• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.581-587
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• 1988

The solvolysis of substituted benzyl bromides was studied in binary solvent mixtures of acetone-water and ethanol-water at $25^{\circ}C$ and $45^{\circ}C$. The rate constants increase with electron-donating substituents in benzene ring and increasing of water contents in both of solvent mixtures. The sensitivity parameter (m) of the solvolysis of substituted benzyl bromides to solvent ionizing power (Y) was decreased in going from the electron-donating group to electron-withdrawing one, whereas their nucleophilic sensitivity increased continuously in going to above same substituents. It was shown that electron-donating (electron-withdrawing) groups make the transition state looser (tighter). The above results were consisted with the account for the potential energy surface model and the quantum mechanical approach.

• Journal of the Korean Chemical Society
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• v.35 no.3
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• pp.196-203
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• 1991

The $pK_a$ values of benzoic acid and meta, para-halogen substituted benzoic acids in MeOH-$H_2O$ mixtures (0∼80% of MeOH) have been determined at 25$^{\circ}$C using a conductometric method on the basis of the Fuoss-Kraus equation, and further verified using modified conductometric method of Gelb. The dependence of $pK_a$ on halogen substituents has been discussed in terms of substituent-constant (${\sigma}$), which is devided into electron-withdrawing inductive contribution (${\sigma}_1$) and electron-donating ${\pi}$-resonance one (${\sigma}_R$). The linear-dependence of ${\sigma}_1$'s on $D^{-1}$ with positive slope and that of ${\sigma}_R$'s on $D^{-1}$ with negative slope have been interpreted on the basis of field effect and through-space interaction of ${\pi}$-lone pair of halogen substituent and ionization center via ${\pi}$-system of benzene ring.

• Journal of the Korean Chemical Society
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• v.7 no.3
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• pp.189-196
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• 1963

Reactions between potassium fluoride with organic halogen-containing carboxylic acids in dimethyl formamide solvent gave a decarboxylation reaction for the case of fluoro carboxylic acids of the type of $CF_3\;COOH,\;C_3F_7COOH,\;and\;C_2F_5COOH,$ whereas an additional partial fluorination together with dimerization reaction occurred for the chlorine containing acids of the type of $CH_2ClCOOH,\;CH_3CHClCOOH, \;CHCl_2COOH\;and\;o-Cl-C_6H_4-COOH.$ The phenyl halides showed no reactivity, but the halides with two electron attracting substituents on the benzene ring gave mainly dimerization reaction. The esters and alcohols gave an usual fluorination reaction. The same reactions in absence of the solvent at the elevated temperature increase the yield of the dimerized product and gave the cyclized product, fluorenone, in case of ο-chlorobenzoic acid. It was found that the fluorination usually precede the decarboxylation reaction by checking the stiochemical sequence of reaction. Catalytic influence of potassium fluoride were discussed and the mechanism of the reaction was considered.

• Korean Journal of Crystallography
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• v.13 no.3_4
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• pp.158-164
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• 2002

Tetrahomodioxa p-phenylcalix(4)arene dihexylether(C/sub66/H/sub68/O/sub6/) has been synthesized and structurally characterized by X-ray diffraction. Reaction of tetrahomodioxa p-phenylcalix(4)arene with hexyl halide and NaH in DMF leads to the dihexyl derivatives, 7,13,21,27-tetraphenyl-29,31-dihexyloxy- 2,3,16,17-tetrahomo-3,17-dioxacalit(4)arenes. The crystal is orthorhombic, P2₁2₁2₁, a= 9.764(2), b=16.167(2), c=32.994(3) Å, V=5208(1) Å, Z= 4, Dc = 1.221 gcm/sup -3/. The structure was solved by direct methods and refined by full-matrix least squares. Refinement converged at R = 0.070 for 2009 observed reflections. This molecule has a C-1,2-alternate conformation with pseudo-centrosymmetry and has two pairs of opposite phenyl rings, which are approximately parallel to each other. The benzene rings A and B are up, and the rings C and D rings are down with respect to the plane of the macrocyclic ring.

