• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.919-924
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• 1992

The kinetics of the hydrolysis of N-benzylidenebenzenesulfonamide derivatives have been investigated by ultraviolet spectrophotometry in $H_2O$ at $25^{\circ}C$. A rate equation which can be applied over a wide pH range was obtained. The substituent effect on the hydrolysis of N-benzylidenebenzenesulfonamide derivatives were studied and rate of hydrolysis is known to be accelerated by electron withdrowing group. Final product of the hydrolysis was benzenesulfonamide and benzaldehyde. Base on the rate equation, substituent effect, general base effect and final products, hydrolysis of N-benzylidenebenzenesulfonamide derivatives seemed to be initiated by the hydronium ion at the pH 0.2${\sim}$2.5 and proceeded by the neutral $H_2O$ molecule at pH 3.0${\sim}$8.0 but proceeded by the hydroxide ion at above pH 8.5.

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.284-292
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• 1984

This paper aims to predict the substituent and Lewis acid catalysis effect or reactivity on the regioselectivity of (4+2) cycloaddition reaction of the substituted-E-arene-diazocyanides and nitrosobenzenes. Frontier orbital theory (FMO) has been applied to thermal and catalyzed Diels-Alder reaction by means of CNDO/2 and EHT-SPD methods. It has been found that: (1) The above reaction is positive rho(${\rho}$) values in Hammett equation, so it takes normal electron demand reaction, and four-frontier orbitals and Anh methods are identical with experimental major regioisomer.(2) When electron withdrawing radicals are substituted HOMO and LUMO energies of dienophiles are reduced, and the reactivity is increased. (3) The major regioisomer is predicted as B type, as the Lewis acid makes complexes of dienophile, and polaries LUMO coefficients of dienophile in an opposite way. (4) The linear correlation of Hammett is indicated in the graph of stabilized energies(${\Delta}$E) and sigma(${\sigma}$).

• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.184-188
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• 1990

Rates for reactions of substituted phenacyl bromides with imidazole and those of substituted imidazoles with phenacyl bromide were measured by an electric conductivity method. The rates were accelerated by electron-withdrawing substituents of phenacyl bromide and these reactions obeyed well both the linear free energy relationship and the isokinetic relationship. The relation between pKa's of substituted imidazoles and reaction constants fit the Bronsted rule. However, the case of 2-methylimidazole deviated far from this rule exerting steric hindrance. The reaction proceeded much faster in acetonitrile than in methanol and the observed ratio, k2 (acetonitrile)/k2 (methanol), was considerably larger than the value calculated from the Kirkwood equation.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.1062-1067
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• 1994

The chemistry of 5-methyl-4-imidazolecarboxylic acid ester synthesis involves three distinct reaction steps. Of these the rate of formation of diketone was found to be a function of oxime and HCl concentration and temperature by the batch experiment. The decomposition of diketone was found to be a slow process whereas temperature was the only variable to affect it significantly. An empirical rate expression for the net formation of diketone fits the experminetal data satisfactorily. The principal objectives of this study are to study the kinetics of the diketone formation reaction and to develop the empirical rate expression.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.189-193
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• 2008

In this study, the effect of reaction conditions on the transesterification of soybean oil and methanol was investigated in a high-pressure-fixed-bed-reactor-system with zinc aluminate catalysts. Without catalysts, high-pressure-reaction at $300^{\circ}C$ and 1,200 psi brought 19% yields of methyl esters, which was caused by the approach of reaction condition to supercritical point of methanol. However, except the specific reaction condition, the yields in the reaction with no catalyst were very low below 4.5%. The zinc aluminate was prepared as catalyst by coprecipitation and characterized with $N_2$ gas adsorption/desorption and X-ray diffraction. With catalyst, the effect of the reaction parameters such as temperature, pressure, and molar ratio of reactants on biodiesel production was demonstrated. The higher temperature, pressure, and methanol molar ratio to soybean oil, the more yields of methyl esters. It was proved that among the reaction parameters, the reaction temperature be the most influential variable on methyl ester yields.

