Reactivity of polystyrene and model compounds toward tert‐butoxy radicals

Abstract tert‐Butoxy radicals were generated by decomposing di‐tert‐butyl hyponitrite. The relative reactivities of substrates were measured from the ratio of tert‐butanol and acetone formed. Polystyrene was found to be less reactive than model compounds. Activation parameters for the hydrogen abstraction reaction for cumene, 3‐phenylpentane, and 2,4‐diphenylpentane are reported and show small differences for the enthalpy of activation; large negative values for the entropy of activation demonstrate the importance of steric hindrance in the hydrogen abstracting step. 2,3‐Diphenylbutane as model compound for head to head links in polystyrene exhibits low reactivity, whereas 2,5‐diphenylhexane, a model for tail to tail links, is more reactive than the dimer head to tail model. Still more reactive is 2,4‐diphenyl‐2‐pentene as model for an unsaturated unit in polystyrene.