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Use of Hydrogen Isotope Effects to Identify the Attacking Nucleophile in the Enolization of Ketones Catalyzed by Acetic Acid C. Gardner Swain, Edward C. Stivers, Joseph F. Reuwer, Jr. Lawrence J. Schaad; J. Am. Chem. Soc.; 1958; 80(21); 5885-5893. doi:10.1021/ja01554a077