Synthesis of o-Hydroxybenzoic Acid Butyl Ester in Continuous Flow Reactor via Ultrasound Assisted Tri-Liquid Phase-Transfer Catalysis

• Main Authors: Guan-Yi Peng, 彭冠益
• Other Authors: 楊鴻銘
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/71619642902832679634

碩士 === 國立中興大學 === 化學工程學系所 === 96 === The present study is to investigate the kinetics of synthesizing o-hydroxybenzoic acid n-butyl ester in a continuous flow reactor via ultrasound-assisted tri-liquid phase-transfer catalysis. The operating parameters including agitation speeds, types of catalyst, amount of catalyst, types of solvent, reaction temperature, types of inorganic salt, amount of reactant, space time, ultrasonic frequency and power, were all performed to find the optimal reaction conditions. Sonochemistry is a technique to increase chemical reaction rate by ultrasounic irradiation. Ultrasound assisted effect can energize to promote the chemical reaction. The reactor was designed by keeping the third-liquid phase in middle part of the reactor, and both of the aqueous phase and organic phase flowing through the third-liquid phase for reaction. The yield of o-hydroxybenzoic acid n-butyl ester increases with the space time, so the flow rates of aqueous phase and organic phase were both controlled at 0.3 ml/min. Increasing the organic reactant concentration butylbromide can increae the reaction activity. The lower ultrasonic frequency makes the yield of product higher. Mass transfer resistance can be neglected by agitation speed more than 150 rpm. The mechanism and kinetics in a continuous-flow reaction were proposed, and we can calculate the kapp by the model. For high product yield and cost effective, the system condition of agitation speed at 150 rpm, catalyst tetrabutylphosphonium bromide (TBPB) at 0.0125 mol, ultrasonic frequency at 28 kHz and power 300 W, the reaction temperature at 70 ℃, the product in the organic phase was 78.8 %. The apparent activation energy can be obtained as 14.5 kcal/mol in the range of 50~80 ℃. Combining agitation and ultrasound irradiation makes the reaction activity advance a lot. The yield of product was 49.7 % without any agitation and ultrasound assisted. Under the agitation, the yield of product was 65.1% without any ultrasound assisted. The yield of product raised to 58.2 % with ultrasound promoting the reaction. Using agitation and ultrasound at the same time, the product yield was obtained 78.2 %, raising the product yield by 57.3% higher than that without any assistance of agitation and ultrasound.