scholarly journals A Kinetic Study on Ethylaminolysis of Phenyl Y-Substituted-Phenyl Carbonates: Effect of Leaving-Group Substituents on Reactivity and Reaction Mechanism

2013 ◽  
Vol 34 (6) ◽  
pp. 1722-1726 ◽  
Author(s):  
Yoon-Ju Song ◽  
Min-Young Kim ◽  
Ik-Hwan Um
Keyword(s):  
Reaction Mechanism ◽  
Kinetic Study ◽  
Leaving Group

Kinetic study on aminolysis of aryl X-substituted-cinnamates in acetonitrile: differential medium effect determines reactivity and reaction mechanism

2019 ◽  
Vol 97 (1) ◽  
pp. 13-19
Author(s):  
Ik-Hwan Um ◽  
Ae-Ri Bae ◽  
Julian M. Dust
Keyword(s):  
Reaction Mechanism ◽  
Kinetic Study ◽  
Secondary Amines ◽  
Medium Effect ◽  
Substitution Reactions ◽  
Concerted Mechanism ◽  
Rate Determining Step ◽  
Leaving Group ◽  
Differential Medium ◽  
Straight Lines

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 Brønsted-type plots for the reactions of 1a–1f are linear with βnuc = 0.47∼0.50, indicating that the bond formation between the amine nucleophile and the electrophilic center is advanced slightly in the transition state. The Brønsted-type plot for the reactions of 2a–2g with piperidine is also linear with βlg = –0.66, which is a typical βlg value for reactions reported previously to proceed through a concerted mechanism. Furthermore, the Hammett plot correlated with σ– constants results in much better linearity than that correlated with σo constants, implying that expulsion of the leaving group is advanced in the rate-determining step (RDS). Thus, the reactions are concluded to proceed through a concerted mechanism. The Hammett plots for the reactions of 1a–1f consist of two intersecting straight lines, whereas the corresponding Yukawa–Tsuno plots exhibit excellent linear correlations with ρX = 0.62∼0.71 and r = 0.65∼0.68. Apparently, the nonlinear Hammett plots are not due to a change in the reaction mechanism (or the RDS) but are caused by stabilization of the substrate possessing an electron-donating group (EDG) in the cinnamoyl moiety through resonance interactions between the EDG and the C=O bond of the substrate. Medium effects on reactivity and reaction mechanism are also discussed.

scholarly journals Kinetic Study on Aminolysis of Y-Substituted-Phenyl X-Substituted-Benzoates: Effects of Substituents X and Y on Reactivity and Reaction Mechanism

2014 ◽  
Vol 35 (2) ◽  
pp. 471-476 ◽  
Author(s):  
Seong Hoon Jeon ◽  
Hyun Soo Kim ◽  
Young Joon Han ◽  
Min-Young Kim ◽  
Ik-Hwan Um
Keyword(s):  
Reaction Mechanism ◽  
Kinetic Study

scholarly journals A kinetic study of rabbit muscle pyruvate kinase

1973 ◽  
Vol 131 (2) ◽  
pp. 223-236 ◽  
Author(s):  
S. Ainsworth ◽  
N. Macfarlane
Keyword(s):  
Reaction Mechanism ◽  
Kinetic Study ◽  
Pyruvate Kinase ◽  
Random Order ◽  
Experimental Results ◽  
Rabbit Muscle ◽  
Dead End ◽  
Inhibition Constants ◽  
Muscle Pyruvate Kinase ◽  
Kinetics Of

The paper reports a study of the kinetics of the reaction between phosphoenolpyruvate, ADP and Mg2+ catalysed by rabbit muscle pyruvate kinase. The experimental results indicate that the reaction mechanism is equilibrium random-order in type, that the substrates and products are phosphoenolpyruvate, ADP, Mg2+, pyruvate and MgATP, and that dead-end complexes, between pyruvate, ADP and Mg2+, form randomly and exist in equilibrium with themselves and other substrate complexes. Values were determined for the Michaelis, dissociation and inhibition constants of the reaction and are compared with values ascertained by previous workers.

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