| Identification | More | [Name]
Benzene | [CAS]
71-43-2 | [Synonyms]
PHENE
BENZOL
Benzen
Fenzen
Benzole
Benzolo
Benzeen
BENZENE
benzol90
BenzeneI
Annulene
ai3-00808
Benzolene
carbonoil
NSC 67315
BenzeneGr
Carbon oil
NCI-C55276
polystream
Pyrobenzol
BENZENE GC
c.?benzene.
Coalnaphtha
(6)annulene
[6]Annulene
PYROBENZOLE
BENZENE 300
BENZENE 5000
BENZENE, ACS
benzin(obs.)
caswellno077
Coal naphtha
BENZENE 99+%
Pure benzene
mixed benzene
Benzene, HPLC
Benzene 99.8%
fenzen(czech)
benzine(obs.)
benzen(polish)
mineralnaphtha
PHENYL HYDRIDE
BENZENE, REAG.
Benzene (I, T)
benzeen,benzen
BENZENE AR/ACS
Benzene, GR ACS
CYCLOHEXATRIENE
BENZENE OEKANAL
Mineral naphtha
Benzene, Reagent
BENZENE,PURIFIED
benzene solution
BENZENE,OMNISOLV
Benzene,AR,99.5%
Benzene, GR 99%+
Benzene AR 2.5LT
Benzene AR 500ML
Benzene, ACS min
Benzene Standard
Benzol Benzolene
BENZENE,PESTISOLV
AKOS BBS-00004227
anhydrous benzene
Benzene, SuperDry
Nitration benzene
Benzol,HPLC Grade
BENZENE, FOR HPLC
BENZENE EXTRA PURE
BENZENE HPLC GRADE
benzene, anhydrous
Benzene 〈H2O<30ppm〉
BENZENE,SPECTROSOLV
BENZENE EMPLURA 1 L
BENZENE GC STANDARD
rcrawastenumberu019
Benzene, OMniSolv(R)
bicarburetofhydrogen
BENZENE extrapure AR
Biperiden Impurity F
Benzene,ACS,99.0%min
Benzene GC-HS, 99.9%
Benzene 5g [71-43-2]
Benzene 1g [71-43-2]
Benzene/METHYLBENZENE
BENZENE REAGENT (ACS)
1,3,5-cyclohexatriene
Benzene (Pure Benzol)
BENZENE EMPLURA 2,5 L
Benzene, PestiSolv(R)
benzene(asimpurityonly
Bicarburet of hydrogen
Rcra waste number U019
cyclohexa-1,3,5-triene
Benzene for HPLC, 99%+
Benzene,GCS,≥99.9%(GC)
Biperiden EP Impurity F
Benzene extrapure 2.5LT
Benzene extrapure 500ML
Benzene,nitration grade
Benzene-Toluene solution
Benzene, synthesis grade
BENZENE ELECTRONIC GRADE
Hsr(HeavyNaptha9Benzene)
BenzeneForUvSpectroscopy
BENZENE, STANDARD FOR GC
BENZENE (UV-IR-HPLC-GPC)
Benzene standard solution
BENZENE, ANHYDROUS, 99.8%
Benzene, for spectroscopy
Benzene, HPLC, 99.5% min.
Benzene, anhydrous, 99,5%
Benzene for HPLC, >=99.9%
Benzene, 99.7%, HPLC grade
Benzene,coking by-products
Benzene, HPLC Grade, 99.5%
Benzene,Thiophene-FreeA.R.
