• Bulletin of the Korean Chemical Society
• /
• v.25 no.3
• /
• pp.420-422
• /
• 2004

• Journal of Radiopharmaceuticals and Molecular Probes
• /
• v.1 no.2
• /
• pp.75-79
• /
• 2015

[$^{18}F$]Fluorobenzaldehyde, which is a versatile radioactive prosthetic group, can undergo reduction, reductive amination, or oxidation to be used for synthesis of diverse radiotracers. This review covers synthesis of [$^{18}F$]fluorobenzaldehyde and its conversion to secondary prosthetic groups, and also highlights its application to the development of radiotracers.

• Bulletin of the Korean Chemical Society
• /
• v.14 no.4
• /
• pp.461-465
• /
• 1993

Reductive transformations of gem-bromonitro compounds and ${\alpha}$-nitro ketones were carried out conveniently with sodium dithionite by using dioctyl viologen as an electron-transfer catalyst in dichloromethane-water two-phase system:the bromine atom in gem-bromonitro compounds and the nitro group in ${\alpha}$-nitro ketones are replaced by hydrogen.

• YAKHAK HOEJI
• /
• v.41 no.4
• /
• pp.480-483
• /
• 1997

The efficient synthesis of p-(acetylamino)phenylacetic acid(7), a antirheumatic agent, is reported. Methyl phenylacetate(3) was prepared from Friedel- Crafts reaction of benzene with methyl ${\alpha}$-chloro-${\alpha}$-(methylthio)acetate(1) followed by reductive desulfurization with zinc dust in acetic acid. Compound(7) was obtained from 3 by a sequence of nitration, reduction, N-acylation, and hydrolysis.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.2
• /
• pp.151-155
• /
• 1997

Stereochemical course of the reductive decyanation of two stereoisomeric 4-t-butyl-1-phenylcyclohexanecarbonitriles 3 and 4 using solvated electron has been studied. While sodium-mediated reactions of both 3 and 4 in the presence of alcohols give the same ratio, 1.5 : 1, in favor of the thermodynamically more stable product 5 over the other one 6, the ratios obtained from the potassium-mediated process are found to be very sensitive to the kind of H-donors. When reactions are performed without H-donors, 5 is only obtained from the experiments with both stereoisomers irrespective of the metal species.

• Journal of Environmental Science International
• /
• v.3 no.1
• /
• pp.65-76
• /
• 1994

The regiospecific potential for the reductive dechlorination of 2-, 3-, 4-, 2, 3-, 2, 4-, and 3, 4-chlorophenols (CPs) was studied in mono- and di-CP(DCP) adapted sediment slurries(10% solids). Freshwater sediments adapted to transform 2-CP dechlorinated all tested mono- and di-CPs except 4-CP without a lag period. Adaptation to 2-CP, thus, enhanced the onset of dechlorination of 3-CP and all ortho-substituted CPs tested. Sediment adapted to transform 3-CP dechlorinated all test CPs, except 4-CP and 2, 4-DCP, without a lag period. Sediment adapted to individual DCPs (2, 3-, 2, 4-, and 3, 4-DCP_ exhibited dechlorination(no lag phase) of 2-CP, 2, 3-, 2, 4-, and 3, 4-CDP. Interestingly, meta-cleavage of 3, 4-DCP in all tested adapted sediment occurred, while para-cleavage occurred in 3, 4-DCP adapted sediment. Sediment adapted to dechlorinate ortho and meta-chlorines exhibited a preference for meta following ortho-cleavage, but not for para-cleavage, while the preference for reductive dechlorination was ortho>meta>para for mono-CPs and ortho>para>meta for DCPs in unadapted freshwater anoxic sediments.

• Journal of the Korean Chemical Society
• /
• v.27 no.3
• /
• pp.194-200
• /
• 1983

Effect of metallic salts added to the ${\alpha}-Fe_2O_3-HCl\;or\;{\alpha}-Fe_2O_3-H_2SO_4$ reaction systems were investigated by colorimetric and gravimetric determinations. While reductive salts exhibited remarkably enhanced reaction rate, non-reductive salts showed inhibitive results. We supposed that the improvement of dissolution rate of ${\alpha}-Fe_2O_3$ by the addition of $FeCl_2$, a reductive salt, to the ${\alpha}-Fe_2O_3-HCl$ system can be attributed to the formation of chloro-bridge between $Fe^{3+}\;and\; Fe^{2+}$, and therefore some partial electronic charge transfer from $Fe^{2+}\;to\;Fe^{3+}$ on the surface of ${\alpha}-Fe_2O_3$ will be easily achieved through the bridged bond. The transferred charge to the surface will reduce the positive charge of initial $Fe^{3+}$, and also result to reduce the lattice energy of that site. Assuming tothat there is a linear relationship between the lattice energy change and the change of activation energy of the reaction system, the transferred partial electronic charge to $Fe^{3+}$ of ${\alpha}-Fe_2O_3$ surface was calculated to be ca. 0.36e.

