BENZENE

Benzene is a chemical that is a colorless or light yellow liquid at room temperature. 
Benzene is an organic chemical compound with the molecular formula C6H6. 
Benzene has a sweet odor and is highly flammable.

CAS Number: 71-43-2
EC Number: 200-753-7
Chemical Formula: C6H6
Molar Mass: 77.81 grams/mole

Synonyms: benzene, benzol, 71-43-2, Cyclohexatriene, benzole, Pyrobenzole, Benzine, Benzen, Phenyl hydride, Coal naphtha, Pyrobenzol, Phene, Mineral naphtha, Bicarburet of hydrogen, Benzolene, Benzin, [6]Annulene, Motor benzol, Benzeen, Benzolo, Fenzen, Nitration benzene, (6)Annulene, Benzol 90, NCI-C55276, Rcra waste number U019, Benzinum, 1,3,5-cyclohexatriene, NSC 67315, UN 1114, CHEBI:16716, phenylmanganese iodide, CHEMBL277500, MFCD00003009, NSC-67315, J64922108F, Benzeen [Dutch], Benzen [Polish], Fenzen [Czech], Benzolo [Italian], BNZ, Benzine (Obs.), Benzin (Obs.), Caswell No. 077, Benzene 100 microg/mL in Methanol, Benzene, ACS reagent, >=99.0%, Benzene, pure, CCRIS 70, 54682-86-9, HSDB 35, 62485-97-6, EINECS 200-753-7, UN1114, benzene,iodomanganese(1+), EPA Pesticide Chemical Code 008801, Benzolum, Benzene (including benzene from gasoline), p-benzene, benzene-, AI3-00808, C6H6, 26181-88-4, 1hyz, 1swi, UNII-J64922108F, [6]-annulene, Benzene ACS Grade, Benzene, for HPLC, {[6]Annulene}, Ph-H, Phenyl; Phenyl Radical, 2z9g, 4i7j, BENZENE [VANDF], BENZINUM [HPUS], Benzene + aniline combo, BENZENE [HSDB], BENZENE [IARC], BENZENE (BENZOL), BENZENE [MI], BENZENE [MART.], Benzene, labeled with carbon-14 and tritium, WLN: RH, BENZENE [USP-RS], BENZENE [WHO-DD], Epitope ID:116867, Benzene, purification grade, EC 200-753-7, Benzene, analytical standard, Benzene, LR, >=99%, ghl.PD_Mitscher_leg0.503, Benzene, anhydrous, 99.8%, Benzene, AR, >=99.5%, DTXSID3039242, 3,4-DNH, 1l83, 220l, 223l, Benzene 10 microg/mL in Methanol, ZINC967532, trans-N-Methylphenylcyclopropylamine, ACT02832, BCP26158, Benzene 20 microg/mL in Triacetin, Benzene, for HPLC, >=99.8%, Benzene, for HPLC, >=99.9%, NSC67315, Tox21_202487, 1,3-Cyclohexadiene-5,6-diylradical, BDBM50167939, BM 613, STL264205, Benzene 5000 microg/mL in Methanol, Benzene, purum, >=99.0% (GC), AKOS008967253, Benzene, SAJ first grade, >=99.0%, CAS-71-43-2, ACETONE IMPURITY C [EP IMPURITY], Benzene [UN1114] [Flammable liquid], Benzene, JIS special grade, >=99.5%, erythro-Phenyl-2-piperidyl-carbinol,(-), NCGC00090744-01, NCGC00090744-02, NCGC00163890-01, NCGC00163890-02, NCGC00260036-01, trans-N, N-Dimethylphenylcyclopropylamine, Cc-34,(+/-), RNG, DS-002542, B0020, FT-0622636, FT-0622637, FT-0622667, FT-0627856, FT-0657604, Q0038, Q2270, Benzene 30 microg/mL in N,N-Dimethylacetamide, Benzene, ACS spectrophotometric grade, >=99%, C01407, Benzene, ReagentPlus(R), thiophene free, >=99%, Benzene, puriss. p.a., Reag. Ph. Eur., >=99.7%, Q26841227, BIPERIDEN HYDROCHLORIDE IMPURITY F [EP IMPURITY], Benzene, Pharmaceutical Secondary Standard; Certified Reference Material, Benzene, puriss., absolute, over molecular sieve (H2O <=0.005%), >=99.5% (GC), 25053-22-9, 200-753-7 [EINECS], 71-43-2 [RN], benzeen [Dutch], Benzen [Czech], Benzen [German], Benzen [Turkish], Benzene [ACD/Index Name] [ACD/IUPAC Name] [Wiki], Benzène [French] [ACD/IUPAC Name], Benzeno [Portuguese], Benzine, Benzol [German] [ACD/IUPAC Name], Benzolo [Italian], MFCD00003009 [MDL number], MFCD00198116 [MDL number], Annulene, Benceno [Spanish] [ACD/IUPAC Name], Benzinum, Benzolum, Bnz, (1,2,3,5-2H4)Benzene [ACD/IUPAC Name], (2H)Benzene, (6)annulene, 14941-52-7 [RN], 14941-53-8 [RN], 1684-46-4 [RN], 19467-24-4 [RN], 200-753-7MFCD00003009, 462-80-6 [RN], BENZENE (1,3,5-D3), Benzene, anhydrous, ACS, Benzene-1,2,4,5-d4, Benzene-1,2,4-d3, Benzene-1,2-d2, Benzene-1,3-d2, Benzene-1,4-d2, Benzene-d2-1, Benzin, benzole, Benzolene, Phene, phenyl hydride, Pyrobenzol, Pyrobenzole, WLN: RH

Benzene is a colorless or light-yellow liquid chemical at room temperature. 
Benzene is used primarily as a solvent in the chemical and pharmaceutical industries, as a starting material and an intermediate in the synthesis of numerous chemicals, and in gasoline. 

Benzene is produced by both natural and man-made processes. 
Benzene is a natural component of crude oil, which is the main source of benzene produced today. 
Other natural sources include gas emissions from volcanoes and forest fires.

Benzene is the simplest organic, aromatic hydrocarbon. 
Benzene is one of the elementary petrochemicals and a natural constituent of crude oil. 

