Sulfides cyclic ring strains

Pell and Pilcher have tabulated the strain energies of cyclic alkanes, ethers, imines, and sulfides (Table 12), which all decrease with ring size in the order 3 > 4 > 5 > 6. Thus if the same fraction of the strain energy is always developed in the transition state, it would be expected that if this were the only controlling factor the rates of reactions that form rings of this type would be in the order 6 > 5 > 4 > 3. 

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