Showing papers by "Kenta Ooi published in 1998"
TL;DR: In this paper, the complex formation behavior between boric acid and triethanolamine (TEA, H3L) in aqueous solutions was thoroughly examined by 11B NMR spectroscopy.
Abstract: The complex formation behavior between boric acid and triethanolamine (TEA, H3L) in aqueous solutions was thoroughly examined by 11B NMR spectroscopy. In chloroform, one 11B NMR signal appeared due to triethanolamine borate (TEA-B, L-B) at −4.6 ppm, whereas in aqueous solutions two signals appeared due to TEA-B and a new boron complex at −5.8and −9.5 ppm, respectively, in addition to a signal ascribed to boric acid and borate ion. The area ratios between the signals at −5.8 and −9.5 ppm were almost constant regardless of the molar ratios between boric acid and TEA, suggesting that the new complex is a 1 : 1 complex between boric acid and TEA. Both complexes were stable in aqueous solutions over the pH range of 6.7 to 10.9. Their chemical shift values were constant and independent of the pH value. This also implies that the new complex has a tetrahedral structure around the boron atom, similar to TEA-B. Based on 1H and 13C NMR spectroscopy and a preliminary examination of complexation between boric acid an...
24 citations
TL;DR: In this paper, the intercalation reaction of 4-phenylazoaniline into montmorillonite pillared with tetramethylammonium ions has been performed successfully in supercritical CO2 at T = 313 K (P = 15 MPa), demonstrating that SCC is a better medium than organic solutions for intercalating large amounts of guest molecules into a host compound.
7 citations
TL;DR: Layered titanium phosphates and heat-treated tin phosphate showed high separation factors (1015-1018) for lithium isotopes; the fractionation properties could be explained by considering two factors: the degree of Li+ dehydration in the solid phase and the affinity of the ion exchange site toward Li+ as mentioned in this paper.
Abstract: Layered titanium phosphates and heat-treated tin phosphate showed high separation factors (1015-1018) for lithium isotopes; the fractionation properties could be explained by considering two factors: the degree of Li+ dehydration in the solid phase and the affinity of the ion-exchange site toward Li+
6 citations