Dichlorobenzene

The Dichlorobenzenes form in chemistry, a hydrocarbon group, consisting of a benzene ring with two chlorine atoms ( Cl - ) as substituents. Due to their different arrangement (ortho, meta or para), three constitutional isomers arise with the formula C6H4Cl2.

Representation

Benzene is reacted directly with chlorine in the presence of a Lewis acid such as iron (III ) chloride or aluminum chloride, is obtained as the main product of chlorobenzene in 80-90 % yield. O -and p- dichlorobenzenes fall in this reaction only in small quantities as by-products.

The amount of the chlorinating agent used increased significantly, larger amounts of p -dichlorobenzene, o-dichlorobenzene addition and bit m-dichlorobenzene can be obtained. Furthermore, chlorobenzene and the higher chlorinated benzenes (eg, a trichlorobenzenes ).

Properties

O- dichlorobenzene and m- dichlorobenzene are colorless oily liquids with a pungent odor; (also called Paradichlorobenzene ( PDCB ) ) p -dichlorobenzene is a solid with a strong odor. The fabric is now worldwide in the air and in water and is readily biodegradable.

Dichlorobenzenes are practically insoluble in water but soluble in organic solvents. The boiling points of the three isomers are relatively close, while they have different melting points clearer. P- dichlorobenzene, which has the highest symmetry, has the highest melting point.

Use

Dichlorobenzenes 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.

Most of the produced o- dichlorobenzene is further processed by nitration to 3,4- dinitrochlorobenzene. The substance is also used as an inert solvent in the preparation of isocyanates. The m- dichlorobenzene is used exclusively as a chemical intermediate.

For the p- dichlorobenzene ( PDCB ), which is a by- product, some very controversial areas of use were found in the past. In many toilet - stones of the material has now been replaced by alternatives. Add stones for urinals in catering but it is still used today, as it strongly, removes raspberry-like, smells like. However, the substance has no germicidal effect. Is also used in mothballs and pesticides PDCB still use.

Hazards

P- dichlorobenzene is a poorly degradable material in the environment. It is toxic to aquatic life ( class 2 ) and may therefore have long-term adverse effects. In the animal organism PDCB harmful acts by preferably liver, kidneys and lungs attacks. Also, it is irritating to skin and eyes. In more recent investigations Paradichlorobenzene to be carcinogenic ( carcinogen / carcinogenic ).