A Study of Solvent Effects in the Solvolysis of Propargyl Chloroformate

The specific rates of solvolysis of propargyl chloroformate (1) are analyzed in 22 solvents of widely varying nucleophilicity and ionizing power values at 25.0°C using the extended Grunwald-Winstein equation. Sensitivities to solvent nucleophilicity (l) of 1.37 and to solvent ionizing power (m) of 0.47 suggest a bimolecular process with the formation of a tetrahedral intermediate. A plot of the rates of solvolysis of 1 against those previously reported for phenyl chloroformate (2) results in a correlation coefficient (R) of 0.996, a slope of 0.86, and an F-test value of 2161. The unequivocal correlation between these two substrates attests that the stepwise association-dissociation (A(N) + D(N)) mechanism previously proposed for 2 is also operative in 1.