• Title/Summary/Keyword: Radical chemistry

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Study of the Kinetics and Mechanisms of Alkoxy Radical Reactions in the Gas Phase (I). Arrhenius Parameters for t-Butoxy Radical Reactions with Isobutane and Cyclohexane

  • Song, Se-Ahn;Choo, Kwang-Yul
    • Bulletin of the Korean Chemical Society
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    • 제5권1호
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    • pp.16-21
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    • 1984
  • The relative Arrhenius parameters for t-butoxy radical decomposition (log $A_d$, $E_d$) and hydrogen abstraction of t-butoxy radical from hydrogen donor (log $A_d$, $E_d$) by competitive method were obtained as follows: for cyclohexane; log $A_a/A_d$ = -4.17 mole/l and $E_d-E_a$ = 9.01 kcal/mole, for isobutane; log $A_a/A_d$ = -5.70 mole/l and $E_e-E_a$= 11.0 kcal/mole. From the reported Arrhenius parameters for t-Butoxy radical decomposition reactions the parameters for t-Butoxy radical reactions with isobutane and cyclohexane are estimated to be log $A(l/mol{\cdot}sec)$ = 8.4, $E_a$ = 4.3 kcal/mol and $log A (l/mol{\cdot}sec)= 9.9,\;E_a$ = 6.3 kcal/mol, respectively.

Radical Scavenging Hydroxyphenyl Ethanoic Acid Derivatives from a Marine-Derived Fungus

  • Li Xifeng;Kim Se-Kwon;Kang Jung-Sook;Choi Hong-Dae;Son Byeng-Wha
    • Journal of Microbiology and Biotechnology
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    • 제16권4호
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    • pp.637-638
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    • 2006
  • Bioassay-guided fractionation of an organic extract of the culture broth from an unidentified marine-derived fungus led to the isolation of a new metabolite, N-[2-(4-hydroxyphenyl) acetyl]formamide (1), along with four known polyketides, 4-hydroxyphenyl acetamide (2), 4-hydroxyphenyl acetic acid (3), 3,4-dihydroxyphenyl acetic acid (4), and N-[2-(4-hydroxyphenyl)ethenyl]formamide (5). The structures of 1-5 were elucidated by spectral data analyses. Among them, compounds 1, 4, and 5 exhibited significant radical scavenging activity against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) with $IC_{50}$ values of 8.4, 11.9, and $0.2{\mu}M$, respectively.

Transient Absorption Spectra of Phenothiazine Derivative in the Vesicle System Containing Ru$^{2+}$ Complex as a Sensitizer

  • Park, Yong-Tae;Kim, Young-Doo;Burkhart, Richard D.;Caldwell, Norris J.
    • Bulletin of the Korean Chemical Society
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    • 제9권2호
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    • pp.84-87
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    • 1988
  • The Photophysical and photochemical properties of Ruthenium bipyridine with two long hydrocarbon chains, $[Ru(bipy)_2(dhbipy)]^{2+}$ and transient phenothiazine derivative cation radical $(PTD^+)$ in the cationic vesicle were studied. Transient absorption spectra of cation radical of phenothiazine derivative in the vesicle system containing the $Ru^{2+}$ complex, $[Ru(bipy)_2(dhbipy)]^{2+}$, (1) as sensitizer and phenothiazine derivative as electron donor was observed by XeCl excimer laser photolysis system. Thus the excited ruthenium complex would be quenched by phenothiazine derivative(PTD) reductively in the vesicle system. The quenching rate constant($K_Q$) of $Ru^{2+}$ with two long hydrocarbon chains in the vesicle by PTD was $9.6{\times}10^8M^{-1}S^{-1}$. The absorption decay kinetics showed that lifetime of phenothiazine derivative cation radical is a value in the 4-8m sec range.

Polymer-Attached Triphenylamine 양이온 라디칼의 합성 (Synthesis of Polymer-Attached Triphenylamine Cation Radical)

  • 차기혁;진명종
    • 공업화학
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    • 제5권3호
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    • pp.438-442
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    • 1994
  • 매우 유용한 양이온 라디칼인 trlphenylaminium hexachloroantimonate가 불용성 폴리머체에 정량적으로 접합되어졌다. 그 폴리머 양이온 라디칼은 딜스-알더 반응형태의 이분자화 반응에 촉매로서 효과적이었으며 여러번 재사용 되어질 수 있음을 알 수 있었다.

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Reactions of Thianthrene Cation Radical Perchlorate with Free Radical. Ⅱ. On the Reaction with tert-Butyl Peroxide$^1$

  • Shin, Jong-Heon;Kim, Kyon-Gtae
    • Bulletin of the Korean Chemical Society
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    • 제5권6호
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    • pp.211-215
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    • 1984
  • Reaction of thianthrene cation radical perchlorate (1) with tert-butyl peroxide (TBP) in acetonitrile gave thianthrene (2), thianthrene 5-oxide (3), cis-thianthrene-5,10-dioxide (4), 5-acetonylthianthrenium perchlorate (9), along with small amount of thianthrene-5,5-dioxide (7) in some cases. Isolation of N-tert-butylacetamide indicated the formation of tert-butyl cation from TBP. The formation mechanisms of these products were proposed.