1,4-Dichlorobenzene

• Paradichlorobenzene
• P-dichlorobenzene
• 1,4- dichlorobenzene

White crystalline solid with kampferartigem odor

Fixed

1.428 g · cm -3 ( 20 ° C)

53 ° C.

174 ° C.

49 mg / l in water (20 ° C)

Attention

• 2.950 mg · kg -1 ( LD50, mouse, oral)
• 500 mg · kg -1 ( LD50, rat, oral)

Template: Infobox chemical / molecular formula search available

1,4- dichlorobenzene, paradichlorobenzene called ( PDCB, p- DCB), is an aromatic chemical compound consisting of a benzene ring with two atoms of chlorine ( Cl ) as a substituent. It arises as a by-product in the production of monochlorobenzene. It is a solid with a strong odor. It belongs with his two constitutional isomers of 1,2-dichlorobenzene and 1,3- dichlorobenzene to the group of Dichlorobenzenes with the formula C6H4Cl2. The fabric is now worldwide in the air and in water and is readily biodegradable.

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. The 1,2 - and 1,4- dichlorobenzenes fall in this reaction only in small quantities as by-products.

The amount of the chlorinating agent used increased significantly, larger amounts of 1,4 -dichlorobenzene are recovered in addition to 1,2- dichlorobenzene and 1,3- dichlorobenzene little. Furthermore, the higher chlorinated benzenes (eg, a trichlorobenzenes ).

Properties

Physical Properties

1,4- dichlorobenzene at room temperature crystallizes in the monoclinic crystal system, space group P21 / a with lattice parameters a = 1480 pm, b = 399 pm, c = 578 pm, and β = 113 °. In the unit cell contains two formula units. The crystals are isomorphic to 1,4- dibromobenzene. Two other solid phases exist, the phase transitions take place at 271.77 K and 304.35 K.

The enthalpy of fusion of 1,4- dichlorobenzene is 17907 J · mol -1. The coefficients of the Antoine equation be for 1,4 -dichlorobenzene A = 4.12290, B = 1575.110 and C = -64.637.

Chemical Properties

The nitration of 1,4- dichlorobenzene to nitric acid and sulfuric acid leads first ,4- dichlorobenzene for 2-nitro- 1, subsequently a mixture of 2,6- dinitro -1 ,4- dichlorobenzene, is produced, and 2,5- dinitro- 1,4- dichlorobenzene in the ratio 7:1.

Use

For 1,4- dichlorobenzene, which is a by- product, some very controversial use areas were found in the past. In many toilet - stones of the material has now been replaced by alternatives such as sodium hydroxide or sodium carbonate. Add stones for urinals in catering but it is still used today because it strongly, removes raspberry-like, smells like. However, the substance has no germicidal effect. Therefore, in urinal odor neutralization with certain cyclodextrins or terpenes by vaporizer or atomizer would be a biologically acceptable and effective solution than with 1,4- dichlorobenzene. Is also used in mothballs ( Globolkugeln ) and pesticides as well as in the coffin Hygiene 1,4- dichlorobenzene still use.

1,4- dichlorobenzene is the starting material for the synthesis of polyphenylene sulfide ( PPS ), a high temperature resistant thermoplastic. In the reaction is the polycondensation of 1,4- dichlorobenzene with sodium sulfide, which is carried out in aprotic solvents such as N- methylpyrrolidone.

1,4- dichlorobenzene ( Globol ) was often used to ( and is still in a small area part ) is used for the disinfection of insects collections.

Hazards

1,4- dichlorobenzene is a poorly degradable material in the environment. He is very toxic to aquatic organisms ( Class 2 ) and may therefore have long-term adverse effects. In the animal organism it acts harmful by preferably liver, kidneys and lungs attacks. It also irritates skin and eyes. In recent studies, 1,4- dichlorobenzene to be carcinogenic ( carcinogen / carcinogenic ). 1,4- dichlorobenzene depolarized nerve cells and thus induces a hyperexcitability, which is comparable to organochlorine insecticides.