Fig. 5. Swain–Lupton plot (variation of a Hammett plot) for reaction between 1^R and O₂ in DMA at 20 °C. The rate constants obtained in triplicate for each substituent are the following: OMe = 0.042 ± 0.01; Et = 0.023 ± 0.005; H = 0.015 ± 0.003; F = 0.018 ± 0.004; NO₂ = 0.0038 ± 0.0006. See Fig. S7† for additional Hammett and Swain–Lupton plots.