuclear magnetic relaxation times both as a function of magnetic field and of concentration of an admixed diamagnetic salt. This procedure enables an unambiguous separation of dynamic effects from ion-pair formation effects, which both can influence the relaxation times. As an application of this method, the complex formation of Mn²⁺ and Cu²⁺ with Br^–, I^–, ClO ₄ ^– , and SO ₄ ^2– in aqueous solution is studied. Thus the hydration numbersn _H2O of these cations as a function of anion concentration are obtained, allowing the detection of weak inner-sphere or outersphere complexes. Also several complex stability constants are derived and are compared with literature data.     

Studies on ion exchange equilibria and kinetics VI. Prediction of ion exchange equilibria of UO 2 2+ −Na+−H+ ternary system

Experimental data are reported for the ion exchange equilibria of the binary systems UO ₂ ²⁺ –H⁺, UO ₂ ²⁺ –Na⁺ and Na⁺–H⁺, and of the ternary system UO ₂ ²⁺ –Na⁺–H⁺ on a strong acid cation exchange resin 001X7 at 25 °C. It is found that the equilibria for any pairs of ions are essentially the same in binary and ternary mixtures and that the prediction method proposed by our laboratory for SO ₂ ^2– –Cl^––NO ₃ ^– -201X7 strong base anion exchange resin system is also applicable to the ternary system studied in this paper. The predictions of the ternary system UO ₂ ²⁺ –Na⁺–H⁺ based solely on the binary data without using resin phase activity coefficients are consistent with the experimental data.     

Study of complexation in the Nd3+-SCN− system

Summary A spectroscopic study of the association in the Nd³⁺-SCN^– system is presented. A characteristic change of the molar absorptivity of the solution with a plateau at 2–4M [SCN^–] and an increase at 4–8M [SCN^–] reflects the change from outer- to innersphere complexation.

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Untersuchungen zur Komplexierung im Nd³⁺-SCN^–-System

Zusammenfassung Es wird eine spektroskopische Studie der Assioziationsverhältnisse im Nd³⁺-SCN^–-System präsentiert. Die charakteristische Änderung in der molaren Absorption der Lösung mit einem Plateau bei 2–4M [SCN^–] und ein Anstieg bei 4–8M [SCN^–] ist auf einen Wechsel von außensphärischer zu innensphärischer Komplexierung zurückzuführen.

     

Temperature Dependence of Excess Molar Volumes of Ethanol + Water + Ethyl Acetate

In order to design and optimize equipment needed for production of distilled alcoholic beverages, an adequate knowledge of their physical properties and phase equilibria is necessary. The key thermodynamic information needed is for those chemicals that are the main components in terms of nonideal behavior. In this paper we present the temperature dependence of the excess molar volumes of the ternary system ethanol + water + ethyl acetate in the range 288.15–323.15 K at atmospheric pressure, due to the importance of ethyl acetate among the flavor compounds contained in this type of beverage. The observed excess molar volumes are usually negative over the whole homogeneous composition range, but take on positive values as the binary ethanol + ethyl acetate system is approached and the liquid phase separation region is observed. Because the current process designs are strongly computer oriented, the accuracy of theoretical model predictions was examined. The experimental data were used to test the capability of the Soave–Redlich–Kwong (SRK) equation of state to predict the ternary mixture behavior from binary mixture interaction parameters, which were obtained from previously published data. Derived properties, such as partial the excess molar volumes, excess isobaric expansibility, and the pressure derivative of excess molar enthalpy at constant temperature were calculated, due to their importance in the study of specific molecular interactions.     

Flavonoid inhibitors of Na+,K+-ATPase

Summary A comparative investigation of the inhibiting influence on transport Na⁺,K⁺-ATPase of four flavone aglycones and eight of their glycosides has been performed on the microsomal fraction of the cells of the cerebral cortex.It has been shown that in concentrations of 1·10^–4 to 5·10^–6 M M myricetin, quercetin, luteolin, and myricetin 3-glucoside possess an appreciable inhibiting effect. For kaempferol and its glycosides, as for the glycosides of quercetin and luteolin, the inhibiting effect is extremely feeble.Institute of Biochemistry, Academy of Sciences of the Uzbek SSR, Tashkent. V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 44–46, January–February, 1977.     

