Method for purifying 1,2,4-trichlorobenzene from trichlorobenzene mixture

Abstract

The invention discloses a method for purifying 1,2,4-trichlorobenzene from a trichlorobenzene mixture, and belongs to the technical field of fine chemical engineering. The method comprises the steps that firstly, trichlorobenzene is mixed in a melt crystallization device, the temperature is lowered to 0 DEG C from room temperature, and uncrystallized mother liquid is drained; secondly, crystallized solids are sweated by increasing the temperature from 0 DEG C, wherein the sweating temperature is 0 DEG C-11 DEG C, the average temperature increasing speed is 0.025 DEG C / min-0.035 DEG C / min, and sweating does not stop until the total mass of sweat generated through sweating accounts for 1 / 9-1 / 2 of the mass of the crystallized solids in the melt crystallization device; lastly, the sweat is drained, the crystallized solids in the melt crystallization device are melted by increasing the temperature, and then 1,2,4-trichlorobenzene is obtained. According to the method, 1,2,4-trichlorobenzene is separated out in the mode of melt crystallization and gradual temperature-increasing sweating, and the advantages of being simple in method, low in cost, high in efficiency and suitable for industrialized production are achieved.

Description

technical field [0001] The invention relates to a separation and purification method, in particular to a method for purifying 1,2,4-trichlorobenzene from a mixture of trichlorobenzenes, and belongs to the technical field of fine chemicals. Background technique [0002] There are three isomers of trichlorobenzene, of which 1,2,4-trichlorobenzene is the most widely used, traditionally used as a non-flammable solvent, as a dye carrier in the textile industry, as an additive for insulating and cooling fluids in the power industry, For example, it is widely used in foreign countries as an additive for immersion liquid of power capacitors and cold-resistant transformer oil, as an additive for dielectric materials and insulating materials, etc. In addition, a variety of important pesticides, medicines and dyes can be synthesized, such as pesticides dicamba, dicamba, sodium pentachlorophenate, etc. [0003] Because the trichlorobenzene that obtains after conventional method chlorin...

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Problems solved by technology

[0005] The present invention aims to solve the problems of high cost, Low efficiency and product purity, unsuitable for industrial production and other issues, a new method for the separation and purification of 1,2,4-trichlorobenzene is proposed, and the method of melting crystallization is used to purify 1,2,4-trichlorobenzene, which has the advantages of Advantages of low energy consumption, low investment and simple operation