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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 32, Number 4
BKCSDE 32(4)
April 20, 2011 

 
Title
Correlation of the Rates of Solvolysis of Phenyl Fluorothionoformate
Author
Song Hee Choi, Mi Hye Seong, Yong Woo Lee*, Jin Burm Kyong*, Dennis N. Kevill
Keywords
Phenyl fluorothionoformate, Grunwald-winstein equation, Leaving group effect, Additionelimination, Solvolysis
Abstract
The specific rates of solvolysis of phenyl fluorothionoformate (PhOCSF, 1) have been determined in 22 pure and binary solvents at 10.0 oC. The extended Grunwald-Winstein equation has been applied to the specific rates of solvolysis of 1 over the full range of solvents. The sensitivities (l = 1.32 ± 0.13 and m = 0.39 ± 0.08) toward the changes in solvent nucleophilicity and solvent ionizing power, and the kF/kCl values are similar to those previously observed for solvolyses of acyl haloformate esters, consistent with the addition step of an additionelimination pathway being rate-determining. The large negative values for the entropies of activation are consistent with the bimolecular nature of the proposed rate-determining step. The results are compared with those reported earlier for phenyl chloroformate and chlorothionoformate esters and mechanistic conclusions are drawn.
Page
1268 - 1272
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