USE OF HYDROGEN ISOTOPE EFFECTS TO DETERMINE THE TIMING OF PROTON TRANSFER RELATIVE TO NUCLEOPHILIC ATTACK IN THE ENOLIZATION OF KETONES AND REACTIONS OF EPOXIDES CATALYZED BY ACETIC ACID

Journal Article · Thu Nov 20 00:00:00 EST 1958 · Journal of the American Chemical Society (U.S.)

DOI:https://doi.org/10.1021/ja01555a024· OSTI ID:4297547

Swain, C G; Di Milo, A J; Cordner, J P

Catalysis by acetic acid of enolization of alpha -phenylisocaprophenone in aqueous dioxane at 100 or of reaction of epichlorohydrin with iodide ion in water solution at 25 is not due to proton transfer during the rate- determining step, i.e., concented with nucleophilic attack, but instead to proton transfer in a prior fast equilibrium step in each case, with the conjugate acid oxonium ion as a true intermediate. The magnitude of the proton/ deuterium isotope effect determined by ruining these reactions in both light and heavy water is approximately unity, which is low considering that acetic acid is a considerably stronger acid than acetic acid-d but explicable if all proton transfers between oxygen atoms are equilibium-controlled. The conspicuous absence of any third-order term in the mutarotation of tetramethylglucose in aqueous acetone catalyzed by pyridinium ion and by pyridine is consistent with a prior equilibrium for protonation by pyridinium ion. Evidence suggests that special cyclic polyfunctional mechanisms are responsible for the third-order acetic acid-acetate ion terra in the enolization of acetone in water at 25 and for the acetic acid term in the mutarotation of glucose in water at 18 . (auth)

• Research Organization: Massachusetts Inst. of Tech., Cambridge
• Sponsoring Organization: USDOE
• NSA Number: NSA-13-002043
• OSTI ID: 4297547
• Journal Information: Journal of the American Chemical Society (U.S.), Vol. Vol: 80; Other Information: Orig. Receipt Date: 31-DEC-59
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CHEMISTRY
ACETIC ACID- ACIDITY- ALKYL RADICALS- BASES- CATALYSIS- CHEMICAL REACTIONS- DEUTERIUM- DIOXANE- EQUILIBRIUM- GLUCOSE- HEAVY WATER- HYDROGEN- IODINE COMPOUNDS- IONS- ISOMERS- ISOTOPE EFFECTS- ISOTOPES- KETONES- MIXING- ORGANIC COMPOUNDS- OXIDES- PHENYL RADICALS- PROTONS- PYRIDINES- SOLUTIONS- SOLVENTS- SUGARS- TEMPERATURE- TRANSPORT THEORY- WATER
ACETONE- AROMATICS- DEUTERIUM COMPOUNDS- HYDROXIDES- MATHEMATICS- MEASURED VALUES- METHYL RADICALS- ORGANIC NITROGEN COMPOUNDS- SUGARS