摘要:

The formation of complex anions in molten halide systems is treated semi-quantitatively by a discrete complex anion model. The treatment is a more general application and extension of an approach reported previously by the author. By assuming the existence of discrete MY42−tetrahalo complex anions, the model gives good agreement to experimental enthalpies and entropies of mixing and electrical conductivities in a large number of different halide systems of the general formula MY2–AY, where M is a divalent metal, and A is an alkali. Very few adjustable parameters are required. The parameters provide semi-quantitative basicity (or acidity) scales by which molten salts and slags may be classified. The relationships of these basicity scales to ionic radii, ligand field stabilization energies, etc. are shown. General thermodynamic and mathematical aspects of the problem of complexing are discussed, particularly as regards the proper method of calculating the degree of dissociation of the complexes.

ISSN:0008-4042    

DOI:10.1139/v71-658

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

With a Tian–Calvet microcalorimeter, heats of dilution at 25 °C have been measured for aqueous and acid (0.2 NHCl) solutions of polyacrylic acid and of propionic acid, and for aqueous solutions of the sodium salts of polyacrylic acid. The results are interpreted in terms of the change in structure of water resulting from the lengthening of the solute molecule. The heat of dilution of moderately concentrated solutions of sodium polyacrylate can be explained by the theory of Eigen and Wicke.

ISSN:0008-4042    

DOI:10.1139/v71-659

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The solubility of hydrogen gas in the dimethyl sulfoxide (DMSO) – water system has been measured as a function of temperature from 25 to 80 °C. A distinct minimum occurs in the solubility, as expressed on the molar scale, in the region 25–35 mol% DMSO at 25 °C. As the temperature is raised towards 80 °C the minimum becomes less pronounced. The maximum deviation from calculated "ideal" behavior is found at 32 ± 5, 35 ± 5, and 32 ± 5 mol% DMSO for 25, 50, and 80 °C, respectively.A maximum is observed for both the partial molal entropy and heat of solution of hydrogen in the same solvent composition region. These results are discussed in terms of a changing entropy and energy of hole formation in the solvent with composition, which in turn is related to DMSO–water interaction in solution.A temperature-dependent equilibrium between DMSO•2H2O and DMSO•3H2O complexes in solution is proposed in an attempt to correlate the considerable data which have been reported in the literature for the DMSO–water system. The second complex is thought to be present in significant quantity only at temperatures well below 25 °C.

ISSN:0008-4042    

DOI:10.1139/v71-660

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The p.m.r. spectra of Dowex AG 50W, X8, resins containing multivalent counterions have been measured. The ionic molal shifts in the exchanger phase are compared with those reported in homogeneous aqueous solutions. The spectral results are consistent with the concentrated electrolyte model of ion-exchange resins. Concentration and temperature dependence of proton chemical shifts in multivalent ionic forms of the resin suggests that ion association at high crosslinkages is more pronounced for counterions with high charge densities. The shapes of the shift-molality plots are explained by postulating that, at high crosslinkages, Mg2+ion and the fixed —SO3−group form "contact-ion pair" while the formation of "solvent-separated ion pair" is important in Be2+and Al3+forms of the resin. The anomalous trend in the hydration number values for magnesium and aluminum resinates can be understood as due to the long-range ordering of water structure in the presence of structure-forming ions. The p.m.r. spectra of resin–methanol system have been recorded at room temperature and at −65 °C. Failure to observe the resonance signal due to the cationic solvation shell at low temperature is attributed to the high degree of ion association under the conditions prevailing in the resin medium.

ISSN:0008-4042    

DOI:10.1139/v71-661

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Isothermal compressibilities of seven organic liquids have been determined by analytical ultracentrifuge techniques, in good agreement with literature values obtained by other methods.A least squares regression equation was derived that correlated the logarithmic values of isothermal compressibilities of 7 organic liquids, determined experimentally, with the liquids' surface tensions. This equation was shown to be valid for 11 other organic liquids (values obtained from literature) over a temperature range of 0° through 50°, and a surface tension range of 13 to 44 dyn per cm.