Benzene has a gasoline-like odour and is a colourless liquid. Benzene is highly toxic and carcinogenic in nature. 
Benzene is primarily used in the production of polystyrene.

Benzene is a naturally occurring substance produced by volcanoes and forest fires and present in many plants and animals, but benzene is also a major industrial chemical made from coal and oil. 
As a pure chemical, benzene is a clear, colourless liquid. 

In industry, benzene is used to make other chemicals as well as some types of plastics, detergents, and pesticides. 
Benzene is also a component of gasoline.

Benzene is a colorless, flammable liquid with a sweet odor. 
Benzene evaporates quickly when exposed to air. 
Benzene is formed from natural processes, such as volcanoes and forest fires, but most people are exposed to benzene through human activities.

Benzene is one of the 20 most widely used chemicals in the United States. 
Benzene is used mainly to make other chemicals, including plastics, resins, lubricants, rubbers, dyes, detergents, drugs, and pesticides. 
In the past Benzene was also commonly used as an industrial solvent (a substance that can dissolve or extract other substances) and as a gasoline additive, but these uses have been greatly reduced in recent decades.

Benzene is also a natural part of crude oil and gasoline (and therefore motor vehicle exhaust), as well as cigarette smoke.

Benzene is registered under the REACH Regulation and is manufactured in and / or imported to the European Economic Area, for intermediate use only.
Benzene is used in articles, in formulation or re-packing, at industrial sites and in manufacturing.

Benzene (C6H6), simplest organic, aromatic hydrocarbon and parent compound of numerous important aromatic compounds. 
Benzene is a colourless liquid with a characteristic odour and is primarily used in the production of polystyrene. 

Benzene is highly toxic and is a known carcinogen.
Exposure to Benzene may cause leukemia. 
As a result, there are strict controls on benzene emissions.

Benzene evaporates into the air very quickly.
Benzene vapor is heavier than air and may sink into low-lying areas.
Benzene dissolves only slightly in water and will float on top of water.

The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. 
Because Benzene contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon.

Benzene is a natural constituent of petroleum and is one of the elementary petrochemicals. 
Due to the cyclic continuous pi bonds between the carbon atoms, benzene is classed as an aromatic hydrocarbon. 

Benzene is a colorless and highly flammable liquid with a sweet smell, and is partially responsible for the aroma of gasoline. 
Benzene is used primarily as a precursor to the manufacture of chemicals with more complex structure, such as ethylbenzene and cumene, of which billions of kilograms are produced annually. 
Although benzene is a major industrial chemical, Benzene finds limited use in consumer items because of Benzene toxicity.

Benzene is formed from both natural processes and human activities.
Natural sources of benzene include volcanoes and forest fires. 

Benzene is also a natural part of crude oil, gasoline, and cigarette smoke.
Benzene is widely used in the United States. 
Benzene ranks in the top 20 chemicals for production volume.

Some industries use benzene to make other chemicals that are used to make plastics, resins, and nylon and synthetic fibers. 
Benzene is also used to make some types of lubricants, rubbers, dyes, detergents, drugs, and pesticides.

Benzene is a clear, colorless, highly flammable and volatile, liquid aromatic hydrocarbon with a gasoline-like odor. 
Benzene is found in crude oils and as a by-product of oil-refining processes. 

In industry benzene is used as a solvent, as a chemical intermediate, and is used in the synthesis of numerous chemicals. 
Exposure to Benzene causes neurological symptoms and affects the bone marrow causing aplastic anemia, excessive bleeding and damage to the immune system. 
Benzene is a known human carcinogen and is linked to an increased risk of developing lymphatic and hematopoietic cancers, acute myelogenous leukemia, as well as chronic lymphocytic leukemia.

Benzene is a colorless liquid with a sweet odor. 
Benzene evaporates into the air very quickly and dissolves slightly in water. 

Benzene is highly flammable and is formed from both natural processes and human activities. 
Benzene is widely used in the United States; Benzene ranks in the top 20 chemicals for production volume. 

Some industries use benzene to make other chemicals which are used to make plastics, resins, and nylon and synthetic fibers. 
Benzene is also used to make some types of rubbers, lubricants, dyes, detergents, drugs, and pesticides. 

Natural sources of benzene include volcanoes and forest fires. 
Benzene is also a natural part of crude oil, gasoline, and cigarette smoke.

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  heavier than air.
are
Outdoor air contains low levels of benzene from tobacco smoke, gas stations, motor vehicle exhaust, and industrial emissions.
Indoor air generally contains levels of benzene higher than those in outdoor air. 

The benzene in indoor air comes from products that contain benzene such as glues, paints, furniture wax, and detergents.
The air around hazardous waste sites or gas stations can contain higher levels of benzene than in other areas.

Benzene leaks from underground storage tanks or from hazardous waste sites containing benzene can contaminate well water.
People working in industries that make or use benzene may be exposed to the highest levels of Benzene.
A major source of benzene exposure is tobacco smoke.

Benzene works by causing cells not to work correctly. 
For example, Benzene can cause bone marrow not to produce enough red blood cells, which can lead to anemia. 

Also, Benzene can damage the immune system by changing blood levels of antibodies and causing the loss of white blood cells.
The seriousness of poisoning caused by benzene depends on the amount, route, and length of time of exposure, as well as the age and preexisting medical condition of the exposed person.

Uses of Benzene:
At one time, benzene was obtained almost entirely from coal tar.
However, since about 1950, these methods have been replaced by petroleum-based processes. 

More than half of the benzene produced each year is converted to ethylbenzene, then to styrene, and then to polystyrene. 
The next largest use of benzene is in the preparation of phenol. 
Other uses include the preparation of aniline (for dyes) and dodecylbenzene (for detergents).

Benzene is used as a constituent in motor fuels; as a solvent for fats, waxes, resins, oils, inks, paints, plastics, and rubber; in the extraction of oils from seeds and nuts; and in photogravure printing. 
Benzene is also used as a chemical intermediate. 
Benzene is also used in the manufacture of detergents, explosives, pharmaceuticals, and dyestuffs.

Benzene was used in the past as a solvent in inks, rubber, lacquers, and paint removers. 
Today, Benzene is used mainly in closed processes to synthesize organic chemicals. 

