riesterification

Riesterification is a term that appears in some chemical texts to denote the esterification of carboxylic acids with alcohols to form esters, typically under acid catalysis. In contemporary practice, the process is generally called esterification, with Fischer esterification serving as the canonical example. The term may appear in older literature or as a regional variant, but it is not widely used in standard modern nomenclature.

Mechanism and scope are consistent with esterification: a proton from an acid catalyst activates the carbonyl group of the carboxylic acid, allowing nucleophilic attack by the alcohol to form a tetrahedral intermediate, followed by dehydration and deprotonation to yield the ester and water. The reaction is reversible, needing strategies to push equilibrium toward ester formation, such as removing water or using an excess of alcohol.

Common catalysts include mineral acids like sulfuric acid and organic acids such as p-toluenesulfonic acid. Conditions vary with substrates and desired rates, often employing elevated temperatures and azeotropic water removal (for example with toluene or benzene) or using non-aqueous dehydrating agents. Lewis acids can also catalyze esterification in some cases.

Applications of esterification cover a broad range, including the synthesis of biodiesel via fatty acid esters, fragrance and flavor esters, and precursors for polymer synthesis (polyesters). Substrate scope spans simple aliphatic and aromatic carboxylic acids and a wide range of alcohols, though steric hindrance and reversibility can limit yields.

See also: esterification, Fischer esterification, transesterification. Notes: riesterification is not a standard term in modern chemical nomenclature, and many texts use esterification as the preferred label.