Katsuko Takaizumi

The freezing process in methanol-, ethanol-, and propanol-water systems as revealed by differential scanning calorimetry

Solid-liquid phase diagrams, including metastable phases, have been obtained by differential scanning calorimetry (DSC) for methanol-, ethanol-, and propanol-water systems. The metastable solid phases which are initially formed on cooling were detected for these three systems, in order to analyze the freezing processes and to correlate the formation of the metastable phases with solution structure.

Regularity on the distribution of scandium chelate in TTA-alcohol system

The distribution of scandium chelate with thenoyltrifluoroacetone (TTA) between 11 alcohols and the aqueous perchlorate solution of ionic strength of 0·1 was studied. After it has been confirmed that the extractable chelate is the same species shown as ScA3 in all alcohol systems, except in 1-butanol and 2-methyl-1-propanol, the distribution coefficient of scandium chelate (PM) and that of TTA (PHA) were compared, and it was found that there is an evident correlation expressed as log PM = n log PHA + const. This correlation is the same with the one obtained in the so-called inert solvent systems.

Liquid–Solid Phase Diagrams of PrOH–Water and BuOH–Water Systems from Differential Scanning Calorimetry

The freezing process in i-PrOH- and tert-BuOH-water systems were investigatedto obtain reliable liquid=nsolid phase diagrams by differential scanning calorimetry(DSC), especially focusing on formation of metastable solid phases. In addition,n-BuOH, sec-BuOH, and i-BuOH were studied within their solubility limits. Inmost systems studied, there exist metastable solid phases and, with increasingbranching of alkyl groups, the number of metstable solid phases increases. Themost complicated is i-PrOH-water where curious phenomena were found,probably because of the abnormally high viscosity of the solution at low temperatures.The relation between hydration in the liquid and formation of solid phases isdiscussed. It is suggested that the positional relation between methyl groups andalcoholic OH groups plays an important role; the increase in number ofalphamethyl group seems to strengthen hydration and stabilizes solid hydrates.

Apparent and partial molar volumes of quaternary phosphonium halides in aqueous solutions

The apparent and partial molar volumes in aqueous solution were obtained for (n-Bu)4PBr and (n-Bu)4-nPhnPCl (n=1–4) at six temperatures from 1 to 55°C. The apparent molar expansibilities were also obtained. The hydrophobic character of the cations is reduced by replacing butyl groups with phenyl groups, as evidenced by the decrease in the magnitudes of the Bv-coefficient (negative for all n) and of the temperature dependent extrema found in the apparent molar volumes and expansibilities as a function of concentration. However, the extrema exist even with BuPh3PCl at low temperatures. The result suggests that the phenyl groups weakly affect the butyl cospheres and cation-cation interactions.

Apparent molal volumes of phosphonium halides at 15, 25 and 35°C

AbstractThe densities of aqueous solutions of the phosphonium halides, Bu4-nPhnPX(n=0–4), some of which were synthesized from the phosphines, were measured at 15, 25 and 35°C. Partial molal volumes at infinite dilution,

Volumetric study on a Co(III) rotaxane complex in aqueous solutions at 25°C

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Volumetric study of the interaction between chloride salts and polyvinylpyrrolidone in aqueous solution

, and Bv coefficients for the apparent molal volumes were determined at each temperature. For the first four cations