The effect of solvent polarity on the rate of the Mitsunobu esterification reaction

Camp, David, Harvey, Peta J. and Jenkins, Ian d. (2015) The effect of solvent polarity on the rate of the Mitsunobu esterification reaction. Tetrahedron, 71 23: 3932-3938. doi:10.1016/j.tet.2015.04.035


Author Camp, David
Harvey, Peta J.
Jenkins, Ian d.
Title The effect of solvent polarity on the rate of the Mitsunobu esterification reaction
Journal name Tetrahedron   Check publisher's open access policy
ISSN 1464-5416
0040-4020
Publication date 2015-01-16
Sub-type Article (original research)
DOI 10.1016/j.tet.2015.04.035
Open Access Status Not yet assessed
Volume 71
Issue 23
Start page 3932
End page 3938
Total pages 7
Place of publication Oxford, United Kingdom
Publisher Pergamon Press
Language eng
Formatted abstract
The rate of the Mitsunobu esterification reaction of ethanol or isopropanol with benzoic acid was found to be much faster in non-polar solvents. The logarithm of the rate constant was inversely proportional to the solvent polarity, as defined by ET values. Typically, the rate constant for ethyl benzoate formation in THF was 100 times greater than that in MeCN. The presence of either sodium benzoate or excess benzoic acid resulted in a decrease in rate. Each of the main species involved in the Mitsunobu esterification reaction, the alcohol starting material, dialkoxyphosphorane, alkoxyphosphonium salt and ester product, was detected by proton NMR analysis. The possible role of ion pair aggregates or clusters, prior to rate-determining SN2 attack of carboxylate on the alkoxyphosphonium ion, is discussed. An explanation is provided as to why the yield in the Mitsunobu reaction is often higher in non-polar solvents.
Keyword Ion-pair
Mechanism
Mitsunobu
Rate
Solvent-polarity
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Institute for Molecular Bioscience - Publications
 
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