Carbon-13 kinetic isotope effects on pyruvate decarboxylation. II. Solvent effects in model systems
Carbon-13 kinetic isotope effects were determined for the decarboxylation of pyruvate by thiamin and for the decarboxylation of 2-(1-carboxy-1-hydroxyethyl)-3,4-dimethylthiazolium chloride (a covalent pyruvate-thiamin adduct) in water and in aqueous ethanol. The kinetic isotope effect for the decarboxylation step in the second system increased from 1.051 in H/sub 2/O to approximately 1.058 in 50% v/v ethanol. The isotope effect in the thiamin catalyzed model reaction increased from the 0.992 inverse effect observed in H/sub 2/O to 1.007 in 50% aqueous ethanol. The rate of decomposition of the covalent thiamin-pyruvate adduct to reactants relative to its rate of decarboxylation is greater in ethanol than in water. Further, the results suggest that the changes of the vibrational force constants in going from the ground state to the transition state are greater in aqueous ethanol than in water.
- Research Organization:
- Rutgers Univ., Newark, NJ
- OSTI ID:
- 6896461
- Journal Information:
- J. Org. Chem.; (United States), Journal Name: J. Org. Chem.; (United States) Vol. 43:14; ISSN JOCEA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
AMINES
AZINES
AZOLES
CARBON 13
CARBON ISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DECARBOXYLATION
EVEN-ODD NUCLEI
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
ISOTOPE EFFECTS
ISOTOPES
KETO ACIDS
LIGHT NUCLEI
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PYRIMIDINES
PYRUVIC ACID
SALTS
STABLE ISOTOPES
THIAMINE
THIAZOLES
VITAMIN B GROUP
VITAMINS