Détermination des chaleurs de mélange des systemes ternaires

Heats of mixing H^E at 303.15 K and 1.013 bar are reported for two ternary liquid mixtures piperidine(1)+n-heptane(2)+cyclohexane(3) and piperidine(1)+n-octane(2)+cyclohexane(3). A Redlich-Kister type smoothing equation was used to represent and correlate the results. A dispersive quasichemical (DISQUAC) theoretical model was used for predicting the heats of mixing H^E at 303.15 K and 1.013 bar for these two ternary liquid mixtures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermodynamique des complexes metalliques ternaires des amino acides: Etude du systeme Ni(II)—Glycine—DL-α-alanine

Standard enthalpies and entropies of formation for binary and ternary Ni(II) complexes with glycine and DL-α-alanine were calorimetrically determined at 25°C in aqueous solution (I = 1 M NaClO₄). The evolution of these values from binary to ternary complexes is discussed on the basis of the stabilization characterizing the stability constants of the ternary species which have been previously calculated under the same experimental conditions.     

Calcul des diagrammes de fusion de melanges ternaires. Technique numerique et application au systeme NaCl-CaCl2-MgCl2

An efficient numerical method for the calculation of the ternary phase diagrams is presented. The results obtained with the NaCl-CaCl₂-MgCl₂ ternary system are given.     

Thermodynamique des complexes metalliques ternaires des amino-acides. II. Etude des systemes Ni(II)—glycine—valine Ni(II)—alanine—valine

Standard enthalpies and entropies of formation for binary and ternary Ni(II) complexes with pairs of the following amino acids as ligands: glycine, DL--alanine and DL-valine, were calorimetrically determined at 25°C in aqueous solution using 1 M ionic strength (NaClO₄).

The results are discussed according to every possible pathway for mixed ligand complex formation and also using the classical statistical methods. Temperature-dependent and temperature-independent components of the thermodynamic data are calculated. In all cases with these ligands involving identical coordination sites, the temperature-independent component of the enthalpy change is closely constant for binary as well as for ternary complexes. All the data show that the stabilization of mixed ligand complexes with respect to the parent binary complexes arises from the entropy term and is maximum for the Ni(II)—glycine—valine system.     

Solvatation preferentielle dans les systemes ternaires polyvinylpyrrolidone/solvant halogene/solvant donneur de proton—II: Etude,par spectroscopie infra-rouge,des interactions hydrogene

We have studied, for dilute solutions of polyvinylpyrrolidone in halogenated solvent/protondonor solvent mixtures, the spectroscopic perturbations of the stretching vibration band v(CO) of the polymer and those of the stretching vibration band v(OH) in the particular case of trifluoroethanol. These measurements indicate a hydrogen-bond association polymer/proton-donor solvent, increasing with the proton-donor concentration in the mixture. The interaction with solvents such as trifluoroethanol and phenol is much stronger than that due to ethanol. Hydrogen-bond complexes are of $\text{1}\text{1}$ type. However, study of the v(CO) and v(OH) bands leads, in the case of trifluoroethanol, to the proposal of a complex of $\text{1}\text{2}$ type the structure of which is suggested.     

Etude des equilibres solide-liquide du systeme pseudo-binaire LiPO3-RbPO3

The LiPO₃-RbPO₃ system was investigated by differential thermal analysis, X-ray diffraction and infrared spectroscopy. The system forms two linear polyphosphate compounds: Li₂Rb(PO₃)₃ and LiRb(PO₃)₂. The first one melts in a peritectic reaction at 552°C and the second one melts congruently at 613°C. It is established that both compounds are mixed polyphosphates with chain structure. Their reticular distances and IR characteristics are given here.

     

Etude viscosimetrique du systeme polystyrene-cyclohexane-acetone

Determinations of viscosities have been made on the polystyrene-cyclohexane-aceton system for various monodisperse polystyrene samples with molecular weights between 50000 and 870000 and for various compositions of cosolvent mixtures. The intrinsic viscosity (η), the parameters B and K_θ exhibit maximum values at the equimolecular composition which also corresponds to the maximum values of the thermodynamic excess functions. The variations of K_θ and B are discussed in terms of the binary interaction parameters χ_ij.     

Etude du systeme binaire selenium-tellure

Integral heats of mixing have been measured at 738 K by drop calorimetry. Liquidus and solidus temperaturesT ₉ and recrystallisation temperatures have been measured by thermal analysis.

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Zusammenfassung Integrale Mischungswärmen wurden bei 738 K kalorimetrisch gemessen. Liquidus-, Solidus- and Rekristallisationstemperaturen sowieT ₉ wurden thermoanalytisch bestimmt.

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738 . , _g .

