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        검색결과 5

        1.
        1993.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The kinetics of the addition of thiourea to cinnamenylisophorone derivatives(X : H, p-Br, p-CH3 m-CH3, p-OCH3) was investigated using ultraviolet spectrophotometry in 20%(v/v) dioxane-H2O at 25℃. A rate equation which can be applied over wide pH range(pH 1.0~13.0) was obtained. In order to investigate the substituent effects of cinnamenylisophorone derivatives. Hammett constant was plotted. As the result, the rate of uncleophilic addition of thiourea to cinnamenylisophorone derivatives was facilitated by electron donating group. It was found that addition of neutral thiourea which was not dissociated at the pH 1.0~9.0 was proceeded, the reaction was proceeded by addition of dissociated anion of thiourea above the pH 10.0. On the basis of this kinetic study, the reaction mechanism of nucleophilic addition of thiourea was investigated.
        4,000원
        2.
        1991.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The kinetics of hydrolysis of cinnamenylisophorone derivatives (rho-H, rho-Br, P-Cl, rho-OCH3) was investigated using ultraviolet spectrophotometry in 20%(v/v) dicxane-H2O at 25℃. A rate equation which can be applied over wide pH range (pH 1.0~13.0) was obtained. In order to investigate the substituent effects on cinnarnenylisophorone derivatives, Hammett constant was plotted. As the result, the rate of hydrolysis of cinnamenylisophorone derivatives was facilitated by electron donating group. Final products of the hydrolysis were benzaldehyde and isophorone, From the measurement of reaction rate constant according to pH changes, substituent effect, and final products, it was found that the hydrolysis of cinnarnenylisophorone derivatives was initiated by the neutral H2O molecule which does not dissociated at below pH 9.0, and in the range of pH 9.0~11.0 this reaction occurs by H2O or hydroxide ion competitively, but proceeded by the hydroxide ion above pH 11.0. On the basis of this kinetic study, the reaction mechanism of the hydrolysis of cinnamenylisophorone derivatives was proposed.
        4,000원
        3.
        1991.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The kinetic of hydrolysis for cinnamylidene aniline derivatives has been investigated by ultraviolet spectrophotometry in 20% (v/v) dioxane - H2O at 25℃. A rate equation which can be applied over wide pH range was obtained. The substituent effects on cinnamylidene aniline derivatives were studied and the hydrolysis was facilitated by electron attracting group. Final products of the hydrolysis were cinnamaldehyde and aniline. From the rate equation, substituent effect and final products, the hydrolysis of cinnamylidene aniline derivatives was initiated by the neutral molecule of H2O which does not dissociate at below pH 9.0~12.0, but proceeded by the hydrogen ion at above pH 5.0~9.0.
        4,000원
        4.
        1990.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Kinetics of the addition of benzalacetophenone derivatives was investigated by ultraviolet spectrophotometery in 5% dioxane H2O at 50℃. A rate equation was obtained in wide range of pH. The substituent effects on benzalacetophenone derivatives were studied, and addition were facilitated by electron attracting groups. The final product was benzalacetophenone-β-thioglycolic acid synthesized by the addition of thioglycolic acid to benzalacetophenone. On the base of the rate equation, substituent effect, general base effect and final product, the plausible addition mechanism was proposed: Below pH 9.0, only neutral thioglycolic acid molecule was added to the carbon-carbon double bond, and in the range of pH 9.0~11.0, neutral thioglycolic acid molecule and thioglycolic acid anion competitively attacted the double bond. By contrast, above pH 11.0, the reaction was dependent upon only the addition of thioglycolic acid anion.
        4,000원
        5.
        1989.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The rate constants of the hydrolysis of cinnamanilide derivatives were determined UV spectrometry in H2SO4 (5~20N), NaOH(5~11N) at 50~110℃ and rate equation could be applied over a strong acid and strong base were obtained. Final product of the hydrolysis was a cinnamic acid. The σ values obtained from the slope of linear plots of log kabs vs. Hammet tΣ constants were slightly negatives, Substituents on cinnamanilide showed a relatively small effect, with hydrolysis facilitated be electron donating group. Activation energy(Ea)was also calculated for the hydrolysis of the cinnamanilide. From this reaction rate equation, substituent effect and experimental of rate constants, that the hydrolysis of cinnamanillde was Initiated by the netural molecule of H2O which do not dissociate at strong acid, and proceeded by hydroxide ion at strong base.
        4,000원