What Is Trichlorobenzene?
Trichlorobenzene (TCB) is an organic compound with the molecular formula C6H3Cl3.
It is a derivative of benzene in which three of the six hydrogen atoms attached to the carbon atom of the benzene ring (tri) have been replaced with chlorine (chloro). There are three isomers with different positions of chlorine substitution: 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, and 1,3,5-trichlorobenzene.
Uses of Trichlorobenzene
Trichlorobenzene is mainly used as an intermediate raw material for dyes and pigments, pharmaceuticals and agrochemicals, and in the manufacturing of chemical products such as solvents, lubricants, and plastics.
Aromatic halogen compounds, such as trichlorobenzene, were once produced in large quantities as raw materials for chlorinated pesticides, primarily dichlorodiphenyl trichloroethane (DDT). Later, as the use of these pesticides was restricted, demand also declined. However, they are now used in herbicides and other agrochemicals.
In addition, organic compounds are highly soluble in aromatic halogens, and trichlorobenzene is widely used as a nonflammable solvent.
Properties of Trichlorobenzene
The physical properties differ depending on the isomer as follows:
1,2,3-trichlorobenzene is a white to slightly brown solid (melting point: 51-55°C, boiling point: about 220°C), 1,2,4-trichlorobenzene is a colorless liquid (melting point: 17°C, boiling point: 213°C), and 1,3,5-trichlorobenzene is a white solid (melting point: 63°C, boiling point: 208°C). The solubility of trichlorobenzene is about 0.5 mg/kg/kg.
Trichlorobenzene is insoluble in water, slightly soluble in alcohols, and readily soluble in benzene, ether, and acetone.
Trichlorobenzene is said to produce dioxins when heated at high temperatures, so care must be taken when handling it.
Other Information on Trichlorobenzene
1. Trichlorobenzene Production Process
Trichlorobenzene is obtained as a byproduct in the chlorination of benzene. When benzene is chlorinated, chlorobenzene with one chlorine substitution, dichlorobenzene with two chlorine substitutions, and trichlorobenzene with three chlorine substitutions are produced. Tetra-, tetra-, and higher order chlorides are also formed, which are separated to yield trichlorobenzene.
A method for producing 1,2,4-trichlorobenzene in high yield includes isomerization of o-dichlorobenzene (ortho-dichlorobenzene) and p-dichlorobenzene (para-dichlorobenzene) to obtain a mixture of m-chlorobenzene (meta-dichlorobenzene) of 50% or more, followed by chlorination. (meta-dichlorobenzene) mixture of 50% or more, followed by chlorination.
2. Handling and Storage of Trichlorobenzene
1,2,3-trichlorobenzene is classified as a newly designated chemical substance. There is a risk of eye irritation, digestive organ damage, and respiratory tract irritation. When burned, it decomposes to produce toxic and corrosive fumes such as hydrogen chloride. Containers should be sealed and stored in a cool, dry, well-ventilated place. Wear appropriate protective clothing, eye protection, respiratory protection, etc., and handle with care.
May cause mild skin irritation, respiratory tract irritation, drowsiness or dizziness.
Since the product decomposes when heated and generates carbon monoxide, carbon dioxide, hydrogen chloride, chlorine, etc. by combustion, keep the container closed and locked away from flames and hot surfaces in a cool, well-ventilated place. Furthermore, it reacts violently with oxidizing agents and acids, so it is important to keep it away from them. When handling, wear appropriate respiratory protection, protective gloves, protective clothing, face protection, etc., and take precautions.