5-치환 2-Furaldehyde류의 염기도 상수

이종팔(Lee, Jong-Pal),임귀택(Im, Gwi-Taek),이용희(Lee, Yong-Hui),구인선(Gu, In-Seon),류준하(Ryu, Jun-Ha) 대한화학회 2002 대한화학회지 Vol.46 No.4

5-치환 2-Furaldehyde류의 양성자화 반응을 25, 황산 수용액 속에서 분광광도법으로 조사하여 각 반응물질의 염기도 상수인 p값을 과산도 (execess acidity)법으로 구하였다. 전자 주게 치환기를 가진 5-methyl-2-Furaldehyde의 염기도 상수는 전자 받게 치환기를 가진 5-nitro-2-Furaldehyde의 염기도 상수보다 크게 나타났으며 pK단위로 3.25정도 차이가 나는 것을 알수 있었다. 각 반응기질의 양성자화 반응으로부터 형성된 짝산의 용매화 정도를 나타내는 m값은 본 반응계와 유사한 반응물질인 acetophenone과 비슷한 크기로 나타남을 알 수 있었다. 2-Furaldehyde의 치환기 변화에 따른 염기고 상수의 변화 값인 -과 m의 상관관계가 좋은 직선성을 보였다 The protonation equilibrium of 5-substituted 2-furaldehydes is investigated spectrophotometrically in aqueous sulfuric acid at and the basicity constants(p) of the substrates is calculated by means of the excess acidity method. The basicity constant of 5-metyl-2-furaldehyde having electron donating group is larger than that of 5- nitro-2-furaldehyde having electron withdrawing group. Difference between the basicity constants(p) of these two compounds was about 3.25 pK unit. The m value which is the degree of solvation of the protonated substrate is similar to that of acetophenone having same protonation site. The dependence of p on m value shows good linear cor-relation.

Aminolysis of 4-Nitrobenzenesulfenyl Chloride

이종팔,이성식,구인선 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.3

N-furoyl-4(5)-nitroimidazole의 가수분해반응에 미치는 촉매효과

이종팔,임춘영 동아대학교 기초과학연구소 2003 基礎科學硏究論文集 Vol.20 No.1

N-furoyl-4(5)-nitroimidazole의 가수분해반응을 25℃에서 분광광도법에 의해 속도론적으로 조사하였다. pH 6.5 이하에서 pH에 무관한 반응과 pH 6.5 이상에서 OH에 의한 촉매반응이 관찰되었다. 가수분해반응속도에 미치는 니트로기의 치환기 효과는 그다지 크게 나타나지 않았다. bifunctional acid & base catalyst 들은 촉매작용은 cacodylate가 가장 효과적이었으며, 염기성형 촉매가 산성형 촉매효과 보다 크게 작용함을 알 수 있었다. 반면 acetate는 촉매효과가 거의 나타나지 않았다. 활성화 엔탈피보다 활성화 엔트로피가 크게 나타났으며 용매동위원소효과가 관찰되었다. The rate constants for the hydrolysis of N-furoyl-4(5)-nitroimidazole are determined in water at the 25℃ under pseudo first order conditions by uv/vis spectrophotometer. The pH independent reaction and the hydroxide ion catalyzed reaction are observed from pH 6.5 to 1.0 and above pH 6.5, respectively. The D₂O solvent isotope effect is observed in the pH independent reaction, that is, k_(0)^(H₂O)/K_(0)^(D₂O)2.0. Activation parameters in the water catalyzed reaction and the hydroxide ion catalyzed reaction are calculated to △H ≠ 9.97 Kcal/mol, △H ≠ 8.51 Kcal/mol and △S ≠ 36.6 e,u., △S ≠-67.1 e.u. respectively. Thus, the water catalyzed reaction and the hydroxide ion catalyzed reaction are more important to nucleophilic attack to the carbonyl carbon than the protonation of the leaving group in the transition state. The most effective catalyst of bifunctional catalysts in the hydrolytic reaction is cacodylate and the base form of this catalyst is more effective, whereas there is no catalytic effect on the acetate.

2-염화안트라퀴논카르보닐과 메타-치환아닐린과의 친핵성치환반응

李鍾八,嚴泰燮 東亞大學校 大學院 1983 大學院論文集 Vol.7 No.-

Pseudo-first order rate constants k ???. were determined for the reaction of Anthrauqinone-2-carbonylchoride with meta-substituted Anilines (m-CH₃,H, m-CL, m-NO₂) in acetone, The second rate constants k²were then determined from k???. The slopes β of Bronsted plot and ρ of Hammett plot have been calculated (β=0.41∼0.47)(ρ=-0.83∼1.18) and studied the transition state variation caused by the effect of substituents. These results suggest that transition state variation which has developed more bond cleavage than bond formation. As isokinetic temperature β values appeared all higher than experiment temperature from isokinetic relationship, reactions proceed entrope control. It was concluded that the reaction proceed via the dissociative S??2 mechanism.

