Continuous synthesis of 4-bromo-3-methylanisole in modular microreaction system
【Abstract】With the development of microreaction technology and the key issues of liquid-liquid batch bromination process for the synthesis of 4-bromo-3-methylanisole, a modular microreaction system was constructed by taking microreactor and microbead-packed bed as the major functional microdevice units to intensify the bromination of 3-methylanisole. And in this modular microreaction system, the liquid-liquid heterogeneous continuous bromination of 4-bromo-3-methylanisole was studied. The following optimized conditions were obtained, concentration of Br217.5 wt%, molar ratio of Br2 to 3-methylanisole1.01, initial reaction temperature (T): 0 °C, residence time (τ): 0.78 min, with yield of 4-bromo-3-methylanisole more than 98%, and percentage of polybrominated side product less than 1%. Compared with the conventional batch process, the continuous microreaction technology has obvious advantages. For example, it can change the traditional batch process to a continuous one with a significant increase in productivity (space time yield: 6.5 × 104 kg/(m3·h)). Besides, since this process is mainly controlled by mass transfer, the modular microreaction system with excellent mass transfer could reduce 50% of polybrominated side product. The study might provide a good foundation for the continuously controllable synthesis of 4-bromo-3-methylanisole in safety.
【Keywords】 microreactor; static mixer; 3-methylanisole; bromination; continuous synthesis; process control;
(Translated by LIN LY)
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