Benzol Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
FARBLOSE FLüSSIGKEIT MIT CHARAKTERISTISCHEM GERUCH.
PHYSIKALISCHE GEFAHREN
Die Dämpfe sind schwerer als Luft und können sich am Boden ausbreiten. Fernzündung möglich. Fließen, Schütten o.ä. kann zu elektrostatischer Aufladung führen.
CHEMISCHE GEFAHREN
Reagiert heftig mit Oxidationsmitteln, Salpetersäure, Schwefelsäure und Halogenen. Feuer- und Explosionsgefahr! Greift Kunststoff und Gummi an.
ARBEITSPLATZGRENZWERTE
TLV: 0.5 ppm (als TWA); 2.5 ppm (als STEL); Hautresorption; Krebskategorie A1(bestätigte krebserzeugende Wirkung beim Menschen); BEI vorhanden (ACGIH 2005).
MAK: Hautresorption; Krebserzeugend Kategorie 1; Keimzellmutagen Kategorie 3A; (DFG 2005).
AUFNAHMEWEGE
Aufnahme in den Körper durch Inhalation, über die Haut und durch Verschlucken.
INHALATIONSGEFAHREN
Beim Verdampfen dieser Substanz bei 20 °C tritt sehr schnell eine gesundheitsschädliche Kontamination der Luft ein.
WIRKUNGEN BEI KURZZEITEXPOSITION
WIRKUNGEN BEI KURZZEITEXPOSITION: Die Substanz reizt die Augen, die Haut und die Atmungsorgane. Verschlucken kann zur Aufnahme in der Lunge führen; Gefahr der Aspirationspneumonie. Möglich sind Auswirkungen auf das zentrale Nervensystem mit nachfolgender Bewusstseinstrübung. Exposition weit oberhalb der Arbeitsplatzgrenzwerte kann zu Bewusstlosigkeit und zum Tod führen.
WIRKUNGEN NACH WIEDERHOLTER ODER LANGZEITEXPOSITION
Die Flüssigkeit entfettet die Haut. Möglich sind Auswirkungen auf Knochenmarkund Immunsystem. Führt zu Abnahme der Blutzellen. Krebserzeugend für den Menschen.
LECKAGE
Zündquellen entfernen. Ausgelaufene Flüssigkeit möglichst in abdichtbaren Behältern sammeln. Reste mit Sand oder inertem Absorptionsmittel aufnehmen und an einen sicheren Ort bringen. NICHT in die Kanalisation spülen! NICHT in die Umwelt gelangen lassen. Persönliche Schutzausrüstung: Vollschutzanzug mit umgebungsluftunabhängigem Atemschutzgerät.
R-Sätze Betriebsanweisung:
R45:Kann Krebs erzeugen.
R46:Kann vererbbare Schäden verursachen.
R11:Leichtentzündlich.
R36/38:Reizt die Augen und die Haut.
R48/23/24/25:Giftig: Gefahr ernster Gesundheitsschäden bei längerer Exposition durch Einatmen, Berührung mit der Haut und durch Verschlucken.
R65:Gesundheitsschädlich: kann beim Verschlucken Lungenschäden verursachen.
R39/23/24/25:Giftig: ernste Gefahr irreversiblen Schadens durch Einatmen, Berührung mit der Haut und durch Verschlucken.
R23/24/25:Giftig beim Einatmen, Verschlucken und Berührung mit der Haut.
S-Sätze Betriebsanweisung:
S53:Exposition vermeiden - vor Gebrauch besondere Anweisungen einholen.
S45:Bei Unfall oder Unwohlsein sofort Arzt zuziehen (wenn möglich, dieses Etikett vorzeigen).
S36/37:Bei der Arbeit geeignete Schutzhandschuhe und Schutzkleidung tragen.
Aussehen Eigenschaften
C6H6. Wasserunlösliche, farblose, charakteristisch riechende Flüssigkeit.
Gefahren für Mensch und Umwelt
Leichtentzündlich. Gefährliche Reaktionen mit starken Oxidationsmitteln oder mit Leichtmetallen in Gegenwart von Chlorkohlenwasserstoffen.
Giftig beim Einatmen, Verschlucken und bei Berührung mit der Haut. Gefahr ernster Gesundheitsschäden bei längerer Exposition.
