Investigations into the Kinetic Modeling of the Direct Alkylation of Benzylic Amines: Dissolution of K2CO3 Is Responsible for the Observation of an Induction Period.

Investigations into the kinetics of a Rh(I)-catalyzed direct C-H alkylation of benzylic amines with alkenes revealed that K2CO3, which is effectively insoluble in the reaction mixture, is only needed in the beginning of the reaction. During the concomitant induction period, K2CO3 is proposed to dissolve to a vanishingly small extent and the Rh-precatalyst irreversibly reacts with dissolved K2CO3 to form the active catalyst. The duration of this induction period is dependent on the molar loading, the specific surface, the H2O content of K2CO3, and agitation, and these dependences can be rationalized based on a detailed kinetic model.