• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.117-123
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• 2015

본 연구에서는 DFT를 이용하여 Nucleophilicity와 Basicity의 연관성에 대한 계산화학적 분석을 수행하였다. Basicity는 선정된 모델 분자의 protonation 반응에서 생성물과 반응물의 enthalpy 변화량인 양성자 친화도(Proton affinity, PA) 값을 구하여 분석하였다. 계산한 결과는 실험을 통해 얻은 PA 결과와 경향성이 거의 일치함을 확인하였다. Nucleophilicity는 모델 분자들과 $CH_3Br$ (electrophile)의 $SN_2$반응에서 gibbs free energy of activation(${\Delta}G^{\ddag}$) 값으로 그 경향성을 분석하였다. 또한 용매의 종류를 다르게 하여 용매에 따른 ${\Delta}G^{\ddag}$ 값의 경향성도 확인하였다. 각 용매에 따라 구한 ${\Delta}G^{\ddag}$와 PA의 상관관계를 비교하였으나, 큰 연관성은 보이지 않았다. 이에 ${\Delta}G^{\ddag}$와 PA의 상관관계를 보여줄 수 있는 parameter를 찾기 위하여 각 모델 분자의 Electronegativity와 Polarizability를 계산하여 연관성을 비교해보았다. Polarizability를 적용했을 때 Nucleophilicity와 Basicity사이의 연관성을 나타낼 수 없었던 반면, Electronegativity를 적용하여 Basicity와 Nucleophilicity의 연관성 보일 수 있음을 이론적으로 규명하였다.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.165-171
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• 2017

Diels-Alder 반응은 고리형 탄소화합물을 만드는 유기 합성 과정에서 매우 중요한 반응이다. 이 반응은 중간생성물 없이 오직 1 step으로 진행되는데, diene이나 dienophile에 결합한 치환기의 electron donating 및 electron withdrawing 성질에 따라 반응성이 달라진다고 알려져 있다. 이 때 반응물인 diene과 dienophile의 분자 오비탈 및 전이 상태의 에너지 변화를 계산화학을 통해 분석한다면 Diels-Alder 반응을 보다 심도 있게 이해할 수 있다. 이에 따라 본 연구에서는 DFT 계산을 통하여 치환기에 따른 활성화 에너지의 크기와 diene의 nucleophilicity 및 dienophile의 electrophilicity를 비교하였다. 이를 통해 electron withdrawing group의 경우 분자의 electrophilicity를 증가시키고, electron donating group의 경우 nucleophilicity를 증가시킨다는 것을 확인할 수 있었다. 그 결과, Diels-Alder 반응이 일어날 때 dienophile의 경우 치환된 electron withdrawing group에 의해 electrophilicity가 증가함에 따라 활성화 에너지가 낮아져 반응이 잘 일어나고, 반대로 diene의 경우 electron donating group이 치환되어 있을 때 nucleophilicity의 증가에 따라 반응이 잘 일어난다는 것을 알 수 있었다.

• Journal of the Korean Chemical Society
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• v.13 no.2
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• pp.115-120
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• 1969

Kinetics of reactions of halide ions with 1-naphthyl methyl halide have been investigated in anhydrous acetone. Semi-quantitative analysis of the results shows that if the softness of the substrate increases remarkably, the nucleophilicity order of halide ions is $I^- > Br^- > Cl^-$ even in dipolar aprotic solvent. But for 1-naphthyl methyl bromide, though the reaction center which was made soft by symbiosis of bromine atom raises the reactivity of soft nucleophile, nucleophilicity order indicates that soft-soft interaction is interfered by perihydrogen.

• Journal of the Korean Chemical Society
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• v.11 no.4
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• pp.121-125
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• 1967

The formation of a charge transfer complex between various amines and organic halogen compounds was closely investigated. A mixture of amine (piperidine, pyridine, diethylamine, ethylamine, triethylamine and triethanolamine) and organic halides(carbon tetrachloride and chloroform) was checked for its UV absorption spectrum in presence of n-hexane solvent. A red shift was observed. The formation of charge transfer complex was observed in the case of triethylamine and diethylamine, whereas the formation of contact complex was distinct in case of piperidine. The relation between the nucleophilicity of amines and their tendency of forming charge transfer complex was discussed.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1451-1456
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• 1999

