• Title/Summary/Keyword: Benzylic

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N3S-ligated Copper(II) Complex Catalyzed Selective Oxidation of Benzylic Alcohols to Aldehydes under Mild Reaction Conditions

  • Dharmalingam, Sivanesan;Koo, Eunhae;Yoon, Sungho;Park, Gyoosoon
    • Bulletin of the Korean Chemical Society
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    • v.35 no.3
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    • pp.715-720
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    • 2014
  • A Cu(II) complex with an three nitrogens and one sulfur coordination environment was synthesized and characterized. Its redox potential was observed at 0.483 V vs. NHE, very similar to that of a Cu-containing fungal enzyme, galactose oxidase, which catalyzes the oxidation of alcohols to corresponding aldehydes with the concomitant reduction of molecular oxygen to water. The Cu(II) complex selectively oxidizes the benzylic alcohols using TEMPO/$O_2$ under mild reaction conditions to corresponding aldehydes without forming any over-oxidation product. Moreover, the catalyst can be recovered and reused multiple times for further oxidation reactions, thus minimizing the waste generation.

Effect of Substituent of Chain Transfer agent in the Free Radical Polymerization (자유 라디칼 중합반응에서 사슬이동제의 치환기 효과)

  • Chung, I.
    • Elastomers and Composites
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    • v.40 no.1
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    • pp.53-58
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    • 2005
  • Carbon tetrachloride is very reactive chain transfer agent due to the resonance stability of the trichlorocarbon radicals after breaking of C-Cl bond. Effect of benzylic radical comparing to trichlorocarbon radicals in the chain tranrfer reactions was investigated. From the structural point of view, cumyl chloride is a good candidate because it has the C-Cl bond with benzylic radicals after displacement of C-Ci bond. The reactivity of free radical polymerization of styrene in the presence of cumyl chloride was compared with that of carbon tetrachloride by calculating chain transfer constants. Results show that the cumyl chloride acts as a stronger chain transfer agent than carbon tetrachloride. The calculated chain transfer constant of cumyl chloride shows higher value (0.0463) than that of carbon tetrachloride (0.0011) in the styrene polymerization. High reactivity of cumyl chloride comparing to that of carbon tetrachloride is probably due to the higher resonance stability or benzylic radical than that or trichlorocarbon radicals after breaking of C-Cl bond. Monte Carlo simulation method is applied for characterizing the validity of kinetic constants according to the ratio of chain transfer agent to monomer.

Determination of Reactivities by MO Theory (XIII). MO Studies on Nonlinear Hammett Correlation of Benzyl Systems (MO 理論에 依한 反應性의 決定 (第13報). 벤질系의 非線型 Hammett 關係에 관한 分子軌道論的 硏究)

  • Ikchoon Lee;Keun Bae Rhyu;Byung Choon Lee
    • Journal of the Korean Chemical Society
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    • v.23 no.5
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    • pp.277-285
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    • 1979
  • CNDO/2 calculations on $XC_6H_4CH_2Cl,\;where\;X = H,\;p-CH_3,\;p-NH_2\;and\;p-NO_2$, and on benzyl radicals, cations and anions have been carried out in order to investigate nonlinear Hammett behavior. Main conclusions reached are: 1. Benzyl chloride exhibits borderline behavior due to ${\sigma}-{\pi}$ conjugation between C-Cl bond and the ring-system. 2. The extent of mutual conjugation can be judged by $\pi$-charge and bond alternation and interfrontier level separation narrowing effects. 3.The electron donating para substituent reduces the HOMO AO coefficient of the benzylic carbon, while the electron withdrawing para substituent reduces the LUMO AO coefficient of the benzylic carbon.

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Synthesis and Phytotoxic Activities of (8S, 9S, 11R)-(-)-Monocerin and (9S, 11R)-(+)-Fusarentin 4, 5-dimethyl ether ((8S, 9S, 11R)-(-)-Monocerin and (9S, 11R)-(+)-Fusarentin 4, 5-dimethyl ether의 합성과 생리활성)

  • Ko, Byoung-Seob
    • Applied Biological Chemistry
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    • v.37 no.5
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    • pp.402-408
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    • 1994
  • For the examination of the role of monocerin(1) on the biological activity, (8S, 9S, 11R)-(-)-monocerin(20) and (9S, 11R)-(+)-fusarentin 4, 5-dimethyl ether(19) were synthesized by a condensation of the benzylic anion of ethyl 2, 3, 4-trimethoxy-6-methylbenzoate(16) with modifyed (R)-ethyl 3-hydroxyhexanoate (9). In a key step, bioreduction with active dried baker's yeast in organic solvent system was employed to get a chiral aldehyde 12. Their phytotoxic activities were tested on rice seedlings and lettuce seeds.

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