안양천변 고수부지 토양중 중금속원소의 분포연구

李 澈,權五千,安商庚 漢陽大學校環境科學硏究所 1987 環境科學論文集 Vol.8 No.-

안양천변 고수부지 토양중에 함유된 중금속 원소의 분포 상황을 연구하기 위하여 천변을 따라 4개의 시료 재취 지점을 선정한 다음 지점별, 깊이별 및 계절별 고수부지 토양을 채취하였다. 시료속에 함유된 카드륨, 비소, 수은, 크롬, 코발트 및 안티몬과 같은 중금속의 함량분석을 중성자방시화분석법에 따라 수행하였다. 이들 데이타로부터 주성분 분석법 및 피서의 판별함수 분석법과 같은 패턴 인지법을 사용하여 시료의 지점별, 깊이별 및 계절별 유사성 및 특이성을 연구 검토하였다. Soil deposited along Anyangchun were sampled at four different sites according to depths and seasons and derermined for the trace contents of heavy metals such as Cd, As, Hg, Cr, Co, and Sb. for this purpose, instrumental neutron activation analysis were carried out nondestructively. Using the elemental contents, the distribution of the metals was studied by pattern recognition methods such as principal compoment analysis and fisher's discriminant analysis so as to characterize the samples with different places, depths and seasons.

The Charge Transfer Complexes of Monoalkylbenzene with Iodine in Carbon Tetrachloride (I)

Oh-Cheun Kwun Korean Chemical Society 1980 Bulletin of the Korean Chemical Society Vol.1 No.2

Ultraviolet spectrophotometric investigations have been carried out the systems of monoalkylbenzene with iodine in carbon tetrachloride. The results reveal the formation of one to one molecular complexes. The equilibrium constants for these complexes of representative monosubstituted benzene reveal the following order of increasing stability: benzene < methyl- < ethyl- < n-propyl-benzene. The value of ${\Delta}H$, ${\Delta}G$, and ${\Delta}S$ for interaction of a number of monoalkyl substituted benzene with iodine has been determinated. In general, as ΛH becomes increasingly negative, corresponding decreases in ${\Delta}G$</TEA> and ${\Delta}S$ values are observed, and these variation are linear. The thermodynamic constants become increasingly negative with increasing monoalkyl substitution of the aromatic donor nucleus. The complex bond is therefore weak, and its formation is accompanied by relatively small entropy changes.

Kinetics of the Bromine-Exchange Reaction of Gallium Bromide with n-Propyl Bromide in 1,2,4-Trichlorobenzene and in Nitrobenzene

Kwun, Oh-Cheun,Kim, Young-Cheul,Choi ,Sang-Up Korean Chemical Society 1981 Bulletin of the Korean Chemical Society Vol.2 No.3

The rate of the bromine-exchange reaction between gallium bromide and n-propyl bromide in 1,2,4-trichlorobenzene and in nitrobenzene was measured at 19, 25 and $40^{\circ}C$, using n-propyl bromide labelled with Br-82. The results indicated that the exchange reaction was second order with respect to gallium bromide and first order with respect to n-propyl bromide. The third-order rate constant determined at $19^{\circ}C$ is $2.9{\times} 10^{-2}l^2{\cdot}mole^{-2}{\cdot}sec^{-1}$ in 1,2,4-trichlorobenzene and $4.5{\times}10^{-3}l^2{\cdot}mole^{-2}{\cdot}sec^{-1}$. in nitrobenzene. The activation energy, the enthalpy of activation and the entropy of activation for the exchange reaction were also determined. Reaction mechanism for the bromine exchange of n-propyl bromide seemed to be similar to those observed in earlier studies with other alkyl bromides.

