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

Abstract

Aromatic nucleophilic substitution reaction of 1-fluoro-2,4-dinitrobenzene with para-substituted and metasubstituted 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. a Standard deviation. b Intercept of the single or multiparameter correlation. c e, a, and b are the coefficients of E N T , α, and β, respectively. ETHYL ACETATE-METHANOL MIXTURES

Deep eutectic solvent as an operative media on structure‐reactivity relationships

“…The reaction kinetics was studied under pseudo–first‐order condition. The pseudo–first‐order and the second‐order rate coefficients were obtained from the absorbance values of product at t and infinity according to the procedure reported elsewhere Figure S2. in the Supporting Information shows a representative outcome of the rate coefficient from experimental data.…”

“…Solvents might also influence the selectivity in the reactions and the position and intensity of spectral absorption bands of molecules as a solute . The effects of both the molecular structure of reactants and solvent on the rate of the aromatic reactions in different binary solvent compositions have been explained using Hammett's equation . These two effects can also be investigated to find a probable correlation among discrete properties.…”

Nucleophilic Aromatic Substitution

“…Fluoronitrobenzenes readily undergo solvolysis to give nitroanilines, while reaction with oxygen and sulfur nucleophiles gives the corresponding substitution products with little competing solvolysis product. 10 There has also been an examination of the solvent effects on the rate of reaction of 1-chloro-4-substituted-2,6-dinitrobenzenes with substituted benzylamines in methanol/acetonitrile mixtures. 8 A kinetic study of the reaction of the aromatic triflone (6) with substituted anilines in methanol shows that nucleophilic attack is rate limiting.…”

“…18 There has also been an investigation of the effects of hydrogen bonding on alkoxydefluorination reactions. DFT studies 20 suggest that the intermediate is stabilized by hydrogen bonding to a water molecule as shown in (10). DFT studies 20 suggest that the intermediate is stabilized by hydrogen bonding to a water molecule as shown in (10).…”

Nucleophilic Substitution Reactions of 2,4-Dinitrobenzene Derivatives with Hydrazine: Leaving Group and Solvent Effects

“…Therefore, the leaving group can determine reactivity in nucleophilic substitution in aromatic system. This has fostered the illusion that the leaving group ability depends upon the pK a of the conjugate acid of the leaving group and will affect the rate of reaction if the leaving group is involved in the rate-determining step (Paghaleh, Harifi-Mood, & Gholami, 2011;Crampton, Emokape, & Isanbor, 2007;Crampton, Emokape, Howard, Isanbor, & Mondal, 2004;Crampton, Emokpae, Howard, & Isanbor, 2004;Annulli, Mencareli, & Stegel, 1983;Stirling, 1979). In fact, several years ago, Bunnett, Garbisch, and Pruitt (1957) strongly supported the hypothesis of a two-step pathway for nucleophilic aromatic substitution, using as a criterion the so-called "element-effect" i.e., the variation in the rate of substitution as a leaving group is varied.…”