• Bulletin of the Korean Chemical Society
• /
• v.24 no.3
• /
• pp.295-298
• /
• 2003

α,β-Unsaturated aldehydes and ketones are regioselectively reduced to the corresponding allylic alcohols with /Dowex1-x8 system in THF at room temperature. This system is also efficient for the conversion of α-diketones and acyloins to the vicinal diols in refluxing THF.

• Journal of the Korean Chemical Society
• /
• v.27 no.3
• /
• pp.189-193
• /
• 1983

The lithium isotopes separation experiments were carried out in hydrochloric acid with cation exchanger systerns. In these experiments were employed porous sulfonated styrene-divinylbenzene copolymer and Dowex 50w-x8 as cation exchanger. The contents of lithium of the fraction were determined with atomic absorption spectrophotometer. The relative mass of lithium isotopes of the fractions was analyzed on a mass spectrometer. The isotope separation factors of lithium were calculated from the isotope compositions of these eluted fractions. Separation factor for the system in hydrochloric acid and porous sulfonated styrene-divinylbenzene copolymer was found to be 1.0020, and for the case of system in hydrochloric acid and Dowex 50w-x8 was 1.0011${\om}$0.0002. From these results, we found that the separation factor for porous sulfonated styrene-divinylbenzene copolymer ionexchanger is larger than value of Dowex 50w-x8 ionexchanger.

• Journal of the Korean Chemical Society
• /
• v.31 no.1
• /
• pp.45-54
• /
• 1987

Dowex 1-X8 resin ion exchanged with calcon carboxylic acid (CCA-Dowex 1-X8) and 2-methyl-8-hydroxyquinoline(MHQ) impregnated-Amberlite XAD-4 resin (MHQ-XAD-4) were examined for the separation and preconcentration of ferric ion from the various matrices. The stabilities of these resins were investigated, and their capacities on ferric ion were also measured. The effect of pH on the adsorption of ferric ion and matrix ions, such as Al(Ⅲ) and Ca(Ⅱ), was investigated to determine the optimun pH ranges. Separation and preconcentration of iron in aluminium foil and mineral water samples were studied by elution method with these resin columns. The recovered ions by 10ml of 2F nitric acid was determined by flame atomic spectrophotometry. SP-Sephadex C-25 column was used to separate ferrous and ferric ion in mineral water by stepwise elution with ferrozine and 1 % ascorbic acid-ferrozine solution. The concentrated and separated each ion could be determined spectrophotometrically at the analytical wavelenth of Fe(Ⅱ)-ferrozine complex (562nm).

• Journal of the Korean Chemical Society
• /
• v.22 no.6
• /
• pp.412-416
• /
• 1978

Die Trennung von Uranisotopen im System HCl/Dowex 50W-X8, 200∼400 mesh wurde versucht. Mit einer 1m Kationenaustauschersaule und extrem geringen Stromungsgeschwindigkeiten konnte eine Anreicherung von Uran 234 und Uran 235 in der Losung nachgewiesen werden.

• Analytical Science and Technology
• /
• v.6 no.5
• /
• pp.463-469
• /
• 1993

HDBPDA ion exchange resin, {(4, 5) : (13, 14)-Dibenzo-6, 9, 12-trioxa-3, 15, 21, -triazabicyclo [15. 3. 1]heneicosa-(1, 17, 19)(18, 20, 21) triene ion exchange resin : HDBPDA ion exchange resin} had a capacity of 3.8meq/g dry resin. The distribution coefficients of alkali and alkaline earth metal ions on HDBPDA and strongly acidic cation exchange resin, Dowex 50W-X8(200-400mesh) in water, and the various concentrations of hydrochloric acid were determined. Concentration of hydrochloric acid have almost not influenced on the distribution coefficients of alkali and alkaline earth metal ions for the HDBPDA ion exchange resin, but generally the distribution coefficient slightly increased with decreasing concentration of hydrochloric acid. The distribution coefficients of metal ions in water are larger than those in various hydrochloric acid concentration. The distribution coefficients of alkali and alkaline earth metal ions for the Dowex 50W-X8 ion exchange resin increased with decreasing hydrochloric acid concentration. Especially, the distribution coefficients of alkaline earth metal ions increased rapidly compared to those for alkali metal ions. The distribution coefficients of alkali and alkaline earth metal ions on HDBPDA ion exchange resin increased in a linear manner with decreasing acid concentration, and the slope, d log Kd/d log $M_{HCl}$ is about -0.2. Of the distribution cofficients of alkali metal ions on Dowex 50W-X8, at range of moderate hydrochloric acid concentration, the slope is about -1, while the slope for alkaline earth metal ions is about -2. However, at very low hydrochloric acid concentration, the linear variation between distribution coefficient and acid concentration was not occurred, but the slope was deviated from above values at low acid concentration.

