136367-45-8Relevant academic research and scientific papers
Kinetic study on nucleophilic displacement reactions of 2-chloro-4-nitrophenyl x-substituted-benzoates with primary amines: Reaction mechanism and origin of the a-effect
Um, Tae-Il,Kim, Min-Young,Kim, Tae-Eun,Um, Ik-Hwan
, p. 436 - 440 (2014/03/21)
Second-order rate constants for aminolysis of 2-chloro-4-nitrophenyl X-substituted-benzoates (1a-h) have been measured spectrophotometrically in 80 mol % H2O/20 mol % DMSO at 25.0 °C. The Bronsted-type plot for the reactions of 2-chloro-4-nitrophenyl benzoate (1d) with a series of primary amines curves downward, which has been taken as evidence for a stepwise mechanism with a change in rate-determining step (RDS). The Hammett plots for the reactions of 1a-h with hydrazine and glycylglycine are nonlinear while the Yukawa- Tsuno plots exhibit excellent linearity with ρX = 1.22-1.35 and r = 0.57-0.59, indicating that the nonlinear Hammett plots are not due to a change in RDS but are caused by stabilization of substrates possessing an electron-donating group (EDG) through resonance interactions between the EDG and C=O bond of the substrates. The α-effect exhibited by hydrazine increases as the substituent X changes from a strong EDG to a strong electron-withdrawing group (EWG). It has been concluded that destabilization of hydrazine through the electronic repulsion between the adjacent nonbonding electrons is not solely responsible for the substituent dependent α-effect but stabilization of the transition state is also a plausible origin of the α-effect.
Kinetic study on aminolysis of y-substituted-phenyl x-substituted- benzoates: Effects of substituents x and y on reactivity and reaction mechanism
Jeon, Seong Hoon,Kim, Hyun Soo,Han, Young Joon,Kim, Min-Young,Um, Ik-Hwan
, p. 471 - 476 (2014/03/21)
A kinetic study on aminolysis of 2-chloro-4-nitrophenyl X-substituted-benzoates (2a-k) in 80 mol % H2O/20 mol % DMSO at 25.0 oC is reported. The Bronsted-type plot for the reactions of 2-chloro-4-nitrophenyl benzoate (2g) with a series of cyclic secondary amines curves downward (e.g., β1 = 0.25, β2 = 0.85 and pKa o = 10.3), which is typical of reactions reported to proceed through a stepwise mechanism with a change in ratedetermining step (RDS). The Hammett plot for the reactions of 2a-k with piperidine consists of two intersecting straight lines, while the corresponding Yukawa-Tsuno plot exhibits an excellent linear correlation with ρX = 1.15 and r = 0.59. Thus, it has been concluded that the nonlinear Hammett plot is not due to a change in RDS but is caused by stabilization of substrates through resonance interactions between the electron-donating substituent and the C=O bond. Substrates possessing a substituent at the 2-position of the leaving aryloxide deviate negatively from the curved Bronsted-type plot for the reactions of Y-substituted-phenyl benzoates (3ai), implying that the steric hindrance exerted by the substituent at the 2-position is an important factor which governs the reactivity of Y-substituted-phenyl benzoates.
Kinetic study on aminolysis of 2-chloro-4-nitrophenyl x-substituted-benzoates in acetonitrile and in H2O Containing 20mol% DMSO: Effects of medium and substituent X on reactivity and reaction mechanism
Kim, Ha-Ram,Yoon, Jung Hwan,Kim, Min-Young,Um, Ik-Hwan
, p. 922 - 927 (2015/02/19)
Second-order rate constants for reactions of 2-chloro-4-nitrophenyl X-substituted-benzoates 1a-1j with a series of cyclic secondary amines in MeCN have been measured. Comparison of the kinetic results with those reported previously for the corresponding reactions carried out in H2O containing 20 mol % DMSO has revealed that amines are less reactive in MeCN. The Bronsted-type plot for the aminolysis of 2-chloro-4-nitrophenyl benzoate (1f) in MeCN is linear with βnuc= 0.64, which is in contrast to the curved Bronsted-type plot reported for the reaction performed in the H2O-DMSO misxture. The Hammett plot for the reactions of 1a-1j with piperidine consists of two intersecting straight lines while the Yukawa-Tsuno plot exhibits an excellent linear correlation with ρX= 1.22 and r = 0.60, indicating that the nonlinear Hammett plot is not due to a change in rate-determining step but is caused by stabilization of substrates possessing an electron-donating substituent through resonance interactions between the substituent and the carbonyl functionality. It has been concluded that medium change from the H2O-DMSO mixture to MeCN forces the aminolysis of 1a-1j to proceed through a concerted mechanism by destabilizing the zwitterionic tetrahedral intermediate (T±).
