As an intermediate of heat-sensitive dye ODB-2 (2-anilino-6-dibutylamino-3-methylfluoran), 4-bromide-3-methyl anisole was synthesized with a continuous flow reaction system, which contained two reactions and one purification step. The whole process started from 3-methyl phenol sodium, and 3-methyl anisole was firstly synthesized by using dimethyl sulfate as the methylation reagent. As a classical phase transfer reaction, a local constrictive tubular reactor was designed to enhance the mixing of phenol sodium aqueous solution and dimethyl sulfate, which created emulsified liquid-liquid two phases. The reaction was successfully operated under adiabatic reaction condition (from 25 to 85 °C), which was benefit for simplifying the scale-up of the reactor. After phase separation of the reaction products, the organic phase was purified by washing with NaOH solution, and &gt;99.5% 3-methyl anisole was obtained. The 3-methyl anisole then reacted with Br<sub>2</sub>/HBr aqueous solution in the second packed bed reactor that operated at 0-5°C, and 96% yield of 4-bromide-3-methyl anisole was obtained in the organic phase product.

Synthesis of 4-bromide-3-methyl anisole with a continuous flow reaction system

256th National Meeting (2018)

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