The synthesis of carboxylic esters is one of the most fundamental and important processes for producing useful compounds in organic chemistry. The classical esterification reaction is condensation of a carboxylic acid and an alcohol under acidic conditions. This is an equilibrium reaction, and in order to effectively generate the ester, the equilibrium need to be shift toward the ester. To achieve this equilibrium shift requires adding one of the substrates in large excess and the removal of the generated water by distillation. However, when both carboxylic acid and alcohol are expensive and not easily available, it is not economical to use one of the substrates in large excess. Thus the classical esterification method is not the best method to use in such a case. Furthermore, when the substrate is unstable to heat, the classical method does not always yield the desired results.
Since esterification is a basic reaction that is applied to many different types of substrates, there is a need for alternative methods which proceed under mild conditions without the need for using large excess of one of the substrates. Over the years, there has been much research done by many chemists, and many useful methods have been reported.