Gasoline in some countries contains a high concentration of benzene (as high as 30%); the U.S. average is 1-3%. 
Workers who remove or clean underground storage tanks may be exposed to significant levels.

Gasoline in North America now contains about 1% benzene.
The European Union (EU) reduced in 2000 the maximum allowed benzene content in gasoline from 5% to 1% by volume. 
Mean exposures in the Swedish petroleum industry are well below the Swedish occupational exposure limits.

EPA restricts benzene emission from specific point sources.
Maximum contaminant level in drinking water is 5 ppb.
FDA prohibits the use of benzene in food.

Benzene is used in manufacture of industrial chemicals such as polymers, detergents, pesticides pharmaceuticals, dyes, plastics, resins. 
Benzene is used organic solvent for waxes, resins, oils, natural rubber, etc. 

Benzene is used for printing and lithography, paint, rubber, dry cleaning, adhesives and coatings, detergents.

Benzene is used to make chemicals used in the manufacture of industrial products such as dyes, detergents, explosives, pesticides, synthetic rubber, plastics, and pharmaceuticals. 
Benzene is found in gasoline and trace amounts are found in cigarette smoke. 

Benzene has been banned as an ingredient in products intended for use in the home, including toys. 
Benzene has a sweet, aromatic, gasoline-like odor. 

Most individuals can begin to smell benzene in air at 1.5 to 4.7 ppm. 
The odor threshold generally provides adequate warning for acutely hazardous exposure concentrations but is inadequate for more chronic exposures.

Benzene is often used as an intermediate to make chemicals needed for the production of plastics, resins, and nylon and other synthetic fibers. 
Benzene is also used to make some types of rubbers, lubricants, dyes, detergents, drugs, and pesticides. 
Natural sources of benzene include emissions from volcanoes, forest fires, crude oil, gasoline, and cigarette smoke.

Benzene is used mainly as an intermediate to make other chemicals, above all ethylbenzene (and other alkylbenzenes), cumene, cyclohexane, and nitrobenzene. 
In 1988 Benzene was reported that two-thirds of all chemicals on the American Chemical Society's lists contained at least one benzene ring.

More than half of the entire benzene production is processed into ethylbenzene, a precursor to styrene, which is used to make polymers and plastics like polystyrene. 
Some 20% of the benzene production is used to manufacture cumene, which is needed to produce phenol and acetone for resins and adhesives. 

Cyclohexane consumes around 10% of the world's benzene production.
Benzene is primarily used in the manufacture of nylon fibers, which are processed into textiles and engineering plastics. 
Smaller amounts of benzene are used to make some types of rubbers, lubricants, dyes, detergents, drugs, explosives, and pesticides. 

In 2013, the biggest consumer country of benzene was China, followed by the USA. 
Benzene production is currently expanding in the Middle East and in Africa, whereas production capacities in Western Europe and North America are stagnating.

Toluene is now often used as a substitute for benzene, for instance as a fuel additive. 
The solvent-properties of the two are similar, but toluene is less toxic and has a wider liquid range. 
Toluene is also processed into benzene.

Component of gasoline:
As a gasoline (petrol) additive, benzene increases the octane rating and reduces knocking. 
As a consequence, gasoline often contained several percent benzene before the 1950s, when tetraethyl lead replaced Benzene as the most widely used antiknock additive. 

With the global phaseout of leaded gasoline, benzene has made a comeback as a gasoline additive in some nations. 
In the United States, concern over Benzene negative health effects and the possibility of benzene entering the groundwater has led to stringent regulation of gasoline's benzene content, with limits typically around 1%.

European petrol specifications now contain the same 1% limit on benzene content. 
The United States Environmental Protection Agency introduced new regulations in 2011 that lowered the benzene content in gasoline to 0.62%.

In many European languages, the word for petroleum or gasoline is an exact cognate of "benzene".

Industrial Processes with risk of exposure:
Metal Preparation and Pouring
Petroleum Production and Refining
Working with Glues and Adhesives
Firefighting
Leather Tanning and Processing
Burning Synthetic Polymers

Activities with risk of exposure:
Smoking cigarettes 
Preparing and mounting animal skins (taxidermy)

Uses at industrial sites:
Benzene is used in the following products: coating products, fillers, putties, plasters, modelling clay, non-metal-surface treatment products, laboratory chemicals and polymers.
Benzene has an industrial use resulting in manufacture of another substance (use of intermediates).
Benzene is used in the following areas: formulation of mixtures and/or re-packaging.
Benzene is used for the manufacture of: rubber products and chemicals.
Release to the environment of Benzene can occur from industrial use: in the production of articles, as an intermediate step in further manufacturing of another substance (use of intermediates), formulation of mixtures and as processing aid.
Other release to the environment of Benzene is likely to occur from: indoor use.

Industry Uses of Benzene:
Adhesives and sealant chemicals
Catalyst
Cleaning agent
Flame retardants
Fuel
Fuel agents
Fuels and fuel additives
Functional fluids (closed systems)
Intermediate
Intermediates
Laboratory chemicals
Monomers
Plasticizers
Processing aids, specific to petroleum production
Solvent
Solvents (which become part of product formulation or mixture)

Consumer Uses of Benzene:
Catalyst
Etching agent
Fuel
Fuel agents
Fuels and fuel additives
Intermediate
Intermediates
Laboratory chemicals
Paint additives and coating additives not described by other categories
Plasticizer
Processing aids, specific to petroleum production
Solvent

Applications of Benzene:

Early Applications:
In the 19th and early 20th centuries, benzene was used as an after-shave lotion because of Benzene pleasant smell.
Prior to the 1920s, benzene was frequently used as an industrial solvent, especially for degreasing metal. 
As Benzene toxicity became obvious, benzene was supplanted by other solvents, especially toluene (methylbenzene), which has similar physical properties but is not as carcinogenic.

In 1903, Ludwig Roselius popularized the use of benzene to decaffeinate coffee. 
This discovery led to the production of Sanka. 

This process was later discontinued. 
Benzene was historically used as a significant component in many consumer products such as liquid wrench, several paint strippers, rubber cements, spot removers, and other products. 
Manufacture of some of these benzene-containing formulations ceased in about 1950, although Liquid Wrench continued to contain significant amounts of benzene until the late 1970s.

