Bicyclobutonium Ion Research Articles

Secondary Hydrogen Isotopes Effects. IV. Solvolysis Rates of Specifically Deuterium Labeled Cyclopropylmethyl Benzenesulfonates

The synthesis of cyclopropylmethyl-1,1-d₂,-2-d,-3,3-d₂, and - 3,3,4,4-d₄ benzenesulfonates is described. Acetolysis and ethanolysis rates were measured and it was found that the first two compounds solvolyze more slowly and the last two more rapidly than the undeuterated analogs. It was also found that the isotope effects are more pronounced in ethanolysis and that the rate increase per atom deuterium is larger with the dideuterated than with the tetradeuterated compound. The results are discussed in terms of rehybridization, hyperconjugation, and induction and are found to be consistent with the solvolysis mechanism postulating the participation of the neighboring cyclopropyl group in the rate-determining step with the formation of a bicyclobutonium ion. (auth)