Chlorokomplexe von Cu2+ und Ni2+ in Dimethylformamid

Zusammenfassung Durch spektrophotometrische Messungen in Dimethylformamid (DMF) werden die Koordinationsformen [CuCl]⁺ und [CuCl₃]^– sowie [NiCl]⁺, [NiCl₃]^– und [NiCl₄]^2– nachgewiesen. Bei Nickel(II)-chlorid und Kupfer(II)-chlorid wird Autokomplexbildung diskutiert. Die Solvate [Cu(DMF)₄] (ClO₄)₂ und [Ni(DMF)₆] (ClO₄)₂ werden isoliert.Im Zuge der Untersuchungen über Chlorokomplexe von Ionen der Übergangsmetalle^{1, 2} in nichtwäßrigen Lösungsmitteln wurden die Spektren der Lösungen von Kupfer(II)- und Nikkel(II)-perchlorat inDMF in Gegenwart verschiedener Mengen Tetraäthylammoniumchlorid aufgenommen.Mit 5 Abbildungen     

Liquid–liquid equilibria of water + ethanol + reformate

Liquid–liquid equilibria (LLE) of the multicomponent system water + ethanol + a synthetic reformate (composed of benzene, n-hexane, 2,2,4-trimethylpentane, and cyclohexane) was studied at atmospheric pressure and at 283.15 and 313.15 K. The mutual reformate–water solubility with addition of anhydrous ethanol was investigated. Different quantities of water were added to the blends in order to have a wide water composition spectrum, at each temperature. We conclude from our experimental results, that this multicomponent system presents a very small water tolerance and that phase separation could result a considerable loss of ethanol that is drawn into the aqueous phase. The results were also used to analyse the applicability of the UNIFAC group contribution method and the UNIQUAC model. Both models fit the experimental data with similar low average root mean square deviations (rsmd ≤ 2.05%) yielding a satisfactory equilibrium prediction for the multicomponent system, although the predicted ethanol (rsmd ≤ 4.6%) compositions are not very good. The binary interaction parameters needed for the UNIQUAC model were obtained from the UNIFAC method.     

An equilibrium and calorimetric investigation of the hydrolysis of L-tryptophan to (indole + pyruvate + ammonia)

Apparent equilibrium constants and calorimetric enthalpies of reaction have been measured for the reaction L-tryptophan(aq) + H₂O(l) = indole(aq) + pyruvate(aq) + ammonia(aq) which is catalyzed by L-tryptophanase. High-pressure liquid-chromatography and microcalorimetery were used to perform these measurements. The equilibrium measurements were performed as a function of pH, temperature, and ionic strength. The results have been interpreted with a chemical equilibrium model to obtain thermodynamic quantities for the reference reaction: L-tryptophan(aq) + H₂O(l) = indole(aq) + pyruvate^–(aq) + NH ₄ ⁺ (aq). At T=25°C and I_m=O the results for this reaction are: K^o=(1.05±0.13)×10^–4, G°=(22.71±0.33) kJ-mol^–1, H°=(62.0±2.3) kJ-mol^–1, and S°=(132±8) J-K^–1-mol^–1. These results have been used together with thermodynamic results from the literature to calculate standard Gibbs energies of formation, standard enthalpies of formation, standard molar entropies, standard molar heat capacities, and standard transformed formation properties for the substances participating in this reaction.Presented at the Symposium, 76^th CSC Congress, Sherbrooke, Quebec, May 30–June 3, 1993, honoring Professor Donald Patterson on the occasion of his 65^th birthday.     

Potentials of Silver and Gold Electrodes of ZrO2-Based Cells in N2+ O2+ CO2+ CO Gas Mixtures

Steady-state electrode potentials in cells with a ZrO₂+ 10 mol % Y₂O₃electrolyte are measured at 400 to 500°C in nonequilibrium N₂+ O₂+ CO₂+ CO gas mixtures containing 0–3 and 0–10 vol % of CO and O₂, respectively. In CO-free mixtures, the potentials obey the Nernst equation. The CO-caused deviation of the potential from its equilibrium value depends on the O₂content and temperature and is due mainly to the CO adsorption at electrodes.     

