Vinyl ether hydrolysis. 9. Isotope effects on proton transfer from the hydronium ion

1977 ◽  
Vol 99 (22) ◽  
pp. 7228-7233 ◽  
Author(s):  
A. J. Kresge ◽  
D. S. Sagatys ◽  
H. L. Chen
Keyword(s):  
Proton Transfer ◽  
Vinyl Ether ◽  
Isotope Effects ◽  
Hydronium Ion

ChemInform Abstract: VINYL ETHER HYDROLYSIS. 9. ISOTOPE EFFECTS ON PROTON TRANSFER FROM THE HYDRONIUM ION

1978 ◽  
Vol 9 (5) ◽  
Author(s):  
A. J. KRESGE ◽  
D. S. SAGATYS ◽  
H. L. CHEN
Keyword(s):  
Proton Transfer ◽  
Vinyl Ether ◽  
Isotope Effects ◽  
Hydronium Ion

Vinyl ether hydrolysis. XXIV. 1-Methoxycyclooctene and the question of reversibility of the carbon protonation step

1991 ◽  
Vol 69 (1) ◽  
pp. 84-87 ◽  
Author(s):  
A. J. Kresge ◽  
Y. Yin
Keyword(s):  
Reaction Mechanism ◽  
Proton Transfer ◽  
Vinyl Ether ◽  
Isotope Effects ◽  
Hydrolysis Rate ◽  
Hydronium Ion ◽  
Mineral Acids ◽  
Dilute Aqueous Solutions ◽  
Solvent Isotope ◽  
Hydrolysis Of

An argument is presented which suggests that hydrolysis of the vinyl ether group of 1-methoxycyclooctene may occur by reversible proton transfer from a catalyzing acid to the β-carbon atom of the substrate, instead of by the conventional reaction mechanism in which this proton transfer is rate determining and not reversible. Hydrolysis of this substrate is then examined by measuring rates of reaction in dilute aqueous solutions of strong mineral acids (perchloric and hydrochloric) as well as in buffer solutions of seven carboxylic acids, biphosphate ion, and 1,1,1,3,3,3-hexafluoro-2-propanol. General acid catalysis is observed and a Brønsted relation with the exponent α = 0.73 is constructed. That, plus the isotope effects kH/kD = 2.9 and 6.0 for catalysis by hydronium ion and acetic acid respectively, as well as the lack of deuterium incorporation into the substrate when the reaction is carried out in D2O with D2PO4−/DPO42− buffer at pD = 8, show that carbon protonation of the substrate is not reversible and that the conventional reaction mechanism is operative. Key words: 1-methoxycyclooctene, vinyl ether hydrolysis, rate-determining proton transfer, Brønsted relation, solvent isotope effect.

Deuterium fractionation factor for unhydrated hydronium ion. Deuterium isotope effects on proton-transfer equilibria in acetonitrile

1984 ◽  
Vol 106 (19) ◽  
pp. 5631-5634 ◽  
Author(s):  
Joseph L. Kurz ◽  
Melissa T. Myers ◽  
Keith M. Ratcliff
Keyword(s):  
Proton Transfer ◽  
Isotope Effects ◽  
Fractionation Factor ◽  
Hydronium Ion ◽  
Deuterium Isotope Effects

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.

Solvent isotope effects upon proton transfer from the hydronium ion

1971 ◽  
Vol 93 (1) ◽  
pp. 9-20 ◽  
Author(s):  
Rory A. More O'Ferrall ◽  
Gerald W. Koeppl ◽  
A. Jerry Kresge
Keyword(s):  
Proton Transfer ◽  
Isotope Effects ◽  
Hydronium Ion ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

Gas-phase proton-transfer reactions of the hydronium ion at 298 K

1979 ◽  
Vol 57 (12) ◽  
pp. 1518-1523 ◽  
Author(s):  
Gervase I. Mackay ◽  
Scott D. Tanner ◽  
Alan C. Hopkinson ◽  
Diethard K. Bohme
Keyword(s):  
Proton Transfer ◽  
Gas Phase ◽  
Rate Constants ◽  
Transfer Reactions ◽  
Flowing Afterglow ◽  
Hydronium Ion ◽  
Proton Transfer Reactions

Rate constants measured with the flowing afterglow technique at 298 ± 2 K are reported for the proton-transfer reactions of H3O+ with CH2O, CH3CHO, (CH3)2CO, HCOOH, CH3COOH, HCOOCH3, CH3OH, C2H5OH, (CH3)2O, and CH2CO. Dissociative proton-transfer was observed only with CH3COOH. The rate constants are compared with the predictions of various theories for ion–molecule collisions. The protonation is discussed in terms of the energetics and mechanisms of various modes of dissociation.

Sign in / Sign up

Export Citation Format

Share Document