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세륨(Ⅳ)에 의한 말론산의 산화반응에 관한 반응속도론적 연구
김왕기,Kim, Wang Gi 대한화학회 1994 대한화학회지 Vol.38 No.10
1M 황산용액에서 세륨(Ⅳ) 이온에 의한 말론산의 산화반응에 관한 반응속도를 분광광도법으로 연구하였다. 말론산이 과량으로 존재하는 조건하에서 측정된 유사일차 속도상수, $k_{obs}$는 말론산의 농도, [MA]에 따라 크게 의존함을 보였으며 $k_{obs}$ = (0.592[MA])/(1+14.5[MA]$^2$)의 관계를 만족하였다. 이에 근거하여 반응메카니즘을 제안하였다. 말론산의 산해리에 의해 생성된 enolate형 음이온과 Ce(Ⅳ)간의 전자이동반응이 반응속도 결정단계이며, MA의 고농도하에서 Ce(Ⅳ)과 enolate형 음이온간의 1:2 chelate생성반응에 의하여 Ce(Ⅳ)의 농도가 감소하여 산화반응이 억제됨을 알 수 있었다. 본 연구에서 제안된 메카니즘에 근거하여 Sengupta 등에 의해 연구된 pH 의존성을 설명할 수 있었다. The kinetics of the oxidation reaction of malonic acid by ceric ion in 1 M sulfuric acid solution at $20^{\circ}C$ have been investigated by spectrophotometric method. The reaction rate at a large excess of malonic acid was found to be pseudo-first order. The observed pseudo-first order rate constants, $k_{obs}$, are dependent on the concentration of malonic acid, [MA], of which relationship has been found to be $k_{obs}$ = (0.592[MA])/(1+14.5[MA]$^2$). A mechanism for the reaction has been suggested on the basis of the above rate equation. The rate determining step may be the electron transfer reaction between enolate type malonate anion, which is formed by the acid dissociation reaction of malonic acid, and Ce(IV). The rate depression in the range of high concentration of MA has been explained by the formation of 1 : 2 chelate between Ce(IV) and malonate. According to the mechanism, the pH dependence of the rate, which was studied by Sengupta et al., has also been explained.
金旺起,鄭炳秀 全南大學校 師範大學 科學敎育硏究所 1986 科學敎育硏究誌 Vol.11 No.1
We have investigated the effect of experimental experiences on the impro vement of creativity. Testing data were obtained fro m sixty high school freshmen(thirty males and thirty females) in Chonnam province by exercising basic training course(8h) and laboratory work (I5h). Creativity-test(Tung and Lee, 1980) was done for all subjects by pretest and posttest to estimate the effect of experimental experiences on the improvements of creativity. In th is study we have concluded that : (1) the experimental experiences show the significant effect on the impro vement of creativity (2) the experimental experiences are more effective for building flexibility, originality, elaboration, fluency and openness than organization personality factor (3) sexual difference makes no significant difference.
金旺起,鄭根鎬,孫昌國 全南大學校 師範大學 科學敎育硏究所 1984 科學敎育硏究誌 Vol.9 No.1
The fundamental concepts for molecular models are explained in terms of the consequences of the VSEPR theory in order to pigeonhole the types and characteristics of them currently available consistituted with three kinds of valence units. From the interchangeability between the shapes and the concepts of models, we discuss the stereochemical phenomena to which these models are effectively applied in chemical education. Finally, we suggest the necessity for the study on the development of the conceptual models to compensate the limitations inherent to iconic models representing images and/or shapes.
Theoretical Studies on the Progonation Equilibria of Benzoyl Derivatives
김왕기,김용빈,김창곤,이본수,Kim, Wang Gi,Kim, Yong Bin,Kim, Chang Gon,Lee, Bon Su Korean Chemical Society 2001 Bulletin of the Korean Chemical Society Vol.22 No.4
The effects of ortho- (R = H and CH3) and Y-substituents (Y = OCH3, CH3H and CN), which are directly attached to the carbonyl carbon, on the protonation equilibria of the para-X-substituted benzoyl derivatives, 4-X -2, 6-di-R-C6H2-C(=O)-Y, are investigated theoretically using the B3LYP method with 6-31+G* basis set. Structurally, both of the (B) and (BH+ ) forms in the species with R = H are nearly coplanar regardless of the Y-substituents implying that the steric repulsion between Y-substituent and R = H is relatively small. In the species with R = CH3 , the tortional angle (Θ) between the carbonyl moiety and aryl ring varies from zero to near right angle depending on the degree of steric repulsion between Y and R = CH3 and the resonance demand. However the reaction energies, ΔG°, for the protonation processes are more favorable for R = CH3 than for R = H due to stronger electron donating effect of R = CH3 , although the species with R = CH3 are unfavorable sterically. On the other hand, the Hammett type plots are progressively better correlated with б+ than with б values on going from Y = OCH3 to Y = CN for both species with R = H and CH3 indicating that the degree of resonance delocalization between carbonyl moiety and X-substituent is increased for a more electron accepting Y-substituent. Nevertheless the effects of R = CH3 on the magnitude of Hammett type reaction constants ( б or б+ ) are not much different from those of R = H.