The Brønsted acid-catalysed hydrolysis of acyl fluorides in aqueous media

In dioxane-water mixtures rich in dioxane, the hydrolysis of benzoyl fluoride is catalysed by hydrogen ions by two mechanisms, one dominant at low, and the other at high, values of [H3O +]. In purely aqueous solutions, and in water-rich dioxane–water mixtures, the only catalysis observed is that at high acid concentrations. The effect of temperature, and of p-substituents suggests this later catalysis involves an A1 mechanism. We tentatively assign an ABAC3 mechanism to the catalysis found at low acid concentrations in dioxane-rich media. The hydrolysis of phenylacetyl fluoride in dioxane-water exhibits a behaviour pattern similar to that found for benzoyl fluoride.