scholarly journals Vinyl ether hydrolysis. XI. The effect of α-phenyl substitution

1978 ◽  
Vol 56 (4) ◽  
pp. 456-460 ◽  
Author(s):  
Y. Chiang ◽  
W. K. Chwang ◽  
A. J. Kresge ◽  
L. H. Robinson ◽  
D. S. Sagatys ◽  
...  
Keyword(s):  
Transition State ◽  
Carboxylic Acids ◽  
Vinyl Ether ◽  
Phenyl Group ◽  
Marcus Theory ◽  
Methyl Substituent ◽  
Initial State ◽  
Carbonium Ion ◽  
Weak Resonance ◽  
Hydrolysis Of

The unexpected inability of an α-phenyl group to accelerate the rate of vinyl ether hydrolysis more strongly than an α-methyl substituent, k(CH2=CPhOEt)/k(CH2=CMeOEt) = 0.2 for catalysis by H3O+ at 25 °C, is examined and is found to be the result of two effects: (i) preferential initial state stabilization by phenyl and (ii) weak resonance interaction with the developing alkoxy carbonium ion in the transition state induced by the reactant-like character of the latter. A curved Brønsted relation for the hydrolysis of 3-methoxyindene catalyzed by carboxylic acids and monohydrogen phosphonate anions gives the Marcus theory parameters ΔG0≠ = 3 ± 1 kcal/mol and wr = 12 ± 1 kcal/mol.

scholarly journals Application of Singh-Jha Equation in the Evaluation of b* Parameter of Laidler-Landskroener Equation in the Hydrolysis of Vinyl Acetate

2010 ◽  
Vol 7 (4) ◽  
pp. 1170-1173
Author(s):  
Sangita Sharma ◽  
Bijal Vyas ◽  
Falguni Thakkar ◽  
Ketan Patel ◽  
J. J. Vora
Keyword(s):  
Organic Solvent ◽  
Transition State ◽  
Vinyl Acetate ◽  
Alkaline Hydrolysis ◽  
Initial State ◽  
Closed Approach ◽  
Rate Of Hydrolysis ◽  
Solvent Molecules ◽  
Hydrolysis Of

Singh-Jha method is applied to calculate b* of Laidler-Landskroener equation, the distance of closed approach of solvent molecules to the activated complexes in alkaline hydrolysis of vinyl acetate. This method is applied to alkaline hydrolysis of vinyl acetate in water enriched ethanol between 30 °C and 35 °C. The rate of hydrolysis decreases with the increase of content of organic solvent at both temperatures. The size of transition state was found to be large as compared to the initial state. The b* was found to be 3.7693Å which is in agreement with the values obtained earlier.

Solvolysis of sulphonyl halides. V. Hydrolysis and deuterolysis of methanesulphonyl chloride

1970 ◽  
Vol 23 (12) ◽  
pp. 2427
Author(s):  
ML Tonnet ◽  
AN Hambly
Keyword(s):  
Transition State ◽  
Thermodynamic Parameters ◽  
Isotope Effect ◽  
Large Reduction ◽  
Butyl Chloride ◽  
Solvent Isotope Effect ◽  
Initial State ◽  
Solvent Isotope ◽  
Hydrolysis Of

The values of the thermodynamic parameters of activation have been determined for the solvolysis of methanesulphonyl chloride in H2O and D2O and their mixtures with moderate amounts of dioxan. Some of the data are not in agreement with the postulate that the kinetic solvent isotope effect and the maximum in the rate of solvolysis produced by the addition of dioxan are due to changes in the initial state of the reacting system rather than to changes in the transition state. The addition of dioxan does not produce a large reduction in the solvent isotope effect as reported for the hydrolysis of t-butyl chloride and predicted to be general. The relative rates of solvolysis in mixtures of H2O and D2O are not in agreement with the analysis of such reactions by Swain and Thornton.

A SURVEY OF THERMODYNAMIC PARAMETERS FOR SOLVOLYSIS IN WATER

1959 ◽  
Vol 37 (4) ◽  
pp. 803-824 ◽  
Author(s):  
R. E. Robertson ◽  
R. L. Heppolette ◽  
J. M. W. Scott
Keyword(s):  
Transition State ◽  
Activation Enthalpy ◽  
Detailed Knowledge ◽  
Standard State ◽  
Initial State ◽  
Enthalpy Of Activation ◽  
Halide Exchange ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of ◽  
Linear Correlations

A method is suggested for determining the standard state entropies [Formula: see text] of the transition state for the neutral hydrolysis of esters in water. This has required the development of methods for approximating initial state parameters where experimental data are lacking.Characteristic linear correlations between the entropy and enthalpy of activation are observed for hydrolysis in water, as well as for the bimolecular halide exchange reaction in acetone and for acid–base equilibria. Explanations are advanced to explain the observed trends.From the derived standard state entropies, a method for estimating the charge development in the transition state for the methyl and isopropyl halides is proposed. With this further detailed knowledge of the transition state in the methyl halide series, reasonable values of the activation enthalpy can be calculated from available thermochemical data.