• Archives of Pharmacal Research
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• v.27 no.10
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• pp.1043-1047
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• 2004

Thirteen compounds were isolated from the $CH_2Cl_2$ fraction of Machilus thunbergii as phospholipase $C{\Upsilon}1\;(PLC{\Upsilon}1)$ inhibitors. These compounds were identified as nine lignans, two neolignans, and two flavans by spectroscopic analysis. Of these, 5,7-di-O-methyl-3',4'-methylenated (-)-epicatechin (12) and 5,7,3'-tri-O-methyl (-)-epicatechin (13) have not been reported previously in this plant. In addition, seven compounds, machilin A (1), (-)-sesamin (3), machilin G (5), (+)-galbacin (9), licarin A (10), (-)-acuminatin (11) and compound 12 showed dose-dependent potent inhibitory activities against $PLC{\Upsilon}1$ in vitro with $IC_{50}$ values ranging from 8.8 to 26.0 ${\mu}M$. These lignans, neolignans, and flavans are presented as a new class of $PLC{\Upsilon}1$ inhibitors. The brief study of the structure activity relationship of these compounds suggested that the benzene ring with the methylene dioxy group is responsible for the expression of inhibitory activities against $PLC{\Upsilon}1$. Moreover, it is suggested that inhibition of $PLC{\Upsilon}1$ may be an important mechanism for an antiproliferative effect on the human cancer cells. Therefore, these inhibitors may be utilized as cancer chemotherapeutic and chemopreventive agents.

• Mass Spectrometry Letters
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• v.13 no.3
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• pp.49-57
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• 2022

During electrospray ionization mass spectrometry (ESI-MS) analysis of proteins, the addition of supercharging agents allows for adjusting the maximal charge state, affecting the charge state distribution, and increases the number of ions reaching the detector thus, improving signal detection. We postulate that in di-substituted arene isomers, molecules with higher polarizability values should generate greater interactions and hence elicit higher signal intensities. Polarizability is an electronic parameter which has been demonstrated to predict many chemical interactions. Many properties can be predicted based on charge polarization. Molecular polarizability is a vital descriptor for explaining intermolecular interactions. We employed DFT (density functional/Hartree-Fock hybrid model, B3LYP)-derived descriptors and computed molecular polarizability for ten disubstituted arene reagents, each set made up of three (ortho, meta, para) isomers, with reported use as supercharging reagents during ESI experiments. The atomic electronic inputs were ionization potential (IP), electron affinity (EA), electronegativity (𝛘), hardness (η), chemical potential (µ), and dipole moment (D). We determined that the para isomers showed the highest polarizability values in nine of the ten sets. There was no difference between the ortho and meta isomers. Polarizability also increased with increasing complexity of the substituents on the benzene ring. Polarizability correlated positively with IP, EA, 𝛘, η, and D but correlated negatively with chemical potential. This DFT study predicts that the para isomers of di-substituted arene isomers should elicit the strongest ESI responses. An experimental comparison of the three isomers, especially of larger supercharging molecules, could be carried out to establish this premise.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.226-226
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• 2021

Tetractycline은 sulfonamides, penicilines 등과 함께 축산계에서 널리 사용되는 대표적인 항생물질의 한 종류이다. 2011년 사료 내 항생제 투여를 금지한 이후 자가치료 및 예방용으로 사용되고 있으며, 가축의 체내로 투여되는 tetracycline는 주로 분뇨에 포함되어 배출되는데, 강우 등 물 순환에 따라 지표수 및 지하수로 이동하여 미생물에 독성을 일으키거나 내성균이 발생하기도 한다. Tetracycline 등의 항생물질 처리 방식으로 흡착 등 다양한 공정이 제시되고 있다. 본 연구에서는 산화제 중 하나인 ferrate(VI)를 이용하여 tetracycline 분해실험을 수행하였다. ferrate(VI)는 염소산화물 및 H₂O₂에 비해 비교적 강한 산화력을 가지며, 처리 후 발생되는 철염(Fe³⁺)은 독성이 없다는 장점이 있다. Ferrate(VI)는 병원균 제거 등에 효과적인 것으로 알려져 있으며, 다양한 난분해성 물질과 항생물질을 성공적으로 분해하여 그 효과를 입증한 바 있다. 본 연구에서는 자체적으로 제조한 potassium ferrate(VI)를 이용하여 다양한 수중 환경에서 tetracycline를 분해하고, 분해특성 및 중간생성물 연구를 수행하였다. Ferrate(VI)는 염기성 환경에서 tetracycline 분해효율이 가장 높은 것으로 나타났으며, 이는 pH에 따른 tetracycline과 ferrate(VI)의 이온화가 가장 큰 원인인 것으로 판단된다. 특히 ferrate(VI)는 pH가 낮을수록 쉽게 환원되는 특징이 있으며, 염기성으로 갈수록 안정화하여 오래 잔류하므로 이러한 결과가 나타난 것으로 판단된다. 중간생성물 조사 결과, ferrate(VI)와 tetracycline 사이의 분해 메커니즘은 주로 OH 라디칼로 인한 것이 대부분이며, hydroxylation과 amino group에서의 demethylation의 형태로 발생하였다. 이후 추가적인 반응으로 benzene ring이 깨지면서 결과적으로 CO₂ 및 H₂O 등으로 무기물화 되는 것으로 판단된다.

