The enthalpy and entropy of activation for ethyl acetate saponification

Abstract

The saponification of ethyl acetate was measured by conductimetry at different temperatures within a batch reactor. A new mathematical model for obtaining concentration profiles from conductivity was presented and used for reaction-kinetics' determination. The Arrhenius parameters (A, E a ) showed good agreement with the previously published values. Basic transition-state theory was used for obtaining the Gibbs energy ( G ‡ ), the enthalpy ( H ‡ ), and the entropy ( S ‡ ) of activation. The low enthalpy of activation and negative entropy of activation were consistent with a reaction pathway when forming a transition-state complex. The suggested mechanism involves OH − , acting as a general base for removing proton from one of the hydroxide hydrating water, placed directly between it and the ester. The nucleophile from the water then attacks at the electrophilic C of the ester, breaking the π bond, and creating a tetrahedral intermediate. C

Kinetic Analysis of 4-Nitrophenol Reduction by “Water-Soluble” Palladium Nanoparticles

“…− on the surface of Pd nanoparticles to form a single activated complex [36,37]. In the case of 200 eq, we obtained a positive value, indicating an increase in achieving the transition state, which frequently signifies a dissociative mechanism in which the activated complex is loosely bound and about to dissociate.…”

“…We noticed a negative value of ΔS ‡ in the case of 150 eq, which signifies that entropy decreased as more ordered structures for the transition state were formed. This frequently indicates an associative mechanism of the adsorption of 4-nitrophenol as well as BH 4 − on the surface of Pd nanoparticles to form a single activated complex [ 36 , 37 ]. In the case of 200 eq, we obtained a positive value, indicating an increase in achieving the transition state, which frequently signifies a dissociative mechanism in which the activated complex is loosely bound and about to dissociate.…”

Kinetic Data for Continuous Processes from Liquid‐Liquid Loop Reactor Experiments

“…E a and k 0 were determined to be 43.0 kJ mol -1 and 5.92 Á 10 6 L mol -1 s -1 , respectively, in agreement to literature values. These range from 38.4 to 54.2 kJ mol -1 for E a and 8.42 Á 10 5 to 1.58 Á 10 8 L mol -1 s -1 for k 0 [6,[11][12][13]19].…”

“…(1)) is a second-order process and proportional to the product of the reactant concentrations (Eq. (2)) [5][6][7][11][12][13].…”

Transesterification Kinetics Investigation of R‐Substituted Phenyl Benzoates with 4‐Methoxyphenol in the Presence of K2CO3 in DMF

“…Acyl transfer reactions have been intensively studied due to their great importance both in biological processes and in synthetic applications . Recently, we have kinetically studied the substituent effect in a nonleaving group on the reactivity of 4‐nitrophenyl benzoates with 4‐chlorophenol and with benzenethiol in the presence of potassium carbonate in DMF .…”