Toluene

Toluene

Overview
Toluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinner
Paint thinner
A paint thinner is a solvent used to thin oil-based paints or clean up after their use, although all such solvents have other uses. Commercially, "paint thinner" is usually a name for mineral spirits.Products used as paint thinners include:*Mineral spirits...

s. It is a mono-substituted benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

 derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3
Methyl group
Methyl group is a functional group derived from methane, containing one carbon atom bonded to three hydrogen atoms —CH3. The group is often abbreviated Me. Such hydrocarbon groups occur in many organic compounds. The methyl group can be found in three forms: anion, cation and radical. The anion...

.

It is an aromatic hydrocarbon
Aromatic hydrocarbon
An aromatic hydrocarbon or arene is a hydrocarbon with alternating double and single bonds between carbon atoms. The term 'aromatic' was assigned before the physical mechanism determining aromaticity was discovered, and was derived from the fact that many of the compounds have a sweet scent...

 that is widely used as an industrial feedstock and as a solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...

. Like other solvents, toluene is sometimes also used as an inhalant
Inhalant
Inhalants are a broad range of drugs whose volatile vapors are taken in via the nose and trachea. They are taken by volatilization, and do not include drugs that are inhaled after burning or heating...

 drug for its intoxicating properties; however, inhaling toluene has potential to cause severe neurological harm.
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Unanswered Questions
Encyclopedia
Toluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinner
Paint thinner
A paint thinner is a solvent used to thin oil-based paints or clean up after their use, although all such solvents have other uses. Commercially, "paint thinner" is usually a name for mineral spirits.Products used as paint thinners include:*Mineral spirits...

s. It is a mono-substituted benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

 derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3
Methyl group
Methyl group is a functional group derived from methane, containing one carbon atom bonded to three hydrogen atoms —CH3. The group is often abbreviated Me. Such hydrocarbon groups occur in many organic compounds. The methyl group can be found in three forms: anion, cation and radical. The anion...

.

It is an aromatic hydrocarbon
Aromatic hydrocarbon
An aromatic hydrocarbon or arene is a hydrocarbon with alternating double and single bonds between carbon atoms. The term 'aromatic' was assigned before the physical mechanism determining aromaticity was discovered, and was derived from the fact that many of the compounds have a sweet scent...

 that is widely used as an industrial feedstock and as a solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...

. Like other solvents, toluene is sometimes also used as an inhalant
Inhalant
Inhalants are a broad range of drugs whose volatile vapors are taken in via the nose and trachea. They are taken by volatilization, and do not include drugs that are inhaled after burning or heating...

 drug for its intoxicating properties; however, inhaling toluene has potential to cause severe neurological harm. Toluene is an important organic solvent, but is also capable of dissolving a number of notable inorganic chemicals such as sulfur.

History


The name toluene was derived from the older name toluol, which refers to tolu balsam
Tolu balsam
Tolu balsam or balsam of Tolu is the resinous secretion of Myroxylon balsamum.The resin is still used in certain cough syrup formulas. However its main use in the modern era is in perfumery, where it is valued for its warm, mellow yet somewhat spicy scent. It is also used as a natural remedy for...

, an aromatic extract from the tropical Colombian tree Myroxylon balsamum
Myroxylon
Myroxylon J.R.Forst. & G.Forst is a synonym of Xylosma.Myroxylon is a genus of two species of Central American and South American trees in the Fabaceae . The tree is well known in the western world as the source for Peru balsam and Tolu balsam. The tree is often called Quina or Balsamo...

, from which it was first isolated. It was originally named by Jöns Jakob Berzelius
Jöns Jakob Berzelius
Jöns Jacob Berzelius was a Swedish chemist. He worked out the modern technique of chemical formula notation, and is together with John Dalton, Antoine Lavoisier, and Robert Boyle considered a father of modern chemistry...

.

Chemical properties


Toluene reacts as a normal aromatic hydrocarbon
Aromatic hydrocarbon
An aromatic hydrocarbon or arene is a hydrocarbon with alternating double and single bonds between carbon atoms. The term 'aromatic' was assigned before the physical mechanism determining aromaticity was discovered, and was derived from the fact that many of the compounds have a sweet scent...

 towards electrophilic aromatic substitution
Electrophilic aromatic substitution
Electrophilic aromatic substitution EAS is an organic reaction in which an atom, usually hydrogen, appended to an aromatic system is replaced by an electrophile...

. The methyl group makes it around 25 times more reactive than benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

 in such reactions. It undergoes smooth sulfonation to give p-toluenesulfonic acid
P-Toluenesulfonic acid
p-Toluenesulfonic acid or tosylic acid is an organic compound with the formula CH3C6H4SO3H. It is a white solid that is soluble in water, alcohols, and other polar organic solvents. The 4-CH3C6H4SO2- group is known as the Tosyl group and is often abbreviated as Ts or Tos...

, and chlorination
Chlorination
Chlorination is the process of adding the element chlorine to water as a method of water purification to make it fit for human consumption as drinking water...

 by Cl2
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 in the presence of FeCl3
Iron(III) chloride
Iron chloride, also called ferric chloride, is an industrial scale commodity chemical compound, with the formula FeCl3. The colour of iron chloride crystals depends on the viewing angle: by reflected light the crystals appear dark green, but by transmitted light they appear purple-red...

 to give ortho and para isomer
Isomer
In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

s of chlorotoluene
Chlorotoluene
Chlorotoluene can refer to any of four isomeric chemical compounds. Three isomers consisist of a disubsituted benzene ring with one chlorine atom and one methyl group...

