Kinetic. cap alpha. secondary deuterium isotope effects for O-ethyl S-phenyl benzaldehyde acetal hydrolysis

Journal Article · Tue Mar 13 23:00:00 EST 1979 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00500a020· OSTI ID:6232650

Ferraz, J P; Cordes, E H

The rate of hydrolysis of O-ethyl S-phenyl benzaldehyde acetal at 25/sup 0/C in 20% dioxane--80% water is independent of pH over the range pH6-12; k/sub obsd/ = 1.9 x 10/sup -7/s/sup -1/. Under more acidic conditions, the rate increases linearly with the activity of the hydrated proton; k/sub 2/ = 2.95 x 10/sup -2/M/sup -1/s/sup -1/. The kinetic ..cap alpha.. secondary deuterium isotope effect for acid-catalyzed hydrolysis of O-ethyl S-phenyl benzaldehyde acetal, measured at 25/sup 0/C in 20% aqueous dioxane containing 0.05 M HCl, is k/sub H//k/sub D/ = 1.038 +- 0.008, a value consistent with a transition state in which the C--S bond is stretched rather little. In contrast, the corresponding isotope effect for the pH-independent hydrolysis of this substrate, measured at 42.5/sup 0/C in 20% dioxane, is 1.13 +- 0.02, a value consistent with complete C--S bond cleavage in the transition state and rate-determining diffusion apart of the ion-pair formed as the initial intermediate, in accord with the suggestion of Jensen and Jencks. 1 figure, 4 tables.

• Research Organization: Univ. of Indiana, Bloomington
• OSTI ID: 6232650
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 101:6; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
400303 -- Organic Chemistry-- Isotope Exchange & Isotope Separation-- (-1987)
ACETALS
ALDEHYDES
AROMATICS
BUFFERS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DATA FORMS
DECOMPOSITION
DEUTERIUM
DEUTERIUM COMPOUNDS
DIOXANE
DISPERSIONS
ETHERS
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
HYDROCHLORIC ACID
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
HYDROLYSIS
INFORMATION
INORGANIC ACIDS
ISOLATED VALUES
ISOTOPE EFFECTS
ISOTOPES
ISOTOPIC EXCHANGE
KINETICS
LABELLING
LIGHT NUCLEI
LYSIS
MEDIUM TEMPERATURE
MIXED SOLVENTS
MIXTURES
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXYGEN COMPOUNDS
PH VALUE
REACTION KINETICS
SOLVENTS
SOLVOLYSIS
STABLE ISOTOPES
TEMPERATURE DEPENDENCE
WATER