High-efficiency and safe synthesis of tonalid via two Friedel-Crafts reactions in continuous-flow microreactors

Tonalid, an important fragrance ingredient with widespread application, was synthesized via two Friedel-Crafts reactions, which were catalyzed by AlCl3. The traditional tonalid production was conducted in batch stirring tank reactors, suffering from low production capacity and the safety hazard of temperature runaway. To solve these problems, the continuous-flow technologies were developed for the high -efficiency and intrinsically safe synthesis of tonalid in microreactors. Catalyst AlCl3 was neatly homoge-nized in proper solvents by forming complex with reactant, which was a necessary step for the contin-uous synthesis in microreactors. Several reaction conditions, including reactant molar ratio, catalyst concentration, temperature, and microchannel hydrodynamic diameter, were investigated for the two Friedel-Crafts reactions in microreactors. At optimized conditions, the yields of the two Friedel-Crafts reactions were 44.15% and 97.55%, respectively. In comparison with the batch reactors, the reaction times of these two reactions could both be reduced by nearly two thirds in microreactors at the similar yield.(c) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.