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임귀택,김양희,성대동 東亞大學校 1994 東亞論叢 Vol.31 No.1
Solvent ionizing power Y and solvent nucleophilicity N have been determined by means of kinetics in l,l,l,3,3,3-hexafluoro-2-propanol(HFP) and 2-propanol(PrOH) solvent mixtures. The solvolytic rate constants are increasing the content of HFP in HFP-PrOH solvent mixtures. This phenomenon is due to the fact that HFP molecules reaveal the strong anion solvation around the leaving group of the substrate. 2-Adamantyl tosylate is better than tert-butyl halides as a standard substrate for determining the ioniging power in most solvents because the rate-determining step of the former is shown as ion-pair intermediate as shown in ?? mechanism. The solvolysis of tert-butyl chloride is close to ?? mechanism, but tert-butyl bromide and iodide is not useful as a standard substrate for determining the solvent ionizing power based on ?? mechanism since a carbocation is formed in the rate-determining step, and simultaneously the mucleophilic solvent assistance takes place. In HFP-PrOH solvent mixtures the ionizing power Y values(??) are increased, but the nucleophilicity N Values(??) are decreased, as the HFP content is increased. Such a tendency is in accord with the fact that the pKa value of HFP is very low compared with most protic solvents and also in accord with the fact that the first ionization energy of HFP is very high. This is due to the fact that the electron density of the lone electron pair in oxygen diminishes remarkably by the inductive effect(electron-withdrawing effect) of six fluorine atoms in HFP molecules which are of higher electron negativity. The magnitude of Y values for every substrate reveals the order of ??. This is due to the fact that the charge delocalization is increased by ?? and ?? which have relatively weak basicity.
Lim, Gui Taek,Lee, Yeong Ho,Ryu, Zoon Ha Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.2
Solvolyses of isobutyl chloroformate (4) in 43 binary solvent mixtures including highly aqueous media, water, $D_2O$, $CH_3OD$, 2,2,2-trifluoroethanol (TFE) as well as aqueous 1,1,1,3,3,3-hexafluoro-isopropanol (HFIP) solvents were performed at $45^{\circ}C$, in order to further investigate the recent results of D'Souza, M. $J^1$. et al.; solvolyses of 4 are found to be consistent with the proposed mechanism ($Ad_E$). The variety of solvent systems was extended to comprise highly ionizing power solvent media ($Y_{Cl}$ > 2.7 excepted for aqueous fluorinated solvents and pure TFE solvent) to investigate whether a mechanistic change occurs as solvent compositions are varied. However, in case of 18-solvent ranges having aqueous fluorinated solvent systems (TFE-$H_2O$ and HFIP-$H_2O$) and/or having $Y_{Cl}$ > 2.7 solvent systems, the solvent effect on reactivity for those of 4 are evaluated by the multiple regression analysis as competition with $S_N2$ - type mechanism. And in pure TFE and 97 w/w % HFIP solvents with high $Y_{Cl}$ and weak $N_T$, these solvolyses are understood as reactions which proceed through an ionization ($S_N1$) pathway.
Photodecomposition Mechanism of Diazoindanones by Laser Photolysis and Lamp Photolysis
Lim, Gui Taek,Uhm, Tae Seop,Sung, Dae Dong,Shin, Joong Soo 東亞大學校 附設 基礎科學硏究所 1994 基礎科學硏究論文集 Vol.11 No.1
The mechanism for the photodecomposition reactions of 2-diazoindan-1-one and 1.3-bis(diazo)indan-2-one have been studied in benzene, toluene, methanol, cyclohexane and acetonitrile solvents using laser photolysis and lamp photolysis. A triplet ketocarbene is observed from the photolysis of bis diazo compounds by the loss of nitrogen molecule from the carbene precursors. It is concluded that the Wolff rearrangement, which involves the formation of a ketene intermediate, can be regarded as a concerted process in nanosecond time scale. The photolytic reactions of diazoindanones in methanol give Wolff rearrangement products, but those in benzene do not involve in the Wolff rearrangement.
