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Oadiazole 유도체의 고리화 첨가반응에 의한 Pyrazole 유도체의 합성
이기창,황성규,이광일,최봉종 ( Ki Chang Lee,Sung Kwy Hwang,Kwang Ill Lee,Bong Jong Choi ) 한국유화학회 1997 한국응용과학기술학회지 Vol.14 No.1
The synthetic method of pyrazole was performed by 1,3-dipolar cycloaddition with dipolarophileinstead of the reaction between diazomethane and acetylene. The cycloaddition mechanism and reac-tivity of 3-phenyloxadiazole derivatives with dipolarophiles was investigated. In order to investigatethe mechanism and reactivity of this cycloaddition, the effect of substituents having various kinds ofelectron withdrawing of releasing groups were examinated. Considering the effect of substituents, anelectron withdrawing group attached at the 4-carbon position in 3-phenyloxadiazole derivatives decrease the reaction rate because of the lack of electron density on oxadiazole ring. The reaction rate of3-phenyloxadiazole derivatives with dipolarophiles were more conveniently measured using UV thanusing a volumetric analysis which was used before. From the result of this study, it was that thecycloaddition was found to be a first-order reaction depending upon the concentration of 3-phenyloxadiazole only.
3-Phenyloxadiazole 유도체의 1,3-dipolar Cycloaddition 반응에 미치는 온도의 영향
황성규,이기창,최봉종,이광일 ( Sung Kwy Hwang,Ki Chang Lee,Bong Jong Choi,Kwang Ill Lee ) 한국유화학회 1997 한국응용과학기술학회지 Vol.14 No.3
Ultraviolet spectrophotometric investigation has been carried out on the rate constants for 1,3-dipolar cycloaddition of 4-substituted-3-phenyloxadiazole derivatives with dipolarophiles such as phenyl acetylene, propiolic acid methyl ester and dimethylacetylene dicarboxylate. From there, the rate constants for 1,3-dipolar cycloaddition were determined at 80, 100 and 120℃, and the reaction rates were increased with increasing temperature, From these rate constants, the values of the thermodynamic activation parameters were obtained. Some thermodynamic activation parameters such as E_a, △H^*, △S^* and △G^* from Arrhenius equation were also calculated for the electrophilic 1,3-dipolar cycloaddition of 3-phenyloxadiazole derivatives with dipolarophiles. In order to the proposal the mechanism and reactivity of 1,3-dipolar cycloadditioin reaction, the effect of substituents having various kinds of electron withdrawing or releasing groups were examinated. Considering the effect of substituents, an electron withdrawing group attached at the 4-carbon position in 3-phenyloxadiazole derivatives decreases the reaction rate because of the lack of electron density in 3-phenyloxadiazole ring.
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,