A Study of the Kinetics of the Esterification of Benzoic Acid with Methyl Alcohol

Abstract

The reaction between methyl alcohol and benzoic �acid to form methyl benzoate is perhaps the most fundamental of all esterification reactions. . . . The forward as well as the reverse reaction is catalyzed by protons (H+), this feature introduces complications by not allowing the reaction to approach completion from either direction. The reaction mechanism is well known and consists of nucleophilic attack of the methanol oxygen on the carbonyl carbon of the acid with the elimination of a hydrogen from the metlfanol and the hydroxy group from the benzoic acid. . . . The theory involved in this is rather straight forward. The carbonyl oxygen of the acid is very electronegative thus allowing the loosely bound electrons to be more closely associated with it. This leaves a partial positivity on the carbonyl carbon. This situation is made more acute by a proton attacking the carbonyl oxygen. The oxygen of the alcohol also has a high electron density due to its electronegativity, enabling this partial negative center to readily attack the carbonyl carbon. Thus, an intermediate is formed . . . The original hydroxy group on the acid and the proton bonded to the alcohol's oxygen leave to form water and the ester is formed. The pro:ton catalyst remains in the vicinity creating the possibility of a reverse reaction. The relative rates between the reverse and forward reactions invalving benzoic acid, methanol and methyl benzoate are the main concern of this paper. [From introductory section]