General method for determination of the activation, deactivation, and initiation rate constants in transition metal-catalyzed atom transfer radical processes

A general method for the determination of the activation (ka), deactivation (kd), and initiation (ki) rate constants in atom transfer radical processes is reported. The method involves the monomer trapping techniques and the analytical solution of the persistent radical effect. For tert-butyl 2-bromopropionate, using ATRP catalyst [CuI.(dNbpy)2][Br] and methyl methacrylate in CH3CN at 22 °C, the values of ka, kd, and ki were determined to be (9.4 ± 0.6) × 10-3 M-1 s-1, (8.5 ± 1.2) × 106 M-1 s-1 and (5.5 ± 0.9) × 104 M-1 s-1, respectively. The determined initiation rate constant was in good agreement with the literature value (6.0 × 104 M-1 s-1), confirming the validity of the proposed approach. For methyl 2-bromopropionate, under the same conditions, ka, kd, and ki values were found to be (26 ± 5.9) × 10-3 M-1 s-1, (29 ± 7.3) × 106 M-1 s-1, and (5.7 ± 1.6) × 104 M-1 s-1, respectively. Copyright © 2002 American Chemical Society.