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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 33, Number 5
BKCSDE 33(5)
May 20, 2012 

Correlation of the Rates on Solvolysis of 2,2,2-Trichloroethyl Chloroformate Using the Extended Grunwald-Winstein Equation
Han Joong Koh,* Suk Jin Kang
2,2,2-Trichloroethyl chloroformate, Extended grunwald-winstein equation, SN2 Mechanism, Solvent kinetic isotope effect
The solvolysis rate constants of 2,2,2-trichloroethyl chloroformate (Cl3CCH2OCOCl, 3) in 30 different solvents are well correlated with the extended Grunwald-Winstein equation, using the NT solvent nucleophilicity scale and the YCl solvent ionizing scale, with sensitivity values of 1.28 ± 0.06 and 0.46 ± 0.03 for l and m, respectively. The activation enthalpies (ΔH≠) are 10.1 to 12.8 kcal·mol−1 and the activation entropies (ΔS≠) are −27.8 to −36.8 cal·mol−1·K−1, which is consistent with the proposed bimolecular reaction mechanism. The kinetic solvent isotope effect (kMeOH/kMeOD) of 2.39 is also in accord with SN2 mechanism probably assisted by general-base catalysis.
1729 - 1733
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