Microwave mediated lipase-catalyzed synthesis of n-butyl palmitate and thermodynamic studies

Abstract Synthesis of n-butyl palmitate, a valuable cosmetic ingredient, was studied in a microwave mediated batch-type reactor. The esterification was performed using Fermase CALB™10,000, a commercial Candida antarctica lipase B, covalently immobilized on hydrophobic and macro porous polyacrylate beads in a solvent-free media. The influence of reaction parameters on the synthesis was studied, and the parameters were optimized. Equilibrium conversion of 97.1% was obtained in 25 min at 60 °C, 1:2 palmitic acid to n-butanol molar ratio, and 3% w/w enzyme loading. Thermodynamic study was used to calculate the value of enthalpy (ΔH), entropy (ΔS), Gibb's free energy (ΔG), and activation energy (Ea) for microwave, ultrasound, and conventional systems. A comparative study with other systems showed that the microwave irradiation method is more efficient and faster in synthesis of n-butyl palmitate. The lipase was reusable up to 6 cycles under microwave energy.