Determination of Reactivity by MO Theory (ⅩⅧ). An Intermolecular Perturbation Study of the Acid-Catalyzed Hydrolysis of Diformamide$^*$

Kwun, Oh-Cheun Korean Chemical Society 1980 Bulletin of the Korean Chemical Society Vol.1 No.3

Ultraviolet spectrophotometric investigations were carried out on monoalkylbenzene-iodine systems in carbon tetrachloride. The results reveal the formation of one-to-one molecular complexes. On the basis of the equilibrium constants for these complexes of representative monosubstituted benzenes, the following order of increasing stability is obtained: i-propyl- <i-butyl- <t-butyl- <n-butyl-benzene. The values of ${\Delta}$H, ${\Delta}$G and ${\Delta}$S for the interaction of a number of monoalkyl substituted benzenes with iodine have been determined. In general, it can be said that as ${\Delta}$H becomes increasingly negative, corresponding decreases in the ${\Delta}$G and the ${\Delta}$S values are observed, and these variations are linear. The thermodynamic constants become increasingly negative with increasing monoalkyl substitution of the aromatic donor nucleus. The complex bond is therefore weak, and its formation is accompanied by relatively small entropy changes. Thus, analysis of these findings is discussed.

Kinetics of the Bromine-Exchange Reaction of Gallium Bromide with i-Butyl Bromide in 1,2,4,-Trichlorobenzene and in Nitrobenzene

Kwun, Oh-Cheun,Kim, Young-Cheul,Choi, Sang-Up Korean Chemical Society 1981 Bulletin of the Korean Chemical Society Vol.2 No.4

The rate of the bromine-exchange reaction between gallium bromide and i-butyl bromide in 1,2,4-trichlorobenzene or nitrobenzene was measured at 19, 25 and $40^{\circ}C$, using i-butyl bromide labelled with Br-82. The results indicated that the exchange reaction was second order with respect to gallium bromide and first order with respect to i-butyl bromide. The third-order rate constant determined at $19{\circ}C$ was $3.28{\times}10^{-2}l^2{\cdot}mole^{-2}{\cdot}sec^{-1}$ in 1,2,4-trichlorobenzene and $9.25{\times}10^{-3}l^2{\cdot}mole^{-2}{\cdot}sec^{-1}$ in nitrobenzene. The activation energy, the enthalpy of activation and the entropy of activation for the exchange reaction were also determined.

The Effect of Pressure on the Solvolysis of Benzylchlorides(Ⅰ). p-Methylbenzyl Chloride in Ethanol-Water Mixtures

Kwun, Oh-Cheun,Kyong, Jin-Burm Korean Chemical Society 1985 Bulletin of the Korean Chemical Society Vol.6 No.5

Rate Constants for the solvolysis of p-methylbenzyl chloride in various ethanol-water mixtures were studied at 30 and $40^{\circ}C$ under various pressures up to 1600 bar. The rates of reaction were increased with increasing temperature and pressure, and decreased with increasing solvent composition of ethanol mole fraction. From the rate constants, the values of the activation parameters (${\Delta}V^{\neq},{\Delta}{\beta}^{\neq},{\Delta}H^{\neq}\;and\;{\Delta}S^{\neq}$) were evaluated. The values of ${\Delta}V^{\neq}\;and\;{\Delta}{\beta}^{\neq}$ exhibit the extremum behavior at about 0.30 mole fraction of ethanol. This behavior is discussed in terms of solvent structure variation (electrostriction). From the relation between the reaction rate and the dielectric constant of solvent or the number of water molecule participated in the transition state, it could be postulated that the reaction proceeds through $S_N1$ mechanism.

A Study of the Ionic Association of the Substituted N-Methyl Pyridinium Iodide (II), 4,N-Dimethyl Pyridinium Iodide in Ethanol-Water Mixture

Kwun, Oh-Cheun,Jee, Jong-Gi Korean Chemical Society 1985 Bulletin of the Korean Chemical Society Vol.6 No.1

The electrical conductance and UV absorbance of 4,N-dimethyl Pridinium Iodide (NDMPI) were measured in the ethanol volume percentage, 95, 90, 80 and 60 of an ethanol-water mixture at 15, 25, 35 and $45^{\circ}C$. Ionic association constants(K) of NDMPI were evaluated in accordance with a combined method of conductance UV absorbance. The ion size parameter (${\gamma}_{\pm}$) and dipole momemt (${\mu}_{A+D-}$) of NDMPI were obtained from the values of K and dielectric constant. The ${\mu}_{A+D-}$- values were in good agreement with the values of transition moment(${\mu}_{mn}$) which is calculated form the UV peak values. The large negative values of the electrical enthalpy (${\Delta}H_{el}^{\circ}$) and entropy (${\Delta}H_{el}^{\circ}$ ) have proved that NDMPI had a positive hydration. The positive values of entropy (${\Delta}S^{\circ}$) means the formation of NDMPI ion goes with dehydration.