Benefits of Benzene:
As a building block chemical, benzene is reacted with other chemicals to produce a variety of other chemistries, materials and, ultimately, consumer goods.

Benzene is used to make other chemicals like ethylbenzene, cumene and cyclohexane, which are then reacted and used in the manufacture of a variety of materials and plastics such as polystyrene, ABS, and nylon. 
There can be many steps in the process that starts with the benzene molecule and ends with a completed material or consumer product. 
For example, benzene is a building block used to make ethylbenzene, which is then used to make styrene, which is used to make polystyrene. 

The end material, polystyrene, is a completely different material chemically than benzene.

For consumer products where benzene is used as a building block or intermediate, the benzene is typically fully reacted in a closed system, with little to no benzene remaining in the finished consumer product.
Benzene also is used to make some types of lubricants, rubbers, dyes, detergents, drugs, explosives and pesticides.

Benzene is naturally found in crude oil. 
Crude oil is refined into gasoline by using heat, pressure and chemicals in the refinery to separate the spectrum of petroleum products from crude oil. 
The refining process yields gasoline and a number of other petroleum products, including diesel and jet fuels, solvents, lubricating oils, many of which include small amounts of benzene.

Characteristics of Benzene:
Modern bonding models (valence-bond and molecular orbital theories) explain the structure and stability of benzene in terms of delocalization of six of Benzene electrons, where delocalization in this case refers to the attraction of an electron by all six carbons of the ring instead of just one or two of them. This delocalization causes the electrons to be more strongly held, making benzene more stable and less reactive than expected for an unsaturated hydrocarbon. 
As a result, the hydrogenation of benzene occurs somewhat more slowly than the hydrogenation of alkenes (other organic compounds that contain carbon-carbon double bonds), and benzene is much more difficult to oxidize than alkenes. 

Most of the reactions of benzene belong to a class called electrophilic aromatic substitution that leave the ring itself intact but replace one of the attached hydrogens. 
These reactions are versatile and widely used to prepare derivatives of benzene.

Experimental studies, especially those employing X-ray diffraction, show benzene to have a planar structure with each carbon-carbon bond distance equal to 1.40 angstroms (Å). 
This value is exactly halfway between the C=C distance (1.34 Å) and C—C distance (1.46 Å) of a C=C—C=C unit, suggesting a bond type midway between a double bond and a single bond (all bond angles are 120°). 
Benzene has a boiling point of 80.1 °C (176.2 °F) and a melting point of 5.5 °C (41.9 °F), and Benzene is freely soluble in organic solvents, but only slightly soluble in water.

Occurrence of Benzene:
Trace amounts of benzene are found in petroleum and coal. 
Benzene is a byproduct of the incomplete combustion of many materials. 

For commercial use, until World War II, much of benzene was obtained as a by-product of coke production (or "coke-oven light oil") for the steel industry. 
However, in the 1950s, increased demand for benzene, especially from the growing polymers industry, necessitated the production of benzene from petroleum. 

Today, most benzene comes from the petrochemical industry, with only a small fraction being produced from coal.
Benzene molecules have been detected on Mars.

Reactions of Benzene:
The most common reactions of benzene involve substitution of a proton by other groups.
Electrophilic aromatic substitution is a general method of derivatizing benzene. 
Benzene is sufficiently nucleophilic that Benzene undergoes substitution by acylium ions and alkyl carbocations to give substituted derivatives.

The most widely practiced example of this reaction is the ethylation of benzene.

Approximately 24,700,000 tons were produced in 1999.
Highly instructive but of far less industrial significance is the Friedel-Crafts alkylation of benzene (and many other aromatic rings) using an alkyl halide in the presence of a strong Lewis acid catalyst. 

Similarly, the Friedel-Crafts acylation is a related example of electrophilic aromatic substitution. 
The reaction involves the acylation of benzene (or many other aromatic rings) with an acyl chloride using a strong Lewis acid catalyst such as aluminium chloride or Iron(III) chloride.

Sulfonation, chlorination, nitration:
Using electrophilic aromatic substitution, many functional groups are introduced onto the benzene framework.
Sulfonation of benzene involves the use of oleum, a mixture of sulfuric acid with sulfur trioxide. 

Sulfonated benzene derivatives are useful detergents. 
In nitration, benzene reacts with nitronium ions (NO2+), which is a strong electrophile produced by combining sulfuric and nitric acids. 

Nitrobenzene is the precursor to aniline. 
Chlorination is achieved with chlorine to give chlorobenzene in the presence of a Lewis acid catalyst such as aluminium tri-chloride.

Hydrogenation:
Via hydrogenation, benzene and Benzene derivatives convert to cyclohexane and derivatives. 
This reaction is achieved by the use of high pressures of hydrogen in the presence of heterogeneous catalysts, such as finely divided nickel. 

Whereas alkenes can be hydrogenated near room temperatures, benzene and related compounds are more reluctant substrates, requiring temperatures >100 °C. 
This reaction is practiced on a large scale industrially. In the absence of the catalyst, benzene is impervious to hydrogen. 

Hydrogenation cannot be stopped to give cyclohexene or cyclohexadienes as these are superior substrates. 
Birch reduction, a non catalytic process, however selectively hydrogenates benzene to the diene.

Metal complexes:
Benzene is an excellent ligand in the organometallic chemistry of low-valent metals. 
Important examples include the sandwich and half-sandwich complexes, respectively, Cr(C6H6)2 and [RuCl2(C6H6)]2.

Resonance of Benzene:
The oscillating double bonds in the benzene ring are explained with the help of resonance structures as per valence bond theory. 
All the carbon atoms in the benzene ring are sp2 hybridized. 

One of the two sp2 hybridized orbitals of one atom overlaps with the sp2 orbital of adjacent carbon atom forming six C-C sigma bonds. 
Other left sp2 hybridized orbitals combine with s orbital of hydrogen to form six C-H sigma bonds. Remaining unhybridized p orbitals of carbon atoms form π bonds with adjacent carbon atoms by lateral overlap.

This explains an equal possibility for the formation of C1 –C2, C3 – C4, C5 – C6 π bonds or C2 – C3, C4 – C5, C6-C1 π bonds. 
The hybrid structure is represented by inserting a circle in the ring as shown below in the figure. 
Hence, Benzene explains the formation of two resonance structures proposed by Kekule.