     

Etude variationnelle d'une double perturbation. Application au calcul des constantes de couplage entre spins nucleaires

The calculation of molecular electronic polarizability tensor components is presented in the CNDO approximation using several methods, on one hand a perturbation calculation, on the other hand a variational method. Results obtained on thirty molecules are used to compare these methods and to discuss their usefulness.

     

Solvatation preferentielle dans les systemes ternaires polyvinylpyrrolidone/solvant halogene/solvant donneur de proton—I: Etude par diffusion de la lumiere

Light scattering measurements of apparent molecular weights show that polyvinylpyrrolidone dissolved in 1,2-dichloroethane (or chloroform)/ethanol (or acetic acid) mixtures adsorbs preferentially either of the two solvents according to the range of composition. The preferential solvation of polyvinylpyrrolidone by proton-donor solvents was confirmed by experiments involving fluoroethanols and phenols. Comparison of our experimental data with preferential adsorption theory leads to rather good agreement for the polyvinylpyrrolidone/chloroform/ethanol system.     

Etude des transformations de quelques proteines au contact du nickel

The purpose of this paper is to study the alteration of some proteins which are in contact with nickel for some time. On the one hand the UV spectroscopy gives us some indications on the modification of biological molecules. On the other hand, the electrochemical behaviour of nickel in protein solutions shows that these molecules may participate to the charge transfert, and also, in some case, to the mass transfert. An important feature of the results is that the biological molecules may be adsorbed on the metal surface, in a large potential range, and so, participate directly to the nickel electrochemical dissolution.     

Etude des systemes donnes par l'hexafluorure d'uranium avec les fluorures de cesium et de nitrosyle

This study is devoted to two typical systems: solid fluoride (CsF), UF₆ and volatile fluoride (NOF), UF₆. The differences in the dissociation pressures of CsUF₇ and Cs₂UF₈ and of NOUF₇ and (NO)₂UF₈ along with spectral observations make it possible to prepare these compounds in a pure form. Vibrational spectroscopic studies and ¹⁹F chemical shift measurements allow one to propose symmetries corresponding to point group D_5h and O_h for the heptafluoroanions and the octafluoroanions respectively. Crystal forces are likely responsible for the observed slight lowering in symmetry form the above idealized structure. At low temperature, a change of structure is observed for NOUF₇, the symmetry for the heptafluoroanion becoming lower or equal to the symmetry corresponding to the C_2v. group.     

Etude variationnelle d'une double perturbation. Application au calcul des constantes de couplage entre spins nucléaires

Fermi contact contribution to nuclear spin coupling constants of the H-D molecule is calculated with two kinds of variational functions which include a singularity at the nuclei. With the first function the total perturbed second order energy is minimized, while with the second one we have used the minimum condition of the self-coupling energy. These calculations necessitate a perturbation operator having a weaker singularity than the classical Fermi operator. We have used the Gregson, Hall, and Rees operator.

Ce travail fait partie de la thèse de Doctorat-ès-Sciences de Monsieur J. Paviot (Bordeaux 1971) enregistrée aux archives originales du C.N.R.S., sous la n^o AO 2755.     

Cinetique de polymerisation de monomeres complexes par des acides de Lewis. Etude du systeme methacrylate de methyl-chlorure de zinc-azobisisobutyronitrile

The polymerisation of methyl methacrylate (MMA) initiated by azo-bis-isobutyronitrile (AIBN) in the presence of ZnCl₂ as complexing agent has been investigated. Increase of the polymerisation rate and a minimum in the average polymerisation degree were observed by increasing the ZnCl₂ concentration. By assuming the existence of complexes {AIBN · ZnCl₂} and {MMA · ZnCl₂}, a kinetic scheme is proposed; it is in good agreement with the experimental results and allows calculation of the characteristics of the system.     

Diagrammes d'equilibre des systemes d'halogenures CuY-MYn

Phase diagrams for the series of CuY-M^IY and CuY-M^IIY systems (whereM ^I=Li, Na, K, Rb, Cs, Tl,M ^II=Zn, Cd, Hg, Sn, Pb andY=Cl, Br, I) were compared. Changes and trends accompanying the increase of charge of the second cation were discussed.

     

Sur la pseudo-compatibilite des systemes polymere-polymere

Compatibility in polymeric systems is discussed. By considering the dimensions of the macromolecules and their restricted mobility, in addition to incompatible and compatible polymeric systems, there are pseudo-compatible mixtures which have great practical significance; because of negligible rate of phase separation, these systems show appreciable “apparent” compatibility. The pseudo-compatible polymeric mixtures are very fine dispersions, stabalized by different forces of interaction, the stability being higher the greater the degree of dispersion.