Benzol zeigt bei akuter oder chronischer Aufnahme unterschiedliche Wirkungen: Höhere Dampfkonzentationen führen zu einer starken Depression des zentralen Nervensystems, zunächst treten jedoch Euphorie und Erregung auf. Danach folgen je nach Konzentration und Einwirkungszeit Kopfschmerzen, Schwindel, unregelmäßiges Sprechen und auch Bewußtlosigkeit. Höhere Konzentrationen sind nach kurzer Zeit tödlich. Bei rechtzeitiger Frischluftzufuhr bleiben keine Schäden zurück. Flüssiges Benzol reizt die Haut und Schleimhäute und wirkt entfettend auf die Haut. Benzol wird leicht durch die Haut aufgenommen! Bei Verschlucken folgen Magenschmerzen und bei verzögerter Entfernung auch Störungen des zentralen Nervensystems.
Die chronische Einwirkung führt nach langer, symptomfreierLatenzzeit zu Schädigungen der Blutbildungsorgane und Bildung von Krebsgewebe.
Stark wassergefährdender Stoff (WGK 3).
Schutzmaßnahmen und Verhaltensregeln
Im Abzug arbeiten! Exposition vermeiden. Von Zündquellen fernhalten. Wenn möglich, Ersatzstoffe verwenden.
Schutzhandschuhe aus Latex und Neopren sind
nicht gegen Benzol beständig (nur als sehr kurzzeitiger Spritzschutz verwendbar).
Verhalten im Gefahrfall
Kleine Spritzer im Abzug verdampfen lassen, größere Mengen mit Absorptionsmaterial (Rench-Rapid) aufnehmen und entsorgen. Dämpfe nicht einatmen. Atemschutz: Kombinationsfilter ABEK.
Brände mit CO
2-Löscher bekämpfen!
Erste Hilfe
Nach Hautkontakt: Mit viel Wasser und Seife abwaschen.
Nach Augenkontakt: Mit Wasser mindestens 15 Minuten bei geöffnetem Lidspalt ausspülen. Augenarzt!
Nach Einatmen: Frischluft. Arzt!
Nach Verschlucken: Paraffinöl verabreichen. Erbrechen vermeiden. Arzt!
Nach Kleidungskontakt: Kontaminierte Kleidung sofort ausziehen.
Ersthelfer: siehe gesonderten Anschlag
Sachgerechte Entsorgung
Als Sondermüll (halogenfreie Lösungsmittel) entsorgen.
Beschreibung
Benzene is a colorless, volatile, highly flammable liquid that is used extensively in the chemical industry and received wide interest in the early days of organic chemistry.
Because of its structure, benzene is a very stable organic compound. It does not readily undergo addition reactions. Addition reactions involving benzene require high temperature, pressure, and special catalysts. The most common reactions involving benzene involve substitution reactions. Numerous atoms and groups of atoms may replace a hydrogen atom or several hydrogen atoms in benzene. Th ree important types of substitution reactions involving benzene are alkylation, halogenation, and nitration. In alkylation, an alkyl group or groups substitute for hydrogen(s).
Chemische Eigenschaften
Benzene is a clear, volatile, colorless, highly flammable liquid with a pleasant, characteristic odor. It is an aromatic hydrocarbon that boils at 80.1 DC. Benzene is used as a solvent in many areas of industries, such as rubber and shoe manufacturing, and in the production of other important substances, such as styrene, phenol, and cyclohexane. It is essential in the manufacture of detergents, pesticides, solvents, and paint removers. It is present in fuels such as gasoline up to the level of 5%.
Physikalische Eigenschaften
Clear, colorless to light yellow watery liquid with an aromatic, musty, phenolics or gasoline-like
odor. At 40 °C, an odor threshold concentration of 190 μg/L in air was determined by Young et al.
(1996). An odor threshold of 4.68 ppm
v was determined by Leonardos et al. (1969). A detection
odor threshold concentration of 108 mg/m
3 (34 ppm
v) was reported by Punter (1983). The average
least detectable odor threshold concentrations in water at 60 °C and in air at 40 °C were 0.072 and
0.5 mg/L, respectively (Alexander et al., 1982).