• KSBB Journal
• /
• v.22 no.3
• /
• pp.134-138
• /
• 2007

It was investigated whether an electrode could serve as an electron donor for biological reductive dechlorination of chlorinated phenols in the bio-electrochemical process. There was no dechlorination in the absence of current and scanning electron microscope image showed that the electrode surface was covered with microorganisms. As a result, the electrode attached cells was responsible for reductive dechlorination. Also, initial high chlorinated phenol concentration such as $437mg/{\ell}$ was rapidly reduced within 5 hours. The maximum dechlorination rate using Monod equation was $5.95mg{\ell}$-h($cm^2$ (electrode surface area)) in the bio-electrochemical reactor.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.212-212
• /
• 2011

In addition to the catalysts' activity and selectivity, the deactivation of catalysts during use is of practical importance. It is crucial to understand the phenomena of the deactivation to predict the loss of activity during catalyst usage so that the high operational costs associated with catalyst replacement can be reduced. In this study, the activity of Ru catalysts, such as nanoparticles (3~6 nm) and polycrystalline thin film (50 nm), have been investigated under CO oxidation and oxidative/reductive reaction conditions at various temperatures with the ambient pressure X-Ray photoelectron spectroscopy (APXPS). With APXPS, the surface oxides on the catalyst are measured and monitored in-situ. It was found that the Ru film exhibited faster oxidation-and-reduction compared to that of nanoparticles showing mild oxidative-and-reductive characteristics. Additionally, the larger Ru nanoparticles showed a higher degree of oxide formation at all temperatures, suggesting a higher stability of the oxide. These observations are in agreement with the catalytic activity of Ru catalysts. The loss of activity of Ru films is correlated with bulk oxide formation, which is inactive in CO oxidation. The Ru nanoparticle, however, does not exhibit deactivation under similar conditions, suggesting that its surface is covered with a highly active ultrathin surface oxide. Since the active oxide is more stable as nanoparticles than as a film, the nanoparticles showed mild oxidative/reductive behavior, as confirmed by APXPS results. We believe these simultaneous observations of both the surface oxide of Ru catalysts and the reactivity in real time enable us to pinpoint the deactivation phenomena more precisely and help in designing more efficient and stable catalytic systems.

• Journal of Environmental Science International
• /
• v.26 no.7
• /
• pp.859-868
• /
• 2017

In this study, the reductive dechlorination of triclosan using zero-valent iron (ZVI, $Fe^0$) and modified zero-valent iron (i.e., acid-washed iron (Aw/Fe) and palladium-coated iron (Pd/Fe)) was experimentally investigated, and the reduction characteristics were evaluated by analyzing the reaction kinetics. Triclosan could be reductively decomposed using zero-valent iron. The degradation rates of triclosan were about 50% and 67% when $Fe^0$ and Aw/Fe were used as reductants, respectively, after 8 h of reaction. For the Pd/Fe system, the degradation rate was about 57% after 1 h of reaction. Thus, Pd/Fe exhibited remarkable performance in the reductive degradation of triclosan. Several dechlorinated intermediates were predicted by GC-MS spectrum, and 2-phenoxyphenol was detected as the by-product of the decomposition reaction of triclosan, indicating that reductive dechlorination occurred continuously. As the reaction proceeded, the pH of the solution increased steadily; the pH increase for the Pd/Fe system was smaller than that for the $Fe^0$ and Aw/Fe system. Further, zero-order, first-order, and second-order kinetic models were used to analyze the reaction kinetics. The first-order kinetic model was found to be the best with good correlation for the $Fe^0$ and Aw/Fe system. However, for the Pd/Fe system, the experimental data were evaluated to be well fitted to the second-order kinetic model. The reaction rate constants (k) were in the order of Pd/Fe > Aw/Fe > $Fe^0$, with the rate constant of Pd/Fe being much higher than that of the other two reductants.