Benzene, SuperDry, J&KSeal
BENZENE, FREE OF THIOPHENE
BENZENE PURIFICATION GRADE
BENZENE, 99.9+%, HPLC GRADE
BenzenePure(Crystallizable)
BENZENE scintillation grade
Benzene ISO 9001：2015 REACH
Benzene extrapure AR, 99.7%
BenzeneSolution,200mg/L,1ml
BenzeneSolution,100mg/L,1ml
BENZENE MOS ELECTRONIC GRADE
Benzene [Sequencing Solvent]
BENZENE 99% A.C.S. REAGENT
BENZENE, ACS REAGENT, >=99.0%
Benzene in dimethyl sulfoxide
Benzene [Sequenation Solvent]
BenzeneSolution,5,000mg/L,1ml
BenzeneSolution,2,000mg/L,1ml
Benzene[SequenationSolvent]>
Benzene for spectroscopy, 99%+
BENZENE, 1X1ML, MEOH, 200UG/ML
epapesticidechemicalcode008801
BENZENE, 1X1ML, MEOH, 5000UG/ML
BENZENE FOR ANALYSIS EMSURE 1 L
Isopropyl alcohol EP Impurity B
BenzeneSolution,5,000mg/L,2x5ml
Benzene [for SpectrophotoMetry]
Benzene[forSpectrophotometry]>
BENZENE FOR ANALYSIS EMSURE 25 L
Benzene, 99.5%, analytical grade
Benzene, 99.5%, for spectroscopy
Benzene, reagent grade, ACS, ISO
BENZENE IN METHANOL NIST STANDARD
benzene, spectrophotometric grade
BENZENE DRIED (MAX. 0,01% H2O) GR
BENZENE, ACS, FOR UV-SPECTROSCOPY
BENZENE-12C6 (13C-DEPLETED) 99.9%
Residual Solvent Class 1 - Benzene
Benzene Dried, 99.7%, water 0.005%
BENZENE For HPLC & UV Spectroscopy
Benzene scintillation grade, 99.9%
BENZENE-ISOBUTANOL SOLVENT, SOLUTION
Benzene extrapure (Sulphur free), 99%
Benzene, spectrophotometric grade,99+%
N-alpha,Nim-Bis-Boc-D-histidine·
BENZENE FOR PROTEIN SEQUENCE ANALYSIS
Benzene, spectroscopy grade, Spectrosol
BENZENE >=99.0% A.C.S. REAGENT (SAFET&
BENZENE REFERENCE SUBSTANCE FOR GAS CHRO
Benzene, anhydrous, with molecular sieves
Benzene, Spectrophotometric Grade, 99.5+%
Benzene for HPLC & UV Spectroscopy, 99.8%
BenzeneSolution,50mg/L,1ml(ForbiddenByAir)
BENZENE, REAGENTPLUS, THIOPHENE FREE, >=99%
BENZENE, ACS REAGENT, >=99%, THIOPHENE-FREE
Benzene( 99%, HyDry, Water≤50 ppm (by K.F.))
Benzene puriss. p.a., Reag. Ph. Eur., >=99.7%
Benzene ReagentPlus(R), thiophene free, >=99%
BENZENE, FOR LIQUID SCINTILLATION, NORMASCINT
Benzene, dried (max. 0,01% H2O), reagent grade
Benzene, 99.7%, SuperDry, water≤20 ppm, J&KSeal
BENZENE, 99+%, A.C.S. SPECTROPHOTOMETRIC GRADE
Benzol
Phenyl hydride
Cyclohexatriene
Coalnaphtha
Benzene (1mg/ml in Methanol) [for Water Analysis]
Standard substance for purity analysis of benzene
Benzene, Exceeds A.C.S. Specifications, HPLC Grade
Benzene, Anhydrous, SeptuM-Sealed Bottle, DriSolv(R)
BENZENE, ABSOLUTE, OVER MOLECULAR SIEVE (H2O <0.005%)
Benzene, 99%, SpcDry, Water≤50 ppM (by K.F.), SpcSeal
Benzene extrapure AR, ACS, ExiPlus, Multi-Compendial, 99.7%
BENZENE R. G., REAG. ACS, REAG. ISO,REAG . PH. EUR., unpaid duty
Benzene, Meets or Exceeds A.C.S. Specifications, SpectroSolv (TM)
Benzene( 99%, HyDry, with molecular sieves, Water≤50 ppm (by K.F.))
