Synthesis
In a 250mL dry three-necked flask add a certain material quantity ratio of freshly evaporated 4-chloro-3-nitrobenzaldehyde and acetic anhydride, and add a certain amount of catalyst, oscillate to make the mixture homogeneous, install a thermometer and a condenser tube (the upper end of which is connected to a calcium chloride drying tube), and stir it magnetically at a certain temperature for a certain period of time for a full reaction. At the end of the reaction, the pH was adjusted to weakly alkaline with saturated Na2CO3 solution. Then steam distillation until the distillate without oil beads, and then a small amount of activated carbon adsorption of impurities, colorless liquid, while hot, filtration, filtrate with hydrochloric acid adjusted to pH = 3 ~ 4, at this time there are a large number of white crystals precipitated. After standing for a period of time filtration, with a small amount of water to wash the crystals, drying 4-chloro-3-nitro cinnamic acid crude products, crude products with water and ethanol mixture (volume ratio of 3:1) for recrystallization, 4-chloro-3-nitro cinnamic acid yellow crystals.
