• Title, Summary, Keyword: Chemical reaction

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The Nature of Acid-Catalyzed Acetalization Reaction of 1,2-Propylene Glycol and Acetaldehyde

  • Cheng, Chen;Chen, Hui;Li, Xia;Hu, Jianli;Liang, Baochen
    • Korean Chemical Engineering Research
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    • v.53 no.4
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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 $r=kC^{nA}_AC^{nB}_B=19.74e^{\frac{-6650}{T}}C^1_AC^1_B$.

Baylis-Hillman Reaction and Chemical Transformations of Baylis-Hillman Adducts

  • Lee, Ka-Young;Gowrisankar, Saravanan;Kim, Jae-Nyoung
    • Bulletin of the Korean Chemical Society
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    • v.26 no.10
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    • pp.1481-1490
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    • 2005
  • Carbon-carbon single bond-forming reaction is the most useful and fundamental reaction in organic synthesis. Most of the basic carbon-carbon single bond-forming reactions, thus, developed in the past. In these respects, conceptually new C-C bond formation reaction can be highlighted. The Baylis-Hillman reaction was found at the early 1970’s. However, extensive studies on this highly potential reaction were started only before 15 years. This review has been written to shed more lights to the importance of Baylis-Hillman reaction. We have focused mainly on the reaction mechanism, conceptually related reactions, and chemical transformations of the Baylis-Hillman adducts.

Effects of the Polarization Resistance on Cyclic Voltammograms for an Electrochemical-Chemical Reaction

  • Chang, Byoung-Yong
    • Journal of Electrochemical Science and Technology
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    • v.6 no.4
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    • pp.146-151
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    • 2015
  • Here I report an electrochemical simulation work that compares voltammetric current and resistance of a complex electrochemical reaction over a potential scan. For this work, the finite element method is employed which are frequently used for voltammetry but rarely for impedance spectroscopy. Specifically, this method is used for simulation of a complex reaction where a heterogeneous faradaic reaction is followed by a homogeneous chemical reaction. By tracing the current and its polarization resistance, I learn that their relationship can be explained in terms of rate constants of charge transfer and chemical change. An unexpected observation is that even though the resistance is increased by the rate of the following chemical reaction, the current can be increased due to the potential shift of the resistance made by the proceeding faradaic reaction. This report envisions a possibility of the FEM-based resistance simulation to be applied to understand a complex electrochemical reaction. Until now, resistance simulations are mostly based on equivalent circuits or complete mathematical equations and have limitations to find proper models. However, this method is based on the first-principles, and is expected to be complementary to the other simulation methods.

A Spectroscopic Study on Singlet Oxygen Production from Different Reaction Paths Using Solid Inorganic Peroxides as Starting Materials

  • Li, Qingwei;Chen, Fang;Zhao, Weili;Xu, Mingxiu;Fang, Benjie;Zhang, Yuelong;Duo, Liping;Jin, Yuqi;Sang, Fengting
    • Bulletin of the Korean Chemical Society
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    • v.28 no.10
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    • pp.1656-1660
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    • 2007
  • Using solid inorganic peroxides (including Li2O2, Na2O2, SrO2 and BaO2) as starting materials, three reaction paths for singlet oxygen (1O2) production were developed and studied. Their 1O2 emission spectra in the near- IR region and visible region from these reaction paths were simultaneously recorded by a near-IR sensitive Optical Multichannel Analyzer and a visible sensitive Optical Spectrum Analyzer, respectively. The comparison of their 1O2 emission spectra indicated that: (1) in term of the efficiency for 1O2 production, the gasliquid- solid reaction path (in which Cl2 or HCl and H2O reacted with the solid inorganic peroxides suspension in CCl4) was prior to the gas-solid reaction path (in which Cl2 or HCl reacted with the solid inorganic peroxides suspension in CCl4), but was inferior to the gas-liquid reaction path (in which Cl2 or HCl reacted with the solid inorganic peroxides solution in H2O or D2O); (2) the alkali metal peroxides (such as Li2O2 and Na2O2) was prior to the alkaline earth metal peroxides (such as SrO2 and BaO2) as the solid reactants, and Cl2 was favorable than HCl as the gas reactant in efficiency for 1O2 production in these reaction paths.

