60154-37-2Relevant articles and documents
Kinetic study on aminolysis of aryl X-substituted-cinnamates in acetonitrile: Differential medium effect determines reactivity and reaction mechanism
Um, Ik-Hwan,Bae, Ae-Ri,Dust, Julian M.
, p. 13 - 19 (2019/01/10)
A kinetic study on nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted-cinnamates (1a-1f) and Y-substituted-phenyl cinnamates (2a-2g) with a series of alicyclic secondary amines in MeCN at 25.0 ± 0.1 °C is reported. The Br?nsted-type pl
Kinetic study on quinuclidinolysis of O-4-nitrophenyl X-substituted thionobenzoates and O-3,4-dinitrophenyl thionobenzoate: Effect of amine nature on reactivity and reaction mechanism
Yang, Eun-Ji,Kim, Min-Young,Um, Ik-Hwan
, p. 1551 - 1556 (2015/07/15)
Second-order rate constants (kquin) have been measured spectrophotometrically for the reactions of O-3,4-dinitrophenyl thionobenzoate (1a) with a series of quinuclidine derivatives and of O-4-nitrophenyl X-substituted thionobenzoates (2a-2f) with quinuclidine in 80 mol% H2O/20 mol% DMSO at 25.0 ± 0.1 °C. Quinuclidine is less reactive toward the thione esters than less basic benzylamine. Steric hindrance exerted by the tertiary amine is responsible for the decreased reactivity. The Hammett plot for the reactions of 2a-2f with quinuclidine consists of two intersecting straight lines, while the Yukawa-Tsuno plot for the same reactions exhibits an excellent linear correlation with ρX = 1.10 and r = 0.71. This indicates that the nonlinear Hammett plot is not due to a change in the rate-determining step but is caused by ground-state stabilization of substrates possessing an electron-donating group in the thionobenzoyl moiety through resonance interactions. Bronstedtype plot for the reactions of 1a with quinuclidines is linear with βnuc = 0.89, which is typical for reactions reported to proceed through a stepwise mechanism. However, the reactions have been concluded to proceed through a forced concerted mechanism. Instability of a plausible intermediate T± forces the reactions to proceed through such a mechanism.
Nucleophilic substitution reactions of phenyl y-substituted-phenyl carbonates with butane-2,3-dione monoximate and 4-chlorophenoxide: Origin of the α-effect
Kim, Min-Young,Min, Se-Won,Um, Ik-Hwan
, p. 49 - 53 (2013/08/24)
Second-order rate constants have been measured spectrophotometrically for the reactions of phenyl Ysubstituted- phenyl carbonates 7a-g with butane-2,3-dione monoximate (Ox-) in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 °C. The α-nucleophile Ox- is 53-95 times more reactive than the corresponding normalnucleophile 4-ClPhO- toward 7a-g, indicating that the α-effect is operative. The magnitude of the α-effect (e.g., the kOx/k4-ClPhO ratio) is independent of the electronic nature of the substituent Y. The cause of the α- effect for the reactions of 7a-g has been suggested to be ground-state (GS) effect rather than transition-state (TS) stabilization through a six-membered cyclic TS, in which Ox- behaves a general acid/base catalyst. This idea is further supported by the result that OH- exhibits negative deviation from the linear Bronsted-type plot composed of a series of aryloxides, while Ox- deviates positively from the linearity. Differential solvation of the GS of Ox- and 4-ClPhO- has been suggested to be responsible for the α-effect exerted by Ox-.
