Solvolysis of 2-(Trifluoromethyl)-2-propyl Trifluoromethanesulfonate. Solvent, Salt, and β-Deuterium Isotope Effects. Sucstituent Effect of a Strongly Deactivating Group and Rate-Limiting Solvent-Assisted Elimination

Article abstract of DOI:10.1021/ja00403a040

Solvolysis rates of 2-(trifluoromethyl)-2-propyl trifluoromethanesulfonate (2c) in a variety of solvents did not show a correlation with rates for 2-adamantyl tosylate in the same solvents.The effect of added salts on the rates of 2c and 2-propyl tosylate in 80percent EtOH was very similar, with significant rate increases for nucleophilic/basic salts.Methyl CD3 isotope effects on the rate of 2c in three solvents showed average values k(d₀)/k(d₃) = 1.78 and k(d₀)/k(d₆) = 3.80.The initial observed product from 2c was CF3C(CH3)=CH2 (4) in all cases.The rate ratio k(i-PrOTf)/k(2c) ranges from a high of 4 x 10⁶ in TFA to a low of 1.5 x 10⁴ in EtOH and shows a high degree of destabilization of a cationic transition state by the CF3 group.The results are interpreted in terms of rate-limiting solvent or salt attack on an intimate ion pair formed from 2c.The observed average product ratio CF3C(CD3)=CH2/CF3C(CH3)=CD2 of 1.9 from 2c-d₃ in CF3CO2D, HFIP, and CD3CO2D is consistent with this conclusion.