Benzene, anhydrous, 99.8%, packaged under Argon in resealable ChemSeal bottles
Benzene, anhydrous, 99.8%, packaged under Argon in resealable ChemSealTM bottles
Benzene, anhydrous, 99.8%, packaged under Argon in resealable ChemSeal^t bottles
Benzene, anhydrous, 99.9%, Active Dry, packaged under Argon in resealable CheMSeal bottles | [EINECS(EC#)]
200-753-7 | [Molecular Formula]
C6H6 | [MDL Number]
MFCD00003009 | [Molecular Weight]
78.11 | [MOL File]
71-43-2.mol |
| Chemical Properties | Back Directory | [Appearance]
Benzene is a clear, volatile, colorless, highly
flammable liquid with a pleasant, characteristic odor. | [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. | [Melting point ]
5.5 °C (lit.) | [Boiling point ]
80 °C (lit.) | [density ]
0.874 g/mL at 25 °C(lit.)
| [vapor density ]
2.77 (vs air)
| [vapor pressure ]
166 mm Hg ( 37.7 °C)
| [refractive index ]
n20/D 1.501(lit.)
| [Fp ]
12 °F
| [storage temp. ]
0-6°C
| [solubility ]
Miscible with alcohol, chloroform, dichloromethane, diethyl ether, acetone and acetic acid. | [form ]
Liquid | [pka]
43(at 25℃) | [color ]
APHA: ≤10 | [Odor]
Paint-thinner-like odor detectable at 12 ppm | [Relative polarity]
0.111 | [Stability:]
Stable. Substances to be avoided include strong oxidizing agents, sulfuric acid, nitric acid, halogens. Highly flammable. | [explosive limit]
1.4-8.0%(V) | [Odor Threshold]
2.7ppm | [Water Solubility ]
0.18 g/100 mL | [λmax]
λ: 280 nm Amax: 1.0
λ: 290 nm Amax: 0.15
λ: 300 nm Amax: 0.06
λ: 330 nm Amax: 0.02
λ: 350-400 nm Amax: 0.01 | [Merck ]
14,1066 | [BRN ]
969212 | [Henry's Law Constant]
10.4 at 45.00 °C, 11.4 at 50.00 °C, 13.3 at 55.00 °C, 14.5 at 60.00 °C, 16.8 at 65.00 °C, 19.2 at
70.00 °C (static headspace-GC, Park et al., 2004) | [Dielectric constant]
2.3（20℃） | [Exposure limits]
TLV-TWA 10 ppm (～32 mg/m3) (ACGIH
and OSHA); ceiling 25 ppm (～80 mg/m3)
(OSHA and MSHA); peak 50 ppm (～160
mg/m3)/10 min/8 h (OSHA); carcinogenicity:
Suspected Human Carcinogen (ACGIH),
Human Sufficient Evidence (IARC). | [InChIKey]
UHOVQNZJYSORNB-UHFFFAOYSA-N | [LogP]
2.130 | [Uses]
Benzene is also known as benzol, benzole, coal tar naphtha, and phenyl
hydride, benzene is a clear, colorless, flammable liquid made by
passing coke gas through oil, which is then distilled to produce
benzene and toluol. The benzene is separated from the toluol
by fractional distillation. Benzene is soluble in alcohol, ether,
chloroform, and glacial acetic acid, but it is insoluble in water.
Benzene was used as a solvent for many photographic operations
in the 19th century. In the collodion process, benzene
was used to dissolve rubber to both subcoat and supercoat
negatives. It was also used as a solvent for Canada balsam in
the Cutting method of sealing ambrotypes and cementing lens
elements. Benzene was also used as a solvent for wax, gums,
resins, and amber and in particular for retouching varnishes
applied to silver bromide gelatin negatives. | [CAS DataBase Reference]
71-43-2(CAS DataBase Reference) | [IARC]
1 (Vol. 29, Sup 7. 100F, 120) 2018 | [NIST Chemistry Reference]
Benzene(71-43-2) | [EPA Substance Registry System]
71-43-2(EPA Substance) |
| Hazard Information | Back Directory | [Chemical Properties]
Benzene is a colorless, flammable liquid with a pleasant odor. It 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%. | [General Description]
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. | [Reactivity Profile]
BENZENE(71-43-2) 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(71-43-2) 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(71-43-2) 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.). | [Air & Water Reactions]
Highly flammable. Slightly soluble in water. | [Hazard]
A confirmed carcinogen. Highly toxic.
