Correlation of alkylamine nucleophilicities with their basicities

The relationship of the nucleophilicity of alkylamines to their basicity is explored with emphasis on steric hindrance to solvation. The equation n = 1.43(−Σσ∗ + δEs) + 6.35, where n is the Swain-Scott nucleophilic value, σ∗ is the Taft polarity value, and δEs is the Taft steric value, correlates the nucleophilic constants of 17 common alkylamines and ammonia over two powers of 10 with a correlation coefficient of 0.98. The equation n − 1.42 δEs = 0.44(pKa + S) + 0.17, where S is the solvation constant, correlates the nucleophilicities of these amines and ammonia with their pKa values over 3 powers of 10 with a correlation coefficient of 0.99. Excessive steric hindrance and nearby functional groups cause deviations from these equations.