Bimolecular nucleophilic substitution at a resonance-stabilized carbenium ion: Elevated value of cross-interaction constant, imbalanced transition state and the non-interactive phenomenon

1994 ◽  
Vol 7 (8) ◽  
pp. 448-454 ◽  
Author(s):  
Ikchoon Lee
Keyword(s):  
Transition State ◽  
Nucleophilic Substitution ◽  
Interaction Constant ◽  
Carbenium Ion

Kinetics and Mechanism of the Aminolysis of S-Aryl O-Ethyl Dithiocarbonates in Acetonitrile

2004 ◽  
Vol 69 (12) ◽  
pp. 2174-2182 ◽  
Author(s):  
Hyuck Keun Oh ◽  
Ji Young Oh ◽  
Dae Dong Sung ◽  
Ikchoon Lee
Keyword(s):  
Transition State ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Interaction Constant ◽  
Kinetics And Mechanism ◽  
Cyclic Structure ◽  
Concerted Mechanism ◽  
Tetrahedral Intermediate ◽  
Kinetic Isotope ◽  
Hydrogen Bonded

The aminolysis of S-aryl O-ethyl dithiocarbonates with benzylamines are studied in acetonitrile at -25.0 °C. The βX (βnuc) values are in the range 0.67-0.77 with a negative cross-interaction constant, ρXZ = -0.24, which are interpreted to indicate a concerted mechanism. The kinetic isotope effects involving deuterated benzylamine nucleophiles (XC6H4CH2ND2) are large, kH/kD = 1.41-1.97, suggesting that the N-H(D) bond is partially broken in the transition state by forming a hydrogen-bonded four-center cyclic structure. The concerted mechanism is enforced by the strong push provided by the EtO group which enhances the nucleofugalities of both benzylamine and arenethiolate from the putative zwitterionic tetrahedral intermediate.

Principles of Nucleophilic Substitution

2018 ◽  
Vol 5 (3) ◽  
Author(s):  
Dr. Aliakbar Muhamdi Ameri
Keyword(s):  
Transition State ◽  
Nucleophilic Substitution ◽  
Substitution Reaction ◽  
Theoretical Paper

The work reported in this theoretical paper deals with types of substitution reaction ( sn1 , sn2 , conditions of both reactions , methods of both reactions , diagram of reactions , energy for reactions, types of reactants , products, rate of reactions , steps of reactions, transition state for reaction) and other reactions.

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