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Unraveling Acid?Base Contributions in P-Nitrophenyl Acetate Hydrolysis: Kinetics, Mechanism, And Activation Parameters in Aqueous Media
Subject area: Science,Engineering and Technology · Area of research: Science
DOI: 10.64388/IREV9I3-1710748-3992
Abstract
Hydrolysis of p-nitrophenyl acetate (PNPA) serves as a classical model for studying acid?base catalysis in aqueous solution. Despite its widespread use in enzymology and mechanistic chemistry, comprehensive datasets unifying acid- and base-catalyzed pathways remain limited. In this study, PNPA hydrolysis was monitored spectrophotometrically across pH 2?11 and temperatures 20?45 ?C. Pseudo-first-order rate constants (kobs) were determined from exponential fits of absorbance?time traces at 400 nm. A characteristic U-shaped pH?rate profile was obtained, confirming contributions from both acid- and base-catalyzed pathways. Arrhenius and Eyring analyses yielded an activation energy (E?) of 54.7 kJ?mol??, enthalpy of activation (?H) of 52.2 kJ?mol??, and entropy of activation (?S) of ?47.8 J?mol???K??, consistent with a bimolecular, ordered transition state. The results bridge existing gaps by integrating acid- and base-mediated hydrolysis within a single mechanistic framework, providing a reference dataset for both physical organic chemistry and enzymatic catalysis.
Keywords
PNPA, Ester Hydrolysis, Acid?Base Catalysis, Activation Parameters, Aqueous Kinetics
References
[1] Ahn, S., Hong, M., Sundararajan, M., Ess, D. H., & Baik, M. H. (2019). Design and optimization of catalysts based on mechanistic insights derived from quantum chemical reaction modeling. Chemical reviews, 119(11), 6509-6560.
[2] Castro Mur, D., & Yepes, D. M. Integrating Characterization, Kinetic, and Thermodynamic Analysis into Pacific Colombian Biomass Residues for Preliminary Bioenergy Assessment Via Coats–Redfern Modeling Under Single-Rate Tga Conditions. Kinetic, and Thermodynamic Analysis into Pacific Colombian Biomass Residues for Preliminary Bioenergy Assessment Via Coats–Redfern Modeling Under Single-Rate Tga Conditions..
[3] Han, L. L., Li, S. J., & Fang, D. C. (2016). Theoretical estimation of kinetic parameters for nucleophilic substitution reactions in solution: an application of a solution translational entropy model. Physical Chemistry Chemical Physics, 18(8), 6182-6190.
[4] Heist, B. (2019). Effect of Ca2+ ions on the hydrolysis of phenyl esters and anilides, p-nitrophenyl acetate and p-nitroacetanilide.
[5] Jorner, K., Brinck, T., Norrby, P. O., & Buttar, D. (2021). Machine learning meets mechanistic modelling for accurate prediction of experimental activation energies. Chemical Science, 12(3), 1163-1175.
[6] Li, W., Lu, Y., Wang, J., & Li, C. (2025). A novel simplified structural design as an artificial enzyme for efficient hydrolysis of PNPA. Scientific Reports, 15(1), 9071.
[7] Li, W., Lu, Y., Wang, J., & Li, C. (2025). A novel simplified structural design as an artificial enzyme for efficient hydrolysis of PNPA. Scientific Reports, 15(1), 9071.
[8] Madhu, R., Muthukumar, J., Arunachalam, P., Gudlur, P., & Kundu, S. (2024). Unraveling Activation Energy with Temperature-Dependent Analyses of CoNiSe2 Electrocatalysts Derived from CoNi-LDH for Water Splitting Reaction. The Journal of Physical Chemistry C, 128(31), 12891-12902.
[9] Raycroft, M. A., Racine, K. É., Rowley, C. N., & Keillor, J. W. (2018). Mechanisms of alkyl and aryl thiol addition to N-methylmaleimide. The Journal of Organic Chemistry, 83(19), 11674-11685.
[10] Vyazovkin, S. (2024). Misinterpretation of thermodynamic parameters evaluated from activation energy and preexponential factor determined in thermal analysis experiments. Thermo, 4(3), 373-381.
[11] Yang, Y., Wang, X., & Dong, H. (2024). Simulating chemical reactions promoted by self-assembled peptides with catalytic properties. In Methods in Enzymology (Vol. 697, pp. 321-343). Academic Press
[12] Zhang, L., & Fang, D. C. (2017). Explicit roles of diverse directing groups in determining transition state energy and reaction exothermicity of C–H activation pathways. Organic Chemistry Frontiers, 4(7), 1250-1260.
How to cite this paper
@article{1710748,
author = {Ghali Muhammad Rabiu, Musa Hamisu, Ladi Lawan, Mohammed Hussaini, Abba Haruna Adamu},
title = {Unraveling Acid?Base Contributions in P-Nitrophenyl Acetate Hydrolysis: Kinetics, Mechanism, And Activation Parameters in Aqueous Media},
journal = {Iconic Research And Engineering Journals},
year = {2025},
volume = {9},
number = {3},
pages = {1117-1120},
issn = {2456-8880},
url = {https://www.irejournals.com/formatedpaper/1710748.pdf},
abstract = {Hydrolysis of p-nitrophenyl acetate (PNPA) serves as a classical model for studying acid?base catalysis in aqueous solution. Despite its widespread use in enzymology and mechanistic chemistry, comprehensive datasets unifying acid- and base-catalyzed pathways remain limited. In this study, PNPA hydrolysis was monitored spectrophotometrically across pH 2?11 and temperatures 20?45 ?C. Pseudo-first-order rate constants (kobs) were determined from exponential fits of absorbance?time traces at 400 nm. A characteristic U-shaped pH?rate profile was obtained, confirming contributions from both acid- and base-catalyzed pathways. Arrhenius and Eyring analyses yielded an activation energy (E?) of 54.7 kJ?mol??, enthalpy of activation (?H) of 52.2 kJ?mol??, and entropy of activation (?S) of ?47.8 J?mol???K??, consistent with a bimolecular, ordered transition state. The results bridge existing gaps by integrating acid- and base-mediated hydrolysis within a single mechanistic framework, providing a reference dataset for both physical organic chemistry and enzymatic catalysis.},
keywords = {PNPA, Ester Hydrolysis, Acid?Base Catalysis, Activation Parameters, Aqueous Kinetics},
month = {September},
doi = {https://doi.org/10.64388/IREV9I3-1710748-3992}
}