O-METHYLATION OF HYDROXYACETOPHENONE USING DIMETHYL CARBONATE WITH IONIC LIQUID AS A CATALYST

摘要

In this work, we have systematically studied the kinetics and mechanism of ionic-liquid-catalyzed solventless liquid-phase O-methylation of 4-hydroxyacetophenone with dimethyl carbonate (DMC). The effects of various parameters such as mass transfer resistance, catalyst loading, mole ratio, initial CO_2 pressure, and temperature were studied. The reaction was found to be pseudo zero order with respect to 4-hydroxyacetophenone and first order with respect to DMC. The values of apparent activation energy for 2-, 3-, and 4-hydroxyacetophenone were found as 30.84, 24.61, and 31.76 kcal/mol, respectively. Ionic liquid, tetrabutylphosphonium bromide, offers excellent activity, selectivity, reusability, recyclability, and stability.