THE INHIBITED AUTOXIDATION OF STYRENE: PART III. THE RELATIVE INHIBITING EFFICIENCIES OF ORTHO-ALKYL PHENOLS

Abstract

The relative rates of reaction of a large number of ortho-alkyl phenols with styrylperoxy radicals have been measured at 65 °C. These groups have both an accelerating effect owing to their electron-donating character and a retarding effect which arises from steric factors. With two ortho-alkyl groups both the reaction rate and the overall polar contribution to the transition state decrease as the size of the alkyl groups is increased. A single o-t-butyl group produces a small enhancement of the reaction rate over and above its polar effect but this is not observed with any other alkyl groups.