Kinetics and mechanism of addition of acids to olefins. Part I. Addition of acetic acid to cyclic and strained bicyclic olefins catalysed by trifluoromethanesulphonic acid

Abstract

The acid-catalysed addition of acetic acid to some cyclic and strained bicyclic olefins has been investigated using trifluoromethanesulphonic acid as the catalyst. For norbornene and related derivatives, the reaction rate was first order with respect to the catalyst acid but for cyclohexene there was evidence of a small contribution from a secondorder term. The addition was essentially non-stereospecific. Values of the kinetic isotope effect were less than unity for cyclic substrates but greater than unity for norborriene suggesting a change to rate-determining proton transfer. Activation parameters are reported together with new values for the acidity function H₀ for CF₃SO₃H in acetic acid. The addition is discussed in terms of intimate and solvent-separated ion-pairs.