Solvolyses of α-methoxy-α-(trifluoromethyl)phenylacetyl chloride in H₂O, D₂O, CH₃OD, 50% D₂O-CH₃OD, and in aqueous binary mixtures of acetone, dioxane, ethanol and methanol are investigated at 25.0℃. The Grunwald-Winstein plots of first-order rate constants for α-methoxy- α-(trifluoromethyl)phenylacetyl chloride with $Y_{Cl}$ show a dispersion phenomenon. Solvent nucleophilicity N has been shown to give considerable im-provement when it is added as an 1N term to the original Grunwald-Winstein for the solvolyses of α-methoxy- α-(trifluoromethyl)phenylacetyl chloride. The dispersions in the Grunwald-Winstein correlations in the present studies are caused by solvent nucleophilicity. The magnitude of l and m values associated with a change of solvent composition predicts the associative $S_N2$ transition state. The kinetic solvent isotope effects determined in deuterated water and methanol are consistent with the proposed mechanism of the general base catalyzed associative $S_N2$ or $S_AN$ mechanism for the of α-methoxy- α-(trifluoromethyl)phenylacetyl chloride.

• Bulletin of the Korean Chemical Society
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• v.26 no.3
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• pp.457-460
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• 2005

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.657-661
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• 2007

The specific rates of solvolysis of isopropyl fluoroformate are well correlated using the extended Grunwald-Winstein equation, with a sensitivity (l ) to changes in solvent nucleophilicity (NT) and a sensitivity (m) to changes in solvent ionizing power (YCl). The sensitivities (l = 1.59 ± 0.16 and m = 0.80 ± 0.06) toward changes in solvent nucleophilicity and solvent ionizing power, and the kF/kCl values are very similar to those for solvolyses of n-octyl fluoroformate, suggesting that the addition step of an addition-elimination mechanism is rate-determining. For methanolysis, a solvent deuterium isotope effect of 2.53 is compatible with the incorporation of general-base catalysis into the substitution process. The large negative values for the entropies of activation are consistent with the bimolecular nature of the proposed rate-determining step. These observations are also compared with those previously reported for the corresponding chloroformate and fluoroformate esters.

• Bulletin of the Korean Chemical Society
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• v.23 no.10
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• pp.1445-1450
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• 2002

Solvolytic rate constants at 25 $^{\circ}C$ are reported for solvolysis of chlorodithioformate (1) in binary mixtures of water with acetone, ethanol, methanol, methanol-d, 50%methanol-d/50%D2O, and 2,2,2-trifluroethanol (TFE), and also in TFE-ethanol mixtures. The Grunwald-Winstein plot shows that the three aqueous mixtures exhibit dispersions into separate line. The correlation is improved only slightly by additional parameters NT for solvent nucleophilicity and/or I for aromatic ring parameter. Rate ratios in solvents of the same $Y_cl$ value, having different nucleophilicity provide measures of the minimum extent of nucleophilic solvent assistance, and the value of 3.35 for $[$k_{40EW}$/$k_97TFE$]_Y$ (EW = ethanol-water), is consistent with an essentially SN1 reaction mechanism. This study has shown that the magnitude of l, m and h values associated with a change of solvent composition is able to predict the SN1 reaction mechanism. log(k/$k_o$) = mY + lN + hI

• Nuclear Engineering and Technology
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• v.1 no.2
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• pp.87-90
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• 1969

Halogen exchange reactions of trans-cinnnamyl chloride and bromide with radioactive chloride, bromide and iodide ions in acetone have teen studied. Relative nucleophilicity of halide ions and relative leaving ability have been discussed invoking the principle of HSAB.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.684-688
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• 2005

Aniline was polymerized in various protonic acid (HF, HC1, HBr, HI, $H_2SO_4$) aqueous solutions with different acidity. During the reaction, the dimer formation and the reaction rate were examined as functions of acidity (pH) and the size of counter ions. Open-circuit potential measurements were carried out to investigate the effect of protonic acid on the reaction rate. The results showed that polymerization rate in HF aqueous solution was very slow and polymerization did not occur in HI aqueous solution. These results were explained in terms of acidity and power of oxidation. The ratio of formation of dimers varied with the kind of protonic acid, and the results were explained with the nucleophilicity, solvation effect, and mobility of counter ions.