Tetrachlorobenzenes
Tetrachlorobenzenes | |||||
Surname | 1,2,3,4-tetrachlorobenzene | 1,2,3,5-tetrachlorobenzene | 1,2,4,5-tetrachlorobenzene | ||
other names | 1,2,3,4-tetrachlorobenzene 1,2,3,4-TeCB |
1,2,3,5-tetrachlorobenzene 1,2,3,5-TeCB |
1,2,4,5-tetrachlorobenzene 1,2,4,5-TeCB |
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Structural formula | |||||
CAS number | 634-66-2 | 634-90-2 | 95-94-3 | ||
PubChem | 12463 | 12468 | 7270 | ||
Molecular formula | C 6 H 2 Cl 4 | ||||
Molar mass | 215.89 g mol −1 | ||||
Physical state | firmly | ||||
Brief description | colorless crystals with a characteristic odor |
gray odorless powder |
gray odorless powder |
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Melting point | 47 ° C | 51 ° C | 139-142 ° C | ||
boiling point | 246 ° C | 246 ° C | 240-246 ° C | ||
density | 1.73 g cm −3 (20 ° C) | - | 1.86 g cm −3 (22 ° C) | ||
solubility | 28 mg l −1 (25 ° C) | very poorly soluble | 0.3 mg l −1 (22 ° C) | ||
practically insoluble in water, soluble in organic solvents | |||||
GHS labeling |
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H and P phrases | 302-410 | ||||
no EUH phrases | |||||
273 | 273-501 | 273 |
The tetrachlorobenzenes form a group of organochlorine compounds consisting of a benzene ring with four chlorine atoms (–Cl) as substituents . Their different arrangement results in three constitutional isomers with the empirical formula C 6 H 2 Cl 4 .
Extraction and presentation
Tetrachlorobenzenes are obtained by catalytic chlorination of trichlorobenzenes (e.g. with iron (III) chloride as a catalyst ).
They are also obtained as an intermediate synthesis product in the manufacture of chlorobenzenes. If the amount of chlorinating agent used is significantly increased during production, larger amounts of dichlorobenzenes can be obtained, with chlorobenzene and the more highly chlorinated benzenes such as tetrachlorobenzenes still being formed as by-products.
properties
The boiling points of the three isomers are relatively close to one another, while their melting points differ more clearly. 1,2,4,5-tetrachlorobenzene, which has the highest symmetry, has the highest melting point. The tetrachlorobenzenes are practically insoluble in water, but soluble in organic solvents.
use
1,2,3,5- and especially 1,2,4,5-tetrachlorobenzene are used as an intermediate product in the manufacture of herbicides , insecticides , defoliants and other chemical compounds such as 2,4,5-trichlorophenol (which, for example, in the Sevesounglück der Case was) used.
In addition, they are used as waterproofing agents in electrical insulation and as temporary protection in seals.
1,2,3,4-Tetrachlorobenzene serves as an intermediate product (as a mixture with the 1,2,4,5-isomer) for pentachloronitrobenzene and as a component of dielectric liquids.
safety instructions
Polychlorinated biphenyls can be formed from tetrachlorobenzenes through exposure to sunlight . When heated, the substances decompose, whereby the formation of hydrogen chloride , carbon monoxide , carbon dioxide , chlorine , phosgene , polychlorodibenzo-p-dioxins and polychlorodibenzofurans is possible. The acute oral LD 50 value is around 1500 mg / kg.
Individual evidence
- ↑ a b c d e f Entry on 1,2,3,4-tetrachlorobenzene in the GESTIS substance database of the IFA , accessed on October 14, 2012(JavaScript required) .
- ↑ a b c d e f Entry on 1,2,3,5-tetrachlorobenzene in the GESTIS substance database of the IFA , accessed on October 14, 2012(JavaScript required) .
- ↑ a b c d e f Entry on 1,2,4,5-tetrachlorobenzene in the GESTIS substance database of the IFA , accessed on October 14, 2012(JavaScript required) .
- ↑ Process for 1,2,4,5-Tetrachlorobenzene (Freepatentsonline)
- ↑ Tetrachlorobenzene (EPA) (PDF file; 8 kB)
- ↑ 1,2,4,5-tetrachlorobenzene (Enius)
- ↑ 1,2,3,5-tetrachlorobenzene (Enius)
- ↑ 1,2,3,4-tetrachlorobenzene (Enius)
- ↑ Toxicity to laboratory animals (VetPharm)
Web links
- Degradation of 1,2,4-Trichloro- and 1,2,4,5-Tetrachlorobenzene by Pseudomonas Strains
- Comparative Hepatocarcinogenicity of Hexachlorobenzene, Pentachlorobenzene, 1,2,4,5-Tetrachlorobenzene, and 1,4-Dichlorobenzene: Application of a Medium-Term Liver Focus Bioassay and Molecular and Cellular Indices
- Pathway: 1,2,4,5-tetrachlorobenzene degradation