scholarly journals Modeling the Alkaline Hydrolysis of Diaryl Sulfate Diesters: A Mechanistic Study

2020 ◽  
Vol 85 (10) ◽  
pp. 6489-6497
Author(s):  
Klaudia Szeler ◽  
Nicholas H. Williams ◽  
Alvan C. Hengge ◽  
Shina C. L. Kamerlin
Keyword(s):  
Alkaline Hydrolysis ◽  
Mechanistic Study ◽  
Hydrolysis Of

scholarly journals Modeling the Alkaline Hydrolysis of Diaryl Sulfate Diesters: A Mechanistic Study

2020 ◽  
Author(s):  
Klaudia Szeler ◽  
Nicholas Williams ◽  
Alvan C. Hengge ◽  
Shina Caroline Lynn Kamerlin
Keyword(s):  
Alkaline Hydrolysis ◽  
Computational Study ◽  
Transition States ◽  
Building Blocks ◽  
Ester Hydrolysis ◽  
Mechanistic Study ◽  
Phosphate Ester ◽  
Sulfate Ester ◽  
The Impact ◽  
Hydrolysis Of

<div> <div> <div> <p>Phosphate and sulfate esters have important roles as biological building blocks and in regulating cellular processes. However, while there has been substantial experimental and computational investigation of the mechanisms and the transition states involved in phosphate ester hydrolysis, there is far less (in particular computational) work on sulfate ester hydrolysis. Here, we report a detailed computational study of the alkaline hydrolysis of diaryl sulfate diesters, using different DFT functionals and both pure implicit solvation as well as mixed implicit/explicit solvation with varying numbers of explicit water molecules. We consider both the impact of how the system is modeled on computed linear free energy relationships (LFER) and the nature of the transition states. Although our calculations consistently underestimate the absolute activation free energies, we obtain good agreement with experimental LFER data when using pure implicit solvent, and excellent agreement with experimental kinetic isotope effects for all models used. Our calculations suggest that the hydrolysis of sulfate diesters proceeds through loose transition states, with minimal bond formation to the nucleophile and with bond cleavage to the leaving group already initiated. Comparison to prior work indicates that these transition states are similar in nature to those of analogous reactions such as the alkaline hydrolysis of neutral arylsulfonate monoesters or charged phosphate diesters and fluorophosphates. Obtaining more detailed insight into the transition states involved assists in understanding the selectivity of enzymes that hydrolyze these reactions; however, this work also highlights the methodological challenges involved in reliably modeling sulfate ester hydrolysis. </p> </div> </div> </div>

scholarly journals Modeling the Alkaline Hydrolysis of Diaryl Sulfate Diesters: A Mechanistic Study

2020 ◽  
Author(s):  
Klaudia Szeler ◽  
Nicholas Williams ◽  
Alvan C. Hengge ◽  
Shina Caroline Lynn Kamerlin
Keyword(s):  
Alkaline Hydrolysis ◽  
Computational Study ◽  
Transition States ◽  
Building Blocks ◽  
Ester Hydrolysis ◽  
Mechanistic Study ◽  
Phosphate Ester ◽  
Sulfate Ester ◽  
The Impact ◽  
Hydrolysis Of

<div> <div> <div> <p>Phosphate and sulfate esters have important roles as biological building blocks and in regulating cellular processes. However, while there has been substantial experimental and computational investigation of the mechanisms and the transition states involved in phosphate ester hydrolysis, there is far less (in particular computational) work on sulfate ester hydrolysis. Here, we report a detailed computational study of the alkaline hydrolysis of diaryl sulfate diesters, using different DFT functionals and both pure implicit solvation as well as mixed implicit/explicit solvation with varying numbers of explicit water molecules. We consider both the impact of how the system is modeled on computed linear free energy relationships (LFER) and the nature of the transition states. Although our calculations consistently underestimate the absolute activation free energies, we obtain good agreement with experimental LFER data when using pure implicit solvent, and excellent agreement with experimental kinetic isotope effects for all models used. Our calculations suggest that the hydrolysis of sulfate diesters proceeds through loose transition states, with minimal bond formation to the nucleophile and with bond cleavage to the leaving group already initiated. Comparison to prior work indicates that these transition states are similar in nature to those of analogous reactions such as the alkaline hydrolysis of neutral arylsulfonate monoesters or charged phosphate diesters and fluorophosphates. Obtaining more detailed insight into the transition states involved assists in understanding the selectivity of enzymes that hydrolyze these reactions; however, this work also highlights the methodological challenges involved in reliably modeling sulfate ester hydrolysis. </p> </div> </div> </div>