술핀아미드의 가수분해반응에 미치는 산 및 친핵체의 촉매작용

李鍾八,嚴泰燮 東亞大學校附設基礎科學硏究所 1997 基礎科學硏究論文集 Vol.14 No.1

술핀아미드류의 가수분해반응에 미치는 산 및 친핵체의 촉매작용을 25℃, 이온세기 0.1 M(NaClO₄)로 조절된 수용액에서 UV/VIS 분광광도법으로 조사하였다. 산 촉매반응은 벤젠술핀아미드의 이탈기 아닐린에 전자주게 치환기를 가진 반응기질과 벤젠술피닐기의 치환기가 전자주게인 반응기질 모두 pH 3 부근에서 가수분해반응속도상수의 대수값이 현저한 차이를 보였다. 이와 같은 현상은 위와 같은 반응기질이 산 촉매가 수분해될 때 초원자가중간체를 거쳐 진행된다는 사실의 속도론적 증거가 됨을 알았다. 반면, 벤젠술핀아미드의 치환기가 전자받게기인 경우는 pH 3 부근에서 변곡점이 생기지 않음을 보였다. 할로겐화이온에 의한 촉매반응은 Br?이 Cl?보다 크게 나타났으며 이때 반응속도는 반응용액의 산의 농도에 영향을 받음을 보였다. 술핀아미드의 치환기효과로부터 얻은 Hammett의 반응상수 ρ값으로부터 예상되는 할로겐화이온에 의한 촉매반응메카니즘은 술포늄 양이온을 거쳐 진행될 것으로 예상할 수 있었다. We have been kinetically studied on acid and nucleophile catalysis for hydrolysis of sulfinamides at 25℃ in aqueous solution at the ionic strength of 0.1M with NaClO₄by spectrophotometrically. The substrates which the leaving group aniline has electron donating group were shown a breakdown of pH-rate profile at near pH 3 as well as the substrate having electron donating group at benzenesulfinyl group. The break is ascribed to a change in the rate determining step of the reaction involving a hypervalent intermediate. However, the substrates which have the leaving group with electron withdrawing group were not observed a breakdown of pH- rate profile at pH3. Catalysis of halide ion was observed in the hydrolysis of sulfinamides. The nucleophile reactivity observed was in the order of Br?>Cl?, but also found to depend upon the acid concentration of solution. From the Hammett's reaction constant ρ values which were obtained by effect of substituent of sulfinamides, we expect that the reaction mechanism may proceed via sulfonium cation.

N-테노일 이미다졸 유도체의 가수분해반응

이종팔,성대동,엄태섭 東亞大學校 大學院 1994 大學院論文集 Vol.19 No.-

The oseudo first order rates for hydrolses of N-thenoylimidazole(N-TI), N-thenoylbenzimidazole and N-thenoyl-2-phenylimidazole(N-TPI) have been determined at over all pH range with the ionic strength of 0.5M KCl at 40℃ by spectrometry. Hydronium ion and hydroxide in catalyzed reaction observed. The reaction of the diprotonated species occured at pH=3.5 in N-TI and at less than pH=6 in N-TPI. Metal ion catalyses were observed very weakly in hydrolyses of these compounds in the presence of divalent metal ions Cu², Ni², or Zn². We have observed that metal ion promoted hydronium ion catalyzed reaction. Saturation effects were observed only in the metal ion catalyzed hydrolysis of N-TI.

헤테로고리 산염화물의 가용매분해반응에서 전이상태의 구조변화

李鍾八,金忠植,成大東 東亞大學校 1983 東亞論叢 Vol.20 No.3

2-염화휴로일, 5-브로모-2-염화휴로일, 2-염화테노일을 가용매분해반응시켯을 때, 전이상태에서 반응물의 구조변화를 예견하여 More O` Ferrall plot에 나타내었다. 각 혼합 용매간의 반응속도상수의 크기는 대체로 EtOH-H₂o>TFE-H₂O>TFE-EtOH순이었다. 가용매분해 반응에서 용매의 친핵성도를 고려하여 Extended Grunwald-Winstein식에 의하여 m값을 구하였고, 결과적으로 반응은 ??메카니즘으로 진행함을 알았다. The prediction of the effects of reactant of variation on transition atate structure in solvolysis of 2-furoyl chloride, 5-bromo-2furoyl chloride and 2-thenoyl chloride has applied to More O` Ferrall plot. The sequence of magnitude for the rate constant of each solvent is EtOH-H₂O>TFE-H₂O>TFF-EtOH. The m values obtained from extended Grunwald-Winstein equation, after due consideration of the nucleophilicity of solvent in solvolytic reaction. As a result of the reactions proceed by a associative ?? mechanism.

