Mechanism of Hydrolysis of Allenyl Acetates

Article abstract of DOI:10.1021/ja00521a042

The acid-catalyzed hydrolyses of R2C=C=CHOAc proceed by two mechanisms depending upon the degree of substitution at C-3.The monomethyl derivative exhibits acidity dependence, activation parameters, and solvent isotope effect, k_H2O/k_D2O = 0.87, characteristic of normal ester hydrolysis, while the dimethyl derivative exhibits behavior characteristic of a slow proton transfer mechanism with k_H2O/k_D2O = 1.46.A study of α- and β-secondary isotope effects in the hydrolysis of the dimethyl derivative strongly supports this conclusion.For this compound, k_H/k_α-D = 1.00 and k_H/k_β-d6 = 1.08.