New protocol to determine the equilibrium constant of atom transfer radical polymerization

A new electrochemical procedure is described to determine the equilibrium constant of atom transfer radical polymerization, KATRP. A rotating disk electrode (RDE) was used to monitor the concentration of the catalyst, CuIL+, during a reaction between the metal complex and an alkyl halide (RX) used as a polymerization initiator. KATRP values with errors in the range ±10% were measured. Conditions were defined to avoid undesired reactions such as catalytic radical termination and competition between RX and X− for the reactive site of copper. The RDE technique was also used to determine the equilibrium constant for association of X− to CuIL+, KXI, a parameter hardly accessible by other methods. The RDE technique was applied to different ligands, initiators, solvent/monomer combinations, and reaction temperatures. Linear correlations between logKATRP and logkact and logkdeact were found. [Display omitted] •Electrochemical procedure for the precise determination of KATRP.•Estimation of the halidophilicity constant for CuI.•One-pot measurement of kact and KATRPvia rotating disk electrode.•Standard free energy, enthalpy and entropy of atom transfer radical polymerization.