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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 28, Number 4
BKCSDE 28(4)
April 20, 2007 

 
Title
Correlation of the Rates of Solvolysis of Isopropyl Fluoroformate Using the Extended Grunwald-Winstein Equation
Author
So Hee Lee, Chan Joo Rhu, Jin Burm Kyong*, Dong Kook Kim, Dennis N. Kevill
Keywords
Isopropyl fluoroformate, Addition-elimination, Grunwald-Winstein equation
Abstract
The specific rates of solvolysis of isopropyl fluoroformate are well correlated using the extended Grunwald-Winstein equation, with a sensitivity (l ) to changes in solvent nucleophilicity (NT) and a sensitivity (m) to changes in solvent ionizing power (YCl). The sensitivities (l = 1.59 ± 0.16 and m = 0.80 ± 0.06) toward changes in solvent nucleophilicity and solvent ionizing power, and the kF/kCl values are very similar to those for solvolyses of n-octyl fluoroformate, suggesting that the addition step of an addition-elimination mechanism is rate-determining. For methanolysis, a solvent deuterium isotope effect of 2.53 is compatible with the incorporation of general-base catalysis into the substitution process. The large negative values for the entropies of activation are consistent with the bimolecular nature of the proposed rate-determining step. These observations are also compared with those previously reported for the corresponding chloroformate and fluoroformate esters.
Page
657 - 661
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