Shigezo Shimokawa

NMR relaxation study of water molecules in concentrated zinc chloride solutions

The proton spin‐lattice relaxation time and self‐diffusion coefficient of water in concentrated aqueous ZnCl2 solutions have been measured as a function of salt concentration and temperatures. The intermolecular and intramolecular contributions of the dipolar interactions to the relaxation rate were determined separately with the aid of the self‐diffusion data. The present data indicate that the translational motion of water molecules in ZnCl2 solutions is retarded more significantly than their rotational motion with decreasing water content.

Analysis of the N.M.R. spectrum of pyrrole

By the N-decoupling technique the signal of the N-H proton in pyrrole was clearly unveiled. Using the full spectrum, including the N-H band, the N.M.R. parameters for all five protons of the system were accurately determined. Assuming an AA′BB′X system, a computer simulation was performed; assignments were made for the observed lines. Based on the assignments, the N.M.R. parameters were determined with high accuracy by an iteration method. By using a partial decoupling experiment, the relative signs of the coupling constants between the N-H proton and the ring protons were determined to be the same.

Effect of far-infrared light irradiation on water as observed by X-ray diffraction measurements

X-ray diffraction measurements were made on water irradiated with far-infrared (FIR) light. It was found that the X-ray diffraction intensity at a 2θ angle of 30° increased by about 2 times with the irradiation. The increase in the X-ray diffraction intensity was interpreted in terms of the destruction of water clusters.

A 13C NMR probe for high-temperature and high-pressure experiments☆

Abstract A simple pressurized, internally heated, high-temperature 13 C NMR probe for work in the temperature range from 293 to 823 K and pressure range from 0.1 to 100 MPa is reported. The sample cell has a capillary opening and the vessel was pressurized by inert gas. From the measurements of 13 C spectra of residue of thermal degradation of polyvinyl chloride, the process of the polycondensation of rings was directly observed. These results show that the 13 C spectra contain more clear information than the corresponding proton spectra.

High temperature and high pressure 1H n.m.r. and e.s.r. studies on coal liquefaction reactions

Changes in chemical reactions during coal liquefaction of Yallourn brown coal and Akabira bituminous coal were monitored by using high temperature and high pressure 1H n.m.r. A simple high temperature and high pressure e.s.r. cell was constructed and the variation in concentration of free radicals during coal liquefaction reactions was monitored under the same experimental conditions as for n.m.r. With the liquefaction and coking reaction, typical spectra of n.m.r. and e.s.r. were obtained and could distinguish the reaction steps: swelling; liquefaction; coking. The combination of high temperature and high pressure n.m.r. and e.s.r. is promising to the chemistry of coal liquefaction reactions.

Analyses of the N.M.R. spectra of pyrrole derivatives: pyrrole-2-carboxylic acid and pyrrole-2-aldehyde

By the N-decoupling technique the spectrum of the N-H proton in pyrrole-2-carboxylic acid and pyrrole-2-aldehyde was clearly unveiled. Using the full spectra including the N-H band, the N.M.R. parameters of the two pyrrole derivatives were determined with a high degree of accuracy by computer simulation. It was demonstrated that two types of long-range coupling exist for the aldehyde proton of pyrrole-2-aldehyde. From partial decoupling experiments by using the third r.f. field the relative signs of all coupling constants were determined to be the same for the two pyrrole derivatives, except for a long-range coupling, J cho-nh , in pyrrole-2-aldehyde. Based on an assumption that the long-range couplings of the aldehyde proton originate from the pi electrons, it was concluded that the absolute signs of all coupling constants among the ring protons of pyrrole-2-aldehyde were positive.

Simultaneous and direct measurement of gas–liquid density at high temperature and high pressure using the nuclear‐spin projection method

A new technique to measure gas–liquid densities using the one‐dimensional projection method is presented. The measurements were made in an NMR autoclave under high‐temperature and high‐pressure conditions. Some of the results of densities of cyclopentane determined from the room temperature to the supercritical regions are reported.

NMR studies of metal-nonmetal transition in lithium-methylamine solutions

Abstract The Knight shift and the spin-lattice relaxation time of 7 Li and 1 H have been measured in Li-methylamine solutions, in which a transition from the metallic to the nonmetallic states occurs.

Clathrate-like Ordering in Liquid Water Induced by Infrared Irradiation

X-ray diffraction experiments revealed that when liquid water is exposed to infrared irradiation a solidlike ordering of water molecules is induced. The ordered structure was found to be either of the clathrate hydrates I and II or their mixture. It takes more than 24 h for the ordered structure to return to the original state, as long as it is kept below 278 K.

High-temperature high-pressure 1H-NMR study on formation of carbon spherules

Donnees sur la formation de spherules de carbone de 2 μm de diametre, environ. Etudes, par spectrometrie RMN- 1 H, haute temperature et haute pression, de processus de carbonisation de petites quantites de poix, dans des hydrocarbures aromatiques