Continuous production method and continuous production equipment for 3, 4-dichloro-trifluorotoluene

Abstract

The invention discloses a continuous production method and continuous production equipment for 3, 4-dichloro-trifluorotoluene. The production method comprises the steps that, chlorine and p-chloro-trifluorotoluene are used as raw materials for multi-stage continuous reaction, and the p-chloro-trifluorotoluene enters from the top of a first-stage tubular reactor; the chlorine enters from the bottomof a tubular reactor of each stage for countercurrent reaction; materials in the tubular reactor of each stage overflow from the bottom of the tubular reactor into a tubular reactor of next stage forcontinuous countercurrent reaction with the chlorine entering from the bottom of the tubular reactor; and the multi-stage continuous reaction adopts a step-by-step gradient cooling reaction mode. Theproduction equipment comprises multi-stage tubular reactors which are connected in series, wherein the multi-stage tubular reactors connected in series are arranged in a ladder shape with certain height differences; and an overflow pipeline is arranged between the bottom of an upper-stage tubular reactor and the top of a lower-stage tubular reactor. According to the production method and production equipment, continuous production can be achieved, moreover, reaction energy consumption is reduced, the reaction effect is good, reaction with less byproduct, and the product yield is high.

Description

technical field [0001] The invention relates to the technical field of organic chemical industry and specifically designs a continuous production technology of 3,4-dichlorobenzotrifluoride. Background technique [0002] 3,4 Dichlorotrifluorotoluene is a colorless and transparent liquid with an odor of halogenated benzene, insoluble in water, and miscible with benzene, toluene, ethanol, ether, and halogenated hydrocarbons. The fluorine atom in the molecular structure of 3,4-dichlorotrifluorotoluene makes it have special activity. It is an important pesticide and pharmaceutical intermediate. It can be used as an intermediate for the insecticide fipronil and for the synthesis of diphenyl ether It is an intermediate of fluorine-containing herbicides, and is widely used in fine organic synthesis fields such as medicine, pesticides, and dyes. [0003] The synthesis of 3,4-dichlorobenzotrifluoride can use toluene as a starting material to obtain p-chlorotoluene or 3,4-dichlorotolu...

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Problems solved by technology

[0008] CN102746108A discloses the "preparation method of 3,4-dichlorobenzotrifluoride", which uses p-chlorobenzotrifluoride and chlorine as raw materials, and uses iron powder and ferric chloride as catalysts to perform chlorination to prepare 3,4- Dichlorobenzotrifluoride, due to the unrestricted source of raw materials, this method is the main preparation method of 3,4-dichlorobenzotrifluoride at present, but this method is also a batch process method, which has the problems of high energy consumption and serious pollution

The batch method uses a tank reactor with mechanical agitation. The residence time of the materials in the reactor is the same, the concentration of the materials in the tank is uniform, and the temperature is easy to control. In the continuous synthesis method, the residence time of the materials in the reactor is not uniform. And a small part of the material has a long residence time, and the chlorine concentration and high temperature will easily lead to an increase in the impurity content

[0013] In summary, the current synthesis of 3,4-dichlorotrifluorotoluene can only use a batch production process, which cannot overcome the technical problems of continuous production, resulting in the continuous production process not being industrialized

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