Flammable, dangerous fire risk. Explosive limits
in air 1.5 to 8% by volume.
| [Health Hazard]
Dizziness, excitation, pallor, followed by flushing, weakness, headache, breathlessness, chest constriction, nausea, and vomiting. Coma and possible death. | [Health Hazard]
Exposure to low concentrations of benzene vapor or liquid causes dizziness, lightheadedness, headache, loss of appetite, stomach upset, and irritation to the nose and throat.
Prolonged exposure to high concentrations of benzene leads to functional irregularities in
the heart beat and in severe cases to death. Benzene is a known carcinogen to humans. It
causes leukemia and blood disorders such as aplastic anemia. The major types of leukemia
related to benzene exposure are (i) acute myelogenous leukemia (AML); (ii) acute lymphocytic leukemia (ALL); (iii) chronic myelogenous leukemia, also called chronic myeloid leukemia (CML); (iv) chronic lymphocytic leukemia (CLL), and hairy cell leukemia (HCL).
Occupational exposure to benzene is frequent, such as in road-tanker drivers and Chinese
glueand shoe-making factory workers. Exposure to benzene has been linked with the
development of rarer forms of leukemia, such as AML and ALL. It has also been linked to
lymphoma and rare blood diseases | [Potential Exposure]
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. | [Fire Hazard]
Behavior in Fire: Vapor is heavier than air and may travel considerable distance to a source of ignition and flash back. | [First aid]
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek medical attention immediately.
If this chemical has been inhaled, remove from exposure,
begin rescue breathing (using universal precautions, including
resuscitation mask) if breathing has stopped and CPR if
heart action has stopped. Transfer promptly to a medical
facility. When this chemical has been swallowed, rinse
mouth, get medical attention. Do not induce vomiting. | [Shipping]
UN1114 Benzene, Hazard Class: 3; Labels: 3—
Flammable liquid | [Incompatibilities]
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. | [Description]
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).
| [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. | [Physical properties]
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 ppmv was determined by Leonardos et al. (1969). A detection
odor threshold concentration of 108 mg/m3 (34 ppmv) 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). | [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 (C14H12O2). | [Definition]
ChEBI: 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. | [Production Methods]
Today benzene, which is a natural component of petroleum, is obtained from petroleum by several processes. Toluene hydrodealkylation involves mixing toluene (C6H5CH3) and hydrogen in the presence of catalysts and temperatures of approximately 500°C and pressures of about 50 atmospheres to produce benzene and methane: C6H5CH3 + H2 → C6H6 + CH4. 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. | [Reactions]
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. | [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. | [Chemical Reactivity]
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. | [Industrial uses]
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. | [Biochem/physiol Actions]
Environmental carcinogen; hematoxin that is linked to increased incidence of leukemia in humans. | [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. | [storage]
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. | [Purification Methods]
