Enantioselective Alkylation of β-Keto Esters by Phase-Transfer Catalysis Using Chiral Quaternary Ammonium Salts

2004 ◽  
Vol 69 (20) ◽  
pp. 6897-6899 ◽  
Author(s):  
Eun Joo Park ◽  
Mi Hee Kim ◽  
Dae Young Kim
Keyword(s):  
Quaternary Ammonium ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
Keto Esters ◽  
Enantioselective Alkylation

Esterification of 1,4-dichlorobutane with sodium formate under solid–liquid phase transfer catalysis. A kinetic study

1989 ◽  
Vol 67 (2) ◽  
pp. 245-249 ◽  
Author(s):  
Hayder A. Zahalka ◽  
Yoel Sasson
Keyword(s):  
Liquid Phase ◽  
Kinetic Study ◽  
Quaternary Ammonium ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Sodium Formate ◽  
Product Distribution ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
Solid Liquid

Kinetic data are reported regarding the esterification of 1,4-dichlorobutane with sodium formate catalyzed by quaternary ammonium salts as a model for reactions in series, under solid–liquid phase transfer conditions. The process was found to follow a consecutive first-order mechanism of the general type A → R → S. The reactivity of the quaternary ammonium salts with regard to the counteranion was Cl− > Br− > 1− > HSO4−. The reaction rate was linearly dependent on catalyst concentration up to 12 mol% of catalyst relative to the substrate. Above this concentration the rate was constant and independent of the amount of the catalyst. The activation energy of the two consecutive steps was found to be similar (21 kcal/mol). Therefore, the product distribution (R/S) is not appreciably affected by temperature. A mechanism termed "Thin aqueous boundary layer" is suggested for nucleophilic displacement reactions under solid–liquid phase transfer conditions. Keywords: phase transfer catalysis, series reactions, kinetic study.

Sign in / Sign up

Export Citation Format

Share Document