Aromaticity of Benzene:
Benzene is an aromatic compound, as the C-C bonds formed in the ring are not exactly single or double, rather they are of intermediate length. 
Aromatic compounds are divided into two categories: benzenoids (one containing benzene ring) and non-benzenoids (those not containing benzene ring), provided they follow Huckel rule. 

According to Huckel rule, for a ring to be aromatic Benzene should have the following property:
Planarity
Complete delocalization of the π electrons in the ring
Presence of (4n + 2) π electrons in the ring where n is an integer (n = 0, 1, 2, . . .)

Structure of Benzene:
X-ray diffraction shows that all six carbon-carbon bonds in benzene are of the same length, at 140 picometres (pm).
The C–C bond lengths are greater than a double bond (135 pm) but shorter than a single bond (147 pm). 

This intermediate distance is caused by electron delocalization: the electrons for C=C bonding are distributed equally between each of the six carbon atoms. 
Benzene has 6 hydrogen atoms, fewer than the corresponding parent alkane, hexane, which has 14. 

Benzene and cyclohexane have a similar structure, only the ring of delocalized electrons and the loss of one hydrogen per carbon distinguishes Benzene from cyclohexane. 
The molecule is planar.

The molecular orbital description involves the formation of three delocalized π orbitals spanning all six carbon atoms, while the valence bond description involves a superposition of resonance structures.
Benzene is likely that this stability contributes to the peculiar molecular and chemical properties known as aromaticity. 
To accurately reflect the nature of the bonding, benzene is often depicted with a circle inside a hexagonal arrangement of carbon atoms.

Derivatives of benzene occur sufficiently often as a component of organic molecules, so much so that the Unicode Consortium has allocated a symbol in the Miscellaneous Technical block with the code U+232C (⌬) to represent Benzene with three double bonds, and U+23E3 (⏣) for a delocalized version.

Benzene derivatives:
Many important chemical compounds are derived from benzene by replacing one or more of Benzene hydrogen atoms with another functional group. 
Examples of simple benzene derivatives are phenol, toluene, and aniline, abbreviated PhOH, PhMe, and PhNH2, respectively. 

Linking benzene rings gives biphenyl, C6H5–C6H5. 
Further loss of hydrogen gives "fused" aromatic hydrocarbons, such as naphthalene, anthracene, phenanthrene, and pyrene. 
The limit of the fusion process is the hydrogen-free allotrope of carbon, graphite.

In heterocycles, carbon atoms in the benzene ring are replaced with other elements. 
The most important variations contain nitrogen. 

Replacing one CH with N gives the compound pyridine, C5H5N. 
Although benzene and pyridine are structurally related, benzene cannot be converted into pyridine. 
Replacement of a second CH bond with N gives, depending on the location of the second N, pyridazine, pyrimidine, or pyrazine.

Human Metabolite Information of Benzene:

Tissue Locations:
Bone Marrow
Epidermis
Leukocyte
Liver

History of Benzene:

Discovery:
The word "benzene" derives from "gum benzoin" (benzoin resin), an aromatic resin known since ancient times in Southeast Asia; and later to European pharmacists and perfumers in the 16th century via trade routes.
An acidic material was derived from benzoin by sublimation, and named "flowers of benzoin", or benzoic acid. 

The hydrocarbon derived from benzoic acid thus acquired the name benzin, benzol, or benzene.
Michael Faraday first isolated and identified benzene in 1825 from the oily residue derived from the production of illuminating gas, giving Benzene the name bicarburet of hydrogen.

In 1833, Eilhard Mitscherlich produced Benzene by distilling benzoic acid (from gum benzoin) and lime. 
He gave the compound the name benzin.

In 1836, the French chemist Auguste Laurent named Benzene "phène".
This word has become the root of the English word "phenol", which is hydroxylated benzene, and "phenyl", the radical formed by abstraction of a hydrogen atom (free radical H•) from benzene.

In 1845, Charles Blachford Mansfield, working under August Wilhelm von Hofmann, isolated benzene from coal tar.
Four years later, Mansfield began the first industrial-scale production of benzene, based on the coal-tar method.

Gradually, the sense developed among chemists that a number of substances were chemically related to benzene, comprising a diverse chemical family. 
In 1855, Hofmann used the word "aromatic" to designate this family relationship, after a characteristic property of many of Benzene members.
In 1997, benzene was detected in deep space.

Ring formula of Benzene:
The empirical formula for benzene was long known, but Benzene highly polyunsaturated structure, with just one hydrogen atom for each carbon atom, was challenging to determine. 
Archibald Scott Couper in 1858 and Johann Josef Loschmidt in 1861 suggested possible structures that contained multiple double bonds or multiple rings, but too little evidence was then available to help chemists decide on any particular structure.

In 1865, the German chemist Friedrich August Kekulé published a paper in French (for he was then teaching in Francophone Belgium) suggesting that the structure contained a ring of six carbon atoms with alternating single and double bonds. 
The next year he published a much longer paper in German on the same subject.

Kekulé used evidence that had accumulated in the intervening years—namely, that there always appeared to be only one isomer of any monoderivative of benzene, and that there always appeared to be exactly three isomers of every disubstituted derivative—now understood to correspond to the ortho, meta, and para patterns of arene substitution—to argue in support of his proposed structure. 
Kekulé's symmetrical ring could explain these curious facts, as well as benzene's 1:1 carbon-hydrogen ratio.

The new understanding of benzene, and hence of all aromatic compounds, proved to be so important for both pure and applied chemistry that in 1890 the German Chemical Society organized an elaborate appreciation in Kekulé's honor, celebrating the twenty-fifth anniversary of his first benzene paper. 
Here Kekulé spoke of the creation of the theory. 
He said that he had discovered the ring shape of the benzene molecule after having a reverie or day-dream of a snake biting Benzene own tail (this is a common symbol in many ancient cultures known as the Ouroboros or endless knot).

This vision, he said, came to him after years of studying the nature of carbon-carbon bonds. 
This was seven years after he had solved the problem of how carbon atoms could bond to up to four other atoms at the same time. 