For most purposes, *benzene can be purified sufficiently by shaking with conc H2SO4 until free from thiophene, then with H2O, dilute NaOH and water, followed by drying (with P2O5, sodium, LiAlH4, CaH2, 4X Linde molecular sieve, or CaSO4, or by passage through a column of silica gel, and for a preliminary drying, CaCl2 is suitable), and distillation. A further purification step to remove thiophene, acetic acid and propionic acid, is crystallisation by partial freezing. The usual contaminants in dry thiophene-free *benzene are non-benzenoid hydrocarbons such as cyclohexane, methylcyclohexane, and heptanes, together with naphthenic hydrocarbons and traces of toluene. Carbonyl-containing impurities can be removed by percolation through a Celite column impregnated with 2,4-dinitrophenylhydrazine, phosphoric acid and H2O. (Prepared by dissolving 0.5g DNPH in 6mL of 85% H3PO4 by grinding together, then adding and mixing 4mL of distilled H2O and 10g Celite.) [Schwartz & Parker Anal Chem 33 1396 1961.] *Benzene has been freed from thiophene by refluxing with 10% (w/v) of Raney nickel for 15minutes, after which the nickel is removed by filtration or centrifugation. Dry *benzene is obtained by doubly distilling high purity *benzene from a solution containing the blue ketyl formed by the reaction of sodium-potassium alloy with a small amount of benzophenone. Thiophene has been removed from *benzene (absence of bluish-green coloration when 3mL of *benzene is shaken with a solution of 10mg of isatin in 10mL of conc H2SO4) by refluxing the *benzene (1.25L) for several hours with 40g HgO (freshly precipitated) dissolved in 40mL glacial acetic acid and 300mL of water. The precipitate is filtered off, the aqueous phase is removed and the *benzene is washed twice with H2O, dried and distilled. Alternatively, *benzene dried with CaCl2 has been shaken vigorously for 0.5hour with anhydrous AlCl3 (12g/L) at 25-35o, then decanted, washed with 10% NaOH, and water, dried and distilled. The process is repeated, giving thiophene-free *benzene. [Holmes & Beeman Ind Eng Chem 26 172 1934.] After shaking successively for about an hour with conc H2SO4, distilled water (twice), 6M NaOH, and distilled water (twice), *benzene is distilled through a 3-ft glass column to remove most of the water. Absolute EtOH is added and the *benzene-alcohol azeotrope is distilled. (This low-boiling distillation leaves any non-azeotrope-forming impurities behind.) The middle fraction is shaken with distilled water to remove EtOH, and again redistilled. Final slow and very careful fractional distillation from sodium, then LiAlH4 under N2, removed traces of water and peroxides. [Peebles et al. J Am Chem Soc 82 2780 1960.] *Benzene liquid and vapour are very TOXIC and HIGHLY FLAMMABLE, and all operations should be carried out in an efficient fume cupboard and in the absence of naked flames in the vicinity. [Beilstein 5 H 175, 5 I 95, 5 II 119, 5 III 469.] Rapid purification: To dry benzene, alumina, CaH2 or 4A molecular sieves (3% w/v) may be used (dry for 6hours). Then benzene is distilled, discarding the first 5% of distillate, and stored over molecular sieves (3A, 4A) or Na wire. | [Toxicity evaluation]
Benzene enters the air, water, and soil as a result of industrial
processes, emissions from burning coal and oil, tobacco
smoke, gasoline exhaust, and gasoline leaks, and from natural
sources, including volcanoes and forest fires. Benzene in the
atmosphere chemically degrades in only a few days. Benzene
released to soil or waterways is subject to volatilization,
photooxidation, and biodegradation. Benzene has a short halflife
in surface water because it is so volatile. | [Toxics Screening Level]
The acute initial threshold screening level (ITSL) for benzene (CAS # 71-43-2) is 30 μg/m3 based on a 24-hour averaging time. | [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. |
| Safety Data | Back Directory | [Hazard Codes ]
F,T | [Risk Statements ]
R45:May cause cancer.
R11:Highly Flammable.
R36/38:Irritating to eyes and skin .
R48/23/24/25:Toxic: danger of serious damage to health by prolonged exposure through inhalation, in contact with skin and if swallowed .
R65:Harmful: May cause lung damage if swallowed.
R39/23/24/25:Toxic: danger of very serious irreversible effects through inhalation, in contact with skin and if swallowed .
R23/24/25:Toxic by inhalation, in contact with skin and if swallowed . | [Safety Statements ]
S53:Avoid exposure-obtain special instruction before use .
S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) .
