• Title/Summary/Keyword: chemical reaction.

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Density Functional Theory Study of Competitive Reaction Pathways of Ti+ with Fluorinated Acetone in the Gas Phase

  • Hong, Ki-Ryong;Kim, Tae-Kyu
    • Journal of the Korean Chemical Society
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    • v.56 no.1
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    • pp.14-19
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    • 2012
  • We investigate the doublet and quartet potential energy surfaces associated with the gas-phase reaction between $Ti^+$ and $CF_3COCH_3$ for two plausible reaction pathways, $TiF_2^+$ and $TiO^+$ formation pathways by using the density functional theory (DFT) method. The molecular structures of intermediates and transition states involved in these reaction pathways are optimized at the DFT level by using the PBE0 functional. All transition states are identified by using the intrinsic reaction coordinate (IRC) method, and the resulting reaction coordinates describe how $Ti^+$ activates $CF_3COCH_3$ and produces $TiF_2^+$ and $TiO^+$ as products. On the basis of presented results, we propose the most favorable reaction pathway in the reaction between $Ti^+$ and $CF_3COCH_3$.

Reaction of $FeC_5H_5^+$ Ion with Neutral Ferrocene: The Dependence of Reaction Pathways on Its Internal Energy

  • 김병주;소훈영
    • Bulletin of the Korean Chemical Society
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    • v.20 no.10
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    • pp.1181-1185
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    • 1999
  • The reaction of FeC5H5+ ion with ferrocene molecule is investigated using FT-ICR mass spectrometry. FeC5H5+ ions are generated by dissociative ionization of ferrocenes using an electron beam. The reaction gives rise to the formation of the adduct ion, Fe2(C5H5)3+, in competition with charge transfer reaction leading to the formation of ferrocene molecular ion, Fe(C5H5)2+·. The branching ratio of the adduct ion increases as the internal energy of the reactant ion decreases and correspondingly the branching ratio for the charge transfer reaction product decreases. The observed rate of the addition reaction channel is slower than that of the charge transfer reaction. The observation of the stable adduct ions in the low-pressure ICR cell is attributed to the radiative cooling of the activated ion-molecule complex. The mechanism of the reaction is presented to account for the observed experimental results.

Linear and Hyperbranched Polymers via Electrophilic Substitution Reaction in Polyphosphoric $Acid/P_{2}O_{5}$

  • Choi, Ja-Young;Jeon, In-Yeop;Tan, Loon-Seng;Baek, Jong-Beom
    • Proceedings of the Polymer Society of Korea Conference
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    • 2006.10a
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    • pp.195-195
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    • 2006
  • A superior electrophilic substitution reaction medium that is non-toxic, relatively less corrosive, and non-volatile electrophilic substitution reaction to afford high molecular weight linear and hyperbranched polyetherketones (PEK' s) was developed. The system has very strong driving force to give extra ordinary high molecular weight linear and hyperbranched PEK' s. The reaction medium was further extended to prepare various types of copolymers and covalently grafted polymers onto carbon nanotube (CNT) or carbon nanofiber (CNF). By using characteristic hydrophilic nature of the reaction medium, hyperbranched PEK' s could be synthesized from commercially available $A_3\;+\;B_2$ monomers without network formation via selective solubility of the monomers.

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Zeolite-Mediated Cation Exchange Enhances the Stability of mRNA during Cell-Free Protein Synthesis

  • Kim, You-Eil;Kim, Dong-Myung;Choi, Cha-Yong
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.11 no.3
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    • pp.258-261
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    • 2006
  • The addition of zeolite particles enhances the stability of mRNA molecules in a cell-free protein synthesis system. When $20{\mu}g/{\mu}L$ of zeolite (Y5.4) is added to a reaction mixture of cell-free protein synthesis, a substantial increase in protein synthesis is observed. The stabilizing effect of zeolite is most dearly observed in an in vitro translation reaction directed by purified mRNA, as opposed to a coupled transcription and translation reaction. Upon the addition of zeolite in the in vitro translation reaction, the life span of the mRNA molecules is substantially extended, leading to an 80% increase in protein synthesis. The effect of zeolite upon the mRNA stability appears be strongly related to the cation exchange (potassium to sodium) reaction. Our results demonstrate the possibility of modifying this biological process using heterogeneous, non-biological substances in a cell-free protein synthesis system.

Catalytic Activity Studies in Transesterification Reaction (에스테르 교환반응(交換反應)의 촉매활성(觸媒活性)에 관(關)한 연구(硏究))

  • Park, Keun-Ho;Kim, Dong-Shik;Jeong, Soon-Wook
    • Journal of the Korean Applied Science and Technology
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    • v.7 no.1
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    • pp.71-76
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    • 1990
  • Transesterification reactions (methyl methacrylate with monoethanolamine, methyl methacrylate with n-butyl alcohol, dimethylphthalate with ethylene glycol, dimethyl phthalate with monoethanolamine) were kinetically investigated in the presense of various metal acetate catalysts at $110^{\circ}C$. The amount of reactants was measured by gas and liquid chromatography, and the reaction rates also measured from the amount of reaction products and reactants upon each catalyst. The transesterification reactions were carried out under the first order conditions respect to the concentration of reactants, respectively. The overall reaction order was 2nd, Maximum reaction rates were appeared at the range of 1.4 to 1.6 in electronegativity of metal ions and maximum catalytic activities were obserbed at the range of 1.5 to 1,8 in instability constant of metal acetates.