Curiously, a similar, humorous depiction of benzene had appeared in 1886 in a pamphlet entitled Berichte der Durstigen Chemischen Gesellschaft (Journal of the Thirsty Chemical Society), a parody of the Berichte der Deutschen Chemischen Gesellschaft, only the parody had monkeys seizing each other in a circle, rather than snakes as in Kekulé's anecdote.
Some historians have suggested that the parody was a lampoon of the snake anecdote, possibly already well known through oral transmission even if Benzene had not yet appeared in print.

Kekulé's 1890 speech in which this anecdote appeared has been translated into English. 
If the anecdote is the memory of a real event, circumstances mentioned in the story suggest that Benzene must have happened early in 1862.

In 1929, the cyclic nature of benzene was finally confirmed by the crystallographer Kathleen Lonsdale using X-ray diffraction methods.
Using large crystals of hexamethylbenzene, a benzene derivative with the same core of six carbon atoms, Lonsdale obtained diffraction patterns. 
Through calculating more than thirty parameters, Lonsdale demonstrated that the benzene ring could not be anything but a flat hexagon, and provided accurate distances for all carbon-carbon bonds in the molecule.

Nomenclature:
The German chemist Wilhelm Körner suggested the prefixes ortho-, meta-, para- to distinguish di-substituted benzene derivatives in 1867.
However, he did not use the prefixes to distinguish the relative positions of the substituents on a benzene ring.

Benzene was the German chemist Carl Gräbe who, in 1869, first used the prefixes ortho-, meta-, para- to denote specific relative locations of the substituents on a di-substituted aromatic ring (viz, naphthalene).
In 1870, the German chemist Viktor Meyer first applied Gräbe's nomenclature to benzene.

Production of Benzene:
Four chemical processes contribute to industrial benzene production: catalytic reforming, toluene hydrodealkylation, toluene disproportionation, and steam cracking etc. 
According to the ATSDR Toxicological Profile for benzene, between 1978 and 1981, catalytic reformates accounted for approximately 44–50% of the total U.S benzene production.

Catalytic reforming:
In catalytic reforming, a mixture of hydrocarbons with boiling points between 60 and 200 °C is blended with hydrogen gas and then exposed to a bifunctional platinum chloride or rhenium chloride catalyst at 500–525 °C and pressures ranging from 8–50 atm. 
Under these conditions, aliphatic hydrocarbons form rings and lose hydrogen to become aromatic hydrocarbons. 

The aromatic products of the reaction are then separated from the reaction mixture (or reformate) by extraction with any one of a number of solvents, including diethylene glycol or sulfolane, and benzene is then separated from the other aromatics by distillation. 
The extraction step of aromatics from the reformate is designed to produce aromatics with lowest non-aromatic components. 
Recovery of the aromatics, commonly referred to as BTX (benzene, toluene and xylene isomers), involves such extraction and distillation steps.

In similar fashion to this catalytic reforming, UOP and BP commercialized a method from LPG (mainly propane and butane) to aromatics.

Toluene hydrodealkylation:
Toluene hydrodealkylation converts toluene to benzene. 
In this hydrogen-intensive process, toluene is mixed with hydrogen, then passed over a chromium, molybdenum, or platinum oxide catalyst at 500–650 °C and 20–60 atm pressure. 
Sometimes, higher temperatures are used instead of a catalyst (at the similar reaction condition). 

Under these conditions, toluene undergoes dealkylation to benzene and methane:
C6H5CH3+H2⟶C6H6+CH4

This irreversible reaction is accompanied by an equilibrium side reaction that produces biphenyl (aka diphenyl) at higher temperature:
2 C6H6 ⇌ H2 + C6H5–C6H5

If the raw material stream contains much non-aromatic components (paraffins or naphthenes), those are likely decomposed to lower hydrocarbons such as methane, which increases the consumption of hydrogen.

A typical reaction yield exceeds 95%. Sometimes, xylenes and heavier aromatics are used in place of toluene, with similar efficiency.
This is often called "on-purpose" methodology to produce benzene, compared to conventional BTX (benzene-toluene-xylene) extraction processes.

Toluene disproportionation:
Toluene disproportionation (TDP) is the conversion of toluene to benzene and xylene.

Given that demand for para-xylene (p-xylene) substantially exceeds demand for other xylene isomers, a refinement of the TDP process called Selective TDP (STDP) may be used. 
In this process, the xylene stream exiting the TDP unit is approximately 90% p-xylene. 
In some systems, even the benzene-to-xylenes ratio is modified to favor xylenes.

Steam cracking:
Steam cracking is the process for producing ethylene and other alkenes from aliphatic hydrocarbons. 
Depending on the feedstock used to produce the olefins, steam cracking can produce a benzene-rich liquid by-product called pyrolysis gasoline. 
Pyrolysis gasoline can be blended with other hydrocarbons as a gasoline additive, or routed through an extraction process to recover BTX aromatics (benzene, toluene and xylenes).

Other methods:
Although of no commercial significance, many other routes to benzene exist. 
Phenol and halobenzenes can be reduced with metals.

Benzoic acid and Benzene salts undergo decarboxylation to benzene. 
The reaction of the diazonium compound derived from aniline with hypophosphorus acid gives benzene. 

Alkyne trimerisation of acetylene gives benzene. 
Complete decarboxylation of mellitic acid gives benzene.

General Manufacturing Information of Benzene:

Industry Processing Sectors:
Adhesive Manufacturing
All Other Basic Organic Chemical Manufacturing
All Other Chemical Product and Preparation Manufacturing
All other Petroleum and Coal Products Manufacturing
Computer and Electronic Product Manufacturing
Construction
Cyclic Crude and Intermediate Manufacturing
Not Known or Reasonably Ascertainable
Oil and Gas Drilling, Extraction, and Support activities
Other (requires additional information)
Petrochemical Manufacturing
Petroleum Refineries
Plastics Material and Resin Manufacturing
Plastics Product Manufacturing
Rubber Product Manufacturing
Soap, Cleaning Compound, and Toilet Preparation Manufacturing
Transportation Equipment Manufacturing
Wholesale and Retail Trade

Health effects of Benzene:
Benzene is classified as a carcinogen, which increases the risk of cancer and other illnesses, and is also a notorious cause of bone marrow failure. 
Substantial quantities of epidemiologic, clinical, and laboratory data link benzene to aplastic anemia, acute leukemia, bone marrow abnormalities and cardiovascular disease.

