Keniti Higasi

The dielectric relaxation of mixtures of water and primary alcohol

Dielectric measurements over a microwave frequency range 10 MHz–15 GHz were carried out by the use of new time domain reflectometry equipment on the mixtures of water with five primary alcohols, viz., methanol, ethanol, and n‐propanol in the concentration range 0≤x≤1 and n‐butanol and amyl alcohol in the range 0≤x≤0.5 at room temperature; x being the mole fraction of water. The systems of water and two alcohols of low molecular weight are characterized by a single relaxation with a distribution parameter of the unity or near to it. The molecular reorientation in the mixtures as well as water and these alcohols is a cooperative process involving a large number of molecules with the hydrogen‐bond linkages (O–H⋅⋅⋅O). Dielectric behavior of the mixtures of water and methyl or ethyl alcohol is due to the structure of a hydrogen‐bonded network being microscopically homogeneous. Microscopic heterogeneity occurs in the mixtures of water and higher alcohols.

The structure of water and methanol in p-dioxane as determined by microwave dielectric spectroscopy

Dielectric measurements were performed on water–p‐dioxane and methanol–p‐dioxane mixtures using time domain reflectometry over the frequency range 0.1–10 GHz. In the case of water–p‐dioxane mixtures, the relaxation strength normalized by the number of water molecules per unit volume is independent of the molar fraction of water xW if xW 0.66. However, the relaxation time of pure methanol is too large for clusters consisting of three molecules. It is suggested that the chainlike clusters form network structures.

A theoretical approach to the dielectric relaxation of liquid alcohols

The dielectric relaxation mechanism of liquid alcohols was studied by assuming the association equilibrium between hydrogen‐bonded chain multimers. The dipole inversion arising from the cooperative rotation of the OH groups of the multimers was considered to be the main mechanism of the dipole relaxation. The stochastic model of one‐dimensional random walk was introduced to explain the dipole inversion process and it was found that the dipole relaxation time of an n‐mer is proportional to n+1. Based on this result and the stoichiometry of the association equilibrium, we calculated the dielectric constants and losses of liquid alcohols as a function of ω, which are in fair agreement with the experimental results.

Infrared and raman studies of the dimeric structures of 1,3-dihydroxyacetone, d(+)- and dl-glyceraldehyde

Abstract 1,3-Dihydroxyacetone was found to crystallize in five different crystal forms, four of which consist of dimers, and the fifth consists of monomers. Infrared and Raman data indicate that dimeric 1,3-dihydroxyacetone has the centrosymmetric structure 2,5-dihydroxymethyl-2, 5-dihydroxy-1,4-dioxane in all the four crystal forms of the dimer, and crystalline DL-glyceraldehyde has the centrosymmetric structure 2,5-dihydroxymethyl-3,6-dihydroxy-l,4-dioxane. D(+)-glyceraldehyde, a viscous liquid at room temperature, was found to be a mixture of the monomers and asymmetric dimers having five-membered and/or six-membered ring structures. In the melted state, both 1,3-dihydroxyacetone and DL-glyceraldehyde exist as mixtures of monomeric and dimeric molecules. Partial assignments of the IR and Raman bands are also made.

Infiiared and raman studies of the structure of crystalline glygolaldehyde

Abstract Two stable crystal forms of glycolaldehyde were obtained by recrystallization from methanol at different temperatures. They are clearly distinguishable from each other by IR and Raman spectra. We conclude, based on IR and Raman data, that the both forms consist of centrosymmetric dimers having 2,5-dihydroxy-1,4-dioxane structures. In the crystal (α form) obtained at higher temperatures above 50 °C the two OH groups both occupy the equatorial position. For the crystal (β form) obtained at lower temperatures below 40 °C, it seems more probable that the two OH groups both occupy the axial position, although the conformation identical with that in the β form is not wholly impossible for the β form. Non-centrosymmetric conformations can be ruled out for either of the two crystal forms. Vibrational assignments are given for some of the modes which are sensitive to deuterium substitution of the OH groups.

Infrared spectra and lattice vibrations of alkali and alkaline—earth metal sulfates

Abstract Infrared spectra from 4000 to 30 cm −1 of Li 2 SO 4 , K 2 SO 4 , Rb 2 SO 4 , Cs 2 SO 4 , BeSO 4 , MgSO 4 and CaSO 4 were measured. Infrared bands due to librational motions of sulfate ions were observed below 200 cm −1 in all the sulfates. The selection rules derived from site group analyses were found to be applicable to librational modes even when internal vibrations of sulfate ions did not observably reflect site symmetry effects. The influence of the nature of metal ions on internal vibrations of sulfate ions as well as lattice vibrations was examined.

Submillimetre absorption of rod-like polar molecules in liquids

An account of calculations of the Poley absorption based on the assumption that this is due to librations of polar molecules within cages of neighbouring molecules is given. Absorption is calculated for two forms of the potential, in which the molecules move, by use of the autocorrelation function method.

Polarity and Molecular Structure of Diphenylene Dioxide

ニフェニレンニオキシド及びその誘導體につき双極子能率を測定し,この分子が平面構造を有せずチアントレン,セレナントレンと同様屏風状構造を有することを確めた.一般にC6H4〓C6H4型分子に就きX原子の原子價角をその双極子能率より算出し,次ぎに其の結果を用ひて光學的異性體存否の問題を論じた.