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Pyun Sang Yong,Paik Kyu Cheol,Han Man So,Cho Bong Rae 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.7
Reactions of 4-nitrophenyl 2-furoates (1a–e) with R2NH/R2NH2 + in 20 mol% DMSO(aq) have been studied. The reactions produced aminolysis products and exhibited second-order kinetics. The Brönsted plots were linear with βnuc values of 0.75–0.89, which remained nearly the same for all 5-furyl substituents. The rate data showed excellent correlations on the Yukawa-Tsuno plots with ρ(x) = 0.72–1.1, and r = 0.55–0.95, respectively. The ρ value increased and r value decreased with a stronger nucleophile, indicating an increase in the electron density at the C O bond and a decrease in the resonance contribution. The results have been interpreted with the addition–elimination mechanism in which the second step is the rds. By comparing with the data for ArC(O)OC6H4-4-NO2 (Ar = Ph, thienyl), the effect of the aryl group on the acyl transfer reaction was assessed.
Kinetic Studies of the Solvolyses of 2,2,2-Trichloro-1,1-Dimethylethyl Chloroformate
Koh, Han-Joong,Kang, Suk-Jin,Kevill, Dennis N. Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.4
The rate constants of solvolyses of 2,2,2-trichloro-1,1-dimethylethyl chloroformate ($\underline{I}$) in 33 solvents can be well correlated using the extended Grunwald-Winstein equation, with incorporation of the $N_T$ solvent nucleophilicity scale and the $Y_{Cl}$ solvent ionizing scale, with sensitivities towards changes in the scale having values of $1.42\;{\pm}\;0.09$ for l and $0.39\;{\pm}\;0.05$ for m, respectively. The activation enthalpies are ${\Delta}H^{\neq}\;=\;12.3$ to $14.5\;kcal{\cdot}mol^{-1}$ and the activation entropies are -28.2 to $-35.5\;cal{\cdot}mol^{-1}{\cdot}K^{-1}$, consistent with the proposed bimolecular reaction mechanism. The kinetic solvent isotope effect of 2.14 in MeOH/MeOD is in accord with a bimolecular mechanism, probably assisted by general-base catalysis.
Kinetic Studies of the Solvolyses of 2,2,2-Trichloro-1,1-Dimethylethyl Chloroformate
고한중,강석진,Dennis N. Kevill 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.4
The rate constants of solvolyses of 2,2,2-trichloro-1,1-dimethylethyl chloroformate (I) in 33 solvents can be well correlated using the extended Grunwald-Winstein equation, with incorporation of the NT solvent nucleophilicity scale and the YCl solvent ionizing scale, with sensitivities towards changes in the scale having values of 1.42 ± 0.09for l and 0.39 ± 0.05 for m, respectively. The activation enthalpies are ΔH≠ = 12.3 to 14.5 kcal·mol‒1 and the activation entropies are ‒28.2 to ‒35.5 cal·mol‒1·K‒1, consistent with the proposed bimolecular reaction mechanism. The kinetic solvent isotope effect of 2.14 in MeOH/MeOD is in accord with a bimolecular mechanism, probably assisted by general-base catalysis.
제초제 Flumioxazine의 가수분해 반응성에 관한 분자 궤도론적 이해
성낙도(Nack-Do Sung),정훈성(Hoon-Sung Jung) 한국농약과학회 2004 농약과학회지 Vol.8 No.4
Hydrolytic reactivities of N-phenylphthalimid herbicide flumioxazine (S) were disccused using molecular orbital (MO) theoretical method. It is revealed that below pH 5.0, the protonation (SH?) to carbonyl oxygene atom (O₂₁) of 1,2-dicarboximino group by general acid catalysis (k<SUB>A</SUB>) with hydronium ion (H₃O?) proceeds via charge controled reaction. Whereas, the specific base catalysis (k<SUB>OH</SUB>) with hydroxide anion via orbital controled reaction occurs above pH 8.0. We may concluded that in the range of pH 5.0~8.0, the hydrolysis proceeds through nucleophilic addition elimination (Ad<SUB>N-E</SUB>) reaction, these two reactions occur competitively.