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RISS 인기검색어
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- 저자 : 곽천근(Gwak, Chun-Geun) (검색결과 4 건)
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N-tert-Butyl-${\alpha}$-Phenylnitrone 유도체의 가수분해 반응메카니즘과 반응속도론적 연구
곽천근,이광일,Gwak, Chun-Geun,Lee, Kwang-Il 한국응용과학기술학회 1998 한국응용과학기술학회지 Vol.15 No.2
The rate constants of hydrolysis of N-tert-butyl-${\alpha}$-phenylnitrone and its derivatives have been determined by UV spectrophotometry at $25^{\circ}C$ and a rate equation which can be applied over a wide pH range was obtained. On the basis of rate equations derived and judging from the hydrolysis products obtained and general base and substituent effects, plausible mechanism of hydrolysis in various pH range have been proposed. Below pH 4.5, the hydrolysis was initiated by the protonation and followed by the addition of water to ${\alpha}-carbon$. Above pH 10.0, the hydrolysis was proceeded by the addition of hydroxides ion to ${\alpha}-carbon$. In the range of 4.5${\sim}$10.0 the addition of water to nitrone was rate controlling step.
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N-tert-Butyl-${\alpha}$ 수식 이미지-Phenylnitrone 유도체의 가수분해 반응메카니즘과 반응속도론적 연구
곽천근(Gwak, Chun-Geun),이광일(Lee, Kwang-Il) 한국유화학회 1998 한국응용과학기술학회지 Vol.15 No.2
The rate constants of hydrolysis of N-tert-butyl-${\alpha}$ 수식 이미지-phenylnitrone and its derivatives have been determined by UV spectrophotometry at $25^{\circ}C$ 수식 이미지 and a rate equation which can be applied over a wide pH range was obtained. On the basis of rate equations derived and judging from the hydrolysis products obtained and general base and substituent effects, plausible mechanism of hydrolysis in various pH range have been proposed. Below pH 4.5, the hydrolysis was initiated by the protonation and followed by the addition of water to ${\alpha}-carbon$ 수식 이미지. Above pH 10.0, the hydrolysis was proceeded by the addition of hydroxides ion to ${\alpha}-carbon$ 수식 이미지. In the range of 4.5${\sim}$ 수식 이미지10.0 the addition of water to nitrone was rate controlling step.
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5,6-Dihydro-1,4-thiazine 유도체의 가수분해 메카니즘과 반응속도론적 연구
이광일,이석우,곽천근,장병만,김영주,이기창,Lee, Gwang Il,Lee, Seok U,Gwak, Cheon Geun,Jang, Byeong Man,Kim, Yeong Ju,Lee, Gi Chang 대한화학회 1994 대한화학회지 Vol.38 No.5
5,6-dihydro-1,4-thiazine 유도체의 가수분해 반응속도를 25$^{\circ}C$의 수용액중에서 자외선 분광기를 사용하여 측정하고 넓은 pH범위에서 적용될 수 있는 반응속도식을 유도하였다. 가수분해 반응속도에 미치는 치환기 효과를 검토하기 위하여 Hammett plot한 결과 전자 주는기에 위하여 반응속도가 촉진됨을 확인할 수 있었다. 가수분해 최종생성물은 2-(N-acetylaminoethylthio)-acetoacetanilide enol형 이었으며 가수분해 반응속도상수 측정실험과 반응속도식의 유도과정, general base 효과, 활성화 파라미터 및 최종생성물의 결과로부터 5,6-dihydro-1,4-thiazine 유도체의 가수분해 반응은 pH 1.0∼10.0 에서는 중성의 물분자에 의해서 시작되며, pH 10.0∼11.0에서는 물분자와 히드록시 이온의 경쟁적인 반응이 pH11.0 이상에서는 히드록시이온에 의하여 진행됨을 알 수 있었다. 이러한 실험결과을 토대로 하여 5,6-dihydro-1,4-thiazine 유도체의 가수분해 반응메카니즘을 규명하였다. The kinetics of the hydrolysis of 5,6-dihydro-1,4-thiazine derivatives was investigated by ultraviolet spectrophotometry in $H_2O$ at 25$^{\circ}C$. A rate equation which can be applied over a wide pH range was obtained. The substituent effects on the hydrolysis of 5,6-dihydro-1,4-thiazine derivatives were studied and the rate of hydrolysis was shown to be accelerated by electron donating groups. Final product of the hydrolysis was 2-(N-acetylaminoethylthio)-acetoacetanilide enol from Judging from the results of the rate equation, general base effect, activation parameters and final products, the hydrolysis of 5,6-dihydro-1,4-thiazine derivatives seemed to be initiated by the neutral $H_2O$ molecule which does not dissociate at pH below 10.0, but proceeded by the hydroxide ion at pH above 11.0, and those two reactions occurred competively at pH 10.0∼11.0 range. On the basis of these findings a plausible mechanism for the hydrolysis of 5,6-dihydro-1,4-thiazine derivative was proposed.
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$\alpha$-(n-Butyl)-N-Phenylnitrone 유도체에 대한 Sodium Thiophenoxide의 친핵성 첨가반응 메카니즘과 그의 반응 속도론적 연구
이광일,이석우,곽천근,김영주,노승일,이기창,Lee, Gwang Il,Lee, Seok U,Gwak, Cheon Geun,Kim, Yeong Ju,No, Seung Il,Lee, Gi Chang 대한화학회 1994 대한화학회지 Vol.38 No.6
The rate constants of the nucleophilic reaction of ${\alpha}$-(n-butyl)-N-phenylnitrone and its derivatives have been determined by ultraviolet spectrophotometry at $25^{\circ}C$ and a rate equation which can be applied over a wide pH range was obtained. Final product of the addition reaction was $\alpha$-phenylthiobutylidene-aniline. Base on the rate equation, genernal base effect, substituent effect and final product, plausible mechanism of addition reaction have been proposed. Below pH 3.0 the reaction was inititated by the addition of thiophenol, and in the range of pH 3.0∼10.0, proceeded by the competitive addition of thiophenol and thiophenoxide anion. Above the pH 10.0, the reaction proceeded through the addition of a thiophenoxide anion. ${\alpha}$-(n-Butyl)-N-Phenylnitrone 유도체의 첨가 반응속도상수를 25^{\circ}C$의 수용액에서 자외선 분광광도법으로 측정하여 넓은 pH범위에서 잘 맞는 반응속도식을 유도하였다. 첨가반응생성물은 ${\alpha}$-phenylthiobutylidene-aniline이었으며, 첨가반응속도상수 측정과 반응속도식의 유도, 일반기염 효과, 치환기 효과 및 최종생성물의 결과로부터 반응 메카니즘을 제안하였다. 즉, pH 3.0 이하에서는 티오페놀의 첨가로 반응이 시작되며, pH 3.0∼10.0에서는 티오페놀과 티오페녹시드 음이온이 경쟁적으로 첨가되어 진행되며, pH10.0이상에서는 티오페녹시드 음이온의 첨가에 의해서 반응이 진행된다.
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