Abstract: The specific rates of solvolysis of isobutyl fluoroformate (1) have been measured at 40.0 °C in 22 pure and binary solvents. These results correlated well with the extended Grunwald-Winstein (G-W) equation, which incorporated the NT solvent nucleophilicity scale and the YCl solvent ionizing power scale. The sensitivities (l and m-values) to changes in solvent nucleophilicity and solvent ionizing power, and the kF/kCl values are very similar to those observed previously for solvolyses of n-octyl fluoroformate, consistent with the additional step of an addition-elimination pathway being rate-determining. The solvent deuterium isotope effect value (kMeOH/kMeOD) for methanolysis of 1 was determined, and for solvolyses in ethanol, methanol, 80% ethanol, and 70% TFE, the values of the enthalpy and the entropy of activation for the solvolysis of 1 were also determined. The results are compared with those reported earlier for isobutyl chloroformate (2) and other alkyl haloformate esters and mechanistic conclusions are drawn.
Keywords: i-butyl fluoroformate; Grunwald-Winstein equation; leaving group effect; addition-elimination; solvolysis
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Lee, Y.; Park, K.-H.; Seong, M.H.; Kyong, J.B.; Kevill, D.N. Correlation of the Rates of Solvolysis of i-Butyl Fluoroformate and a Consideration of Leaving-Group Effects. Int. J. Mol. Sci. 2011, 12, 7806-7817.
Lee Y, Park K-H, Seong MH, Kyong JB, Kevill DN. Correlation of the Rates of Solvolysis of i-Butyl Fluoroformate and a Consideration of Leaving-Group Effects. International Journal of Molecular Sciences. 2011; 12(11):7806-7817.
Lee, Yelin; Park, Kyoung-Ho; Seong, Mi Hye; Kyong, Jin Burm; Kevill, Dennis N. 2011. "Correlation of the Rates of Solvolysis of i-Butyl Fluoroformate and a Consideration of Leaving-Group Effects." Int. J. Mol. Sci. 12, no. 11: 7806-7817.