The specific hematologic malignancies that benzene is associated with include: acute myeloid leukemia (AML), aplastic anemia, myelodysplastic syndrome (MDS), acute lymphoblastic leukemia (ALL), and chronic myeloid leukemia (CML).

The American Petroleum Institute (API) stated in 1948 that "Benzene is generally considered that the only absolutely safe concentration for benzene is zero".
There is no safe exposure level; even tiny amounts can cause harm.

The US Department of Health and Human Services (DHHS) classifies benzene as a human carcinogen. 
Long-term exposure to excessive levels of benzene in the air causes leukemia, a potentially fatal cancer of the blood-forming organs. 

In particular, acute myeloid leukemia or acute nonlymphocytic leukemia (AML & ANLL) is caused by benzene.
IARC rated benzene as "known to be carcinogenic to humans".

As benzene is ubiquitous in gasoline and hydrocarbon fuels that are in use everywhere, human exposure to benzene is a global health problem. 
Benzene targets the liver, kidney, lung, heart and brain and can cause DNA strand breaks and chromosomal damage. 

Benzene causes cancer in animals including humans. 
Benzene has been shown to cause cancer in both sexes of multiple species of laboratory animals exposed via various routes.

Handling and Storage of Benzene:

Nonfire Spill Response:
ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. 
All equipment used when handling the product must be grounded. 

Do not touch or walk through spilled material. 
Stop leak if you can do Benzene without risk. 

Prevent entry into waterways, sewers, basements or confined areas. 
A vapor-suppressing foam may be used to reduce vapors. 

Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. 
Use clean, non-sparking tools to collect absorbed material. 

LARGE SPILL: 
Dike far ahead of liquid spill for later disposal. 
Water spray may reduce vapor, but may not prevent ignition in closed spaces.

Storage Conditions of Benzene:
Keep in well closed containers in a cool place and away from fire.
Storage site should be as close as practicable to lab in which carcinogens are to be used, so that only small quantities required for expt need to be carried. 

Carcinogens should be kept in only one section of cupboard, an explosion-proof refrigerator or freezer (depending on chemicophysical properties) that bears appropriate label. 
An inventory should be kept, showing quantity of carcinogen & date Benzene was acquired.
Facilities for dispensing should be contiguous to storage area.

Conditions for safe storage, including any incompatibilities: 
Keep container tightly closed in a dry and well-ventilated place. 
Containers which are opened must be carefully resealed and kept upright to prevent leakage.

First Aid Measures of Benzene:

EYES: 
First check the victim for contact lenses and remove if present. 
Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. 

Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. 
IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. 

SKIN: 
IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. 
Gently wash all affected skin areas thoroughly with soap and water. 

IMMEDIATELY call a hospital or poison control center even if no symptoms (such as redness or irritation) develop. 
IMMEDIATELY transport the victim to a hospital for treatment after washing the affected areas. 

INHALATION: 
IMMEDIATELY leave the contaminated area.
Take deep breaths of fresh air. 

IMMEDIATELY call a physician and be prepared to transport the victim to a hospital even if no symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop. 
Provide proper respiratory protection to rescuers entering an unknown atmosphere. 

Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used.
If not available, use a level of protection greater than or equal to that advised under Protective Clothing. 

INGESTION: 
DO NOT INDUCE VOMITING. 
Volatile chemicals have a high risk of being aspirated into the victim's lungs during vomiting which increases the medical problems. 

If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. 
IMMEDIATELY transport the victim to a hospital. 

If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. 
DO NOT INDUCE VOMITING. 
IMMEDIATELY transport the victim to a hospital. 

OTHER: 
Since this chemical is a known or suspected carcinogen you should contact a physician for advice regarding the possible long term health effects and potential recommendation for medical monitoring. 
Recommendations from the physician will depend upon the specific compound, Benzene, physical and toxicity properties, the exposure level, length of exposure, and the route of exposure.

Fire Fighting of Benzene:

CAUTION: 
The majority of these products have a very low flash point. 
Use of water spray when fighting fire may be inefficient. 

SMALL FIRE: 
Dry chemical, CO2, water spray or regular foam. 

LARGE FIRE: 
Water spray, fog or regular foam. Avoid aiming straight or solid streams directly onto the product. 
If Benzene can be done safely, move undamaged containers away from the area around the fire. 

FIRE INVOLVING TANKS OR CAR/TRAILER LOADS: 
Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. 
Cool containers with flooding quantities of water until well after fire is out. 

Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. 
ALWAYS stay away from tanks engulfed in fire. 

For massive fire, use unmanned master stream devices or monitor nozzles.
If this is impossible, withdraw from area and let fire burn.

Fire Fighting Procedures of Benzene:
Approach fire from upwind to avoid hazardous vapors. 
Use water spray, dry chemical, foam, or carbon dioxide. 
Use water spray to keep fire-exposed containers cool.

If material on fire or involved in fire: 
Do not extinguish fire unless flow can be stopped. 

Use water in flooding quantities as fog. 
Solid streams of water may spread fire. 

Cool all affected containers with flooding quantities of water. 
Apply water from as far a distance as possible. 
Use foam, dry chemical, or carbon dioxide.

Suitable extinguishing media: 
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.

Advice for firefighters: 
Wear self contained breathing apparatus for fire fighting if necessary.
Use water spray to cool unopened containers.

Accidental Release Measures of Benzene:

IMMEDIATE PRECAUTIONARY MEASURE: 
Isolate spill or leak area for at least 50 meters (150 feet) in all directions. 

LARGE SPILL: 
Consider initial downwind evacuation for at least 300 meters (1000 feet). 

FIRE: 
If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions.
Also, consider initial evacuation for 800 meters (1/2 mile) in all directions.

Spillage Disposal of Benzene:
Remove all ignition sources. 
Evacuate danger area! Consult an expert! 

Personal protection: 
complete protective clothing including self-contained breathing apparatus. 
Do NOT wash away into sewer. 

Do NOT let this chemical enter the environment. 
Collect leaking and spilled liquid in sealable containers as far as possible. 