ISSN:0008-4042    

DOI:10.1139/v71-662

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Epimerizations in alkaline medium, by which the methyl 3,6-dideoxy-3-nitrohexopyranosides having the α-L-gluco(1), α-L-galacto(2), α-L-manno(3), and α-L-talo(4) configurations are mutually interconverted, were investigated quantitatively by n.m.r. spectroscopy and by preparative separation of products. The epimeric equilibrium compositions obtained depend on whether an equimolar or a catalytic amount of alkali is supplied. In the first case they are governed by the thermodynamic stabilities of the nitronate anions, and in the second case, by those of the free nitro glycosides. The results are discussed in terms of conformational analysis, and a value of 2 kcal/mol is found for the contribution of the A(1,3)interaction to the conformational free energy in the nitronates. The A(1,3)effect strongly influences not only the product composition at the nitronate equilibrium but also the pathway of epimerization.

ISSN:0008-4042    

DOI:10.1139/v71-663

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The enthalpies of mixing for the charge asymmetrical molten salt systems; MnCl2-ACl, FeCl2–ACl, CoCl2–ACl, NiCl2–ACl, MgCl2–ACl, and CdCl2–ACl (where A represents Li, Na, K, Rb, and Cs) have been calculated by separating the mixing process into two parts. One part of enthalpy of mixing results from the "reaction" to form a tetrahedral complex, MCl42−, and another part of the enthalpy of mixing arises from the "mixing" of the complexed species with the remaining free components. The "complex" species are treated as orderly configurations defined by shorter anion to cation distances within which the central metal cation interacts with the surrounding other metal cations through bridging chloride ions. The model takes into account the difference in the coordination number of the mono- and divalent components. The interaction parameters are shown to depend upon the radii of the alkali metal cations.

ISSN:0008-4042    

DOI:10.1139/v71-664

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The decomposition and phase transitions that occur during the heating and cooling of Ag2CO3were studied by differential thermal analysis at heating rates of 7 to 14° per min. In helium, the Ag2CO3was partially decomposed evolving CO2(7–35% depending upon the method of preparation) giving rise to peaks at 190 to 200°; at 350 to 400°, two endothermic peaks were observed at which CO2and O2were given off simultaneously, leaving silver metal. In CO2the initial partial decomposition gave rise to a peak at about 265°. The partially decomposed Ag2CO3(Ag2O•nCO2, wherenis less than one) gave the same X-ray diffraction pattern as Ag2O, which slowly converted to that for Ag2CO3if left exposed to air or CO2. The Ag2O•nCO2undergoes two distinct "reversible" phase transitions at 180 and 197° on subsequent reheatings. The Ag2O•nCO2behaves like a clathrate-type of structure in which CO2can be entrapped in the Ag2O lattice.

ISSN:0008-4042    

DOI:10.1139/v71-665

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The Raman and infrared spectra have been obtained for a series of rhodium-arylazo complexes RhCl2(PPh3)2(p-XC6H4N2) where X = H, F, Br, CF3, NO2, OCH3, NEt2. The N=N stretching frequency ν(N=N) has been unambiguously identified from its strong appearance in the Raman spectrum and from isotopic substitution studies using15N. Trends in the value of ν(N=N) with thep-substituent X are discussed, in terms of the apparent degree of metal–ligand π-interaction.

ISSN:0008-4042    

DOI:10.1139/v71-666

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Preparations and various interconversion reactions are described for the complexes: [M2X2(PPh2O)2(PPh2OH2], [MX(PPh2O)(PPh2OH)2], [MX(PPh2O)(PPh2OH)(PEt3)], and [M(PPh2O)2]nwhere M = palladium or platinum, X = chloride or bromide, Ph = phenyl, and Et = ethyl. [Pt(PPh2O)2(PPh2OH)2] and [Pt2(PPh2O)4(PPh2OH)2] are also described and all the complexes are assigned structures on the basis of their infrared spectra.

ISSN:0008-4042    

DOI:10.1139/v71-667

出版商:NRC Research Press    

年代:1971

数据来源: NRC