• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1999-2001
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• 2000

Impulse breakdown voltage characteristics of sulphur-hexafluoride/nitrogen ($SF_{6}-N_{2}$) mixtures were presented. The applied voltages were the positive and negative lightning impulse (1.2/44${\mu}s$) and oscillating impulse ($0.4{\mu}s$/2.08MHz) voltages. The predischarge current was observed to clarify the breakdown mechanism. The electrode system was consisted of plane to plane configuration with a needle-shaped protrusion whose length and diameter are 10mm and 1mm. The measurements were carried out at the gas pressure of mixtures up to 0.5MPa with nitrogen concentrations varying from 5 to 20%. The electrical breakdown in $SF_{6}-N_{2}$ mixtures develops with steplike pulses in leader mechanism. The minimum breakdown voltages for the negative lightning and oscillating impulse voltages were higher than those for the positive.

• 공업화학
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• 제21권3호
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• pp.278-283
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• 2010

폭발성기를 가진 azido기($-CH_2N_3$), nitrato기($-CH_2ONO_2$) 그리고 hydrazino기(-$CH_2N_2H_3$)로 치환된 옥소란 고폭 화약류의 산 촉매 하에서 중합반응을 반경험적인 MINDO/3, MNDO, AM1 방법 등을 사용하여 이론적으로 고찰하였다. 옥소란 고폭 화약류의 친핵성 및 염기성은 옥소란 산소원자의 음전하크기로 설명할 수 있고, 중합하의 성장단계에서 옥소란의 반응성은 옥소란의 반응중심 탄소원자의 양전하크기와 친전자체의 낮은 LUMO 에너지에 좌우됨을 알 수 있다. 옥소란 고폭 화약류의 고리형 oxonium 이온형이 열린 carbenium 이온형으로 전환되는 과정은 oxonium 이온과 carbenium 이온 사이의 계산된 안정화 에너지(17.950~30.197 kcal/mol)에 의하면 carbenium 이온이 더 유리함을 예측 할 수 있다. 평형상태의 고리형 oxonium 이온과 열린 carbenium 이온의 농도 크기가 반응 메카니즘의 결정단계이며, 산 촉매 하의 형태와 계산을 기초로 하여 빠른 평형을 예상하여 볼 때 선폴리머(prepolymer) 성장단계에서 $S_N1$ 메카니즘이 $S_N2$ 메카니즘보다 빠르게 반응 할 것으로 예측된다.

• Archives of Pharmacal Research
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• 제2권1호
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• pp.9-16
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• 1979

3-Amino-2-phenylthietane derivatives were considered as a useful tool to elusidate the mechanism of inhibiton of MAO by tranylcypromine-type inhitors. The synthesis of 3-benzoylamino-2-phenylthieetane, 3-amino-2-phenylthietane, and 3-N, N-dimentylamino-2-p-nitrophenythietane was attempted using the reaction between 1, 3 dihalogeno alkanes with alkali sulfide. When 1-pheny1-1, 3-dihalo-2-benzolaminopropane was treated with sodium sulfide, 2-pheny 1-4 benzylidene-2-oxazoline was isolated, indicating the case of elimination reaction compared to ring formation. The reaction of 1-p-nitropheny1-1, 3-dichloro-2-N, N-dimethylaminopropane with sodium sulfide gave bis (1-p-nitropheny1-2-N, N-dimethylamino-3-chloropropane)sulfide. The mechanism of reaction was discussed.

• Bulletin of the Korean Chemical Society
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• 제9권3호
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• pp.157-160
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• 1988

The rates of hydrolysis of N-(benzenesulfonyl) benzimidoyl chlorides (p-H, $p-CH_3,\;p-CH_3,\;p-NO_2\;and m-NO_2$) have been measured by UV spectrometry in 60% methanol-water at $25^{\circ}C$ and a rate equation which can be applied over wide pH range was obtained. Below pH 7.00, the substituent effect on the hydrolysis rate of N-(benzenesulfonyl) benzimidoyl chloride was found to conform to the Hammett ${\sigma}$ constant with ${\rho}$ = -0.91, whereas above pH 9.00, with ${\rho}$ = 0.94. On the basis of the rate equation obtained and the effect of solvent, substituents and salt, the following reaction mechanism were proposed; below pH 7.00, the hydrolysis of N-(benzenesulfonyl) benzimidoyl chloride proceeds by $S_N1$ mechanism, however, above pH 9.00, the hydrolysis is initiated by the attack of the hydroxide ion and in the range of pH 7.00-9.00, these two reactions occur competitively.

• Bulletin of the Korean Chemical Society
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• 제20권12호
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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.

