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.

Vinyl ether hydrolysis. XIII. The failure of I-strain to produce a change in rate-determining step

1980 ◽  
Vol 58 (2) ◽  
pp. 124-129 ◽  
Author(s):  
Y. Chiang ◽  
W. K. Chwang ◽  
A. J. Kresge ◽  
S. Szilagyi
Keyword(s):  
Vinyl Ether ◽  
Acid Catalysis ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Mineral Acid ◽  
Buffer Solutions ◽  
Rate Determining Step ◽  
Kinetic Isotope ◽  
Acetic Acid Buffer ◽  
Hydrolysis Of

Rates of hydrolysis of 1-ethoxy-3,3,5,5-tetramethylcyclopentene and 1-methoxy-2,3,3,5,5-pentamethylcyclopentene measured in mineral acid and formic and acetic acid buffer solutions show general acid catalysis and give large kinetic isotope effects in the normal direction (kH/kD > 1). This indicates that these reactions proceed by the conventional mechanism for vinyl ether hydrolysis in which proton transfer from the catalyzing acid to the substrate is rate-determining, and that the I-strain in these substrates is insufficiently great to shift the reaction mechanism to rapidly reversible substrate protonation followed by rate-determining hydration of the ensuing cationic intermediate.

Vinyl ether hydrolysis. XXIX. 1-Methoxy-1,3-butadiene: reaction mechanism and implication for hydrolysis of the mutagen fecapentaene-12

1994 ◽  
Vol 72 (7) ◽  
pp. 1632-1636 ◽  
Author(s):  
Yvonne Chiang ◽  
Robert Eliason ◽  
Gary H.-X. Guo ◽  
A. Jerry Kresge
Keyword(s):  
Vinyl Ether ◽  
Trans Isomer ◽  
Acid Catalysis ◽  
Isotope Effects ◽  
Hydronium Ion ◽  
Rapid Formation ◽  
Methyl Vinyl Ether ◽  
Cis And Trans ◽  
Hydrolysis Of ◽  
Cis Isomer

The hydrolysis of cis- and trans-1-methoxy-1,3-butadiene in aqueous solution occurs by hydron transfer to the δ-carbon atom with little or no β-hydronation to give crotonaldehyde as essentially the sole aldehyde product. The reaction gives appreciable hydronium-ion isotope effects in the normal direction [Formula: see text] and shows general acid catalysis; five carboxylic acid catalytic coefficients for hydrolysis of the trans isomer give a good Brønsted relation with the exponent α = 0.59. This is taken as evidence that these reactions occur by the conventional mechanism for vinyl ether hydrolysis involving rate-determining hydron transfer to substrate carbon followed by rapid formation and decomposition of a hemiacetal intermediate. Comparison of the reactivity of the present dienyl ethers with that of their monoenyl analog, methyl vinyl ether, shows that introduction of the second double bond decreases reactivity considerably: the hydronium-ion catalytic coefficient is reduced by a factor of 8.3 for the trans isomer and by a factor of 160 for the cis isomer. This reduction supports a hypothesis advanced to explain the occurrence of reaction by a different mechanism recently discovered in the hydrolysis of the strongly mutagenic polyenyl ether, fecapentaene-12.

Cyclization and acid-catalyzed hydrolysis of O-benzoylbenzamidoximes

1986 ◽  
Vol 51 (12) ◽  
pp. 2786-2797
Author(s):  
František Grambal ◽  
Jan Lasovský
Keyword(s):  
Reaction Rate ◽  
Kinetic Isotope ◽  
Acid Base Equilibrium ◽  
Mineral Acids ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Ph Scale ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Derivatives Of

Kinetics of formation of 1,2,4-oxadiazoles from 24 substitution derivatives of O-benzoylbenzamidoxime have been studied in sulphuric acid and aqueous ethanol media. It has been found that this medium requires introduction of the Hammett H0 function instead of the pH scale beginning as low as from 0.1% solutions of mineral acids. Effects of the acid concentration, ionic strength, and temperature on the reaction rate and on the kinetic isotope effect have been followed. From these dependences and from polar effects of substituents it was concluded that along with the cyclization to 1,2,4-oxadiazoles there proceeds hydrolysis to benzamidoxime and benzoic acid. The reaction is thermodynamically controlled by the acid-base equilibrium of the O-benzylated benzamidoximes.

Kinetics of acid-catalyzed hydrolysis of butyn-3-al acetals

1974 ◽  
Vol 23 (10) ◽  
pp. 2274-2275
Author(s):  
A. N. Volkov ◽  
A. N. Khudyakova
Keyword(s):  
Acid Catalyzed ◽  
Kinetics Of ◽  
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.

Acid-catalyzed Solvolysis of Isonitriles. I

1971 ◽  
Vol 49 (14) ◽  
pp. 2455-2459 ◽  
Author(s):  
Y. Y. Lim ◽  
A. R. Stein
Keyword(s):  
Formic Acid ◽  
Acid Catalysis ◽  
Hydrolysis Product ◽  
Rate Dependence ◽  
Linear Rate ◽  
First Order ◽  
Methyl Amine ◽  
Acid Catalyzed ◽  
Pseudo First Order ◽  
Hydrolysis Of

The acid-catalyzed hydrolysis of methyl isonitrile has been examined. The initial hydrolysis product is N-methylformamide which is further hydrolyzed to methyl amine and formic acid at a much slower rate. The hydrolysis to N-methylformamide is pseudo-first order in methyl isonitrile and shows a linear rate dependence on concentration of general (buffer) acid at fixed pH. The significance of general acid-catalysis in terms of the mechanism of the hydrolysis is considered and taken as evidence for carbon protonation rather than nitrogen protonation as the initiating step.

scholarly journals Effect of a Substituent in the Benzene Ring upon the Kinetics of Acid-Catalyzed Hydrolysis of exo-2-Norbornyl Phenyl Ether.

1997 ◽  
Vol 51 ◽  
pp. 515-520 ◽  
Author(s):  
Martti Lajunen ◽  
Marja Himottu ◽  
Kirsi Tanskanen-Lehti ◽  
Maamar Hamdi ◽  
Suzanne Fery-Forgues ◽  
...  
Keyword(s):  
Benzene Ring ◽  
Phenyl Ether ◽  
Acid Catalyzed ◽  
Kinetics Of ◽  
Hydrolysis Of

Kinetics of the acid-catalyzed hydrolysis of tetraethoxysilane (TEOS) by 29Si NMR spectroscopy and mathematical modeling

2018 ◽  
Vol 86 (2) ◽  
pp. 316-328 ◽  
Author(s):  
J. C. Echeverría ◽  
P. Moriones ◽  
G. Arzamendi ◽  
J. J. Garrido ◽  
M. J. Gil ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Nmr Spectroscopy ◽  
29Si Nmr ◽  
Acid Catalyzed ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
29Si Nmr Spectroscopy

Kinetics of the hydrolysis of the dichromate ion. V. General acid catalysis

1969 ◽  
Vol 73 (12) ◽  
pp. 4391-4394 ◽  
Author(s):  
R. Baharad ◽  
Berta Perlmutter-Hayman ◽  
Michael A. Wolff
Keyword(s):  
Acid Catalysis ◽  
General Acid ◽  
Kinetics Of ◽  
Hydrolysis Of
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