Synthesis of glyceryl monocaffeate using ionic liquids as catalysts

Glyceryl monocaffeate (GMC) is the hydrophilic derivative of caffeic acid (CA), which can be used in cosmetic and food industries. In this paper, GMC was prepared by the reaction of glycerol with different caffeoyl donors (CA, or ethyl caffeic (EC)). Seven functionalized ionic liquids ([PSO3HMIM]HSO4, [BSO3HMIM]TS, [BSO3HMIM]OTF, [BSO3HMIM]HSO4, [AAMIM]11504, [BSO3HMIM]HPO4 and [HMIM]HSO4) were used as catalysts. Effects of reaction variables (reaction temperature, time, pressure, catalyst load and molar ratio of substrates) on CA conversion and GMC yield were investigated. For the esterification of glycerol with CA, high CA conversion (95.6 +/- 2.1%) and GMC yield (93.8 +/- 32%) were achieved using [BSO3HMIM]TS as catalyst under the following conditions: 90 degrees C, CA/glycerol 1:10 (mol/mol), catalyst load 10% (relative to the weight of all substrates), 2 h. Activation energies (Ea) of CA conversion and GMC formation were 84.53 kJ/mol and 86.67 kJ/mol, respectively, which were lower than those (111.79, 116.24 kJ/mot) of EC as caffeoyl donor. (C) 2017 Elsevier B.V. All rights reserved.