• 대한화학회지
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• 제43권5호
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• pp.505-510
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• 1999

n-butanol 용매 내에서 titanium n-butoxide의 가수분해 반응에 의하여 $TiO_2$ 분말을 합성하였고, 가수분해 반응 메카니즘은 UV-Vis 분광법에 의하여 조사하였다. 가수분해 반응시 물의 농도를 과량으로 하여 반응이 유사일차반응으로 진행하도록 하였다. 이러한 농도 조건에서 얻어진 분말의 상(phase)을 XRD에 의하여 확인하였으며 반응속도는 Guggenheim method를 이용하여 계산하였다. 합성 결과 얻어진 분말은 생성 초기 비결정 상태에서 열처리 과정을 거치면서 rutile 구조로 상전이 하였다. 속도상수로부터 얻어진 물분자수(n-value)와 열역학적 파라미터로부터 titanium n-butoxide의 가수분해 반응은 Interchange-Associative(Ia)메카니즘으로 진행하는 것으로 추정되었다.

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4361-4365
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• 2011

The nucleophilic substitution reactions of bis(N,N-dimethylamino) phosphinic chloride (3) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at $65.0^{\circ}C$. The anilinolysis rate of 3 is rather slow to be rationalized by the conventional stereoelectronic effects. The magnitudes of ${\rho}_X$ (= -6.42) and ${\beta}_X$ (= 2.27) values are exceptionally great. The deuterium kinetic isotope effects (DKIEs; $k_H/k_D$) are secondary inverse ($k_H/k_D$ = 0.69-0.96). A concerted $S_N2$ mechanism involving a backside attack is proposed on the basis of secondary inverse DKIEs and the variation trend of the $k_H/k_D$ values with X. The anilinolyses of six phosphinic chlorides in MeCN are briefly reviewed by means of DKIEs, steric effects of the two ligands, positive charge of the reaction center phosphorus atom, and selectivity parameters to obtain systematic information on phosphoryl transfer reaction mechanism.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3293-3297
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• 2012

The solvolysis rate constants of 5-nitro-2-furoyl chloride (5-$NO_2(C_4H_2O)$-2-COCl, 1) in 27 different solvents are well correlated with the extended Grunwald-Winstein equation, using the $N_T$ solvent nucleophilicity scale and YCl solvent ionizing scale, with sensitivity values of $1.20{\pm}0.05$ and $0.37{\pm}0.02$ for l and m, respectively. The activation enthalpies (${\Delta}H^{\neq}$) were 5.63 to $13.0kcal{\cdot}mol^{-1}$ and the activation entropies (${\Delta}S^{\neq}$) were -25.9 to $-43.4cal{\cdot}mol^{-1}{\cdot}K^{-1}$, which is consistent with the proposed bimolecular reaction mechanism. The solvent kinetic isotope effect (SKIE, $k_{MeOH}/k_{MeOD}$) of 2.65 was also in accord with the $S_N2$ mechanism and was possibly assisted using a general-base catalysis. The product selectivity (S) for solvolysis of 1 in alcohol/water mixtures was 1.2 to 11, which is also consistent with the proposed bimolecular reaction mechanism.

• 대한화학회지
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• 제35권6호
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• pp.673-679
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• 1991

N-Tert-butylbenzothiazole-2-sulfenamide (TBBS;가황촉진제)의 전기화학적 환원을 직류와 시차펄스 폴라로그래피, 순환 전압전류법, 조절전위 전기량법으로 연구하였다. TBBS의 전극환원과정은 단일 환원파(-2.31 volts vs. Ag/0.1M AgN$O_3$)에서 비가역으로 4전자가 이동하는 E-C-E-C 반응기구로 진행되었다. 조절전위 전기분해 결과 sulfenamide(-S-N=)결합이 끊어지고 mercaptobenzothiazole (MBT)과 유리된 황 그리고 benzothiazole disulfide (MBT dimer) 등이 생성물로 얻어졌다. 생성물의 분석결과와 pH변화에 따른 폴라로그램의 해석을 바탕으로 전기화학적 반응기구를 제안하였다.

• Journal of Photoscience
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• 제12권1호
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• pp.51-54
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• 2005

The electronic excitationenergy quenching of 2, 5-diphenyl-1, 3, 4-oxadiazole (PPD) by Carbon tetrachloride ($CCl_4$) in different solvents viz, n-hexane, n-heptane, toluene, benzene, cyclohexane, 1, 4- dioxane has been carried out at room temperature to understand the role of quenching mechanism. The Stern-Volmer plots have been found to be linear. As probability of quenching per encounter 'p' is less than unity, and the activation energy for quenching '$E_a$' is greater than the activation energy of diffusion '$E_d$', it is inferred that the fluorescence quenching mechanism is not due to material diffusion alone.