Occurrence
Detectable levels of benzene have been found in a number of soft drinks that contain either a sodium or potassium benzoate preservative and ascorbic acid, and 'diet' type products containing no added sugar are reported to be particularly likely to contain benzene at detectable levels. Surveys carried out in the USA, the UK and Canada have all confirmed that a small proportion of these products may contain low levels of benzene. For example, in a survey of 86 samples analysed by the FDA between April 2006 and March 2007, only five products were found to contain benzene at concentrations above 5 ug kg-1. The levels found were in a range from approximately 10–90 ug kg-1. A survey of 150 UK-produced soft drinks by the Food Standards Agency (FSA) published in 2006 showed that four products contained benzene at levels above 10 ug kg-1, and the highest level recorded was 28 ug kg-1. However, it has been reported that higher levels may develop in these products during prolonged storage, especially if they are exposed to daylight.
Benzene may also be formed in some mango and cranberry drinks in the absence of added preservatives, because these fruits contain natural benzoates.
History
Benzene was discovered in 1825 by Michael Faraday (1791–1867), who identified it in a liquid residue from heated whale oil. Faraday called the compound bicarburet of hydrogen, and its name was later changed to benzin by Eilhardt Mitscherlich (1794–1863), who isolated the compound from benzoin (C
14H
12O
2).
Verwenden
Manufacturing of ethylbenzene (for styrene
monomer), dodecylbenzene (for detergents), cyclo-
hexane (for nylon), phenol, nitrobenzene (for ani-
line), maleic anhydride, chlorobenzene, diphenyl,
benzene hexachloride, benzene-sulfonic acid, and
as a solvent.
Vorbereitung Methode
Today benzene, which is a natural component of petroleum, is obtained from petroleum by several processes. Toluene hydrodealkylation involves mixing toluene (C
6H
5CH
3) and hydrogen in the presence of catalysts and temperatures of approximately 500°C and pressures of about 50 atmospheres to produce benzene and methane: C
6H
5CH
3 + H
2 → C
6H
6 + CH
4. Hydrodealkylation strips the methyl group from toluene to produce benzene. Toluene disproportionation involves combining toluene so that the methyl groups bond to one aromatic ring, producing benzene and xylene. Benzene can also be obtained from petroleum reforming in which temperature, pressure, and catalysts are used to convert petroleum components to benzene, which can then be extracted using solvents and distillation processes. Another source of benzene is pyrolysis gasoline or pygas.
Definition
ChEBI: Benzene is a six-carbon aromatic annulene in which each carbon atom donates one of its two 2p electrons into a delocalised pi system. A toxic, flammable liquid byproduct of coal distillation, it is used as an industrial solvent. Benzene is a carcinogen that also damages bone marrow and the central nervous system.
Reaktionen
Benzene reacts (1) with chlorine, to form (a) substitution products (one-half of the chlorine forms hydrogen chloride) such as chlorobenzene, C6H5Cl; dichlorobenzene, C6H4Cl2(1,4) and (1,2); trichlorobenzene, C6H3Cl3(1,2,4); tetrachlorobenzene (1,2,3,5); and (b) addition products, such as benzene dichloride C6H6Cl2; benzene tetrachloride, C6H6Cl4; and benzene hexachloride, C6H6Cl6. The formation of substitution products of the benzene nucleus, whether in benzene or its homologues, is favored by the presence of a catalyzer, e.g., iodine, phosphorus, iron; (2) with concentrated HNO3, to form nitrobenzene, C6H5NO2; 1,3- dinitrobenzene, C6H4(NO2)2 (1,3), 1,3,5-trinitrobenzene, C6H3(NO2)3 (1,3,5); (3) with concentrated H2SO4, to form benzene sulfonic acid, C6H5SO3H, benzene disulfonic acid, C6H4(SO3H)2(1,3), benzene trisulfonic acid, C6H3(SO3H)3 (1,3–5); (4) with methyl chloride plus anhydrous aluminum chloride (Friedel-Crafts reaction) to form toluene, monomethyl benzene, C6H5CH3; dimethyl benzene C6H4(CH3)2; trimethyl benzene, C6H3(CH3)3; (5) with acetyl chloride plus anhydrous aluminum chloride (Friedel-Crafts reaction) to form acetophenone (methylphenyl ketone), C6H5COCH3.
Allgemeine Beschreibung
Benzene appears as a clear colorless liquid with a petroleum-like odor. Flash point less than 0 °F. Less dense than water and slightly soluble in water. Hence floats on water. Vapors are heavier than air.
Air & Water Reaktionen
Highly flammable. Slightly soluble in water.
