SECONDARY DEUTERIUM ISOTOPE EFFECTS IN THE ADDITION EQUILIBRIA OF KETONES

Journal Article · Tue Dec 20 04:00:00 EST 1960 · Journal of the American Chemical Society (U.S.)

DOI:https://doi.org/10.1021/ja01509a033· OSTI ID:4118758

Jones, J M; Bender, M L

The equilibrium constants of reactions involving the ad dition of methanol to the ketones, acetone, acetone-d/sub 6/, cyclopentanone, and cyclopentanone-2,2,5,5-d/sub 4/, to form their respective hemiketals were determined. The ratio of hemiketal dissociation constants for the acetone and acetone-d/sub 6/ reactions in dioxane solution is K/sub H//K/sub D/ = 1.29 plus or minus 0.09. For the cyclopentanone and cyclopentanone-2,2,5,5-d/sub 4/ equilibria in methanol, the ratio, extrapolated to infinite dilution, is K/sub H// K/sub D/ = 1.44 plus or minus 0.09. These deuterium isotope effects indicate that the transformation of the trigonal carbonyl carbon atom of the ketone to the tetrahedral carbon atom of the hemiketal is facilitated by beta-deuierium atoms. This result is in qualitative agreement with the reverse kinetic secondary deuterium isotope effect in the hydrolysis of ethyl acetate in which a trigonal carbon atom in the ground state is transformed into an approximately tetrahedral carbon atom in the transition state. A semiquantitative correlation of frequency changes with deuterium isotope effects in carbonyl compounds indicates that the isotope effects need not be explained in terms of electronic effects but rather may be explained solely on the basis of mass effects on the fundamental vibrational frequencies of the molecules. (auth)

• Research Organization: Illinois Inst. of Tech., Chicago
• Sponsoring Organization: USDOE
• NSA Number: NSA-15-007262
• OSTI ID: 4118758
• Journal Information: Journal of the American Chemical Society (U.S.), Journal Name: Journal of the American Chemical Society (U.S.) Vol. Vol: 82; ISSN JACSA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ACETATES
ACETONE
ALKYL RADICALS
CARBON
CARBONYLS
CHEMISTRY
CONFIGURATION
CYCLOALKANES
DEUTERIUM
DIOXANE
FREQUENCY
ISOTOPE EFFECTS
KETONES
METHANOL
MOLECULES
OSCILLATIONS
PENTANE
SOLUTIONS