Elimination Reactions ofN-Alkyl-N-chlorothenylamines Promoted by MeONa−MeOH and Et2NH−MeCN. Effect of the β-Aryl Group on the Imine-Forming Transition State

2005 ◽  
Vol 70 (13) ◽  
pp. 5327-5330 ◽  
Author(s):  
Sang Yong Pyun ◽  
Dong Choon Lee ◽  
Yoon Je Seung ◽  
Bong Rae Cho
Keyword(s):  
Transition State ◽  
Aryl Group ◽  
Elimination Reactions

Elimination Reactions of Aryl Furylacetates Promoted by R2 NH in MeCN: Effects of Base Solvent and β-Aryl Group on the Ketene-forming Transition State

2017 ◽  
Vol 38 (11) ◽  
pp. 1306-1309 ◽  
Author(s):  
Sang Yong Pyun ◽  
Kyu Cheol Paik ◽  
Man So Han ◽  
Byung Tae Kim ◽  
Bong Rae Cho
Keyword(s):  
Transition State ◽  
Aryl Group ◽  
Elimination Reactions

scholarly journals Force-modulated reductive elimination from platinum(ii) diaryl complexes

2021 ◽  
Author(s):  
Yichen Yu ◽  
Chenxu Wang ◽  
Liqi Wang ◽  
Cai-Li Sun ◽  
Roman Boulatov ◽  
...  
Keyword(s):  
Transition State ◽  
Reductive Elimination ◽  
Mechanical Force ◽  
Elimination Reactions

The influence of mechanical force on the rates of model reductive elimination reactions depends on the structure of the force-transducing ligand and provides a measure of geometry changes upon reaching the transition state.

Aminolysis of naphthyl acetates catalyzed by cyclodextrins

1999 ◽  
Vol 77 (5-6) ◽  
pp. 950-959 ◽  
Author(s):  
Oswald S Tee ◽  
Michael J Boyd
Keyword(s):  
Aqueous Solution ◽  
Transition State ◽  
Rate Constants ◽  
Nucleophilic Attack ◽  
Reactivity Ratios ◽  
Aryl Group ◽  
First Order ◽  
Free Amine ◽  
Transition State Stabilization ◽  
Pseudo First Order

The effects of cyclodextrins (CDs) on the rate of nucleophilic attack on 1- and 2-naphthyl acetates (1-NA and 2-NA) in aqueous solution have been investigated. Analysis of the variation of the pseudo-first-order rate constants with [nucleophile] and [CD] affords rate constants for reaction of the nucleophiles with free ester (kN) and with ester bound to the CD (kcN). The reaction of 1-NA and 2-NA with the trifluoroethoxide anion is slowed down by β-CD as the ratios kcN/kN are 0.11 and 0.30, respectively. For reaction with the anion of 2-mercaptoethanol in the presence of α-CD, β-CD, "hydroxypropyl-β-CD" (hp-β-CD) and γ-CD, the reactivity ratios kcN/kN vary between 0.04 and 2.4, ranging from strong retardation to modest catalysis; the retardations arise with β-CD and hp-β-CD, which bind the esters strongly. By contrast, the attack of primary alkylamines is generally accelerated, and in many cases substantially so. For the aminolysis of 1-NA in the presence of β-CD, values of kcN/kN range from 7 to 460, assuming that free amine reacts with CD-bound ester. Alternatively, if the CD-catalyzed reaction involves free ester reacting with CD-bound amine, with rate constant kNc, the ratios kNc/kN vary from 43 to 140. Either way, there is appreciable catalysis of the aminolysis of 1-NA by β-CD. For the aminolysis of 2-NA, the effects are less dramatic: the ratios kcN/kN range from 0.19 to 17, and values of kNc/kN vary from 17 to 110. The reaction of 1-NA with n-hexylamine is also catalyzed by γ-CD. The variations of kinetic parameters with alkylamine chain length suggest that the CD-catalyzed aminolysis basically takes place by the attack of CD-bound amine on the free ester. However, there must be some stabilizing interactions between the aryl group of the ester and the CD during the reaction, since the transition state stabilization is different for 1-NA and 2-NA, as well for other esters.Key words: aminolysis, catalysis, cyclodextrin, ester cleavage, kinetics.

Sign in / Sign up

Export Citation Format

Share Document