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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}$10.0 the addition of water to nitrone was rate controlling step.
α-Phenyl-N-iso-Propylnitrone 유도체의 가수분해 반응 메카니즘과 반응 속도론적 연구
곽천근,장병만,이석우,이기창 ( Chun Geun Kwak,Byung Man Jang,Seok Woo Lee,Ki Chang Lee ) 한국유화학회 1994 한국응용과학기술학회지 Vol.11 No.1
The rate constants of hydrolysis of α-phenly-N-iso-propylnitrone and its derivatives have been determined by UV spectrophotmetry at 25℃ and a rate equation which can be applied over a wide pH range was obtained. On the basis of rate equations derived and judging from the hydrolysis products obtained and general base and substituent effect, plausible mechanism of hydrolysis in various pH range have been proposed. Below pH 4.5, the hydrolysis was initiated by the protonation and followed by the addition of water to α-carbon. Above pH 10.0, the hydrolysis was proceeded by the addition of hydroxide ion to α=carbon. In the range of 4.5~10.0, the addition of water to nitrone was rate controlling step.
N-tert-Butyl-${\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.
α-Phenyl-N-iso-propylnitrone유도체에 대한 Sodium Thiophenoxide의 친핵성 첨가반응 메카니즘과 그의 반응 속도론적 연구
이광일(李光一),김영주(金榮珠),곽천근(郭仟根),장병만(張炳萬),이기창(李基昌) 한국유화학회 1995 한국응용과학기술학회지 Vol.12 No.2
The rate constant of Nucleophilic addition of sodium thiophenoxide to nitrone were determined by UV Spectrophotometry and a rate equation which can be applied over wide pH range was obtained. Base on the rate equation, general base effect, substituent effect and final product, plausible mechanism of addition reaction have been proposed. Blow pH 3.0, the reaction was initiated 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.
α-phenyl-N-iso-propylnitrone유도체에 대한 1-propanethiol의 친핵성 첨가반응에 관한 연구
이광일(Lee Kwang Il)(李光一),곽천근(Kwak Chun Geun)(郭仟根),장병만(Jang Byung Man)(張炳萬),김영주(Kim Young Ju)(金榮珠),지윤섭(Ji Yun Seup)(池允燮),이기창(Lee Ki Chang)(李基昌) 한국유화학회 1995 한국응용과학기술학회지 Vol.12 No.2
The rate constant of the nucleophilic addition of 1-propanethiol to α-phenyl-N-iso-propylnitrone derivatives were determined at various pH and a rate equation which can be applied over wide pH range is obtained. Final product of the addition reaction was α-thiopropyl-p-phenylbenzylideneamine. Base on the rate equation, general base effect, substituent effect and final product, plausible mechanism of addition reaction have been proposed. Below pH 3.0, the reaction was initiated by the addition of 1-propanthiol, and in the range of pH 3.0-10.0, proceeded by the competitive addition of 1-propanethiol and propanethiolate. Above the pH 10.0, the reaction proceeded through the addition of propanethiolate.
