• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.545-549
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• 2001

We have produced electrolyte solution out of 1.15M $LiPF_6$ EC/EMC/DEC/PC(30/55/10/5 by vol%) as a reference, and at the same time, performed basic physical property test using a single solvent of 1.15M $LiPF_6$ DEC, DMC, EMC and a 2 component electrolyte solution of 1.15M $LiPF_6$ EC/DEC(1/2 by vol%) and PC/DEC(1/2 by vol%). Cyclic Voltammetry Analysis showed that, compared to existing carbonate organic solvent, the addition of DEC,DMC and EMC brought the de-decomposition peak of salt anion of $PF_6$ and the solvent at lower oxidization potential of 2.3V, 0.7V and 2.1V(vs. $Li/Li^+$). In addition, a kinetics current peak, in which intercalation of Lt is proceeded at 750mV, 450mV(vs. $Li/Li^+$), was confirmed. These findings suggest that the DEC solvent decomposition occurred at an electric potential lower than that of oxidization of existing carbonate organic solvent. Through the impedance analysis, we checked electric charge transfer resistance($R_{ct}$) according to the electric potential of $Li^+$ intercalation at 750mV(vs. $Li/Li^+$), which was the same as the resistance ($R_f$) and cyclic voltammetry of SEI film that was formed at Reference. By doing so, we found that the significant decrease of polarization resistance($R_p$) when Reference was played a part in the formation of compact SEI layer at the initial decomposition reaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.545-549
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• 2001

We have produced electrolyte solution out of 1.15M LiPF$\sub$6/ EC/EMC/DEC/PC(30/55/10/5 by vol%) as a reference, and at the same time, performed basic physical property test using a single solvent of 1.15M LiPF$\sub$6/DEC, DMC, EMC and a 2 component electrolyte solution of 1.15M LiPF$\sub$6/ EC/DEC(1/2 by vo%%) and PC/DEC(1/2 by vol%). Cyclic Voltammetry Analysis showed that, compared to existing carbonate organic solvent, the addition of DEC, DMC and EMC brought the de-decomposition peak of salt anion of PF$\sub$6/$\^$-/ and the solvent at lower oxidization potential of 2.3V, 0.7V and 2.1V(vs. Li/Li$\^$+/\`). In addition, a kinetics current peak, in which intercalation of Li$\^$+/ is proceeded at 750mv, 450mv(vs. Li/Li$\^$+/), was confirmed. These findings suggest that the DEC solvent decomposition occurred at an electric potential lower than that of oxidization of existing carbonate organic solvent. Through the impedance analysis, we checked electric charge transfer resistance(R$\sub$ct/) according to the electric potential of Li$\^$+/ intercalation at 750mv(vs. Li/Li$\^$+/), which was the same as the resistance (R$\sub$f/) and cyclic voltammetry of SEI film that was formed at Reference. By doing so, we found that the significant decrease of polarization resistance(R$\sub$p/) when Reference was played a part in the formation of compact SEI layer at the initial decomposition reaction.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.419-424
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• 1987

Kinetic studies on the solvolysis of para-methyl benzyl nitrate and benzyl nitrate were carried out in aqueous methanol, ethanol, acetonitrile, acetone, tetrahydrofuran and dioxane mixtures at 60$^{\circ}$C. The rates were faster in protic solvent mixtures than in aprotic solvent mixtures. This was considered in the light of transition state stabilization by hydrogen bonding solvation of protic solvent mixtures. Grunwald-Winstein equation, extended Grunwald-Winstein equation and correlation between E$_T$(30) and rate constant were applied in order to discuss the transition state variations caused by changing benzyl substituents and solvents. The results showed that strong electrophilic assistance of solvent is operative in the the water-rich solvents.