Synthesis of Neopentyl Biphenylsulfonates Using the Suzuki-Miyaura Reaction

  • Cho, Chul-Hee;Kim, Chul-Bae;Sun, Myung-Chul;Park, Kwang-Yong
    • Bulletin of the Korean Chemical Society
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    • v.24 no.11
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    • pp.1632-1636
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    • 2003
  • Palladium-catalyzed cross-coupling reactions of neopentyloxysulfonylphenyl bromides with arylboronic acids provided a variety of neopentyl biphenylsulfonates in good yields. 2-Bromo- and 4-bromobenzenesulfonates underwent the coupling reaction more rapidly than 3-bromobenzenesulfonate, while chlorobenzenesulfonate did not produce the coupling product under the standard reaction conditions.

Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones

  • Hah, Hyun-Dae;Sung, Shi-Joon;Cho, Ki-Yun;Jeong, Yong-Cheol;Park, Jung-Ki
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.772-775
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    • 2006
  • Cinnamate polymers are well known photoreactive polymers due to [2+2] cycloaddition reaction of cinnamate side group. In this work, we have found that the cinnamate side groups could be also reacted by thermal energy, and this reaction is presumed to attribute to the radical reaction of carbon double bond in the cinnamate groups. Contrary to the photocycloaddition reaction of the cinnamate side groups, the thermal reaction of cinnamate side group was closely related to the flexibility of polymer backbone. The difference of the mechanism between the photocycloaddition reaction and thermal crosslinking reaction was confirmed by $^1H-NMR$$ and $^{13}C-NMR$ analysis of the model compound.

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Initial Reaction of Hexachlorodisilane on Amorphous Silica Surface for Atomic Layer Deposition Using Density Functional Theory

  • Kim, Ki-Young;Yang, Jin-Hoon;Shin, Dong-Gung;Kim, Yeong-Cheol
    • Journal of the Korean Ceramic Society
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    • v.54 no.5
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    • pp.443-447
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    • 2017
  • The initial reaction of hexachlorodisilane ($Si_2Cl_6$, HCDS) on amorphous silica ($SiO_2$) surface for atomic layer deposition was investigated using density functional theory. Two representative reaction sites on the amorphous $SiO_2$ surface for HCDS reaction, a surface hydroxyl and a two-membered ring, were considered. The reaction energy barrier for HCDS on both sites was higher than its adsorption energy, indicating that it would desorb from the surface rather than react with the surface. At high temperature range, some HCDSs can have kinetic energy high enough to overcome the reaction energy barrier. The HCDS reaction on top of the reacted HCDS was investigated to confirm its self-limiting characteristics.

Optimization and analysis of reaction injection molding of polydicyclopentadiene using response surface methodology

  • Kim, Hyeon-Gook;Son, Hye Jeong;Lee, Dong-Koo;Kim, Dong-Woo;Park, Hye Jin;Cho, Deug-Hee
    • The Korean Journal of Chemical Engineering
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    • v.34 no.7
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    • pp.2099-2109
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    • 2017
  • Reaction injection molding (RIM) process conditions for polydicyclopentadiene (PolyDCPD) were optimized by using a Box-Behnken design (BBD) from the response surface methodology (RSM). The RIM process parameters, such as smoke time, exotherm time, highest exotherm and PolyDCPD conversion, were tuned by changing the variables (the amount of catalyst, cocatalyst and moderator). Under the optimized condition, the ring-opening metathesis polymerization reaction of dicyclopentadiene did not occur within 100 s, the maximum temperature was reached within 4 min, and the polydicyclopentadiene conversion was over 98%. Therefore, dicyclopentadiene could be safely put into the mold in a total cycle time of less than 6 min and produce PolyDCPD with mechanical properties sufficient for industry applications.

An Analysis on the Reaction of Crushed Aggregates (국내 쇄석골재의 화학반응성 분석)

  • 이장화;김성욱;최일섭
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.97-102
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    • 1993
  • In the country, due to short comings of natural aggregates of good quality, it is common to use crushed stones. However, the investigation has not been done on the chemical reaction of crushed stones. This study tested and analyzed the aggregate chemical reaction by Petrographic Examination(ASTM C 295),Chemical Metho(ASTM C 289) and Mortar-Bar Method (ASTM C 227). As a result, most of test aggregates didn't show any reaction but many have common deleterious mineral. Therefore, there exists the possibility of chemical reaction in petrographic point of view.

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