The sulfonation of olefiris with p-and &branches was found to give predominantly unsaturated sulfonic acid. The position of the double bond (a, B or P. 7) in these unsaturated sulfonic acids appcars to be determined primarily by steric factors. Evidence is presented to show that the unsaturated sulfonic acids are formed from carbonium-sulfonate or 8-sultone intermediates rather than by a unc-step concerted mechanism.