The Thermodynamics of Formation of Benzene-Iodine Charge Transfer Complex

Kwun,Oh Cheun 漢陽大學校 1974 論文集 Vol.8 No.-

벤젠과 요오드계의 전하이동 착물을 사염화탄소 용액에서 분광 광도법에 의하여 연구한 결과 1 : 1의 분자 착물이 형성 됨을 알았다. 이들 착물의 생성에 대한 25°에서의 평형상수를 구하였다. 그리고 이들 벤젠과 요오드 상호작용에 대한 ΔH, ΔG 및 ΔS의 열역학적 함수도 구하여 고찰하였다.

고압하의 전하이동착물에 대한 물성론적 연구 : 사염화탄소 용액내에서 헥사메틸벤젠과 테트라시아노에틸렌과의 전하이동착물 생성에 대한 압력과 온도의 영향

권오천,김명자 漢陽大學校 基礎科學硏究所 1993 基礎科學論文集 Vol.12 No.-

헥사메틸벤젠과 테트라시아노에틸렌과의 반응을 사염화탄소 용액내에서 반응시켜 여러온도와 압력하에서 착물들의 평형상수를 분광광도법으로 구하였다. 착물 형성에 대한 평형상수는 압력증가에 따라 증가하고 온도상승과 더불어 감소함을 알았으며, 이 값으로부터 열역학적 파라미터들을 산출하였다. 또한 압력증가에 의한 적색이동, 온도증가에 의한 청색이동 현상 및 압력변화에 의한 진동자세기의 열역학 함수와 관계지워 설명하였다. The equilibrium constants for the formation of the complex of tetracyanoethylene with hexamethylbenzene in carbon tetrachloride have been investigated by spectrophotometric measurements at various temperature and pressure. The equilibrium constants of the complex were increased with pressure and decreased with temperature rising. From those constants, the thermodynamic parameters(ΔV, ΔH, ΔS and ΔG)were evaluated. The red-shift at higher pressure, the blue-shift at higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic functions.

Methylene Chloride 용매내에서 Tetramethyltin 과 Iodine 의 ?? 분해반응에 대한 압력의 영향

권오천,경진범,이영훈 漢陽大學校 基礎科學硏究所 1988 基礎科學論文集 Vol.7 No.-

디클로로메탄 용매내에서 요오드와 테트라메틸주석간의 전하이동 상호작용을 분광학적 방법으로 연구하였다. 이들의 결과로 부터 일시적인 전하이동착물의 흡수 스펙트럼이 ??=270nm에서 관찰되었으며, 흡수 스펙트럼의 후속적인 감소현상이 요오드에 의한 테트라메탈주석의 분해반해반응임을 알았다(iododestannylation). 따라서, iododestannylation에 대한 속도 상수를 온도 10˚,25˚및 35℃, 압력을 1600 bar까지 변화시켜 가면서 측정하였으며, 이때의 반응 속도상수는 온도와 압력에 따라 증가함을 보였다. 이 반응 속도상수로부터 ??, ??, ??, 및 ??의 값을 얻었으며, 이들 값으로 부터 전이 상태의 용매구조 변화 및 메카니즘을 규명하였다. 이러한 사실로 부터 본 반응은 ??메카니즘이 지배적이며 압력이 증가함에 따라 ??성격이 약화됨을 알았다. Ultraviolet spectrophotometric investigation has been carried out on the system of charge-transfer(CT) complex with iodine and tetramethyltin in methylene chloride. From the results, the transient CT absorption spectrum can be observed in ??=270nm and the subsequent disappearance of CT absorption spectrum is accompained by the cleavage of tetramethyltin with iodine(iododestannylation). Therefore, the rate constants for the iododestannylation were determined at 10˚,25˚and 35℃ up to 1600 bar and the rates of reaction were increased with increasing temperature and pressure. From these rate constants, the values of the activation parameters?? were obtained and discussed in terms of solvent structure variation of transition state and mechanism from these values. It could postulated that the reaction is followed with ?? mechanism and Weakened ?? mechanism nature by increasing pressure.