Reaction kinetics investigation of 1-fluoro-2,4-dinitrobenzene with substituted anilines in ethyl acetate-methanol mixtures using linear and nonlinear free energy relationships

• Published in: Journal of physical organic chemistry 2011-11, Vol.24 (11), p.1095-1100
• Main Authors: Jamali-Paghaleh, Javad, Harifi-Mood, Ali Reza, Gholami, Mohammad Reza
• Format: Article
• Language: English
• Subjects: aromatic nucleophilic substitution reaction; Hammett equation; preferential solvation; solvent effects; solvent-solvent interactions
• ISSN: 0894-3230; 1099-1395
• DOI: 10.1002/poc.1861

Aromatic nucleophilic substitution reaction of 1‐fluoro‐2,4‐dinitrobenzene with para‐substituted and meta‐substituted anilines was kinetically investigated in the mixtures of ethyl acetate and methanol at room temperature. The correlation of second‐order rate coefficients with Hammett's substituent constants yields a fairly linear straight line with negative slope in different mole fractions of ethyl acetate–methanol mixtures. The measured rate coefficients of the reaction demonstrated a dramatic variation in ethyl acetate–methanol mixtures with the increasing mole fraction of ethyl acetate. Linear free energy relationship (LFER) investigations confirm that polarity has a major effect on the reaction rate whereas the hydrogen‐bonding ability of the media has a slight effect on it. Nonlinear free energy relationship based on preferential solvation hypothesis showed differences between the microsphere solvation of the solute and the bulk composition of the solvents, and non‐ideal behavior is observed in the trend of the rate coefficients, which cover the LFER results. Copyright © 2011 John Wiley & Sons, Ltd. In this paper, aromatic nucleophilic substitution reaction of 1‐fluoro‐2, 4‐dinitrobenzene with para and meta substituted anilines was investigated in ethyl acetate‐methanol mixtures. Hammett's equation showed a fairly linear straight line with negative slope. Linear free energy relationship and preferential solvation models confirm solvent polarity as a major factor on the reaction rate and differences between microsphere solvation of solute and bulk composition of the solvents, respectively.