Aromatic Sulfonation 26: Kinetics and mechanism of the sulfonation of some polyfluorobenzenes in fuming sulfuric acid

Abstract

AbstractThe mechanism of sulfonation in oleum proposed by Brand et al. 3 ‐ stepwise attachment of SO3 and H+ to the substrate, followed by the loss of the proton from the benzene ring ‐ is shown to be inconsistent with the substrate isotope effects reported 3 by these authors. The sulfonation kinetics of p‐di‐, 1,2,3,4‐tetra‐, and penta‐fluorobenzene in 97‐109% sulfuric acid are discussed in terms of an extrapolation of the mechanism proposed recently 7 for aqueous sulfuric acid. In weak oleum — below 104% sulfuric acid — the rate‐limiting step ismagnified image