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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: https://doi.org/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
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}
}