• Journal of the Korean Chemical Society
• /
• v.24 no.5
• /
• pp.356-360
• /
• 1980

Octahedral Co(Ⅲ) complexes of the glycine methyl ester have been prepared and characterized by elemental analysis, infrared, and NMR spectrum. Co(Ⅲ) glycine methyl ester complex has been isolated from the reaction of glycine and glycine methyl ester in aqueous solution by cation exchange resin, Dowex 50W-X8 (hydrogen form). It has been observed that the complexes have $C_1-cis(0-0), C_2-cis(0-0), trans(0-0)$ geometry.

• Nuclear Engineering and Technology
• /
• v.21 no.4
• /
• pp.277-286
• /
• 1989

Destructive methods are used for the turnup determination of an irradiated PWR fuel. One of the methods includes U, Pu, Nd-148 and Nd-(145+146) determination by an isotope dilution mass spectrometry using triple spikes (U-233, Pu-242 and Nd-150). The method involves two sequential ion exchange resin separation procedures. Pu is eluted from the first anion exchange resin column (Dowex AG 1$\times$8) with 12 M HCl-0.1 M HI mixed solution, followed by U elution with 0.1 M HCl. Nd is isolated from other fission products on the second anion exchange resin column (Dowex AG 1$\times$4) with a nitric acid-methanol eluent. Each fraction is analysed by thermal ionization mass spectrometry. The difference between Nd-148 and Nd-(145+146) method is found with an average 2.07%. The results are compared with those by the heavy element method using U and Pu isotopes and by the destructive y-spectrometric measurement of Cs-137. The dependences of isotope composition of U and Pu on burn-up, and correlation between those isotopes are illustrated graphically.

• Journal of Life Science
• /
• v.6 no.2
• /
• pp.120-128
• /
• 1996

In the screening of actinomycetes culture filtrate for inhibitor of adenosine deaminase, a novel inhibitor was found in a cultured broth of strain J-144K. The optimum conditions for the adenosine deaminase inhibitor production from the isolated strain J-144K were evaluated. This strain showed the maximum yield of adenosine deaminase inhibitor when grown at pH 7.0 and 30$\circ$C for 60 hours in the medium of 1.0% dextrose, 0.5% yeast extract, 0.5% peptone and 0.1% KH$_{2}$PO$_{4}$ under the aerobic condition. Through the activated charcoal extraction, methanol fractionation, Dowex 50 H$^{+}$ X-8 ion exchange column chromatography, Dowex CI$^{-}$ X-8 ion exchange column chromatography, and Sephadex G-15 gel filtration procedures, this inhibitor was purified with three materials.

• Journal of the Korean Chemical Society
• /
• v.37 no.5
• /
• pp.513-522
• /
• 1993

The purpose of this study is to optimize the selectivity of mobile phase solvents for separation of 25 phenols in reversed phase liquid chromatography and to accomplish the simultaneous preconcentration and separation of trace phenols from water samples. Phenols used in this study were classified into three groups, chloro-, methyl-, and nitrophenols. Quaternary solvent mobile phases were employed to improve the selectivity. Overlapping resolution maps(ORM) as a statistical simplex techniques was used to predict the optimum solvent system. Additional criterion such as pH and temperature were also investigated. In order to improve the resolution and decrease the analysis time, isoselective multisolvent gradient elution system was employed with ORM-Prism method. The simultaneous preconcentration and separation of trace phenols from water samples were performed by using XAD-2/Dowex 1-X8 tandem column. When the extraction efficiency was evaluated by sampling up to 1 L of distilled water, recovery of the phenols, except phenol, was above 90% and the limit of detection of the phenols was 5 ppb. The XAD-2/Dowex 1-X8 method was superior to C18 cartridge in terms of recovery and selectivity.

• Journal of the Korean Chemical Society
• /
• v.25 no.1
• /
• pp.21-25
• /
• 1981

A study was made of the influence of butyl alcohol on the distribution coefficients of barium and mercury ions between the ion exchange resin, Dowex 50w-x8, 200~400 mesh and solutions containing hydrochloric acid, butyl alcohol and water. The determination of the distribution coefficients of barium and mercury are made by using the batch method. The distribution coefficients of metal ions decrease generally as the number of branches of carbon in the molecule of butyl alcohol increase. It shows that solubility in water and stereo-isomerism of the butyl alcohol have influence upon the distribution coefficient of barium and mercury.