Esterification of p-hydroxybenzoic acid with glucose using a γ-Al2O3/SO4 catalyst

Abstract

Esterification of p-hydroxybenzoic acid with glucose can be expected to produce esters. The rate of esterification reaction is usually very slow and, therefore, needs an acid catalyst to accelerate it. This research examined the performance of a heterogeneous catalyst made of γ-Al 2 O 3 impregnated with a protic acid, H 2 SO 4 . The heterogeneous catalyst, γ-Al 2 O 3 /SO 4 , was characterized using XRD, XRF, and BET methods. The esterification reactions were conducted using dimethyl sulfoxide (DMSO) solvent at a temperature of 100 0 C and observed after they lasted for 1 to 24 hours (reaction time). The esterification of p-hydroxybenzoic acid with glucose used two catalysts, namely 3% SO 4 2- /Al 2 O 3 and 5% SO 4 2- /Al 2 O 3 . The reaction products were analyzed using HPLC, IR, and LC-MS methods. The % yield was the highest at Hour 24 for both catalysts, while the % conversion fluctuated during the esterification time. The LC-MS showed that the three produced esters had molecular weights of 300, 420, and 540.