Fig. 4. (a) Plots of log k _DMSO vs. log K _CPET for reactions of 2a (black) and 2b (red) with phenols ^XArOH (X labeled). Linear fits have slopes of 0.47 (R ² = 0.94) and 0.44 (R ² = 0.84), respectively. (b) Plots of log k _DMSO vs. E _1/2(^XArOH⁺˙/^XArOH) (X indicated) for their reactions with 2a (black) and 2b (red). The point for ^CF₃ArOH is not included as the corresponding E _1/2 is not known. Linear fits have slopes of –2.5 (R ² = 0.84) and –2.1 (R ² = 0.76), respectively. (c) Plots of log k _DMSO vs. pK _a of the phenols ^XArOH (X indicated) for their reactions with 2a (black) and 2b (red). Linear fits do not include the data points for X = NO₂ and have slopes of 1.1 (R ² = 0.85) and 0.94 (R ² = 0.93), respectively. The wide arrow indicates the X = NO₂ outliers.