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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 34, Number 2
BKCSDE 34(2)
February 20, 2013 

 
Title
Further Kinetic Studies of Solvolytic Reactions of Isobutyl Chloroformate in Solvents of High Ionizing Power Under Conductometric Conditions
Author
Gui Taek Lim, Yeong Ho Lee, Zoon Ha Ryu*
Keywords
Extended Grunwald-Winstein equation, Solvolysis, Kinetic solvent isotope effect, Solvent effect
Abstract
Solvolyses of isobutyl chloroformate (4) in 43 binary solvent mixtures including highly aqueous media, water, D2O, CH3OD, 2,2,2-trifluoroethanol (TFE) as well as aqueous 1,1,1,3,3,3-hexafluoro-isopropanol (HFIP) solvents were performed at 45 oC, in order to further investigate the recent results of D'Souza, M. J1. et al.; solvolyses of 4 are found to be consistent with the proposed mechanism (AdE). The variety of solvent systems was extended to comprise highly ionizing power solvent media (YCl > 2.7 excepted for aqueous fluorinated solvents and pure TFE solvent) to investigate whether a mechanistic change occurs as solvent compositions are varied. However, in case of 18-solvent ranges having aqueous fluorinated solvent systems (TFE-H2O and HFIP-H2O) and/or having YCl > 2.7 solvent systems, the solvent effect on reactivity for those of 4 are evaluated by the multiple regression analysis as competition with SN2 - type mechanism. And in pure TFE and 97 w/w % HFIP solvents with high YCl and weak NT, these solvolyses are understood as reactions which proceed through an ionization (SN1) pathway.
Page
615 - 621
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