Absorb remaining liquid in sand or inert absorbent. 
Then store and dispose of according to local regulations.

Cleanup Methods of Benzene:
For spills on water, contain with booms or barriers, use surface acting agents to thicken spilled materials. 
Remove trapped materials with suction hoses.

Small spills of benzene can be taken up by sorption on carbon or synthetic sorbent resins. 
Flush area with water. 

For large quantities, if response is rapid, benzene can be skimmed off the surface. 
Straw may be used to mop slicks.

A high-efficiency particulate arrestor (HEPA) or charcoal filters can be used to minimize amt of carcinogen in exhausted air ventilated safety cabinets, lab hoods, glove boxes or animal rooms.
Filter housing that is designed so that used filters can be transferred into plastic bag without contaminating maintenance staff is avail commercially. 

Filters should be placed in plastic bags immediately after removal.
The plastic bag should be sealed immediately.

The sealed bag should be labelled properly.
Waste liquids should be placed or collected in proper containers for disposal. 

The lid should be secured & the bottles properly labelled. 
Once filled, bottles should be placed in plastic bag, so that outer surface is not contaminated.

The plastic bag should also be sealed & labelled.
Broken glassware should be decontaminated by solvent extraction, by chemical destruction, or in specially designed incinerators.

Identifiers of Benzene:
CAS Number: 71-43-2
ChEBI: CHEBI:16716
ChEMBL: ChEMBL277500
ChemSpider: 236
ECHA InfoCard: 100.000.685
EC Number: 200-753-7
KEGG: C01407
PubChem CID: 241
RTECS number: CY1400000
UNII: J64922108F
CompTox Dashboard (EPA): DTXSID3039242
InChIInChI=1S/C6H6/c1-2-4-6-5-3-1/h1-6H
Key: UHOVQNZJYSORNB-UHFFFAOYSA-N
SMILES: c1ccccc1

Chemical formula: C6H6
Molar mass: 77.81 grams/mole
Melting point: 5.5oC
Boiling point: 80.1oC

Properties of Benzene:
Chemical formula: C6H6
Molar mass: 78.114 g·mol−1
Appearance: Colorless liquid
Odor: sweet aromatic
Density: 0.8765(20) g/cm3
Melting point: 5.53 °C (41.95 °F; 278.68 K)
Boiling point: 80.1 °C (176.2 °F; 353.2 K)

Solubility in water: 
1.53 g/L (0 °C)
1.81 g/L (9 °C)
1.79 g/L (15 °C)
1.84 g/L (30 °C)
2.26 g/L (61 °C)
3.94 g/L (100 °C)
21.7 g/kg (200 °C, 6.5 MPa)
17.8 g/kg (200 °C, 40 MPa)

Solubility: Soluble in alcohol, CHCl3, CCl4, diethyl ether, acetone, acetic acid

Solubility in ethanediol: 
5.83 g/100 g (20 °C)
6.61 g/100 g (40 °C)
7.61 g/100 g (60 °C)

Solubility in ethanol: 
20 °C, solution in ethanol: 1.2 mL/L (20% v/v)

Solubility in acetone: 

20 °C, solution in aceton:
7.69 mL/L (38.46% v/v)
49.4 mL/L (62.5% v/v)
Solubility in diethylene glycol: 52 g/100 g (20 °C)
log P: 2.13

Vapor pressure: 
12.7 kPa (25 °C)
24.4 kPa (40 °C)
181 kPa (100 °C)[8]

Conjugate acid: Benzenium
Conjugate base: Benzenide
UV-vis (λmax): 255 nm
Magnetic susceptibility (χ): −54.8·10−6 cm3/mol

Refractive index (nD): 
1.5011 (20 °C)
1.4948 (30 °C)

Viscosity: 
0.7528 cP (10 °C)
0.6076 cP (25 °C)
0.4965 cP (40 °C)
0.3075 cP (80 °C)

Molecular Weight: 78.11
XLogP3: 2.1
Hydrogen Bond Donor Count: 0
Hydrogen Bond Acceptor Count: 0
Rotatable Bond Count: 0
Exact Mass: 78.0469501914
Monoisotopic Mass: 78.0469501914
Topological Polar Surface Area: 0 Ų
Heavy Atom Count: 6
Complexity: 15.5
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes

Structure of Benzene:
Molecular shape: Trigonal planar
Dipole moment: 0 D

Thermochemistry of Benzene:
Heat capacity (C): 134.8 J/mol·K
Std molar entropy (S⦵298): 173.26 J/mol·K[8]
Std enthalpy of formation (ΔfH⦵298): 48.7 kJ/mol
Std enthalpy of combustion (ΔcH⦵298): -3267.6 kJ/mol[8]

Related Compounds of Benzene:
Toluene
Borazine

Names of Benzene:

Regulatory process names:
Benzene
BENZENE
Benzene (Cyclohexatriene)
Benzène

Translated names:
benceno (es)
Benseen (et)
Bentseeni (fi)
benzeen (nl)
benzen (cs)
benzen (da)
benzen (hr)
benzen (no)
benzen (pl)
benzen (ro)
benzen (sl)
benzen (sv)
benzenas (lt)
benzene (it)
benzeno (pt)
Benzol (de)
benzol (hu)
benzols (lv)
benzène (fr)
benzén (sk)
βενζόλιο (el)
бензен (bg)

CAS name:
Benzene

IUPAC names:
BENZENE
Benzene
benzene
BENZENE
Benzene
benzene
Benzene / EC: 200-753-7
Benzene-1,3-diamine
Benzol
Benzol
Petroleum benzene

Trade names:
Annülene
Benceno
Benzen ropný
Benzene
benzene
Benzene (8CI, 9CI)
Benzene - E
Benzene SP
Benzol
Benzole
Coal naphtha
Cyclohexatriene
Petrobenzene
Petroleum benzene
Phene
Phenyl hydride
Pur Benzene
Pure benzene
Pyrobenzol
Pyrobenzole
Reinbenzol

Other names:
Benzol (historic/German)
Phenane
Phenylene hydride
Cyclohexa-1,3,5-triene; 1,3,5-Cyclohexatriene (theoretical resonance isomers)
Annulene
Phene (historic)