Chitosan 및 Chitosan 유도체를 이용한 중금속 이온 흡착에 관한 연구
이광일,곽천근,장병만,김영주,박태홍,노승일,이기창 ( Kwang Ill Lee,Chun Geun Kwak,Young Ju Kim,Tae Hong Park,Seung IlI Roh,Ki Chang Lee ) 한국유화학회 1996 한국응용과학기술학회지 Vol.13 No.3
We have synthesized the water-insoluble chitosan derivative, N-dithiocarboxy chitosan sodium salt, through the reaction of chitosan with carbon disulfide in the presence of alkali metal hydroxide, Chitosan itselt has been prepared using chitin, one of the most abundant compounds in nature, as a starting material. To elucidate this natural polymer the capacity of adsorbing heavy metal ions, we have performed adsorption experiments using chitosan derivatives of various average molecular weights with different contents of sulfur. The effect of pH, adsorption time and temperature on adsorption efficiency was also studied. The adsorbent derived from chitosan of average molecular weight ranging 5,700~20,000 was shown to have the highest capacity of adsorbing heavy metal ions. Adsorbing efficiency was increased as the reaction time was increased and as the reaction temperature range of 25~45℃. The adsorption capacity at various pH, however, appeared to vary depending on the heavy metal ions studied,
수용성 Chitosam 유도체를 이용한 중금속 이온 흡착에 관한 연구
이광일,곽천근,김영주,장병만,김상호,이기창 ( Kwang Il Lee,Chun Geun Kwak,Young Ju Kim,Buyng Man Jang,Sang ho Kim,Ki Chang Lee ) 한국유화학회 1996 한국응용과학기술학회지 Vol.13 No.2
Chitosan itself has been prepared using chitin, one of the most abundant compounds in nature, as a starting material. We have synthesized the water-soluble chitosan derivative, N-dithiocarboxy chitosan sodium salt, through the reaction of water-soluble chiotsan with carbon disulfide in the presence of alkali metal hydroxide. To elucidate this natural polymer capacity of adsorbing heavy metal ions, we have performed adsorption experiments using the water-soluble chitosan derivative various average molecular weight and of different percent contents of sulfur. The effect of pH, adsorption time and temperature on adsorption efficiency was also studied, The adsorbent derived from water-soluble chitosan of average molecular weight ranging 9,000~120,000 was shown to have the highest capacity of adsorbing heavy metal ions. On the whole, adsorbing efficiency was increased as the reaction time goes longer and also increased as the reaction temperature goes higer in temperature range of 15℃~45℃. The adsorption capacity at various pH, however, was appeared to vary depending on the heavy metal ions studied Judging from these finding, water-soluble N-dithiocarboxy chitosan sodium salt, a derivative of a biodegradable nature polymer, is believed to be a potential adsorbent for heavy metal ions since it not only is shown to lower the concentration of heavy metal ions to below the drainage quality standard, but also it would not cause acidification and hardening of soil which is one of the detrimental effects of synthetic macromolecular adsorbents present.
담지된 Pb 촉매에 의한 Ethylene Glycol 로부터 Oxalic Acid 의 합성
이광일,곽천근,장병만 ( Kwang Il Lee,Chun Geun Kwak,Byung Man Chang ) 한국공업화학회 1995 공업화학 Vol.6 No.6
Pd 금속을 활성탄에 담지 시킨 촉매를 제조하여 주 촉매로 사용하였고, 아울러 Pd와 Ni, Cu 및 Co와 같은 함금 촉매를 제조하여 ethylene glycol로부터 oxalic acid의 합성에 관하여 연구하였다. 본 연구에서 사용된 촉매는 함침법 중 흡착법과 초기 함침법으로 제조하였으며, 초기 함침법에서는 함침 과정이 끝난 촉매를 120℃에서 12시간 건조 시킨 후 430℃에서 수소 가스를 통과 시키면서 8시간 소성하여 환원 시킬 때 수율이 좋은 결과를 나타냈다. 값비싼 귀금속 촉매의 양을 줄이고 Ni, Cu 및 Co 등을 조촉매로 사용하여 활성도를 조사한 결과, Co를 사용한 촉매에서 활성이 우수하였다. 촉매의 특성을 조사하기 위하여 SEM-EDAX, X-ray diffraction 및 BET장치를 이용하였으며 촉매의 제조방법에 따라 촉매의 활성도가 다르게 나타남을 알 수 있었다. To investigate the optimum catalytic condition in the synthesis of oxalic acid from ethylene glycol, we empolyed palladium catalyst supported on activated carbon or bimetallic catalysts such as palladium-cobalt, palladium-nickel and palladium-copper supported on activated carbon. In this way, catalysts were prepared either by adsortion method or by incipient wetness method. The most effective catalyst was obtained when the catalyst was dried at 120℃ for 12hrs, followed by the reduction at 430℃ under the stream of hydrogen gas for 8hrs. In an attempt to reduce the amount of expensive noble metals to be used as a catalyst, we studied the effect of metallic promoters such as cobalt, nickel and copper as a co-catalyst. Cobalt was the only effective one when used along with palladium catalyst. In order to characterize the catalyst, we utilized scanning electron microscopy-energy dispersive X-ray spectrometer, X-ray diffraction and BET surface area. The activity of catalyst was shown to be changed depending upon how it was prepared.