Borderline between E1cB and E2 Mechanisms. Chlorine Isotope Effects in Base-Promoted Elimination Reactions

The chlorine leaving group isotope effect has been measured for the base-promoted elimination reaction of 1-(2-chloro-2-propyl)indene (1-Cl) in methanol at 30 °C:  k 35/k 37 = 1.0086 ± 0.0007 with methoxide as the base and k 35/k 37 = 1.0101 ± 0.0001 with triethylamine (TEA) as the base. These very...

Full description

Saved in:
Bibliographic Details
Published inJournal of organic chemistry Vol. 67; no. 1; pp. 177 - 181
Main Authors Jia, Zhi Sheng, Rudziński, Juliusz, Paneth, Piotr, Thibblin, Alf
Format Journal Article
LanguageEnglish
Published Washington, DC American Chemical Society 11.01.2002
Subjects
Chemistry
Exact sciences and technology
Kinetics and mechanisms
Organic chemistry
Reactivity and mechanisms
E2 mechanism
E1CB mechanism
Energy diagram
Experimental study
Leaving group effect
Kinetic isotope effect
Organic solvent
Chlorides
Transition state
Reaction mechanism
Basic medium
Indene derivatives
Kinetics
Methanol
Online AccessGet full text

Cover

More Information
Summary:The chlorine leaving group isotope effect has been measured for the base-promoted elimination reaction of 1-(2-chloro-2-propyl)indene (1-Cl) in methanol at 30 °C:  k 35/k 37 = 1.0086 ± 0.0007 with methoxide as the base and k 35/k 37 = 1.0101 ± 0.0001 with triethylamine (TEA) as the base. These very large chlorine isotope effects combined with large kinetic deuterium isotope effects of 7.1 and 8.4, respectively, are consistent not with the irreversible E1cB mechanism proposed previously (J. Am. Chem. Soc. 1977, 99, 7926) but with the E2 mechanism with transition states having large amounts of hydron transfer and very extensive cleavage of the bond to chlorine.
Bibliography:istex:C19CB077B4A8EA96AAA03040C7AA88B273EC816B
ark:/67375/TPS-DXFQ4FR7-K
ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:0022-3263
1520-6904
DOI:10.1021/jo0159340