The invention relates to a method for synthesizing 4-chloro-2, 3, 5-tetramethylpiperidine by using a
microreactor. According to the method, intermediate 2, 5-dimethoxychlorobenzene of 4-chloro-2, 5-dimethoxynitrobenzene and
nitric acid are used as raw materials, 4-chloro-2, 5-dimethoxynitrobenzene is synthesized through the
microreactor, in the reaction process, the
mass fraction of
nitric acid is50%-95%, and the
mass fraction of a 2, 5-dimethoxychlorobenzene solution is 15%-50%; the feeding
molar ratio of
nitric acid to 2, 5-dimethoxychlorobenzene is (1.0-1.5): 1, the
reaction temperature is50-85 DEG C, the feeding temperature is not higher than 50 DEG C, and the reaction
retention time is 30-120 seconds. According to the method, on one hand, the
process conditions such as the materialratio and the
reaction temperature are accurately controlled, the dosage of nitric acid is reduced, the method is
environmentally friendly, the conversion rate of 2, 5-dimethoxychlorobenzene reaches 99.98%, and the yield of 4-chloro-2, 5-dimethoxynitrobenzene reaches 99.5% or above; on the other hand, the key problems of corrosivity of nitric acid, difficulty in controlling the
reaction temperature, poor
mass and
heat transfer effect, poor safety and the like in the conventional synthesis process are solved, and the reaction risk is low; strong
operability.