Vinyl ether hydrolysis. XII. Use of cis–trans isomerism to probe the reaction mechanism

1978 ◽  
Vol 56 (4) ◽  
pp. 461-464 ◽  
Author(s):  
Y. Chiang ◽  
A. J. Kresge ◽  
C. I. Young
Keyword(s):  
Reaction Mechanism ◽  
Vinyl Ether ◽  
Hydrolysis Reaction ◽  
Trans Isomers ◽  
Vinyl Methyl ◽  
Reaction Conditions ◽  
Carbonium Ion ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Hydrolysis Of

Rates of hydrolysis of cis- and trans-β-phenylvinyl methyl ethers, cis- and trans-β-(p-nitrophenyl)vinyl methyl ethers, and cis- and trans-β-cyanovinyl ethyl ethers were measured in concentrated (10–55 wt%) aqueous perchloric acids. The results show that these cis and trans isomers do not interconvert under the hydrolysis reaction conditions, and that formation of the alkoxy carbonium ion intermediate in these reactions is therefore not reversible.

The Mechanism of Hydrolysis of Aryldiazonium Ions Revisited: Marcus Theory vs. Canonical Variational Transition State Theory

2013 ◽  
Vol 2013 (27) ◽  
pp. 6098-6107 ◽  
Author(s):  
Antonio García Martínez ◽  
Santiago de la Moya Cerero ◽  
José Osío Barcina ◽  
Florencio Moreno Jiménez ◽  
Beatriz Lora Maroto
Keyword(s):  
Transition State ◽  
Transition State Theory ◽  
State Theory ◽  
Marcus Theory ◽  
Variational Transition State Theory ◽  
Mechanism Of Hydrolysis ◽  
Hydrolysis Of ◽  
Variational Transition State

Kinetic solvent effects on acid-catalyzed hydrolysis of sucrose in aqueous mixtures of some protic, aprotic, and dipolar aprotic solvents

1986 ◽  
Vol 64 (8) ◽  
pp. 1638-1642 ◽  
Author(s):  
Urmila Mandal ◽  
Kaushik Das ◽  
Kiron Kumar Kundu
Keyword(s):  
Transition State ◽  
Optical Rotation ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Initial State ◽  
Composition Profiles ◽  
Acid Catalyzed ◽  
Solvent Systems ◽  
Hydrolysis Of ◽  
Reference Electrolyte

Rate constants of acid-catalyzed hydrolysis of sucrose (S) to D-glucose and L-fructose have been determined at 25 °C by optical rotation measurements in aqueous mixtures of protophobic protic glycerol (GL), protophilic protic urea (UH), aprotic dioxane (D), and dipolar aprotic dimethyl sulphoxide (DMSO). Transfer free energies of the substrate sucrose, [Formula: see text] have also been determined in the solvents from solubility measurements. These values as well as those of H+, as obtained earlier by use of the widely used tetraphenylarsonium tetraphenylboron (TATB) reference electrolyte assumption, yielded transfer free energies of the transition state. The observed log (ks/kw) – composition profiles reveal that the rates increase monotonically in GL–water mixtures, that decrease more or less monotonically in UH– and DMSO–water mixtures, and decrease up to 10 mol% D in D–water mixtures, beyond which the values tend to increase. Examination of [Formula: see text]–composition profiles for the different species in each case indicates that the initial and transition state solvation get more or less compensated and the observed rates are dictated by the increased solvation of H+ in aqueous UH, DMSO, and D co-solvent systems. But in GL–water mixtures the decreased solvation of the transition state compared with the initial state is overcome by the decreased solvation of H+, thus resulting in the gradual enhancement of the rates of the reaction. The observed linearity of the correlative plots of −δ(ΔG≠) [= RT ln (ks/kw)] vs. [Formula: see text] with distinctly different slopes in the two cases also substantiates the relative importance of H+ solvation in dictating the rates of the reaction in these widely different aqueous co-solvents.

Initial State and Transition State Contributions to Reactivity Trends of Base-Catalyzed Hydrolysis of Some Nitro Chromen-2-One Derivatives

2011 ◽  
Vol 225 (2) ◽  
pp. 235-248 ◽  
Author(s):  
Ezz. A. Abu-Gharib ◽  
Rafat. M. EL-Khatib ◽  
Lobna A. E. Nassr ◽  
Ahmed M. Abu-Dief
Keyword(s):  
Transition State ◽  
Initial State ◽  
Hydrolysis Of
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