• Bulletin of the Korean Chemical Society
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• 제8권5호
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• pp.408-414
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• 1987

The rate of bromine-exchange reaction between antimony tribromide and ${\alpha}-phenyl-n-butyl$ bromide in nitrobenzene has been determined, using antimony tribromide labelled with Br-82. The results indicate that the exchange reaction follows the first-order kinetics with respect to the organic bromide, and either the second- or first-order kinetics with respect to antimony tribromide depending on its concentration. The third-order rate constant obtained was 7.50 ${\times}10^{-2}l^2mol^{-2}s^{-1}$ at 28$^{\circ}$C. Similar study on the bromine-exchange reaction between antimony tribromide and ${\alpha}$-phenyl-i-butyl bromide has also been carried out. The results of the study show the same kinetic orders as the ones observed with $\alpha$-phenyl-n-butyl bromide. The third-order rate constant observed was 2.40 ${\times} 10^{-2} l^2mol^{-2}s^{-1}$ at 28$^{\circ}$C. The activation energy, the enthalpy of activation and the entropy of activation for the two exchange reactions mentioned above have been determined. The reaction mechanisms for the exchange reactions are discussed.

• 한국환경과학회지
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• 제25권12호
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• pp.1717-1726
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• 2016

In this study, the reductive decolorization of three acid and basic dyes using modified zero-valent iron (i.e., acid-washed iron (Aw/Fe) and palladium coated iron (Pd/Fe)) at various pH conditions (pH 3~5) was experimentally investigated and the decolorization characteristics were evaluated by analyzing the absorbance spectra and reaction kinetics. In the case of acid dyes such as methyl orange and eriochrome black T, color removal efficiencies increased as initial pH of the dye solution decreased. However, the color removal of methylene blue, a basic dye, was not affected much by the initial pH and more than 70% of color was removed within 10 min. During the decolorization reaction, the absorbance of methyl orange (${\lambda}_{max}=464nm$) and eriochrome black T (${\lambda}_{max}=528nm$) decreased in the visible range but increased in the UV range. The absorbance of methylene blue (${\lambda}_{max}=664nm$) also decreased gradually in the visible range. Pseudo-zero order, pseudo-first order, and pseudo-second order kinetic models were used to analyze the reaction kinetics. The pseudo-second order kinetic model was found to be the best with good correlation. The decolorization reaction rate constants ($k_2$) of methylene blue were relatively higher than those of methyl orange and eriochrome black T. The reaction rate constants of methyl orange and eriochrome black T increased with a decrease in the initial pH.

• Korean Chemical Engineering Research
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• 제53권4호
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• pp.463-467
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• 2015

We investigated catalytic activity of ion-exchange resins in acetalization of 1,2-propylene glycol with acetaldehyde. The impacts of reaction variables, such as temperature, reaction time, catalyst loading and feedstock composition, on the conversion of 1,2-propylene glycol were measured. The life of the catalyst was also studied. Furthermore, the reaction kinetics of 1,2-propylene glycol acetalization was studied. It was found that reaction rate followed the first-order kinetics to acetaldehyde and 1,2-propylene glycol, respectively. Therefore, overall acetalization reaction should follow the second-order reaction kinetics, expressed as. Key words: 1,2-propylene Glycol, 2,4-dimethyl-1,3-dioxolane, Ion-exchange Resin, Polyhydroxy Compounds, Acetalization $r=kC^{nA}_AC^{nB}_B=19.74e^{\frac{-6650}{T}}C^1_AC^1_B$.

• 한국응용과학기술학회지
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• 제25권4호
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• pp.418-428
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• 2008

Transesterification of fat of Tra catfish with methanol in the presence of the KOH catalyst yields fatty acid methyl esters (FAME) and glycerol (GL). The effects of the reaction temperature and reaction time on rate constants and kinetic order were investigated. Three regions were observed. In the initial stage, the immiscibility of the Tra fat and methanol limited the reaction rate, hence this region was controlled by the mass transfer. Subsequent to this region, produced FAME like a co-solvent made the reaction mixture homogeneous, therefore the conversion rate increased rapidly so it was controlled by the kinetic parameters of the reaction until the equilibrium was approached in the final slow region. A second-order kinetic mechanism was proposed involving second regions for the forward reaction. The rate determining step for the overall KOH catalyzed-methanolysis of Tra fat was the conversion of triglycerides (TG) to diglycerides (DG). This rate constant was increased from 0.003 to $0.019min^{-1}$ when the reaction temperature was increased from 35 to $60^{\circ}C$. Its calculated activation energy was 14.379 ($kcal.mol^{-1}$).

