Toward the Efficient Synthesis of Pseudoionone from Citral in a Continuous-Flow Microreactor

Pseudoionone (PI) is a well-known and widely used precursor for ionones, which have been substantially applied in flavor, fragrance and pharmaceutical industry. The phase behavior in respect to the synthesis of PI was investigated through the combination of simulation and experiment to better understand the reaction process. A continuous-flow microreactor for efficient synthesis of PI was introduced. Various conditions (temperature, molar ratio of acetone to citral, citral concentration, NaOH concentration, residence time, and volume ratio of ethanol to water) were investigated to improve the synthesis process of PI. The condensation reaction preformed in the tubular and packed-bed microreactor under continuous-flow conditions was compared. Using a continuous-flow microreactor, PI could be efficiently synthesized from citral and a high PI yield of 93.8% could be achieved under the optimized conditions. Furthermore, a simplified kinetic model was developed to provide guidance for the synthesis of PI.