Preparation method of 4-Chlorobenzotrifluoride

Abstract

The invention discloses a preparation method of the 4-Chlorobenzotrifluoride. The method includes step 1: placing the 4-Chlorobenzotrifluoride into a reaction unit, emptying air, feeding chlorine gas into the reaction unit after heating, adding an initiator suspension, and adding the initiator suspension at intervals continuously in the reaction process; and stopping feeding the chlorine gas when the content of dichlorotoluene parachlorotoluene is reduced to 0.5wt%, andemptying the chlorine gas to obtain p-chlorobenzotrichloride; and step 2: placing the p-chlorobenzotrichloride obtained through the step 1 into a reactor, adding hydrogen fluoride liquid, performing heating, starting to maintain constant pressure when the pressure reaches 2.2 MPa to 2.7 PMa, starting to maintain the constant temperature when the temperature reaches 90 DEG C to 105 DEG C, reducing the temperature and releasing the pressure when the temperature is maintained for 50 min to 60 min, adding hydrogen fluoride for a second time when the reactor is reduced to a normal temperature and normal pressure, repeating the reaction until the reaction is over, and obtaining the p-chlorobenzotrichloride. According to the preparation method of the p-chlorobenzotrichloride, product purity and product yield can be improved.

Description

technical field [0001] The invention belongs to the technical field of organic chemical industry, and in particular relates to a preparation method of p-chlorobenzotrifluoride. Background technique [0002] 4-Chlorobenzotrifluorotoluene, English name: 4-Chlorobenzotrifluoride, also known as p-chlorotrifluorobenzyl, trifluoromethyl chlorobenzene, p-chlorobenzyl trifluoride, referred to as PCBTF. p-Chlorobenzotrifluoride is an important organic synthesis intermediate, which can be used to synthesize a series of fluorine-containing pesticides, such as insecticides and herbicides. Fluorine-containing aromatic hydrocarbons can also be used to synthesize sedatives and diuretics. In addition, some fluorine-containing aromatic hydrocarbons are used in the printing and dyeing industry to make their colors bright. [0003] At present, the synthesis process of p-chlorobenzotrifluoride in China generally adopts the chlorination and fluorination method. Chlorination is the bottleneck ...

AI Technical Summary

Problems solved by technology

At present, the most commonly used method in this industry in China is the liquid-phase fluorination method. This method has the advantages of low reaction temperature, less equipment corrosion, and easy recovery of excess hydrogen fluoride. However, this reaction is a reversible reaction. When the chemical equilibrium is reached, the reaction It is not easy to carry out in depth, so it affects the product yield, and the product content is only about 90%