• 한국응용과학기술학회지
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• 제3권2호
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• pp.41-47
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• 1986

The transesterification reaction between diethanolamine and methyl-methacrylate was kinetically investigated in the presence of various metal acetate catalysts at $120^{\circ}C$. The quantity of methylmethacrylate reacted in the reaction flask was measured by gas chromatography and liquid chromatography, and the reaction rate was investigated by measuring of the quantity of products and reactnts under various catalysts. The transesterification reaction was carried out in the first order reaction kinetics with respect to the concentration of diethanolamine and methylmethacrylate, respectively. The apparent rate constant was found to obey first-order kinetics with respect to the concentration of catalyst. The linear relationship was shown between apparent rate constant and reciprocal absolute temperature, and by the Arrhenius plot, the activation energy has been calculated as 11.08 Kcal with zinc acetate catalyst, 17.99 Kcal without catalyst. The maximum reaction rate was appeared at the range of 1.4 to 1.6 of electronegativity of metal ions and instability constant of metal acetates.

• 한국환경과학회지
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• 제17권3호
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• pp.351-357
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• 2008

In order to develope an efficient way for the synthesis of highly pure 1,4-sorbitan solution from sorbitol, some experimental studies were performed. The reaction showed first order reaction with activation energy of 118.3 KJ/mol. Color of the product solutions changed to brown with reaction temperature and reaction time. The equilibrium contents of 1,4-sorbitan increased with decrease in reaction pressure, but the content of major impurity, sorbide, showed maximum about 550 torr vacuum with $H_3PO_4$ catalyst. The reasonable catalyst configuration was 0.26 wt% PTSA and 1 wt% $H_3PO_2$ and optimum reaction temperature and pressure range was $110\sim120^{\circ}C$ and $700\sim720$ torr vacuum, respectively. At optimum reaction conditions, we could obtain white product solutions of highly pure 1,4-sorbitan with sorbide less than 10 wt%. This white product solution is advantageous for preparation of high quality span, anti-fogging agent.

• 대한화학회지
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• 제16권5호
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• pp.290-297
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• 1972

메탄올(95%) 용매내 $0{\sim}40^{\circ}C$에서 푸르푸랄, 5-메틸 및 5-브로모푸르푸랄의 알코올성 수산화칼륨에 의한 Cannizzaro 반응은 4차반응이며 푸르푸랄은 5-메틸푸르푸랄보다 3배, 5-브로모푸르푸랄은 푸르푸랄보다 10배 빠르게 진행된다. 그리고 이 반응에서 푸르푸랄, 5-메틸푸르푸랄, 5-브로모푸르푸랄의 활성화에너지는 각각 10.46 Kcal/mole, 16.27 Kcal/mole, 9.62 Kcal/mole이며 ${\Delta}H^{\neq}$ 와 ${\Delta}S^{\neq}$를 계산한 바 5-브로모푸르푸랄, 푸르푸랄, 5-메틸푸르푸랄의 순으로 증가 되었다.

• 폴리머
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• 제25권1호
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• pp.25-32
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• 2001

${\circ}C$ 범위에서 아연과 망간촉매를 사용하여 에스테르 교환반응시켜 반응속도를 살펴보았다. 반응은 반회분식 반응기에서 비등온 조건으로 진행되었고 반응온도와 메탄올 유출량으로 반응성을 평가하였다. 반응모델로서는 관능기 모델과 분자종 모델을 적용하여 상호 비교하였다. 아연촉매를 사용할 경우 DMN과 EG의 반응속도는 methyl hydroxyethyl naphthalate(MHEN)와 EG의 반응속도에 비해 1.4배정도 였으나 망간촉매를 사용할 경우 4.3배정도로 촉매 종류에 따라 반응성이 크게 차이가 있음을 알 수 있었다. 아연촉매의 경우 DMN 및 MHEN과 EG의 반응에 대한 촉매농도의 반응차수는 1보다 작았으나, 망간촉매의 경우 오히려 1보다 컸다. 활성화에너지는 DMN과 MHEN의 분자종 차이에 관계없이 아연과 망간촉매의 경우 각각 25000, 28750 cal/mol이었다. 두 가지 반응모델을 비교하여 본 결과 분자종 모델이 반응현상을 잘 표현함을 알 수 있었다.

• 한국세라믹학회지
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• 제20권3호
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• pp.255-259
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• 1983

Am(rphous aluminosilicate zeolite A and hydroxysodalite were obtained by reaction of Hadong kaolin(halloysite) with IN sodium hydroxide solntion in the temperature range of 60 to 10$0^{\circ}C$ For determination of the mechanism of the reaction Various possible mechanisms were compared with the experimental results. It was observed that the reaction mechamism of zeolite A synthesis from Hadong kaolin was first order consecu-tive reaction as follows : halloysitelongrightarrowamorphous aluminosilicatelongrightarrowzeolite Alongrightarrowhydroxysodalite

• Bulletin of the Korean Chemical Society
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• 제16권11호
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• pp.1119-1121
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• 1995

The method for the Schlo"gl model with the first order transition is extended to the Scho;gl model with the second order transition for a photochemical reaction. We obtain the explicit results of the time-dependent average and the time correlation function at the unstable steady state of the model in the neighborhood of the Gaussian white noise and then discuss the effect of noise on the dynamic properties.