Intramolecular general acid catalysis of sulfate transfer — Nucleophilic attack by oxyanions on the SO3– group

2005 ◽  
Vol 83 (9) ◽  
pp. 1629-1636 ◽  
Author(s):  
Anthony J Kirby ◽  
José Carlos Gesser ◽  
Florian Hollfelder ◽  
Jacks P Priebe ◽  
Faruk Nome
Keyword(s):  
Hydrogen Bond ◽  
Transition State ◽  
Acid Catalysis ◽  
Nucleophilic Attack ◽  
General Acid ◽  
State Transfer ◽  
Carboxylate Anions ◽  
Mechanism Of Hydrolysis ◽  
Intramolecular Hydrogen ◽  
Hydrolysis Of

The mechanism of hydrolysis of 8-N,N-dimethylaminonaphthyl sulfate closely resembles that of the corresponding phosphate monoester. Nucleophilic attack by water on the sulfate group of the zwitterion is catalyzed by the neighbouring dimethylammonium group, acting as a particularly efficient general acid through the intramolecular hydrogen bond. This hydrogen bond is present in both reactant and product, but is strongest in the transition state. Transfer of the sulfuryl group to oxygen nucleophiles, including water and carboxylate anions, shows steric and electrostatic effects, and a sensitivity to basicity which is low, but significantly higher than expected for uncatalyzed transfer of the SO3– group.Key words: sulfate, sulfatase, intramolecular, general acid catalysis, promiscuity.

Zur Theorie des kinetischen Lösungsmittel-Isotopeneffektes auf säurekatalytische organische Reaktionen II

1964 ◽  
Vol 19 (6) ◽  
pp. 461-467 ◽  
Author(s):  
Alfred V. Willi
Keyword(s):  
Partition Function ◽  
Transition State ◽  
Isotope Effect ◽  
Acid Catalysis ◽  
Free Energies ◽  
Solvent Isotope Effect ◽  
General Acid ◽  
Solvent Isotope ◽  
Hydrolysis Of ◽  
Limiting Value

From the known difference of free energies of liquid H2O and D2O at 25°, the following partition function ratio may be calculated: QD2O/QH2O = 1416. By combination with the constant L=11.0 for the equilibrium 2 D3O⊕ +3 H2O ⇆ 2H3O⊕ + 3D2O, one obtains QD3O/QH3O = 16100. The partition function ratio of an organic acid ROH is approximated by QROD/QROH ≈ (QD2O/QH2O)½. KH/KD≈ 3.3 is calculated for the solvent isotope effect on the acidity of ROH. Correspondingly, the approximation QSD/QSH ≈ (QD3O/QΗ3O)⅓ is introduced for conjugate acids (SH®) of ethers and carbonyl compounds, leading to the solvent isotope effect: KH/KD ≈ 2.2. - In the acid-catalysed hydrolysis of acetals, the formation of the transition state involves the complete transformation from the H3O⊕ to the H2O state of 2 OH bonds and the partial transformation of one more OH bond. Consequently, the limits 1/3.3 < kH/kD < 1/2.2 are calculated for the kinetic solvent isotope effect. The following equation is valid for the general acid catalysis by HA of the enolisation of acetone: kHA/kDA = (KHA/KDA) / (KSH/KSD). Theoretical values are calculated which agree well with experimental data. - On the basis of a simple model for the transition state, the solvent isotope effect on rate determining H® transfer from acetic acid to a substrate (general acid catalysis) may be calculated. (kHA/kDA) min = 5.7 is obtained as a limiting value.

Intramolecular General Acid Catalysis of Phosphate Transfer. Nucleophilic Attack by Oxyanions on the PO32-Group

2005 ◽  
Vol 127 (19) ◽  
pp. 7033-7040 ◽  
Author(s):  
Anthony J. Kirby ◽  
Neil Dutta-Roy ◽  
Davi da Silva ◽  
Jonathan M. Goodman ◽  
Marcelo F. Lima ◽  
...  
Keyword(s):  
Acid Catalysis ◽  
Nucleophilic Attack ◽  
General Acid

General acid catalysis in the hydrolysis of benzo[a]pyrene 7,8-diol 9,10-epoxides

1979 ◽  
Vol 101 (17) ◽  
pp. 5086-5088 ◽  
Author(s):  
Dale L. Whalen ◽  
Angela M. Ross ◽  
Jean A. Montemarano ◽  
Dhiren R. Thakker ◽  
Harukiko Yagi ◽  
...  
Keyword(s):  
Acid Catalysis ◽  
General Acid ◽  
Hydrolysis Of

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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