Fig. 5. Scalable decarboxylative deuteration of carboxylic acids. Standard conditions: 1 (5.0 mmol), PC-I (2 mol%), 2a (10 mol%), 2,4,6-collidine (1.0 equiv.), DCM/D₂O (4 : 1, v/v, 25 mL), blue LEDs, peristalsis rate = 30 mL min⁻¹, 8–16 h. ^aCesium carboxylate (2.0 mmol), PC-III (0.5 mol%), 2a (5 mol%), 18-crown-6 (1.0 equiv.), DCM/D₂O (4 : 1, v/v, 10 mL), blue LEDs, peristalsis rate = 80 mL min⁻¹, 9 h. ^bYields are determined by GC due to the volatility. ^c1 (50.0 mmol), PC-I (1 mol%), 2a (5 mol%), 2,4,6-collidine (1.0 equiv.), DCM (80 mL), D₂O (22.0 equiv., 20.9 mL), 45 W blue LEDs, peristalsis rate = 80 mL min⁻¹, 16 h.