Trichlorobenzene

The trichlorobenzenes form in chemistry, a hydrocarbon group, consisting of a benzene ring with three chlorine atoms ( Cl - ) as substituents. Due to their different arrangement of three structural isomers with molecular formula C6H3Cl3 result.

Production and representation

Trichlorobenzenes be obtained by catalytic chlorination of dichlorbenzenes.

They fall in large quantities as an intermediate of synthesis. Benzene is reacted directly with chlorine in the presence of a Lewis acid such as iron (III ) chloride or aluminum chloride, as is obtained as the main product of chlorobenzene in 80-90 % yield. Trichlorobenzenes fall in this reaction only in small quantities as by-products. However, the amount of the chlorinating agent used increased significantly, larger amounts can be obtained dichlorobenzenes, wherein continue chlorobenzene and the higher chlorinated benzenes eg. trichlorobenzenes formed as by- product.

Properties

The boiling points of the three isomers are relatively close, while they have different melting points clearer. The 1,3,5 -trichlorobenzene, which has the highest symmetry, has the highest melting point. The trichlorobenzenes are practically insoluble in water, soluble in organic solvents.

Use

Trichlorobenzenes are increasingly being employed as starting materials and intermediates for pharmaceuticals, pesticides, dyes and pesticides. They serve as a solvent for paints, rubber, waxes, resins and disinfectants.

1,2,3- trichlorobenzene is used as a herbicide.

1,2,4-trichlorobenzene is used as the heat transfer agent, termite poison solvent in the processing of polyester fibers, additives in oils and lubricants, and as intermediates in the preparation of herbicides. The former use as a dielectric in transformers was stopped due to the formation of highly toxic polychlorinated dioxins and dibenzofurans.

1,3,5 -trichlorobenzene is used as a termite controlling agent and coolant. It is still included in electrical insulators and transformer oil.

Safety

The MAK Commission for 1,2,3 - set a value of 5 or 38 mg/m3 ml/m3 and 1,3,5 -trichlorobenzene. 1,2,4- trichlorobenzene as carcinogen category 3B ( Substances that cause for concern because of its demonstrated / possible carcinogenic effect ) classified. The vapors of 1,3,5 -trichlorobenzene may form an explosive mixture with air when the substance is heated above its flash point. 1,2,3 - and 1,2,4 -trichlorobenzene are very toxic to aquatic organisms.

In general, the compounds decompose in the heat, with phosgene and hydrogen chloride are free.