The Neutral Hydrolysis of the Methyl Halides

The rate of hydrolysis of methyl chloride, methyl bromide and methyl iodide have been measured in water over a wide range of temperature by a conductance method. The tempera­ture dependence of the rate was shown to conform to an equation of the general form log10 k = A/T + B log10 T + C within experimental error. This implies that d∆Cp/dT = 0. By combining thermodynamic parameters derived from these data for the activation process with the corresponding terms for the gas-solution process and those for the gas phase, ‘absolute’ parameters for the transition state have been determined. A re-examination of the probable mechanism of hydrolysis is made in terms of a hypo­thetical gaseous ionization and the probable contribution of interaction of the water with the quasi-ionic transition state.