Kinetic studies on saponification of ethyl acetate using an innovative conductivity‐monitoring instrument with a pulsating sensor

Abstract

An innovative conductometric measurement technique using a nonconventional but high-performance (high-precision, high-resolution, rapid response features for online graphic display) in house-built pulsating conductivity monitoring instrument has been deployed to study the kinetic behavior during the reaction of ethyl acetate and NaOH. A laboratorymade constant temperature reaction bath with the facility of continuous stirring of solution for homogeneous mixing was used to carry out experiments at desired solution temperatures. Rate constants of the saponification reaction in the temperature range at various temperatures (30-55 • C) were determined, and the results were compared with the reported values. Although the reported data exhibit wide scatter, our data are in agreement with some of the literature data. From these data, thermodynamic parameters such as activation energy, activation enthalpy, activation entropy, and activation free energy have been evaluated. With the introduction of this novel conductometric measurement technique, the determination of rate constants at various solution temperatures becomes much simpler and faster. C 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: [648][649][650][651][652][653][654][655][656] 2011

Extraction of Soluble Fiber from Distillers' Grains

“…Saponification occurs when fats and oils, classified as extractives, react with sodium hydroxide to form glycerol and fatty acid salts. Saponification reactions are accelerated at higher temperatures [26], indicating that excess sodium hydroxide may be needed for the degradation of hemicellulose to SDF. Results shown in Table 2 support this theory as higher sodium hydroxide concentrations up to 2.0% produced higher recoveries of SDF.…”

Determination of the kinetics of biodiesel saponification in alcoholic hydroxide solutions

“…The aim of this section is to explain quantitatively the reduction in fatty acid alkyl esters in homogeneously alkalicatalysed biodiesel production at various reaction times and catalyst concentrations. The saponification rate of FAME in an alcoholic hydroxide solution was analysed based on bimolecular collisions of the metal hydroxide and FAME, with FAME as the limiting reactant [3,8,9].…”

“…For instance, the Arrhenius activation energies of 41.40-63.18 kJ mol À1 [3,5,6,11] for alkyl esters saponification in aqueous/protic medium were too small to account for the desolvation energy of 423.4 kJ mol À1 [9] required for the desolvation of OH À in the aqueous medium. The values of the activation energies for alky esters saponification suggest that the direct collision of desolvated OH À ions is implausible.…”

“…methanol and dichloromethane [7]. It has been reported that saponification of carboxylic acid esters in hydroxide solutions is a bimolecular reaction, which is first order for ester and hydroxide ions [3,8]. Hydroxide ions attack the carbonyl to form a tetrahedral intermediate, which then decomposes to the products (Fig.…”

“…Saponification of alkyl esters can occur in aqueous hydroxide solutions [3], mixtures of water and soluble organic solvents, such as dimethyl sulphoxide (DMSO) [4], ethanol [5,6] and mixtures of protic solvents, e.g. methanol and dichloromethane [7].…”