• Journal of the Korean Chemical Society
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• v.37 no.3
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• pp.351-354
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• 1993

Z-1-Ethyl-2-nitro-l-butenyl-(4'-methyl)-phenyl sulfone, C$_{13}$H$_{17}$NO$_4$S, Mr = 293.4, monoclinic space group P2$_1$/c, a = 12.194(7), b = 7.290(4), c = 16.532(14)${\AA}$, ${\beta}$ = 103.4(2)$^{\circ}$, V = 1429.5 ${\AA}^3$, Z = 4, D$_c$ = 1.32 gcm$^{-3}$, ${\lambda}$(Mo K${\alpha}$) = 0.71069 ${\AA}$, ${\mu}$ = 2.2 cm$^{-1}$, F(000) = 600, T = 298 K, R = 0.030 for 1762 unique observed reflections with I > 1.0${\sigma}$(I). A molecule has a cis-typed molecular structure having the form of "the substituted butene backbone, C-C(S)=C(NO$_2$)-C, connecting to a sulfur atom with the methylbenzene ring and to a nitro group. The methylbenzene ring and the substituted butene moiety are nearly planar with the maximum deviations from their own molecular planes, 0.018 ${\AA}$ for the C(1) atom of the benzene group and 0.045 ${\AA}$ for the N atom of the NO$_2$ group, respectively. The angles to the plane of the butene backbone are 88.5$^{\circ}$from the plane of the methyl-benzene and 78.6$^{\circ}$from the plane of the nitro group. Rotation of the nitro group from the butene plane seems to reduced contribution of resonance structure involving the nitro group, and resultant repulsion between the O(2) atom of SO$_2$ and the O(3) atom of NO$_2$ appears to be 2.894 ${\AA}$ longer than an expected van der Waals distance of 2.80 ${\AA}$.

• Analytical Science and Technology
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• v.24 no.2
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• pp.135-141
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• 2011

MMPs (Matrix metalloproteinases) are enzymes playing an important role to turnover and remodel main protein compositions of extracellular matrix. MMP-2 and MMP-9 of MMPs having a catalytic domain which is apart from a hemopexin-like domain part, are different from the other MMPs pertaining fibronectinlike domain close to hemopexin-like domain. It was reported that the development of MMP-9 restrainer can prevent the transfer of liver cancer. In this study, MMP-9 restrainers were extracted and purified from Hovenia dulcis Thunberg. The each fractionary part was examined to investigate the inhibitory effect on MMPs. Three compounds, compound A and B eluted with ethyl acetate (EA) and compound C with methanol, were identified by $^1H$ and $^{13}C$ NMR, GC/MS, and FT-IR. Compound A is considered as a kind of catechine type compound having a benzene ring substituted by hydroxyl and methoxyl groups. Compound B and C are nobiletin type compound pertaining a carbonyl group. Compound A, B and C showed 76%, 66% and 71% of inhibition effect on MMP-9 at 1.0% concentration, respectively. Compound A showed the best inhibition effect on MMP-9.

• Korean journal of applied entomology
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• v.51 no.3
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• pp.245-253
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• 2012

Benzylinedeneacetone (BZA) is a bacterial metabolite which is synthesized by at least two entomopathogenic bacteria, namely Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata. It has been shown to possess inhibitory effects on insect cellular and humoral immune responses as well as antimicrobial activities against various species of bacteria and fungi. However, its relatively high phytotoxicity, and nonsystematic effect have thus far prevented its development into an optimal pesticide. This study screened five different BZA derivatives in order to select an optimal compound, which would have relatively high solubility and low phytotoxicity while retaining sufficient degrees of the immunosuppressive and antimicrobial activities associated with BZA. Hydroxylation of the benzene ring of BZA was found to significantly suppress its immunosuppressive and antimicrobial activities. Transformation of the ketone of BZA by carboxylation also suppressed the inhibitory activities. However, a shortening of the aliphatic chain of BZA into acetate form (4-hydroxyphenylacetic acid: HPA) did not decrease the inhibitory activity. HPA also showed much less phytotoxicity against the hot pepper plant Capsicum annuum, when compared to BZA. This study identified an optimal BZA derivative, which exhibited relatively little phytotoxicity, but retained a high degree of inhibitory activity to suppress insect immune responses and antimicrobial activities against plant pathogens.