Gui, Tai-Long,Yin, Jing-Hua,Wang, Dong-Xing,Jin, Sung-Ho,Lim, Kwon Taek,Kim, Bong-Shik,Lee, Won-Chul,Gal, Yeong-Soon TaylorFrancis 2007 Molecular Crystals and Liquid Crystals Vol.463 No.1
<P> A new conjugated polymer with bulky substituents was synthesized by the polymerization of ethynylestradiol 3-methyl ether (EEDME) by such transition metal catalysts as PdCl2, RuCl3, and (NBD)PdCl2. The polymerization proceeded well in homogeneous manner to give a moderate yield of polymer. The chemical structure of poly(EEDME) was characterized to have the conjugated polymer backbone with the designed substituents. From the CV measurements, the HOMO energy level of the polymer was calculated to be 5.02 eV. The photoluminescence spectra of poly(EEDME) showed that the two photoluminescence peaks are located at 434 and 406 nm corresponding to the photon energy of 2.86 and 3.06 eV, respectively.</P>
Electro-Optical and Electrochemical Properties of Poly(2-ethynyl-N-glycidylpyridinium bromide)
Gui, Tai-Long,Wang, Yue,Wang, Jian-Min,Jin, Sung-Ho,Shim, Sang-Yeon,Park, Jong-Wook,Lim, Kwon Taek,Gal, Yeong-Soon TaylorFrancis 2009 Molecular Crystals and Liquid Crystals Vol.513 No.1
<P> An ionic polyacetylene with the pendent N-glycidylpyridinium bromide, poly(2-ethynyl-N-glycidylpyridinium bromide), was synthesized in 91% yield by the activated polymerization of 2-ethynylpyridine with epibromohydrin without any additional catalyst or catalyst. This polymer exhibited characteristic UV-visible absorption band at 515 nm and yellow PL spectrum at 598 nm corresponding to the photon energy of 2.07 eV. The cyclovoltamograms of polymer exhibited the electrochemically stable window in the region of -1.4 ∼ 1.8 V and the redox current value gradually increased as the scan rate increased. The kinetics of the redox process of polymer was found to be well-controlled by the reactant diffusion process from the experiment of the oxidation current density of PEGPB versus the scan rate.</P>
Ryu, Zoon-Ha,Lim, Gui-Taek,Bentley, T. William Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.9
Rate constants at various temperatures and activation parameters are reported for solvolyses of acyl chlorides (RCOCl), with R = Me, Et, i-Pr, t-Bu, cyclopentylmethyl, benzyl, thiophenylmethyl, 2-phenylethyl, diphenylmethyl, and phenylthiomethyl in 100% ethanol, 100% 2,2,2-trifluoroethanol (TFE), 80% v/v ethanol/ water and 97% w/w TFE/water. Additional rate constants for solvolyses with R = Me, t-Bu, and $PhCH_2$ are reported for TFE/water and TFE/ethanol mixtures, and for solvolyses with R = t-Bu, and PhCH2 are reported for 1,1,1,3,3,3-hexafluoropropan-2-ol/water mixtures, as well as selected kinetic solvent isotope effects (MeOH/MeOD and TFE). Taft plots show that electron withdrawing groups (EWG) decrease reactivity significantly in TFE, but increase reactivity slightly in ethanol. Correlation of solvent effects using the extended Grunwald-Winstein (GW) equation shows an increasing sensitivity to solvent nucleophilicity for EWG. The effect of solvent stoichiometry in assumed third order reactions is evaluated for TFE/ethanol mixtures, which do not fit well in GW plots for R = Me, and t-Bu, and it is proposed that one molecule of TFE may have a specific role as electrophile; in contrast, reactions of substrates containing an EWG can be explained by third order reactions in which one molecule of solvent (ethanol or TFE) acts as a nucleophile, and a molecule of ethanol acts as a general base catalyst. Isokinetic relationships are also investigated.
물과 에탄올 이성분 혼합용매 계에서 부피 및 온도 변화에 관한 연구
김용권,임귀택 한국초등과학교육학회 2001 초등과학교육 Vol.20 No.1
This paper is to study on the change of volume and temperature of the solution which mixed water with ethanol. And its main purpose is to examine closely how the volume changes, and to find the method to maximize the change of the volume. The summaries for results of the study are; First, we were known that water and ethanol are homogeneously mixed. But two solvents does not mix homogeneously by different specific gravity at early stages. Second, we could see that the volume changed large at homogeneous mixed water with ethanol by stirrer, the change of volume is the largest value when water mixed with ethanol in the ratio of one to one. Third, when water mixed with ethanol in the ratio of one to one, the change of temperature is very large by activated hydrogen bond. We conclude that it is the best result when ratio of water and ethanol is one to one and the solution is well mixed.