• Title/Summary/Keyword: Chemical reactions

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Thermal and Photochemical Reactions of Benzosilacyclobutenes with Alcohols. Intermediacy of o-Silaquinone Methide in the Photochemical Reactions

  • Kang, Kyung-Tae;Yoon, Ung-Chan;Seo, Hee-Chan;Kim, Kwang-Nam;Song Hwan Young;Lee, Jae-Chul
    • Bulletin of the Korean Chemical Society
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    • v.12 no.1
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    • pp.57-60
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    • 1991
  • Benzosilacyclobutenes were prepared from the reactions of 1,1-dichlorobenzosilacyclobutene with Grignard reagents or t-butyllithium. In the thermal reactions with alcohols, benzosilacyclobutenes underwent both benzyl-silicon and aryl-silicon bond rupture to yield (dialkyl)alkoxy-o-tolylsilanes and (dialkyl)alkoxybenzylsilanes, respectively. The photochemical reactions, however, produced only the former products via o-silaquinone methides.

The Chemically Induced Hot Electron Flows on Metal-Semiconductor Schottky nanodiodes During Hydrogen Oxidation

  • Lee, Hyosun;Lee, Youngkeun;Lee, Changhwan;Kim, Sunmi;Park, Jeong Young
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.152-152
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    • 2013
  • Mechanism of energy conversion from chemical to electrical during exothermic catalytic reactions at the metal surfaces has been a fascinating and crucial subject in heterogeneous catalysis. A metal-semiconductor Schottky nanodiode is novel device for direct detection of chemically induced hot electrons which have sufficient energy to surmount the Schottky barrier. We measured a continuous chemicurrent during the hydrogen oxidation under of 760 Torr of O2 and 6 Torr of H2 by using Pt/Si and Pt/TiO2 nanodiodes at reaction temperatures and compared the chemicurrent with the reaction turnover rate. The thermoelectric current was measured by carrying out an experiment under O2 condition for elimination of the background current. Gas chromatograph and source meter were used for measurement of the chemical turnover rate and the chemicurrent, respectively. The correlation between the chemicurrent and the chemical turnover rate under hydrogen oxidation implies how hot electrons generated on the metal surface affect hydrogen oxidation.

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Efficient Synthesis of Spirobarbiturates and Spirothiobarbiturates Bearing Cyclopropane Rings by Rhodium(II)-Catalyzed Reactions of Cyclic Diazo Compounds

  • Wang, Xue;Lee, Yong Rok
    • Bulletin of the Korean Chemical Society
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    • v.34 no.6
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    • pp.1735-1740
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    • 2013
  • Rhodium(II)-catalyzed reactions of cyclic diazo compounds derived from barbituric acid and thiobarbituric acid with a variety of styrene moieties were examined. These reactions provide rapid synthetic routes to the preparations of spirobarbiturates and spirothiobarbiturates bearing cyclopropane rings.

Rh2(Opiv)4-Catalyzed Reactions of Diazo Compound Derived from Meldrum's Acid and Styrenes. Efficient Synthesis of Cyclopropanes

  • Lee, Yong-Rok;Choi, Jung-Hyun
    • Bulletin of the Korean Chemical Society
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    • v.27 no.4
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    • pp.503-507
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    • 2006
  • The rhodium(II)-catalyzed reactions of diazo compound derived from Meldrum's acid with a variety of styrenes have been examined. These reactions provide a rapid route to the preparation of cyclopropanes with a variety of substituents on the benzene ring. The mechanistic pathway for the formation of these products has been also described in terms of a stepwise mechanism.

A DSMC Technique for the Analysis of Chemical Reactions in Hypersonic Rarefied Flows (화학반응을 수반하는 극초음속 희박류 유동의 직접모사법 개발)

  • Chung C. H.;Yoon S. J.
    • Journal of computational fluids engineering
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    • v.4 no.3
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    • pp.63-70
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    • 1999
  • A Direct simulation Monte-Carlo (DSMC) code is developed, which employs the Monte-Carlo statistical sampling technique to investigate hypersonic rarefied gas flows accompanying chemical reactions. The DSMC method is a numerical simulation technique for analyzing the Boltzmann equation by modeling a real gas flow using a representative set of molecules. Due to the limitations in computational requirements. the present method is applied to a flow around a simple two-dimensional object in exit velocity of 7.6 km/sec at an altitude of 90 km. For the calculation of chemical reactions an air model with five species (O₂, N₂, O, N, NO) and 19 chemical reactions is employed. The simulated result showed various rarefaction effects in the hypersonic flow with chemical reactions.

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Kinetics of the Photochemically Generated t-Butoxy Radical Reactions with Phosphine(PH$_3)^*$

  • Park Chan Ryang;Choo Kwang Yul
    • Bulletin of the Korean Chemical Society
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    • v.6 no.4
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    • pp.206-209
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    • 1985
  • The gas phase reactions of the photochemically generated t-butoxy radicals with phosphine ($PH_3$) were studied in the temperature range of $35-80^{\circ}C.$ We found the significant differences between high temperature thermal reactions and low temperature photo reactions. In comparison with the reactions of t-butoxy radicals with other hydrogen donors, some possible mechanistic suggestions were made for the explanation of the results.

Efficient One-Pot Synthesis of Acridinediones by Indium(III) Triflate-Catalyzed Reactions of β-Enaminones, Aldehydes, and Cyclic 1,3-Dicarbonyls

  • To, Quang Huy;Lee, Yong-Rok;Kim, Sung-Hong
    • Bulletin of the Korean Chemical Society
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    • v.33 no.4
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    • pp.1170-1176
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    • 2012
  • An efficient one-pot synthesis of acridinediones by $In(OTf)_3$-catalyzed reactions was developed starting from ${\beta}$-enaminones, aldehydes, and cyclic 1,3-diketones. The key strategies of these reactions involve domino Knoevenagel condensation/Michael addition/cyclodehydration reaction.