2-Hydroxyethylammonium Bisulfate (2-HEAS) as a Brønsted Acidic Ionic Liquid Catalyst for Esterification

Brønsted acidic ionic liquids (BAILs) with great variety as effective catalysts for the synthesis of valuable chemicals such as esters have attracted particular attention. In this work, an ionic acid 2-hydroxyethylammonium bisulfate (2-HEAS) was successfully synthesized and used to catalyze esterification reactions. The powerful FTIR and NMR techniques were used to determine the ionic liquid properties. All results and data showed that the ionic liquid has been synthesized successfully. The catalytic activity of IL during esterification of acetic acid in the presence of various alcohols was investigated. The impacts of a few imperative parameters such as reaction time and temperature, molar ratio of acid to alcohol, and catalyst dosage were investigated. The results showed that the 2-HEAS catalyst is suitable for esterification of methanol, ethanol, and butanol. Furthermore, the esterification efficiencies of methyl acetate, ethyl acetate, and butyl acetate produced were high and quantitative. Moreover, a homogeneous catalyst was employed to separate esters from the reaction medium. Additionally, the catalyst was easily removed from products and was reusable six times.