Theoretical investigation of the structure and stability of salt molecules LiOF,LiOCl, LiSF,LiSCl and ion-molecular complexes Li+·F2, Li+·FCl,and Li+·Cl2

Institute of New Chemical Problems, Russian Academy of Sciences, Chernogolovka. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 1, pp. 3–9, January–February, 1992.     

Diffusion of Cs+ and Zn2+ through Nafion-117 ion exchange membrane

This paper discusses the diffusion of Cs⁺ and Zn²⁺ ions through Nafion-117 cation exchange membrane using radiotracer technique. The validity of the Donnan's equation is checked for these ions using⁶⁵Zn and¹³⁷Cs radiotracers. The paper also discusses the diffusion of Cl^– and I^– anions studied by using³⁶Cl and¹³¹I radiotracers. The probable mechanism of diffusion of these anions in the presence of Zn²⁺ cations is suggested.     

[2+4]Cycloaddition of perfluoroazomethines

Conclusions Perfluoroazomethines react with cyclopentadiene at 160–180°C to form [2 + 4]-cycloadducts, viz., fluorine derivatives of 5-azabicyclo[2.2.1]hept-2-ene. These derivatives were used to obtain the products of the radical addition of chlorine, bromine, and bis(trifluoromethyl)-nitroxyl.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1437–1440, June, 1986.     

Radioisotope excited EDXRF analysis of sediment core samples from the southern part of the Black Sea +

In all 43 sediment samples were collected as gravity cores in depthfrom 70 to 150 cm, from the 20 sampling sites of the continental slope ofthe southern part of the Black Sea, during 1978. The samples were quantitativelyanalyzed by radioisotope excited energy dispersive X-ray fluorescence spectrometry(EDXRF) using fundamental parameter technique (FTP). The investigated sedimentsamples were the organic rich-mud components of the core samples, which wereknown as rich in metals. The metal concentration ranges were as follows: Ca(3.1–12.9%), Ti (1000–2000 µg/g), V (40–150 µg/g),Cr (30–200 µg/g), Mn (200–1500 µg/g), Ni (25–100µg/g), Cu (20–70 µg/g), Zn (20–50 µg/g), Br(15–670 µg/g), Rb (5–90 µg/g), Sr (80–700 µg/g),Y (10–20 µg/g), Mo (10–111 µg/g), Zr (20–190µg/g), Cd ( <1–5 µg/g), Sb ( <1–5 µg/g),I (10–430 µg/g), Ba (100–1650 µg/g), La (5–18µg/g), Ce (12–38 µg/g) and Nd (6–17 µg/g). Thesediment cores systematically collected in 1978 by Mineral Research and ExplorationInstitute of Turkey (MTA) are the oldest available sediment samples from theTurkish coastline of the Black Sea. Therefore, the results may be used asreferences for monitoring possible future metal pollution.     

Coordination and spectral-luminescence characteristics of Ce3+ in nonaqueous solutions

By means of luminescence spectroscopy, through the characteristics of interconfiguration transitions 4f^n–1 5d 4fⁿ, a study has been made of the composition and structure of the coordination sphere of Ce³⁺ in anhydrous alcohols in the presence of the inorganic anions ClO^– ₄, Cl^–, Br^–, and SCN^–. For solutions of CeCl₃ - or CeBr₃ or Ce(SCN)₃ ^–, it has been shown that the inner-sphere complexes Ce(R - OH)_8–XA_X ^{3 -x} dominate (where R 0B is a solvent molecule; A is an anion) in the concentration interval from 10^–4 to 10^–2 M, x = l. In solutions of Ce· (ClO )₄ in addition to the inner-sphere complex' an anion-freer form Ce(R³⁺ OH)_{6 3+} has been found. In the solutions that were investigated, dynamic equilibrium constants were determined, and also the absorption and luminescence characteristics of the individual species.A. N. Sevchenko Scientific-Research Institute of Applied Physics Problems, Belorussian University, Minsk. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, No. l, pp. 114–119, January–February, 1991. Original article submitted May 3, 1990.