Further Kinetic Studies of Solvolytic Reactions of Isobutyl Chloroformate in Solvents of High Ionizing Power Under Conductometric Conditions

임귀택,Yeong Ho Lee,류준하 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.2

Solvolyses of isobutyl chloroformate (4) in 43 binary solvent mixtures including highly aqueous media, water, D2O, CH3OD, 2,2,2-trifluoroethanol (TFE) as well as aqueous 1,1,1,3,3,3-hexafluoro-isopropanol (HFIP) solvents were performed at 45 oC, in order to further investigate the recent results of D'Souza, M. J1. et al.; solvolyses of 4 are found to be consistent with the proposed mechanism (AdE). The variety of solvent systems was extended to comprise highly ionizing power solvent media (YCl > 2.7 excepted for aqueous fluorinated solvents and pure TFE solvent) to investigate whether a mechanistic change occurs as solvent compositions are varied. However, in case of 18-solvent ranges having aqueous fluorinated solvent systems (TFE-H2O and HFIP-H2O) and/or having YCl > 2.7 solvent systems, the solvent effect on reactivity for those of 4 are evaluated by the multiple regression analysis as competition with SN2 - type mechanism. And in pure TFE and 97 w/w % HFIP solvents with high YCl and weak NT, these solvolyses are understood as reactions which proceed through an ionization (SN1) pathway.

극성이 큰 용매의 이온화력 척도와 친핵도와 상관관계

임귀택,김양희,성대동 東亞大學校 1994 東亞論叢 Vol.31 No.1

Solvent ionizing power Y and solvent nucleophilicity N have been determined by means of kinetics in l,l,l,3,3,3-hexafluoro-2-propanol(HFP) and 2-propanol(PrOH) solvent mixtures. The solvolytic rate constants are increasing the content of HFP in HFP-PrOH solvent mixtures. This phenomenon is due to the fact that HFP molecules reaveal the strong anion solvation around the leaving group of the substrate. 2-Adamantyl tosylate is better than tert-butyl halides as a standard substrate for determining the ioniging power in most solvents because the rate-determining step of the former is shown as ion-pair intermediate as shown in ?? mechanism. The solvolysis of tert-butyl chloride is close to ?? mechanism, but tert-butyl bromide and iodide is not useful as a standard substrate for determining the solvent ionizing power based on ?? mechanism since a carbocation is formed in the rate-determining step, and simultaneously the mucleophilic solvent assistance takes place. In HFP-PrOH solvent mixtures the ionizing power Y values(??) are increased, but the nucleophilicity N Values(??) are decreased, as the HFP content is increased. Such a tendency is in accord with the fact that the pKa value of HFP is very low compared with most protic solvents and also in accord with the fact that the first ionization energy of HFP is very high. This is due to the fact that the electron density of the lone electron pair in oxygen diminishes remarkably by the inductive effect(electron-withdrawing effect) of six fluorine atoms in HFP molecules which are of higher electron negativity. The magnitude of Y values for every substrate reveals the order of ??. This is due to the fact that the charge delocalization is increased by ?? and ?? which have relatively weak basicity.

Syntheses and Antibacterial Activities of 7-(5-Methylthio-2,7-diazabicyclo[3.3.0]oct-7-yl)quinolone-3-carboxylic Acids

이재욱,임귀택,이길성,Jae Wook Lee,Gui Taek Lim,Kilsung Lee Korean Chemical Society 2003 대한화학회지 Vol.47 No.5

친핵성 치환반응에서 최대속도현상과 Hammett 상관관계

성대동,임귀택,김양희,김민식 한국식품영양학회 1995 韓國食品營養學會誌 Vol.8 No.3

등유전성 용매로 알려진 methanol과 acetonitrile의 이성분 혼합용매에서 p-치환 benzyl bromide와 p-치환 N, N-dimethylaniline과의 친핵성 치환반응을 반응속도론적으로 연구하여 다음과 같은 결론을 얻었다. 1. Hammett ρ_X값으로부터 전이상태에서 반응기질의 반응 중심 원자에 양(+)하전이 증가하고 결합 형성보다는 결합파괴가 진전됨을 알 수 있었다. 그러나 친핵체에 -NO_2기가 치환된 Y-p-NO_2인 경우 반응 중심 원자에 음(-)하선이 증가하여 결합파괴와 동시에 결합형성도 크게 진전되었음을 알 수 있었다. 2. Hammett ρ_Y값으로부터 기질의 치환기가 전자주게기일수록 결합형성이 작게 되고 기질의 치환기가 전자 받게기일수록 결합형성이 크대 되었음을 알 수 있었다. 3. 교차 상호작용 상수, ρ_XY값으로부터 80%(v/v)의 methanol조성에서 친핵체가 반응 기질을 공격하는 능력이 가장 크게 나타나고 동시에 결합형성이 잘 진전됨을 보여 주었다. 4. 퍼텐셜 에너지 표면 모델에 적용했을 때 반응은 각 반응지수로부터 구한 반응물의 전이상태의 구조와 잘 일치하였다. 5. 분광용매화 피라미터식에 적용하였더니 본 반응은 용매의 편극-극성 효과에 크게 지배됨을 알 수 있었다. The nucleophilic substitution reactions of p-substituted benzyl bromide with p-substituted N.N-dimethylanilines in methanol and acetonitnle binary solvent mixture which is known to an isodielectric solvent system kinetically and the results are as follows. The positive charge is developed on the reaction center of the substrate and it means that the bond cleavage is preceded more than bond formation in the transition state on the analogy of Hammett ρX values. The bond formation is not progressed in the case of electron donating substituent of substrate. However, the bond formation is much developed in the case of electron withdrawing substituent of substrate on the analogy of Hammett ρY values. The nucleophilic attacking ability is shown a highest at 80%(V/V) methanol content and the bond formation is well progressed at the same methanol composition on the result of a cross interaction coefficient, ρXY. The result of transition state structure that is applicated to the potential energy surface model is in accord with the result that is applicated to the reaction susceptibilities. The reaction is subject to the polarity-polarizability term more than the hydrogen bond donor acidity term by application to the solvatochromic parameter equation.

