(a) Time profiles of the yield of p-tolualdehyde in the photo-oxygenation of p-xylene (3.0 × 10−2 M) in oxygen-saturated CD3CN containing Acr+–Mes (2.0 × 10−4 mM) and [(tmpa)CuII]2+ (0–3.0 mM). (b) Time profiles of the yield of H2O2 in the photooxygenation of p-xylene (3.0 × 10−2 M) in oxygen-saturated CD3CN containing Acr+–Mes (2.0 × 10−4 M) and [(tmpa)CuII]2+ (0 mM, black; 0.05 mM, orange; 0.10 mM, green; 0.5 mM, blue; 1.0 mM, red; 2.0 mM, grey and 3.0 mM, brown).