• Journal of the Korean Chemical Society
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• v.27 no.3
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• pp.167-177
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• 1983

The kinetics of 2-anthracenesulfonyl chloride in methanol-water, ethanol-water, acetone-water and acetonitrile-water has been studied by electroconductometric method. For media in which water has the same mole fraction, the rate was greater in protic solvent than in dipolar aprotic solvent and it was greater consistently in methanol-water than in ethanol-water over the whole range of solvent composition investigated, while the two rates in acetone-water and acetonitrile-water inverted at about 0.9 of mole fraction of water. Both m value, susceptibility of rate to the ionizing power and n value, solvent participation number in the transition state were much smaller in protic solvent. These values and the activation parameters show that solvolysis of 2-anthracenesulfonyl chloride proceeds by $ S_N2$ mechanism.

• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.433-440
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• 1986

The direct current polarographic behavior of 4n-BAR in dimethylsulfoxide as an aprotic solvent have been investigated. The reduction of 4n-BAR in 0.05M sodium perchlorate solution proceeds along two one-electron steps to give the corresponding compound containing hydrazo groups, each reduction wave was considerably diffusion controlled and irreversible. By addition of acid HAc to 4n-BAR in DMSO solvent, the two reduction waves have coalesced into one in the condition M $\geq$ mole ratio, acid/reductant(M = 2), the slope of $log(i_d-i)(Mi_d/2-i)/i$/ vs. (-E) is irreversible along one-electron steps reduction waves.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2909-2912
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• 2009

The amines studied in this study are less reactive toward ethyl propiolate (3) in MeCN than in H$_2$O although they are 7 to 9 pK$_a$ units more basic in the aprotic solvent. The reactivity of morpholine and deuterated morpholine toward 3 is found to be identical, indicating that proton transfer occurs after rate-determining step (RDS). The fact that kinetic isotope effect is absent excludes a stepwise mechanism in which proton transfer occurs in RDS as well as a concerted mechanism in which nucleophilic attack and proton transfer occur concertedly through a 4-membered cyclic transition state (TS). Thus, the reactions have been concluded to proceed through a stepwise mechanism in which proton transfer occurs after RDS. Brønsted-type plots are linear with small ${\beta}_{nuc}$ values, i.e., ${\beta}_{nuc}$ = 0.29 in H$_2$O and ${\beta}_{nuc}$ = 0.51 in MeCN, indicating that bond formation is not advanced significantly in RDS. The small ${\beta}_{nuc}$ value also supports the conclusion drawn from the study of kinetic isotope effect.

• Journal of the Korean Chemical Society
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• v.28 no.2
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• pp.130-134
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• 1984

The polarographic behavior of benzeneazoresorcinol (BAR) in acetonitrile as an aprotic solvent has been investigated by direct current polarography and controlled-potential coulometry. The reduction of BAR in $1.0{\times}10^{-2}$M tetraethylammonium perchrolate solution proceeds along four one-electron steps to give the corresponding amine compounds. Each reduction wave was considerably diffusion-controlled and not completely reversible.

• Journal of the Korean Chemical Society
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• v.27 no.1
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• pp.24-30
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• 1983

The polarographic behavior of 1-(2-pyridylazo)-2-naphthol (PAN) in acetonitrile as an aprotic solvent has been investigated. The reduction of PAN in $10^{-2}$ molarity of tetraethyl-ammonium perchlorate acetonitrile solution proceeds along two one-electron steps to give the corresponding hydrazo compound. Every reduction wave was diffusion controlled and considerably reversible. The reduction mechanism of PAN in acetonitrile is estimated as follows;

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_1
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• pp.47-53
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• 2001

We carroed our to measure the variations of potential with current density (polarization curves) for poly(ethyleneterephthalate). The results were particularly examined to identify the influences on corrosion potential and corrosion rate of various factors including temperature, pH, exposure time, salt, and enzyme. The Tafel slope for anodic dissolution was determined by the polarization effect depending on these conditions. The optimum conditions were established for each case. The second anodic current density peak and maximum passive current density were designated as the relative corrosion sensitivity$(I_r/I_f)$. The mass transfer coefficient value$(\alpha)$ was determined with the Tafel slope for anodic dissolution based on the polarization effect with optimum conditions.

• 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.