The reactivities of novel heterocyclic diarylamine radical-trapping antioxidants (RTAs) are profiled in a heavy hydrocarbon at 160 °C, conditions representative of those at which diphenylamine RTAs are used industrially. While carboxylic acids produced during the autoxidation are shown to deactivate these more basic RTAs, the addition of a sacrificial base leads to efficacies that are unprecedented in the decades of academic and industrial research in this area.
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