• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.619-625
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• 2017

In this study, the formation of hydroxyl radical and decomposition characteristics of bisphenol A (BPA) was investigated by quantifying hydrogen peroxide formed as a reaction by-product during the formation stage of hydroperoxyl radical. The direct oxidation reaction by ozone only decomposed BPA just like the Criegee mechanism under the condition where radical chain reactions did not occur. Non-selective oxidation reactions occurred under the conditions of pH 6.5 and 9.5 where radical chain reactions do occur, confirming indirectly the formation of hydroxyl radical. The decomposition efficiency of BPA by the added catalysts appeared in the order of $O_3$/PAC ${\geq}$ $O_3/H_2O_2$ > $O_3$/high pH > $O_3$ alone. 0.03~0.08 mM of hydrogen peroxide were continuously measured during the oxidation reactions of ozone/catalyst processes. In the case of $O_3$/high pH process, BPA was completely decomposed in 50 min of the oxidation reaction, but reaction intermediates formed by oxidation reaction were not oxidized sufficiently with 29% of the removal ratio for total organic carbon (TOC, selective oxidation reaction). In the case of $O_3/H_2O_2$ and $O_3$/PAC processes, BPA was completely decomposed in 40 min of the oxidation reaction, and reaction intermediates formed by the oxidation reaction were oxidized with 57% and 66% of removal ratios for TOC, respectively (non-selective oxidation reactions).

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3565-3569
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• 2013

A home-made pinhole-type glass nozzle was employed to generate vibronically excited but jet-cooled benzyl-type radicals from precursor 2-fluoro-4-chlorotoluene with a large amount of carrier gas He, from which the visible vibronic emission spectrum was recorded with a long-path monochromator. From an analysis of the spectrum observed, it was found that two benzyl-type radicals, 2-fluorobenzyl and 2-fluoro-4-chlorobenzyl radicals, were formed from the precursor in corona discharge. The possible pathway for the production of benzyl-type radicals that can explain the spectroscopic observation is herein proposed. In addition, the electronic energy of the $D_1{\rightarrow}D_0$ transition and the vibrational mode frequencies in the $D_0$ state of the 2-fluoro-4-chlorobenzyl radical were determined for the first time.

• Korean Journal of Pharmacognosy
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• v.28 no.1
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• pp.54-58
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• 1997

The cytotoxic activities of methanolic extract and its fractions of Ailanthi Cortex Radicis and column chromatographic eluates of its dichloromethane fraction (DCM fr.) were investigated. DCM fr. Showed the strongest cytotoxicity against hepatoma cells. Furthermore, the active equates 1-3, 8 and 9 were obtained. Effects on free radical generation and the growth of vascular endothelial cells were tested to elucidate the action mechanism of anticancer activity. Eluates 1-3 stimulated free radical generation, while eluates 8 and 9 showed no changes. Especially, eluates 8 and 9 efffectively inhibited the proliferation of vascular endothelial cells in a dose- dependant manner. It is speculated that the anticancer effects of eluates 1-3, 8 and 9 might be due to free radical generation and inhibition of endothelial cell growth, respectively.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.319-322
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• 2008

The viability of acetylene addition in each step of aromatic formation initiated by vinyl radical and acetylene also with its competition with structure rearrangement is investigated by determining optimal geometries and barrier and reaction energies using quantum mechanical methods. In principle, the addition reaction has more difficult in term of free energy and enthalpy compared to geometry arrangement. Under combustion conditions, i.e. T = 1200 K, acetylene addition is unfavorable mechanism as the barrier energy values rise much higher than that of geometry arrangement. However, in longer chain hydrocarbon case, e.g. n-CxHx+1 where x ³ 8, C-C bond rotation is rather difficult and requires high energy to form a ring structure, elongation chain is preferable.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_3
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• pp.127-137
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• 2001

The sonochemical Process has been applied as a treatment method and was investigated its effect on the decomposition of humic substances(HS). The reaction kinetics and mechanisms in the Process of sonochemical treatment for humic substances(HS) in wastewater have also been discussed. It was observed that the metal ions such as Fe(II) and Mn(II) showed catalytic effects, while Al(III), Ca(II), and Mg(II) had inhibitory effects on the decomposition of humic substances in sonochemical reaction with hydrogen peroxide. Experimental results also showed factors such as hydrogen peroxide dose affected the formation of disinfection by-products. Two trihalomethanes, chloroform and dichlorobromomethane were formed as major disinfection by-products during chlorination. The mechanism of radical reaction is controlled by an oxidation process. The radicals are so reactive that most of them are consumed by HS radicals and hydroxyl radicals can be acted on organic solutes by hydroxyl addition, hydrogen abstraction, and electron transfer. The depolymerization and the radical reaction of HS radicals appear to occur simultaneously. The final steps of the reaction are the conversion of organic acids to carbon dioxide.

