A comparative study on formation of propionates by esterification of propionic acid with different alcohols

Abstract

The present work is a comparative study on the formation of propionates by esterification of propionic acid with three different alcohols: n-propanol, n-butanol and n-pentanol.  The study essentially comprised of investigating the effect of temperature, catalyst concentration and mole ration on the rate constant of the esterification reaction.  Three different temperatures viz., 50^oC, 60^oC and 70^oC; three mole ratios:  05, 1.0 and 1.5; and three catalyst concentrations: 1, 2 and 3 wt% were the experimental conditions employed.  Chemical analysis has been carried out using TLC, IR spectroscopy and NMR spectroscopic methods.  From these analyses it was observed that only the main reaction occurred and no side reactions were present at the experimental conditions.  It was further noticed that the reactivity of the alcohol with propionic acid was found to increase with increasing number of carbon atoms and was in the order of n-pentanol > n-butanol > n-propanol.  The effect of branching was also investigated and found that n-propanol has higher reactivity than 2-propanol.  Finally the data were subjected to least squares regression analysis and useful equations for prediction of rate constant were obtained.