Reaktivität anzeigen
Benzene reacts vigorously with allyl chloride or other alkyl halides even at minus 70°C in the presence of ethyl aluminum dichloride or ethyl aluminum sesquichloride. Explosions have been reported [NFPA 491M 1991]. Ignites in contact with powdered chromic anhydride [Mellor 11:235 1946-47]. Incompatible with oxidizing agents such as nitric acid. Mixtures with bromine trifluoride, bromine pentafluoride, iodine pentafluoride, iodine heptafluoride and other interhalogens can ignite upon heating [Bretherick 5th ed. 1995]. Benzene and cyanogen halides yield HCl as a byproduct (Hagedorn, F. H. Gelbke, and Federal Republic of Germany. 2002. Nitriles. In Ullman Encyclopedia of Industrial Chemistry. Wiley-VCH Verlag GmbH & Co. KGaA.). The reaction of Benzene and trichloroacetonitrile evolves toxic chloroform and HCl gasses. (Hagedorn, F., H.-P. Gelbke, and Federal Republic of Germany. 2002. Nitriles. In Ullman Encyclopedia of Industrial Chemistry. Wiley-VCH Verlag GmbH & Co. KGaA.).
Hazard
The acute toxicity of benzene is low. Inhalation of benzene can cause dizziness, euphoria, giddiness, headache, nausea, drowsiness, and weakness. Benzene can cause moderate irritation to skin and severe irritation to eyes and mucous membranes. Benzene readily penetrates the skin to cause the same toxic effects as inhalation or ingestion. The chronic toxicity of benzene is significant. Exposure to benzene affects the blood and blood-forming organs such as the bone marrow, causing irreversible injury; blood disorders including anemia and leukemia may result. The symptoms of chronic benzene exposure may include fatigue, nervousness, irritability, blurred vision, and labored breathing. Benzene is regulated by OSHA as a carcinogen (Standard 1910.1028) and is listed in IARC Group 1 ("carcinogenic to humans"). This substance is classified as a "select carcinogen" under the criteria of the OSHA Laboratory Standard.
Flammability and Explosibility
Benzene is a highly flammable liquid (NFPA rating = 3), and its vapors may travel a
considerable distance to a source of ignition and "flash back." Vapor-air mixtures are
explosive above the flash point. Carbon dioxide and dry chemical extinguishers
should be used to fight benzene fires.
Chemische Reaktivität
Reactivity with Water No reaction; Reactivity with Common Materials: No reactions; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.
Industrielle Verwendung
Benzene (C6H6, CAS No. 71-43-2) is an aromatic hydrocarbon compound used extensively in the chemical industry as an intermediate in the manufacture of polymers and other products. It is also a common atmospheric contaminant and is present in motor vehicle exhaust emissions and cigarette smoke.
In 1990, it was discovered by the USA soft drinks industry that benzene could be produced at low levels in certain soft drinks containing a benzoate preservative and ascorbic acid. Since benzene is a known human carcinogen, its presence in food and beverages is clearly undesirable.
Sicherheitsprofil
Confirmed human carcinogen producing myeloid leukemia, Hodgkin's dsease, and lymphomas by inhalation. Experimental carcinogenic, neoplastigenic, and tumorigenic data. A human poison by inhalation. An experimental poison by skin contact, intraperitoneal, intravenous, and possibly other routes. Moderately toxic by ingestion and subcutaneous routes. A severe eye and moderate sktn irritant. Human systemic effects by inhalation and ingestion: blood changes, increased body temperature. Experimental teratogenic and reproductive effects. Human mutation data reported. A narcotic. In industry, inhalation is the primary route of chronic benzene poisoning. Poisoning by skin contact has been reported. Recent (1 987) research indicates that effects are seen at less than 1 ppm. Exposures needed to be reduced to 0.1 ppm before no toxic effects were observed. Elimination is chiefly through the lungs.
mögliche Exposition
Benzene is used as a constituent in
motor fuels; as a solvent for fats; inks, oils, paints, plastics,
and rubber, in the extraction of oils from seeds and
nuts; in photogravure printing. It is also used as a chemical
intermediate. By alkylation, chlorination, nitration, and
sulfonation, chemicals, such as styrene, phenols, and
malefic anhydride are produced. Benzene is also used in
the manufacture of detergents, explosives, pharmaceuticals;
in the manufacture of cyclohexane and ethylbenzene;
and dye-stuffs. Increased concern for benzene as a significant
environmental pollutant arises from public exposure
to the presence of benzene in gasoline and the increased
content in gasoline due to requirements for unleaded fuels
for automobiles equipped with catalytic exhaust
converters.