A Mechanistic Study of the Alkaline Hydrolysis of Diaryl Sulfate Diesters

2004 ◽  
Vol 69 (26) ◽  
pp. 9043-9048 ◽  
Author(s):  
Jarod M. Younker ◽  
Alvan C. Hengge
Keyword(s):  
Alkaline Hydrolysis ◽  
Mechanistic Study ◽  
Hydrolysis Of

Influence of medium on alkaline hydrolysis of succinic acid monomethyl and monopropyl esters

1980 ◽  
Vol 45 (11) ◽  
pp. 2873-2882
Author(s):  
Vladislav Holba ◽  
Ján Benko
Keyword(s):  
Succinic Acid ◽  
Kinetic Parameters ◽  
Alkaline Hydrolysis ◽  
Specific Interactions ◽  
Nonaqueous Media ◽  
The Media ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of alkaline hydrolysis of succinic acid monomethyl and monopropyl esters were studied in mixed aqueous-nonaqueous media at various temperatures and ionic strengths. The results of measurements are discussed in terms of electrostatic and specific interactions between the reactants and other components of the reaction mixture. The kinetic parameters in the media under study are related to the influence of the cosolvent on the solvation sphere of the reactants.

Synthesis of Normuramic Acid Carba Analog and Its Glycopeptide Derivative Resistant to β-Elimination Splitting of the Side Chain

2000 ◽  
Vol 65 (11) ◽  
pp. 1726-1736 ◽  
Author(s):  
Miroslav Ledvina ◽  
Radka Pavelová ◽  
Anna Rohlenová ◽  
Jan Ježek ◽  
David Šaman
Keyword(s):  
Ethyl Ester ◽  
Alkaline Hydrolysis ◽  
Benzyl Ester ◽  
Side Chain ◽  
Propanoic Acid ◽  
Hydrolysis Of

Carba analogs of normuramic acid, i.e., 3-(benzyl 2-acetamido-2,3-dideoxy-4,6-O-isopropylidene-α-D-glucopyranosid-3-yl)propanoic acid derivatives (nitrile or esters) 3a-3c were prepared by addition of radicals generated from benzyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-3-O-[(methylsulfanyl)thiocarbonyl]- (2a) or -3-O-(phenoxythiocarbonyl)-α-D-glucopyranoside (2b) with Bu3SnH to acrylonitrile or acryl esters. Alkaline hydrolysis of ethyl ester 3c afforded 3-(benzyl 2-acetamido-2,3-dideoxy-4,6-O-isopropylidene-α-D-glucopyranosid-3-yl)propanoic acid (5). Coupling of acid 5 with L-2-aminobutanoyl-D-isoglutamine benzyl ester trifluoroacetate and subsequent deprotection of the intermediate 6 furnished N-[3-(2-acetamido-2,3-dideoxy-α-D-glucopyranosid-3-yl)propanoyl]-L-2-aminobutanoyl-D-isoglutamine (7).

Kinetic study of hydrolysis of benzoates. part xxvii. ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous Bu4NBr

2009 ◽  
Vol 74 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Vilve Nummert ◽  
Mare Piirsalu ◽  
Signe Vahur ◽  
Oksana Travnikova ◽  
Ilmar A. Koppel
Keyword(s):  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Pure Water ◽  
Substituent Effects ◽  
Benzoic Acids ◽  
Resonance Effects ◽  
The Media ◽  
Substituted Benzoic Acids ◽  
Hydrolysis Of ◽  
Ortho Substituent

The second-order rate constants k (in dm3 mol–1 s–1) for alkaline hydrolysis of phenyl esters of meta-, para- and ortho-substituted benzoic acids, X-C6H4CO2C6H5, have been measured spectrophotometrically in aqueous 0.5 and 2.25 M Bu4NBr at 25 °C. The substituent effects for para and meta derivatives were described using the Hammett relationship. For the ortho derivatives the Charton equation was used. For ortho-substituted esters two steric scales were involved: the EsB and the Charton steric (υ) constants. When going from pure water to aqueous 0.5 and 2.25 M Bu4NBr, the meta and para polar effects, the ortho inductive and resonance effects in alkaline hydrolysis of phenyl esters of substituted benzoic acids, became stronger nearly to the same extent as found for alkaline hydrolysis of C6H5CO2C6H4-X. The steric term of ortho-substituted esters was almost independent of the media considered. The rate constants of alkaline hydrolysis of ortho-, meta- and para-substituted phenyl benzoates (X-C6H4CO2C6H5, C6H5CO2C6H4-X) and alkyl benzoates, C6H5CO2R, in water, 0.5 and 2.25 M Bu4NBr were correlated with the corresponding IR stretching frequencies of carbonyl group, (ΔνCO)X.

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