[2]Pseudorotaxanes Containing the Tertiary Alkylammonium Salts as Strings and Cucurbit[6]uril as a Bead

이재욱,임귀택,Lee, Jae-Wook,Lim, Gui-Taek Korean Chemical Society 2005 대한화학회지 Vol.49 No.1

물과 에탄올 이성분 혼합용매 계에서 부피 및 온도 변화에 관한 연구

김용권,임귀택 한국초등과학교육학회 2001 초등과학교육 Vol.20 No.1

This paper is to study on the change of volume and temperature of the solution which mixed water with ethanol. And its main purpose is to examine closely how the volume changes, and to find the method to maximize the change of the volume. The summaries for results of the study are; First, we were known that water and ethanol are homogeneously mixed. But two solvents does not mix homogeneously by different specific gravity at early stages. Second, we could see that the volume changed large at homogeneous mixed water with ethanol by stirrer, the change of volume is the largest value when water mixed with ethanol in the ratio of one to one. Third, when water mixed with ethanol in the ratio of one to one, the change of temperature is very large by activated hydrogen bond. We conclude that it is the best result when ratio of water and ethanol is one to one and the solution is well mixed.

Photodecomposition Mechanism of 2-Methoxy-1,2-diphenyl Diazoethane

성대동,임귀택,김민식,박동규,Seong, Dae Dong,Im, Gwi Taek,Kim, Min Sik,Park, Dong Gyu Korean Chemical Society 1995 Bulletin of the Korean Chemical Society Vol.16 No.1

The mechanism of the photodecomposition of 2-methoxy-1,2-diphenyl diazoethane has been investigated in methanol and isoprene using time-resolved laser flash photolysis techniques. The reaction of triplet carbene which is generated from 2-methoxy-1,2-diphenyl diazoethane with methanol is believed to proceed via thermal excitation to the singlet state. The activation energy and enthalpy are consistent with a mechanism involving thermal equilibrium between the triplet and singlet state followed by the reaction of the singlet with methanol to give ether.

5-치환 2-Furaldehyde류의 염기도 상수

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

5-치환 2-Furaldehyde류의 양성자화 반응을 25$^{\circ}C$, 황산 수용액 속에서 분광광도법으로 조사하여 각 반응물질의 염기도 상수인 p$K_{BH+}$값을 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 -${\Delta}pK_{BH+}$과 m의 상관관계가 좋은 직선성을 보였다 The protonation equilibrium of 5-substituted 2-furaldehydes is investigated spectrophotometrically in aqueous sulfuric acid at $25^{\circ}C$ and the basicity constants(p$K_{BH+}$) 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$K_{BH+}$) 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$K_{BH+}$ on m value shows good linear cor-relation.

Solvolyses of meta-, and para- Substituted Benzoyl Chlorides in MeOH-MeNO₂and MeOH-MeCN Solvent Mixtures

Uhm, Tae-seop,Ryu, Zoon-ha,Sung, Dae-dong,Lim, Gui-taek 東亞大學校 大學院 1988 大學院論文集 Vol.13 No.-

m- 및 p-치환 염화벤조일의 가용매분해반응 속도상수를 MeOH-MeNO₂2성분혼합용매계에서 결정하였다. 그 결과 물리화학적으로 혼합용매 조성이 일률적으로 변하지 않고 이상성을 보이는 MeOH-MeNO₂계에서 para-위치에 전자주게기가 치환된 경우는 최대속도 현상이 나타났으나 전자받게기의경우는 좋은 직선성을 보였다. 전자주게기가 치환된 염화벤조일은 전이상태에서 용매효과가 전이상태의 구조변화에 크게 영향을 미치지 않는 반면 전자받게기는 용매의구조변화와 밀접한 관계가 있음을 보여주었다. 열역학적 활성화 파라미터와 이온화력의 크기와의 비교에서 반응은 S??2메카니즘으로 진행함을 알 수 있었다.

Tetradecanoic acid를 추출제로 사용하는 용매추출에 의한 란타늄과 세륨의 분리

김정훈,강호철,김영운,이은수,임귀택,방경모,빈혜선 한국폐기물자원순환학회 2012 한국폐기물자원순환학회지 Vol.29 No.3