• Bulletin of the Korean Chemical Society
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• v.10 no.6
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• pp.509-514
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• 1989

Reactions of thianthrene cation radical perchlorate (1) with N-(p-methoxyphenyl)benzenesulphonamide (14) in acetonitrile at room temperature afforded various products : thianthrene (3), N-(p-hydroxyphenyl)benzenesulphonamide (16), benzenesulphonamide (18), hydroquinone (20); 5-(5-benzenesulphonamido-2-methoxyphenyl)-thia nthrenium perchlorate(21), 2-benzenesulphonamido-2'-hydroxy-5,5'-dimethoxy biphenyl(24), 2-benzenesulphonamido-2',5'-dihydroxy-5-methoxy -biphenyl(25), and a traceable amount of p-quinone(23). The formations of part of (3) and (21) can be explained by either disproportionation or half-regeneration mechanism but those of the remainders by diverse reactions of sulphonamidyl radical (27) derived from (14) (through single electron transfer, followed by deprotonation processes). Similar results were observed from the reaction with N-(p-methoxyphenyl)methanesulphonamide (15).

• Bulletin of the Korean Chemical Society
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• v.15 no.5
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• pp.353-356
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• 1994

The $CN(B^2{\Sigma}^+)$ radical was produced in a jet using an electric dc discharge of the precursor $CH_3CN$ with inert carrier gases. The rotationally resolved Fourier transform emission spectra of the 0-0 band of the $(B^2{\Sigma}^+{\to}X^2{\Sigma}^+)$ transition of CN have exhibited different distribution of the intensity for the carrier gases He and Ar, respectively. From the analysis of intensity distribution in the spectra, the mechanism for rotational cooling process of CN radical in a supersonic expansion has been suggested.

• Bulletin of the Korean Chemical Society
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• v.21 no.9
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• pp.901-904
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• 2000

The mechanism for the photo-Fries rearrangement of phenyl acetate andbiphenylyl acetates were reinvestigat-ed in phenol (or phenol derivatives) containing media. The results showed that the phenol (or phenol deriva-tives) which is the most common by-product of Fries reaction reacts with acyl radical togive Fries-product. These phenol (or phenol derivatives) contributions to the Fries-products were suggested as the Trivial mecha-nism for the photo-Fries reaction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.2
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• pp.133-140
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• 2008

A reduced chemical kinetic mechanism is developed in order to predict the flame phenomena in premixed $CO/H_2/Air$ flames at atmospheric pressure, aimed at studying the coal gas combustion for the IGCC applications. The reduced mechanism is systematically derived from a full chemical kinetic mechanism involving 11 reacting species and 66 elementary reactions. This mechanism consists of four global steps, and is capable of explicitly calculating the concentration of 7 non-steady species and implicitly predicting the concentration of 3 steady state species. The fuel blend contains two fuels with distinct thermochemical properties, whose contribution to the radical pool in the flame is different. The flame speeds predicted by the reduced mechanism are in good agreement with those by the full mechanism and experimental results. In addition, the concentration profiles of species and temperature are also in good agreement with those by the full mechanism.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.593-602
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• 2009

For a long time, there is much interest in the superoxide anion radical as one of reactive oxygen species (ROS) not only in the basic research field of chemistry and physics but also in the life science (or biotechnology). Recently, it is becoming ever more vital since the toxic property of nanomaterials as well as advanced oxidation processes (AOP) frequently employed for controlling pollutants are connected with the formation of superoxide anion radicals. Despite many researches on superoxide anion radical, the quantitative information of its presence and its detailed reaction mechanism in aqueous environments remains largely unclear, causing the controversy and confusion. In this review paper, we attempted to summarize the physicochemical property, mechanisms, and applications of superoxide anion radical. In addition, we briefly incorporated the important application of superoxide anion radical in AOP, nanomaterials, and life science (or biotechnology).