Transition State Analysis of Acid-Catalyzed Hydrolysis of an Enol Ether, Enolpyruvylshikimate 3-Phosphate (EPSP)

2012 ◽  
Vol 134 (31) ◽  
pp. 12947-12957 ◽  
Author(s):  
Meiyan Lou ◽  
Meghann E. Gilpin ◽  
Steven K. Burger ◽  
Ayesha M. Malik ◽  
Vivian Gawuga ◽  
...  
Keyword(s):  
Transition State ◽  
Enol Ether ◽  
Acid Catalyzed ◽  
Hydrolysis Of ◽  
State Analysis

Transition state activity coefficients in the acid-catalyzed hydrolysis of esters

1975 ◽  
Vol 97 (18) ◽  
pp. 5223-5231 ◽  
Author(s):  
Robert A. McClelland ◽  
Tomasz A. Modro ◽  
Malcolm F. Goldman ◽  
Keith Yates
Keyword(s):  
Transition State ◽  
Activity Coefficients ◽  
State Activity ◽  
Acid Catalyzed ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of

The enol content of simple carbonyl compounds: a kinetic approach

1979 ◽  
Vol 57 (7) ◽  
pp. 797-802 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Carbonyl Compound ◽  
Excellent Agreement ◽  
Rate Constants ◽  
Carbonyl Compounds ◽  
Methyl Ketone ◽  
Sufficient Data ◽  
Enol Ether ◽  
Thermochemical Method ◽  
Acid Catalyzed ◽  
Hydrolysis Of

Following a suggestion of Lienhard and Wang, we demonstrate that the enol content of simple carbonyl compounds can be estimated as the ratio of the rate constants for acid-catalyzed enolization of the carbonyl compound and acid-catalyzed hydrolysis of the corresponding methyl enol ether. Values so estimated are in excellent agreement with those determined by our thermochemical method. Sufficient data are available for the following; compound, pKEnol: acetaldehyde, 4.7; propionaldehyde, 4.2; isobutyraldehyde, 2.7; acetone, 7.0; cyclopentanone, 6.7; cyclohexanone, 5.3; cycloheptanone, 7.2; cyclooctanone, 6.6; p-nitroacetophenone, 4.9; p-bromoacetophenone, 6.2; acetophenone, 6.6; p-methylacetophenone, 7.0; p-methoxyacetophenone, 7.3; and by estimating the rate constants for enolization, the following; indanone, 7; 2-phenyl-2-propanone, 4; cyclopropyl methyl ketone, 8; chloroacetaldehyde, 2 (corrected for hydration); phenylacetaldehyde, 2.

Transition state activity coefficients in the acid-catalyzed hydrolysis of amides

1977 ◽  
Vol 55 (16) ◽  
pp. 3050-3057 ◽  
Author(s):  
Tomasz A. Modro ◽  
Keith Yates ◽  
Françoise Beaufays
Keyword(s):  
Transition State ◽  
Bond Cleavage ◽  
Protonated Form ◽  
State Activity ◽  
Alkyl Derivatives ◽  
Amide Hydrolysis ◽  
Conjugate Acid ◽  
Acid Catalyzed ◽  
Hydrolysis Of ◽  
Nitrogen Bond

The transition-state activity coefficient [Formula: see text] approach has been applied to the acid-catalyzed hydrolysis of benzamide and its N-alkyl derivatives. For all systems (with the exception of the N-tert-butyl derivative which reacts via carbon–nitrogen bond cleavage) a uniform type of medium dependence of [Formula: see text] is observed. The reaction shows a pronounced destabilization of S≠ over the whole region of acidity studied, practically identical to that found for the AAc-2 type of ester hydrolysis. This is interpreted in terms of an AoT2 mechanism of amide hydrolysis, that is the rate-determining formation of the oxonium-type tetrahedral intermediate from the O-protonated form of substrate conjugate acid.

PRESSURE EFFECT AND MECHANISM IN ACID CATALYSIS: VIII. HYDROLYSIS OF ACETAMIDE AND BENZAMIDE

1961 ◽  
Vol 39 (5) ◽  
pp. 1101-1108 ◽  
Author(s):  
A. R. Osborn ◽  
T. C-W. Mak ◽  
E. Whalley
Keyword(s):  
Water Molecule ◽  
Transition State ◽  
Perchloric Acid ◽  
Acid Catalysis ◽  
Pressure Effect ◽  
Protonated Form ◽  
Dilute Acid ◽  
Additional Information ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The effect of pressures up to 3 kbar on the rate of the acid-catalyzed hydrolysis of acetamide and benzamide in both dilute and concentrated perchloric acid has been measured. The volumes of activation in dilute acid are consistent with a transition state that is not highly polar. It follows from this that if the attacking water molecule adds to the amidium ion then the reactive amidium ion is the O-protonated form, and if the attacking water molecule substitutes then the reactive amidium ion is the N-protonated form.The volume of activation for acetamide in concentrated acid provides no additional information about the mechanism. That for benzamide in concentrated acid is tentatively interpreted as favoring the O-protonated benzamidium ion as the reactive ion.

Transition State Analysis of Acid-Catalyzed dAMP Hydrolysis

2007 ◽  
Vol 129 (22) ◽  
pp. 7055-7064 ◽  
Author(s):  
Joe A. B. McCann ◽  
Paul J. Berti
Keyword(s):  
Transition State ◽  
Acid Catalyzed ◽  
State Analysis

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.

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