• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2571-2574
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• 2010

We investigate the mechanism of $S_NAr$ fluorination reactions under the influence of protic solvents and ions. We find that counterion or protic solvent alone retards the $S_NAr$ reactions, but together they may promote the reaction. In this mechanism, the protic solvent acts on the counterion as a Lewis base, and the nucleophile reacts as an ion pair. We also show that an anion (mesylate) may exhibit catalytic effects, suggesting the role of ionic liquids for accelerating the $S_NAr$ reactions.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1535-1538
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• 2009

We present calculations for $S_N$2/E2 reactions in protic solvents (t-butyl alcohol, ethylene glycol). We focus on the role of the hydroxyl (-OH) groups in determining the $S_N$2/E2 rate constants. We predict that the ion pair E2 mechanism is more favorable than the naked ion E2 reaction in ethylene glycol. E2 barriers are calculated to be much larger (~ 9 kcal/mol) than $S_N$2 reaction barriers in protic solvents, in agreement with the experimental observation [Kim, D. W. et al. J. Am. Chem. Soc. 2006, 128, 16394] of no E2 products in the reaction of CsF in t-butyl alcohol.

• Journal of the Korean Chemical Society
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• v.22 no.3
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• pp.111-116
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• 1978

The kinetics of phenylmethanesulfonyl chloride in methanol-water, ethanol-water, acetone-water and acetonitrile-water has been investigated. The rate was faster in protic solvents than in aprotic solvents while susceptibility of rate to the ionizing power, i. e., m of the Winstein plot and solvation number of the transition state were much smaller in protic solvents. This was considered in the light of initial state stabilization by hydrogen-bonding solvation of the protic solvents. It was concluded that the reaction proceeds by an $S_N2$ mechanism in which bond-formation precedes bond-breaking at the transition state in all solvent systems.

• 한국전기화학회:학술대회논문집
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• 1998.12a
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• pp.153-166
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• 1998

Lithium ion Batteries commercially available since the early nineties in Japan are going to be more and more important for portable electronic devices and even EV applications. Today several companies around the world are working hard to join to market for Lithium secondary batteries. Based on the growing interest for commercial use of batteries also the materials have to be reviewed in order to meet large scale production needs. The requirements especially for electrolytes for lithium batteries are extremely high. The solvents and the lithium salts should be of highest purity. So the supply of these chemicals including packaging, transportation and storage but also the handling in production are critical items in this field. Frolic impurities are very critical for LiPF6 based electrolytes. The influence of water is tremendous. But also the other protic impurities like alcoholes are playing an Important role for the electrolyte quality. The reaction of these species with LiPF6 leads to formation of HF which further reacts with cathode materials (spinel) and anode. To understand the role of the protic impurities more clearly the electrolyte was doped with such compounds and was analyzed for protic impurities and HF. These results which directly show the relation between impurities and quality will be presented and discussed. In addition several investigations on different packaging materials as well as methods to analyze and handle the sensititive material will be addressed. These questions which are only partly discussed in literature so far and never been investigated systematically cover some of the key parameters for understanding of the battery chemicals. This investigation and understanding however is of major importance for scientist and engineers in the field of Lithium ion and Lithium polymer batteries.

• Bulletin of the Korean Chemical Society
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• v.8 no.6
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• pp.441-444
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• 1987

The circular dichroism(CD) spectra of the optically active [$Co(acac)_2(diamine)]^+$ complexes were measured in the several protic and aprotic solvents, where acac = acetylacetonate anion and diamine = ethylenediamine and trimethylenediamine. The degree of the CD variation in protic solvents was enhanced as the dielectric constant decreases except n-butanol and benzylalcohol. And the degree of the CD variation in aprotic solvents was roughly increased as both dipole moment and dielectric constant decrease except aromatic solvents and the solvents having no dipole moment. It was deduced that the CD variations of the complexes have been due to the conformational change of acetylacetonate ligands coordinated to Co(III) ion.

