Steric effects on reaction rates. XI. Solvolysis of tertiary carbon substrates rationalized by molecular mechanics calculations

The steric energy difference (ΔEst) between tertiary carbenium ions (R+) and the corresponding alcohols has been calculated by MM2 for a series of tertiary nonbridgehead substrates and correlated with their rate of solvolytic reactivity. Satisfactory correlation is obtained, except for p‐nitrobenzoates of highly congested substrates. The slope and intercept of the correlations remain almost unchanged if bridge‐head substrates are included in the plot. However, the quality of the fit is better for bridgehead substrates alone.