• Resources Recycling
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• v.12 no.4
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• pp.30-37
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• 2003

A kinetics study on the dissolution reaction of zinc-ferrite has been made with aqueous sulfuric acid in various temperature and concentration. Fraction reacted(R) and apparent rate constant(K) increased with increasing temperature and concentration of sulfuric acid solution. The rate of dissolution is shown by $1-(1-K)^{1/3}=Kt$ for the initial stage of the reaction in aqueous sulfuric acid, where K is apparent rate constant, R is fraction reacted and t is reaction time, respectively. Activation energy associated with reaction was determined to be 16.3 kcal/mole. The dissolution of zinc-ferrite in sulfuric acid solution is dissolved by sto-ichiometric composition, but Fe and Zn did not dissolved, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.34-37
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• 2001

폐수처리분야에 널리 사용되어 온 펜톤산화반응을 응용한 Fe$^{\circ}$/$H_2O$$_2$시스템을 이용하여 고농도 유류오염 미세호양(100$\mu\textrm{m}$이하)의 화학적 산화처리 실험을 수행하였다. 반응은 100$m\ell$, 삼각프라스크에 오염토양(5g)과 반응시약을 주입한 후 자석교반기를 이용하여 회분 식으로 진행하였으며 일정 시간(0, 1, 2, 4, 8, 24hr)별로 TPH를 측정하였다. 그리고 각 조건별 시간에 따른 반응특성을 살펴보았다. 일반적으로 알려진 펜톤산화반응의 수요 반응조건인 초기 pH /$H_2O$$_2$ 및 Fe$^{\circ}$의 주입농도, 그리고 초기 디젤오염농도의 조건을 변화하며 각 조건별 처리효과를 알아보았다. 본 연구결과에서 최적 pH조건은 3인 것으로 나타났으며, 분말철(Fe$^{\circ}$)과 $H_2O$$_2$의 주입농도를 증가함에 따라 오염토양의 TPH 제거효율도 비례적으로 향상되었다. 초기오염농도에 따른 최종 처리효율은 큰 차이가 없었으나. 고농도 오염일수록 제거된 디젤의 총량은 크게 나타나. 본 논문에서 제시한 방법이 고농도 오염토양일수록 더 큰 효과를 얻을 수 있음을 보여주었다. 대부분의 반응이 반응개시 후 약 8시간 이내에 이루어졌는데, 반응에 수반되는 pH 상승과 그에 따른 반응성의 저감효과를 일정 pH 조절에 의해 감소시킴으로써 반응성의 향상을 좀 더 높일 수 있을 것으로 판단된다. 결론적으로, Fe$^{\circ}$/$H_2O$$_2$시스템을 이용한 화학적 산화처리방법은 경제성과 처리성능에서 고농도 유류오염 미세토양의 효율적인 처리방안으로서 향후 적용 가능성이 높을 것으로 기대된다.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.2
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• pp.14-27
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• 2020

Differential scanning calorimetry and numerical analysis were performed to estimate the performance degradation and ignition characteristics of the pyrotechnic device due to aging. The reaction kinetics extracted from the calorimetry are implemented into the numerical simulation of the igniter and the pyrotechnic delay, subjected to natural, thermal, and hygrothermal aging conditions. Also, combustion experiments are conducted to confirm that aging due to moisture is a major cause of performance failure of the pyrotechnic device as shown from the present numerical simulations.

• Journal of the Korean Chemical Society
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• v.18 no.6
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• pp.423-429
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• 1974

The rate constant of the addition of hydrogen cyanide to $ ${\alpha}$-cyano-\beta-piperonylacrylic$ acid (CPA) were determined by UV spectrophotometry at various pH and a rate equation which can be applied over wide pH range was obtained. From this equation, one may conclude that below pH 3 the reaction is started by the addition of hydrogen cyanide molecule to CPA, however, at pH 6~8, hydrogen cyanide is added to $ {\alpha}$-cyano-$ {\beta}$-piperonyl acrylate anion. From pH 3 to 6, these two reaction are competitive. Above pH 9, the reaction is proceeded by the addition of cyanide ion to $ {\alpha}$-cyano-$ {\beta}$-piperonyl acrylate ion. From pH 3 to 9, the complex reaction mechanism can also be fully explained by the rate equation obtained.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.580-587
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• 1994

The oxidative coupling of methane was studied kinetically using $Na^+(50wt%)/MgO$ catalyst at 710, 730, 750, 770 and $790^{\circ}C$ in a fixed bed flow reactor at the atmospheric pressure under differential conversion conditions. Through curve fitting, it was found that the Langmuir-Hinshelwood type mechanism was fitted to this reaction rather than Rideal-Redox type or Eley-Rideal type mechanism. Therefore, it was proposed that the $O_2{^-}$ or $O_2{^{2-}}$ species on the surface was related to the production of $CH_3{\cdot}$. The estimated activation energy of $CH_3{\cdot}$ production was about 39.3kcal/mol. Moreover, as the result of curve fitting, the stoichiometric coefficient of $O_2$ for the production of $CH_3{\cdot}$ to produce $CO_x$was approximately 1.5. Accordingly, it could be concluded that the $CH_3O_2{\cdot}*$ was prouduced through the partial oxidation of $CH_3{\cdot}$ with the surface oxygen.