Acid-catalyzed hydrolysis of vinyl acetals. Reaction through the acetal rather than the vinyl ether functional group

1989 ◽  
Vol 111 (18) ◽  
pp. 7185-7190 ◽  
Author(s):  
Y. Chiang ◽  
W. K. Chwang ◽  
A. J. Kresge ◽  
Y. Yin
Keyword(s):  
Vinyl Ether ◽  
Functional Group ◽  
Acid Catalyzed ◽  
Vinyl Acetals ◽  
Hydrolysis Of

Vinyl ether hydrolysis. XVII. Oxacyclonon-2,8-diene and the question of the unorthodox reaction mechanism for 9-methoxyoxacyclonon-2-ene

1984 ◽  
Vol 62 (1) ◽  
pp. 74-76 ◽  
Author(s):  
R. A. Burt ◽  
Y. Chiang ◽  
A. J. Kresge ◽  
S. Szilagyi
Keyword(s):  
Reaction Mechanism ◽  
Vinyl Ether ◽  
Membered Ring ◽  
Specific Rate ◽  
Ether Group ◽  
Reaction Proceeds ◽  
Great Reactivity ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The acid-catalyzed hydrolysis of the nine-membered ring cyclic vinyl ether, oxacyclonon-2,8-diene, occurs with a normal isotope effect, [Formula: see text], which indicates that this reaction proceeds by the conventional vinyl ether hydrolysis mechanism involving rate-determining proton transfer to carbon. The specific rate of this reaction, [Formula: see text], may then be used to show that there is no significant ring-size effect on the rate of hydrolysis of a vinyl ether group in a nine-membered ring. The previously noted unusually great reactivity of the vinyl ether group in 9-methoxyoxacyclonon-2-ene, for which an unorthodox reaction mechanism has been claimed, must therefore be due to some other cause.

scholarly journals Vinyl ether hydrolysis. XIV. 2-Methoxy-2,3-dihydropyran: concurrent reaction of vinyl ether and acetal functional groups

1980 ◽  
Vol 58 (21) ◽  
pp. 2199-2202 ◽  
Author(s):  
R. A. Burt ◽  
Y. Chiang ◽  
A. J. Kresge
Keyword(s):  
Vinyl Ether ◽  
Isotope Effect ◽  
Reaction Rate ◽  
Functional Group ◽  
Minor Amount ◽  
Cyanoacetic Acid ◽  
Buffer Solutions ◽  
Hydrogen Isotope Effect ◽  
A Minor ◽  
Hydrolysis Of

The hydrolysis of 2-methoxy-2,3-dihydropyran shows a normal isotope effect (kH/kD > 1) under catalysis by the hydrogen ion and gives an accurately linear dependence of reaction rate upon undissociated acid concentration in cyanoacetic acid and formic acid buffer solutions. This substrate, therefore, unlike its higher homolog, 9-methoxyoxacyclonon-2-ene, provides no evidence in support of an anything but a normal mechanism for vinyl ether hydrolysis. Analysis of the hydrogen isotope effect suggests that a minor amount (8%) of this hydrolysis occurs via reaction of the acetal functional group.

Vinyl ether hydrolysis XXVIII. The mechanism of reaction of methyl α-(2,6-dimethoxyphenyl)vinyl ether

1993 ◽  
Vol 71 (1) ◽  
pp. 38-41 ◽  
Author(s):  
J. Jones ◽  
A. J. Kresge
Keyword(s):  
Vinyl Ether ◽  
Nucleophilic Attack ◽  
Tracer Study ◽  
Solvent Isotope Effect ◽  
Methyl Group ◽  
Hydronium Ion ◽  
Mechanism Of Reaction ◽  
Acid Catalyzed ◽  
Solvent Isotope ◽  
Hydrolysis Of

The acid-catalyzed hydrolysis of methyl α-(2,6-dimethoxyphenyl)vinyl ether in aqueous solution at 25 °C occurs with the hydronium ion catalytic coefficient [Formula: see text] and gives the solvent isotope effect [Formula: see text] this indicates that reaction occurs by rate-determining proton transfer from the catalyst to the substrate to generate an alkoxycarbocation intermediate. An oxygen-18 tracer study shows further that, despite the steric hindrance provided by its two ortho substituents, this cation then reacts by addition of water to the cationic carbon atom to generate a hemiacetal, and not by nucleophilic attack of water on the methyl group remote from the carbocationic center:[Formula: see text]

Vinyl ether hydrolysis. XVIII. The two-stage reaction of 2,3-dimethoxy-1,3-butadiene

1987 ◽  
Vol 65 (8) ◽  
pp. 1753-1756 ◽  
Author(s):  
A. Jerry Kresge ◽  
Ya Yin
Keyword(s):  
Vinyl Ether ◽  
Acid Catalysis ◽  
Inductive Effect ◽  
Isotope Effects ◽  
Resonance Effect ◽  
Stage I ◽  
Initial Substrate ◽  
Acid Catalyzed ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of acid-catalyzed hydrolysis of 2,3-dimethoxy-1,3-butadiene (1) to 3-methoxy-3-buten-2-one (2) and the subsequent 104 times slower conversion of the latter to biacetyl (3):[Formula: see text]were studied in aqueous solution at 25 °C. Both stages of this process give substantial hydrogen ion isotope effects, [Formula: see text] for Stage I and [Formula: see text] for Stage II, and Stage I shows general acid catalysis in formic and acetic acid buffers; both stages are therefore assigned the conventional mechanism for vinyl ether hydrolysis involving rate-determining proton transfer from catalyzing acid to substrate. The second vinyl ether group of the initial substrate (1) is found to have only a slight (3-fold) accelerative effect on the reactivity of the first group, but the acetyl substituent present in the intermediate 2 decreases its reactivity by a factor of 104; the latter appears to be due largely to the electron-withdrawing inductive effect of acetyl, with little or no influence from a countervailing electron-supplying resonance effect.

scholarly journals Acid-catalyzed hydrolysis of the vinyl ether group of 4-methoxy-1,2-dihydronaphthalene. Effect of conformation on reactivity

ARKIVOC ◽  
2001 ◽  
Vol 2002 (4) ◽  
pp. 12-17
Author(s):  
A. Awwal ◽  
W. E. Jones ◽  
A. J. Kresge ◽  
Q. Meng
Keyword(s):  
Vinyl Ether ◽  
Ether Group ◽  
Acid Catalyzed ◽  
Hydrolysis Of
Sign in / Sign up

Export Citation Format

Share Document