자연과학대학, 화학과

이종팔,엄태섭,성대동 東亞大學校 大學院 1988 大學院論文集 Vol.13 No.-

The nucleophilic substitution reaction of p-substituted anilines and solvolyses of various substrates in tetrahydrofuran and methanol binary solvent mixtures have been investigated by means of conduct metrically. In order to investigate solvent effect on the rate of reaction, the solvatochromic parameters of tetrahyd rofuran and methanol bianry solvent mixtures have been determined by mean of UV-vis. sepctrophotometer. From the results of rate constants the following conlution have been obtatined. The values of solvatochromic parameters, α,βand π?? values increased with the methanol content, the increase in the αvalues being the greatest. And hence the solvent effect is controlled mainly by αvalues, i.e., hydrogen bond donor ability, of the transition state and the reactants. As the substituent of benzenesulfonyl chloride is varied from one of electorn donating to that of withdrowing, ???? values increase, while the variation of the substituent in aniline to one of electron donating caused ?? values to increase. The reaction center, sulfer atom has shown to develope negative charge and nitogen atom on the nucleophile has shown to develope positie charge in the transition state. From application of potential energy surface model, teh reacton are shown to proceed by an associative S??2 reaction which is in between the S??N and S??2 mechanism.

아실이동반응의 전이상태구조

이종팔,박현석,성대동 東亞大學校附設基礎科學硏究所 1992 基礎科學硏究論文集 Vol.9 No.1

30℃ 물속에서 N-acetylimidazole유도체의 가수분해반응을 속도론적으로 조사하였다. 분광광도법에 의해 얻은 속도자료는 물 촉매반응 경우 N-acetyl-(2,4,5-triphenyl)-imidazole (N-ATPI)이 N-acetyl-(4,5-diphenyl)-imidazole(N-ADPI)보다 빨랐으며 ?? 촉매반응은 N-ATPI의 경우 pH=9 가까이에서 나타났고, N-ADPI의 경우 pH=7.3 근처에서 일어남을 알았다. N-ATPI의 물 촉매반응에 대한 전이상태의 구조를 알아보기위한 H₂O 와 D₂O 에서의 속도자료비가 ?/?됨을 보였다. 또한 염기의 농도변화에 대한 물의 촉매방응속도를 조사한 결과 Bronsted의 β값이 0.31로 보임에 따라 전이상태(TS)에서 물분자의 결합이 느슨함을 암시하였다. pH=6.05에서 N-ATPI의 반응에서 구한 △??와 △??는 각각 7.29 ㎉/㏖, -35.5 e.u 가 됨을 알았다. 구한 자료에 의해 본 반응의 전이상태구조는 early TS에서 약간 loose한 구조가 예상되었다. The hydrolysis of N-acetylimidazoles have been studied kinetically in water at 30℃. The kinetic data by spectrometry was shown that rate constants of N-acetyl- (2,4,5-triphenyl)-imidazole(N-ATPI) are a little bit faster than those of N-acetyl-(4,5-diphenyl)-imidazole(N-ADPI) in the regions of reaction. In the case of N-ATPI, general base catalysis has been observed in near pH=9, while in the case of N-ADPI has been observed in pH=7. In order to investigate transition state structure for hydrolysis of N-ATPI in pH independent reaction region, we obtained solvent isotope effect, ??/??. △?? =7.29 ㎉/㏖, △?? = -35.5 e.u. From these results, the transition state structure of pH independent reaction is expected loose structure which is located in early TS.

S-(4-methylphenyl)-4-chlorothiobenzoate의 아민 첨가 분해 반응

이종팔,전정남 東亞大學校附設基礎科學硏究所 1995 基礎科學硏究論文集 Vol.12 No.1

We have been studied for the aminolysis of s-(4-methylphenyl)-4-methylthiobenzoate with secondary alicyclic amines in water and at 40℃, 0.2M ionic strength with KCI by spectrophotometric method. The Bronsted plot for the second order rate constant is biphases with slopes β₁=0.12 and β₂=0.41 at high and low pKa region, respectively. The curved Bronsted plot can be explained by the exitance of a Zwitterionic tetrahedral intermediate in the reaction path and a change in the rate determing step. We found, when the nucleophile is weakly basic than the leaving group, the second step(breakdown of intermediate) should be rate determing step and, the nucleophile is strong base, such like piperidine, the first step(formation of intermediate) should be rate determing step.