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91.
Keiichi Satoh Zhang Xiang-Yu Masashi Miya-iri Akiko Honma Kiyoshi Sawada 《Monatshefte für Chemie / Chemical Monthly》2006,137(11):1375-1383
Summary. The ion-pair solvent extraction behavior of ethylenediaminetetraacetate (EDTA) anion by various tetraalkylammonium ions was investigated at 25.0 ± 0.1°C. The extraction of EDTA exceeded 90% from the basic aqueous solution into the organic solvents such as n-hexane and benzene derivatives containing tri-n-octylmethylammonium chloride, but EDTA was hardly extracted from acidic solution. Among the chemical species of EDTA in aqueous solution, edta
4− is the most extractable one. On the other hand, the extraction of EDTA was less than 1% into chloroform and 1,2-dichloroethane even from the basic aqueous solution. The effect of the structure
of alkylammonium ion was also examined. Tetra-n-hexylammonium and tetra-n-octylammonium ions could not extract EDTA even from the basic aqueous solution, while the use of tri-n-octylmethylammonium and di-n-lauryldimethylammonium ions enhances the extraction of EDTA. These results suggest that the steric hindrance in the ion-pair of alkylammonium and EDTA anion in the organic phase affects the extractability of EDTA containing ion-pair. The solution structure of ion-pair in the organic phase was calculated by MMFF force field and the steric
effect in the ion-pair was also suggested. From the extraction constants obtained, the possibility of the extraction separation
of EDTA has been shown.
Present address: Chemistry Department, Heilongjiang University, Harbin, China 相似文献
92.
93.
[reaction: see text] We have developed an efficient copper-catalyzed allylation of carbonyl derivatives using allyl(2-pyridyl)silanes, in which the strong directing effect of the 2-pyridyl group was observed. A useful synthesis and allylation of substituted allyl(2-pyridyl)silanes is also described. 相似文献
94.
Tanaka K Mori M Xu Q Helaleh MI Ikedo M Taoda H Hu W Hasebe K Fritz JS Haddad PR 《Journal of chromatography. A》2003,997(1-2):127-132
In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression. 相似文献
95.
Yoshida H. Yang M. Masaka K. Houshito Y. Mashiko K. Nakamura S. 《Journal of Thermal Analysis and Calorimetry》2002,70(3):703-711
Phase transition behavior of polyesters derived from 2,7-phenanthrene dicarbonic acid diethylester and alkanediols with even
methylene carbon number was investigated by the simultaneous DSC-XRD method. The smectic A phase was observed on cooling from
the molten state. The transition entropy from the isotropic state to the smectic A phase was about 9.0 J mol-1 K-1, which depended on the methylene carbon number. The linear expansion coefficients, based on the (001) spacing of the crystalline
phase at room temperature, were 1.3·10-4 K-1 (crystalline phase), 5.7·10-4 K-1 (crystallization region), 1.7·10-3 K-1 (smectic A phase) during cooling, and 1.5·10-4 K-1 (crystalline phase), and 1.0·10-3K-1(melting region) on heating.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
96.
Hiroshi Suda Masatoahi Motoi Masatoshi Fujii Shigeyoshi Kanoh Hiroshi Yoshida 《Tetrahedron letters》1979,20(47):4565-4568
Enantioselective reductions of prociral ketones with chiral hydride reagent prepared from optically active 2,2′-diamino-6,6′-dimethylbiphenyl and lithium aluminum hydride were accomplished in O.Y. more than 50%. 相似文献
97.
Transport phenomenon of three sulfonated azo dyes, C.I. Acid Red 88, C.I. Direct Yellow 12, and C.I. Direct Blue 15 into water-swollen cellulose membranes has been analyzed on the basis of parallel transport theory by surface and pore diffusion. Langmuir equation was applied into the mass balance equation to estimate dye concentration in the pores. The results were compared with the results obtained by applying Freundlich equation in our previous papers. The surface diffusivity (D
s) and the pore diffusivity (D
p) for the parallel diffusion model obtained by applying Langmuir equation agreed with those obtained by applying Freudlich equation. The theoretical concentration profiles for parallel diffusion calculated usingD
s andD
p coincided accurately with the experimental data when we applied either Langmuir or Freundlich equations. 相似文献
98.
Kiyoshi Tanemura Yoko Nishida Tsuneo Suzuki Koko Satsumabayashi Takaaki Horaguchi 《Journal of heterocyclic chemistry》1997,34(2):457-460
1,3-Dithianes 1 , 1,3-dithiolanes 2 , and diphenyl dithioacetals 3 derived from cinnamaldehydes reacted with 2,3-dichloro-5,6-dicyano-p-benzoquinone in aqueous solvents to give benzaldehydes 4 . Hydride transfer from 1–3 to 2,3-dichloro-5,6-dicyano-p-benzoquinone followed by hydrolysis and oxidative carbon-carbon bond cleavage would produce benzaldehydes 4 . 相似文献
99.
Patrícia P. C. Sartoratto I. Valria P. Yoshida 《Journal of polymer science. Part A, Polymer chemistry》1992,30(11):2333-2340
In this work several polyorganosilylenes were synthesized including homo-and copolymers containing SiMe2 and SiPh2 units. A Wurtz-type coupling reaction of the respective dichlorodiorganosilanes with sodium metal, varying the Ph2SiCl2/Me2SiCl2 ratio was the chosen synthesis method. Products with different characteristics for solubility, structure (cyclic or linear), composition, and molecular weight distribution could be obtained depending on the comonomer ratios employed. The polysilane derivatives were characterized by infrared spectroscopy (IR), proton nuclear magnetic resonance (1H-NMR), and gel permeation chromatography (GPC). Valuable information related to the comonomers' reactivities was obtained, such as molecular weight distribution, composition, and relationships between yields of soluble, insoluble, and cyclic materials of each polycondensation reaction. © 1992 John Wiley & Sons, Inc. 相似文献
100.
The structural change from the porphyrin free base to monoacid and diacid by successive protonation has been studied by the IR, visible and NMR spectroscopy. The results have indicated that the cation and anion of the porphyrin diacid are strongly associated through H-bonding. The far IR spectra show especially marked differences in the free base, monoacid, and diacid due to the changes of the inner core of the porphyrin ring. 相似文献