The rates of the reactions of the colored para-substituted phenylacetonitrile anions 1a−c and the phenylpropionitrile anions 2a−c with Michael acceptors (3a−u) were determined by UV−vis spectroscopy in DMSO at 20 °C. The reactions follow second-order kinetics, and the corresponding rate constants k2 obey the linear-free-energy relationship log k2(20 °C) = s(N + E), from which the nucleophile-specific