| Summary: | 碩士 === 國立中興大學 === 化學工程學系所 === 99 === The use of immobilized lipase from Candida antarctica (Novozym® 435) to catalyze synthesis of 4′-O-acetyl resveratrol from resveratrol and vinyl acetate was investigated in this study. Response surface methodology and five-level-four-factor central composite rotatable design were adopted to evaluate the effects of synthesis variables, including reaction time (24-72 h), temperature (25-65 °C), substrate molar ratio (1:15-1:75; RV:VA), and enzyme amount (600-3000 PLU) on the percentage molar conversion of 4′-O-acetyl resveratrol. The results showed that reaction temperature and enzyme amount were the most important parameters on percent molar conversion. Based on ridge max analysis, the optimum conditions for synthesis were: reaction time 60 h, reaction temperature 64 oC, substrate molar ratio 1:56 and enzyme amount 2293 PLU. The molar conversions of predicted and actual experimental values were 103% and 95%, respectively.
In the second part, ultrasonication provided a very effective mixing in the reaction solution due to cavitations in the liquid medium. The 3-level-3-variables Box-Behnken design was adopted to evaluate the effects of synthesis variables, and the optimum conditions were as follows: reaction time 10.78 h, enzyme amount 5492 PLU, and ultrasonic power 147.8 W. The molar conversions of predicted and actual experimental values were 96% and 95%, respectively.
The reaction kinetic was agreed with Ping-Pong mechanism, and the kinetic constants of the shaker and ultrasonic system were studied. Vmax obtained were 10.58 mM for shaker system and 41.84 mM for ultrasonic system; According to our results, we found using ultrasound could accelerate synthesis 4′-O-acetyl resveratrol.
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