The influence of intermediate carbenium ion stabilization on the mechanism of the acid-catalysed hydrolysis of α-acetoxystyrenes

The hydrolysis of α-acetoxystyrenes 1a-f in 37% sulfuric acid and 1e at different acid strengths to the corresponding acetophenone 2a-f exhibits pseudo-first-order kinetics. Apparent rate constants (k h) have been measured spectroscopically at 23 °C by following the change in absorbance with time at a wavelength of 280 nm. Good linearity has been found for the log (k h) versus log [H+] plot, but not for the plot against H 0. A linear relationship also exists between log (k h) and the electron density of the terminal vinylic carbon atom. The mechanistic implications of the data are discussed.