There is a vigorous debate about the mechanism of copper mediated C/LRP processes in the presence of zerovalent copper. One mechanism assumes that the process is similar to ARGET-ATRP, with copper(0) acting as the reducing agent. In that mechanism copper(0) can participate as a supplemental activator. The other proposed mechanism is SET-LRP, which assumes that copper(0) is the major activator, and copper(I) instantaneously disproportionates to copper(0) and copper(II). This paper uses model reactions to measure the rate constants for comproportionation, disproportionation and copper(0) activation, to discriminate between these mechanisms. The experiments show comproportionation of copper(I) with Me6TREN, is favored in DMSO. The activation rate constant of alkyl bromides by copper(0) is determined to be 2.4�10-4 cm s-1 in DMSO.  These kinetic parameters are used in PREDICI simulations to show that copper(I) is the primary activator and that copper(I) activation dominates disproportionation. These results disprove the fast copper(0) activation and copper(I) disproportionation hypotheses in SET-LRP. Instead, the experimental and theoretical data suggest that the process is similar to ARGET-ATRP, although in this system copper(0) acts as both a supplemental activator (SA) and reducing agent (RA), leading to SARA-ATRP.

Supplemental activator and reducing agent: The true role of copper(0) in ATRP

242nd National Meeting (2011)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.