Elimination Reactions of (E)-O-Pivaloylbenzaldoximes

Article abstract of DOI:10.1021/jo00067a022

Elimination reactions of (E)-O-pivaloylbenzaldoximes promoted by Et3N-MeCN, t-BuOK-t-BuOH and t-BuOK-DMSO have been studied kinetically.The reactions produce benzonitrile quantitatively.The reactions are second-order and exhibit substantial values of ρ, β, and k_H/k_D and an E2 mechanism is evident.The rate of elimination from (E)-O-pivaloylbenzaldoxime increased with base-solvent system variation and gave relative rates of 1, 14.8, and 4.31*10⁴ for Et3N-MeCN, t-BuOK-t-BuOH, t-BuOK-DMSO, respectively.The k_H/k_D value increased, but the Hammett ρ value increased and then decreased, with this change in the base-solvent system.These results are compared with the predictions of the More O'Ferral-Jencks reaction coordinate diagramm to assess its scope and limitations in the interpretation of the elimination reactions.