Enthalpy and Entropy in Ring Closure Reactions

The strain and entropy effects of the lactone formation from ω-bromoalkane-carboxylate ions in ring sizes 3 to 23 is reevaluated. We find that ΔH‡is the largest contributor to the observed rates (ΔG‡) for ring sizes 3 to 6, while −TΔS‡has little influence, −TΔS‡has more effect on the observed rates for ring sizes 8 and larger.