• Membrane Journal
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• v.25 no.1
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• pp.32-41
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• 2015

High performance polysulfone microfiltration membranes with a high were successfully prepared by vapor induced phase separation (VIPS) coupled with non-solvent induced phase separation (NIPS) process. Asymmetric Membranes were prepared with PSF/DMF/PVP/PEG/DMSO/water mixed solutions and water/IPA coagulant. PSF, DMF, PVP, PEG, DMSO, water was used as a membrane polymer, a solvent, a hydrophilic polymer additive, a polar protic liquid polymer, a polar aprotic nonsolvent, and a polar protic nonsolvent in the casting solution, respectively. The addition of polar aprotic nonsolvents, and polar protic nonsolvents is a convenient and effective method to control membrane structure. In order to control the morphology of polymeric membranes, the spontaneous emulsification induced by drawing water vapor into the exposed casting solution surface has been used. Control of the internal morphology of polymeric membranes by using mixed coagulation solution such as water and IPA is discussed in the present work. The pure water permeability, pore size distribution, surface hydrophilicity and membrane morphology were investigated. Due to the addition of DMSO to casting solution, the mean pore size increased almost $0.2{\mu}m$ and the water flux increased about 1000-1800 LMH.

• Analytical Science and Technology
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• v.22 no.2
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• pp.159-165
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• 2009

The thermochromism of fluoran has been examined. The DCF exists as a colorless lactone in aprotic solvents. However, the DCF exists in the form of an equilibrium mixture of a colored zwitter-ion and a colorless lactone in protic solvents. When an acid is added to the solution, the DCF exists an equilibrium mixture as a colorless lactone and a colored cation even in aprotic solvents. In order to understand the interaction between the DCF and the solvent, absorption spectra of the DCF in various solvents were measured. The thermodynamic parameters of the DCF have also been investigated. From the variation of absorbance with temperature, the standard enthalpy changes ${\Delta}H^0$ of the equilibrium between the lactone and the zwitter-ion in various solvents have been determined. The standard enthalpy change ${\Delta}H^0$ is approximately -2.0 kJ/mol in protic solvents. In acidic solution, the standard enthalpy change is measured to be to zero in protic solvents within the experimental error. When the carboxylic group is protonated in acidic solution, a poor interaction between the dye and the solvent is expected.

• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.461-471
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• 2013

Use of low bandgap polymers is the most suitable way to harvest a broader spectrum of solar radiations for solar cells. But, still there is lack of most efficient low bandgap polymer. In order to solve this problem, we have synthesised a new low bandgap polymer and investigated its interaction with the ILs to enhance its conductivity. ILs may undergo almost unlimited structural variations; these structural variations have attracted extensive attention in polymer studies. In addition to this, UV-Vis spectroscopy, confocal Raman spectroscopy and FT-IR spectroscopy results have revealed that all studied ILs (tributylmethylammonium methyl sulfate [$N_{1444}$][$MeSO_4$] from ammonium family) and 1-methylimidazolium chloride ([MIM]Cl, and 1-butyl-3-methylimidazolium chloride [Bmim]Cl from imidazolium family) has potential to interact with polymer. Further, protic ILs shows enhanced conductivity than aprotic ILs with low bandgap polymer. This study provides the combined effect of low bandgap polymer and ILs that may generate many theoretical and experimental opportunities.

• Journal of the Korean Chemical Society
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• v.27 no.1
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• pp.1-8
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• 1983

Solvent effects on nucleophilic substitution reaction of naphthalene sulfonyl chlorides with pyridine in protic and aprotic solvent have been studied by means of conductometry. Results showed that the rate constants increased with dielectric constants for protic solvents, while they decreased with dielectric constants for aprotic solvents, except for acetonitrile which has a higher dielectric constant but had also greater rate constant. The rate constants were shown to be more susceptible to polarity-polarizability parameter, , than to hydrogen bond donor acidity parameter, ${\alpha}$, indicating that the pulling effect of hydrogen bonding solvent.

• Rapid Communication in Photoscience
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• v.1 no.2
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• pp.35-37
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• 2012

Photoinduced electron-transfer process of 1,8-naphthalimide-linker-trimethylsilane (NI-O3-TMS, O3 = 3,6,9-trioxaundecyl) and NI-O3 has been investigated using the transient absorption measurements in $CH_3CN$ and $CH_3CN/H_2O$. The excitation of NI-O3-TMS in $CH_3CN$ produced the NI radical anion ($NI^{{\cdot}-}$) with a transient absorption band around 413 nm, via the intermolecular electron-transfer between NI moieties in the excited singlet state. In contrast, in a protic polar solvent mixture of $CH_3CN/H_2O$, a proton abstraction process occurred from $NI^{{\cdot}-}$ to generate the NI ketyl radical ($NIH^{\cdot}$), which showed a transient absorption band around 405 nm. The decay time constants of $NIH^{\cdot}$ were quite long compared to those of $NI^{{\cdot}-}$ in $CH_3CN$.