S36/37:Wear suitable protective clothing and gloves . | [OEB]
E | [OEL]
TWA: 0.1 ppm, STEL: 1 ppm | [RIDADR ]
UN 1114 3/PG 2
| [WGK Germany ]
3
| [RTECS ]
CY1400000
| [F ]
3-10 | [Autoignition Temperature]
560 °C | [TSCA ]
Yes | [HazardClass ]
3 | [PackingGroup ]
II | [HS Code ]
29022000 | [Safety Profile]
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. A
common air contaminant.
heat or flame. Explodes on contact with
diborane, bromine pentafluoride,
permanganic acid, peroxornonosulfuric acid,
and peroxodisulfuric acid. Forms sensitive,
explosive mixtures with iodine
pentafluoride, silver perchlorate, nitryl
perchlorate, nitric acid, liquid oxygen,
ozone, and arsenic pentafluoride +
potassium methoxide (explodes above
30℃). Ignites on contact with sodium
peroxide + water, dioxygenyl
tetrafluoroborate, iodine heptafluoride, and
dioxygen difluoride. Vigorous or
incandescent reaction with hydrogen +
Raney nickel (above 210℃), uranium
hexafluoride, and bromine trifluoride. Can
react vigorously with oxidzing materials,
such as Cla, Cr03,02, NClO4,03,
perchlorates, (ACl3 + FClO4), (H2SO4 +
permanganates), K2O2(, NH4OH + acetic
acid), Na2O2. Moderate explosion hazard
A dangerous fire hazard when when exposed to heat or flame. Use with
adequate venulation. To fight fire, use foam,
CO2, dry chemical.
Poisoning occurs most commonly via
inhalation of the vapor, although benzene
can penetrate the skin and cause poisoning.
Locally, benzene has a comparatively strong
irritating effect, producing erythema and
burning, and, in more severe cases, edema
and even blistering. Exposure to high
concentrations of the vapor (3000 ppm or
higher) may result from failure of equipment
or spillage. Such exposure, while rare in
industry, may cause acute poisoning,
characterized by the narcotic action of
benzene on the central nervous system. The
anesthetic action of benzene is sirmlar to
that of other anesthetic gases, consisting of a
preluninary stage of excitation followed by
depression and, if exposure is continued,
death through respiratory failure. The
chronic, rather than the acute, form of
benzene poisoning is important in industry.
It is a recognized leukemogen. There is no
specific blood picture occurring in cases of
chronic benzol poisoning. The bone marrow
may be hypoplastic, normal, or hyperplastic,
the changes reflected in the peripheral
blood. Anemia, leucopenia, macrocytosis,
reticulocytosis, thrombocytopenia, hgh
color index, and prolonged bleeding time
may be present. Cases of myeloid leukemia
have been reported. For the worker,
repeated blood examinations are necessary,
inclulng hemoglobin determinations, white
and red cell counts, and dlfferential smears.
Where a worker shows a progressive drop in
either red or white cells, or where the white
count remains below <5000/mm3 or the red
count remains below 4.0 d o n / m m 3 , on
two successive monthly examinations, the
worker should be immediately removed
from benzene exposure. Elimination is
chefly through the lungs, when fresh air is
breathed. The portion that is absorbed is
oxidized, and the oxidation products are
combined with sulfuric and glycuronic acids
and eliminated in the urine. This may be used as a lagnostic sign. Benzene has a
definite cumulative action, and exposure to a
relatively hgh concentration is not serious
from the point of view of causing damage
to the blood-forming system, provided the
exposure is not repeated. In acute poisoning,
the worker becomes confused and dizzy,
complains of tightening of the leg muscles
and of pressure over the forehead, then
passes into a stage of excitement. If allowed
to remain exposed, he quickly becomes
stupefied and lapses into coma. In nonfatal
cases, recovery is usually complete with no
permanent disabhty. In chronic poisoning
the onset is slow, with the symptoms vague;
fatigue, headache, dizziness, nausea and loss
of appetite, loss of weight, and weakness are
common complaints in early cases. Later,
pallor, nosebleeds, bleeding gums,
menorrhagia, petechiae, and purpura may
develop. There is great inlvidual variation
in the signs and symptoms of chronic
benzene poisoning. | [Hazardous Substances Data]
71-43-2(Hazardous Substances Data) | [Toxicity]
LD50 orally in young adult rats: 3.8 ml/kg (Kimura) | [IDLA]
500 ppm |
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