Kinetic study of the homogeneous acid-catalyzed esterification of malic acid with methanol to form dimethyl malate

Abstract

<p>The dearth of literature on the esterification of dicarboxylic acids containing a hydroxyl group attached to the chain was the lodestar behind this project. Since Malic acid typifies molecules belonging to this sect of hydroxydicarboxylic acids, a synthesis and kinetic study of the liquid-phase Sulfuric acid-catalyzed Fischer esterification reaction of Malic acid with Methanol to form Dimethyl Malate are presented. The preliminary synthesis study involved adjustments of operating conditions in isothermal reactions staggered in temperatures between (80-100) ℃, at a milder catalyst concentration, and at distended reaction times to obtain a yield of the desired ester (87-91) % which was comparable to the figures obtained from previous synthesis studies. Then, using these conditions at their dialed-back states, for conducting similar reactions, a kinetic study was conducted and experimental data were extracted. Afterwards, the effect of temperature, catalyst concentration and reactant molar ratio (in an uncatalyzed regime) were investigated and the findings discussed. A kinetic model was subsequently proposed based on certain assumptions and tested for fitness through computation and regression analysis of the kinetic data. They were revealed to be good fits in most conditions under investigation and an explanation was given for the circumstance in which the model seemingly-failed. A rationalization for the failure of the model, with a basis upon which another model can be developed, were adduced therein and can be used for the design and simulation of processes such as the reactive distillation for Dimethyl Malate formation.</p>