Carcinogenicity
Benzene is known to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in humans.
Environmental Fate
Benzene is released to air primarily by vaporization and combustion emissions associated with its use in gasoline. Other sources are vapors from its production and use in manufacturing other chemicals. In addition, benzene may be in industrial effluents discharged into water and accidental releases from gas and oil production, refining and distribution industries. Benzene released to soil will either evaporate very quickly or leach to groundwater. It can be biodegraded by soil and groundwater microbes. Benzene released to surface water should mostly evaporate within a few hours to a few days, depending on quantity, temperature, water turbulence, etc. Although benzene does not degrade by hydrolysis, it may be biodegraded by microbes.
Lager
work with benzene
should be conducted in a fume hood to prevent exposure by inhalation, and splash
goggles and impermeable gloves should be worn at all times to prevent eye and skin
contact. Benzene should be used only in areas free of ignition sources.
Versand/Shipping
UN1114 Benzene, Hazard Class: 3; Labels: 3—
Flammable liquid
Inkompatibilitäten
Incompatible with oxidizers (chlorates,
nitrates, peroxides, permanganates, perchlorates, chlorine,
bromine, fluorine, etc.); contact may cause fires or explosions.
Keep away from alkaline materials, strong bases,
strong acids, oxoacids, epoxides, many fluorides and perchlorates,
nitric acid.
Waste disposal
Dissolve or mix the material
with a combustible solvent and burn in a chemical incinerator
equipped with an afterburner and scrubber. All federal,
state, and local environmental regulations must be
observed. Dilution with alcohol or acetone to minimize
smoke is recommended. Bacterial degradation is also
possible.
Verordnung (Regulations)
Current USA and EU legislation does not set maximum limits for benzene in soft drinks. However, the FDA has adopted the Environmental Protection Agency (EPA) maximum contaminant level (MCL) for drinking water of 5 ppb as a quality standard for bottled water. ThisMCL has been used to evaluate the significance of benzene contamination in the soft drinks tested in surveys. The FSA has used the World Health Organization (WHO) guideline level for benzene in water of 10 mg kg-1 as a point of reference for its own survey results.
Benzol Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
1-Aziridinethanol
5-TERT-BUTYL-1H-INDOLE-2-CARBOXYLIC ACID ETHYL ESTER
1-Phenylnonan-1-on
tert-Pentylbenzol
4-Benzoylbuttersaeure
Isobutyrophenon
Ethyl-3-(4-pyridyl)-3-oxopropionat
2-Methoxyphenylisocyanat
3-Acetamido-2,4,6-triiodbenzoesure
Aminoethanolcarboxylate heptadecyl carbonate
3-THIOPHEN-2-YL-BENZALDEHYDE
2-(N-HEPTANOYL)THIOPHENE
2-Chlorphenylisocyanat
Butyl-3-mercaptopropionat
Phenylquecksilbernitrat
4-BROMO-7-CHLOROQUINOLINE
2,5-Dimethylhexin-2,5-diol
4-Methoxyphenylisocyanat
2-FLUOROPHENYL ISOCYANATE
Cyclohexylphenylketon
ISOCYANIC ACID
Isomerase, Glucose
Natrium-N-(6-chlorpyridazin-3-yl)sulfanilamidat
3-Nitrobenzoylchlorid
Pesticide synergist agent
1,3-DIMETHYL-2-(2-THIENYL)IMIDAZOLIDINE
3-Brompropiononitril
Octyl cyanoacetate
PHENYLBORON DICHLORIDE
4-Fluorphenylisocyanat
2-Nitro-4,5-xylidin
1-Bromo-1-phenyl-2-propanone
2-ACETAMIDO-5-PICOLINE
4-Amino-3-chloropyridine
Methyl-3,4,5,6-tetrahydro-7H-azepin-2-ylether
5-FORMYL-2-THIOPHENECARBOXYLIC ACID
Pyrazincarbonylchlorid
4-Fluorphenylisocyanat
2-Chloro-6-methylpyrimidin-4-ylamine
METHYL 6-(ACETYLAMINO)NICOTINATE