. It undergoes nitration
Nitration
Nitration is a general chemical process for the introduction of a nitro group into a chemical compound. The dominant application of nitration is for the production of nitrobenzene, the precursor to methylene diphenyl diisocyanate...

 to give ortho and para nitrotoluene isomers, but if heated it can give dinitrotoluene
Dinitrotoluene
2,4-Dinitrotoluene or Dinitro is an organic compound with the formula C6H32. This pale yellow crystalline solid is well known as a precursor to trinitrotoluene but is mainly used in the polymer industry....

 and ultimately the explosive trinitrotoluene (TNT).



With other reagents the methyl side chain
Side chain
In organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called "main chain" or backbone. The placeholder R is often used as a generic placeholder for alkyl group side chains in chemical structure diagrams. To indicate other non-carbon...

 in toluene may react, undergoing oxidation. Reaction with potassium permanganate
Potassium permanganate
Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...

 and diluted acid (e.g., sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

) or potassium permanganate
Potassium permanganate
Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...

 with concentrated sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

, leads to benzoic acid
Benzoic acid
Benzoic acid , C7H6O2 , is a colorless crystalline solid and the simplest aromatic carboxylic acid. The name derived from gum benzoin, which was for a long time the only source for benzoic acid. Its salts are used as a food preservative and benzoic acid is an important precursor for the synthesis...

, whereas reaction with chromyl chloride
Chromyl chloride
Chromyl chloride is a chemical compound with the formula CrO2Cl2. This compound is an opaque dark blood-red liquid at room temperature and pressure. It is tetrahedral, somewhat like SO2Cl2. CrO2Cl2 is similar to the most commonly encountered chromium derivative chromate, [CrO4]2−; both are...

 leads to benzaldehyde
Benzaldehyde
Benzaldehyde is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. This colorless liquid has a characteristic pleasant almond-like odor...

 (Étard reaction
Etard Reaction
The Étard reaction is a chemical reaction that involves the direct oxidation of an aromatic or heterocyclic bound methyl group to an aldehyde using chromyl chloride. It is named for the French chemist Alexandre Léon Étard...

). Halogenation
Halogenation
Halogenation is a chemical reaction that incorporates a halogen atom into a molecule in substitution of hydrogen atom. Halogenation takes place in the gas phase. There are four types of halogenation: fluorination, chlorination, bromination, and iodination...

 can be performed under free radical conditions. For example, N-bromosuccinimide
N-Bromosuccinimide
N-Bromosuccinimide or NBS is a chemical reagent which is used in radical substitution and electrophilic addition reactions in organic chemistry. NBS can be considered a convenient source of cationic bromine.-Preparation:...

 (NBS) heated with toluene in the presence of AIBN leads to benzyl bromide
Benzyl bromide
Benzyl bromide, or α-bromotoluene, is an organic compound consisting of a benzene ring substituted with a bromomethyl group. It can be prepared by the bromination of toluene at room temperature in air, using manganese oxide as a heterogeneous catalyst...

. Toluene can also be treated with elemental bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...

 in the presence of UV light (direct sunlight) to yield benzyl bromide
Benzyl bromide
Benzyl bromide, or α-bromotoluene, is an organic compound consisting of a benzene ring substituted with a bromomethyl group. It can be prepared by the bromination of toluene at room temperature in air, using manganese oxide as a heterogeneous catalyst...

. Toluene may also be brominated by treating it with HBr and H2O2 in the presence of light .

Catalytic hydrogenation
Hydrogenation
Hydrogenation, to treat with hydrogen, also a form of chemical reduction, is a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically...

 of toluene to methylcyclohexane
Methylcyclohexane
Methylcyclohexane is a colourless liquid with a faint benzene-like odour. Its molecular formula is C7H14. Methylcyclohexane is used in organic synthesis and as a solvent for cellulose ethers. It is a component of jet fuel and is also a component of correction fluids.-Structure:Monosubstituted...

 requires a high pressure of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 to go to completion, because of the stability of the aromatic system.
pKa is approximately 45.

Production


Toluene occurs naturally at low levels in crude oil and is usually produced in the processes of making gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

 via a catalytic reformer
Catalytic reforming
Catalytic reforming is a chemical process used to convert petroleum refinery naphthas, typically having low octane ratings, into high-octane liquid products called reformates which are components of high-octane gasoline...

, in an ethylene
Ethylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...

 cracker
Cracking (chemistry)
In petroleum geology and chemistry, cracking is the process whereby complex organic molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon-carbon bonds in the precursors. The rate of cracking and the end products...

 or making coke
Coke (fuel)
Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

 from coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

. Final separation (either via distillation
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....

 or solvent extraction) takes place in a BTX plant.

Preparation


1. From benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

 (Friedel–Crafts reaction)

Benzene reacts with methyl chloride in presence of anhydrous aluminium chloride to form toluene.
The formation follows an electrophilic substitution reaction mechanism:

CH3Cl + AlCl3 → CH3+ + AlCl4-

C6H5H + CH3+ + AlCl4- → C6H5CH3 + HCl + AlCl3

The following catalysts can be used in place of AlCl3:

AlCl3 > SbCl3 > SnCl4 > BF3 > ZnCl2 > HgCl2

Note that the reaction is not very useful as the mono-alkyl derivative formed readily undergoes further alkylation at a still-greater speed to produce polysubstituted products.

2. From bromobenzene  (Wurtz-Fittig reaction
Wurtz-Fittig reaction
The Wurtz-Fittig reaction is the chemical reaction of aryl halides with alkyl halides and sodium metal to give substituted aromatic compounds....

)

The Wurtz-Fittig reaction is the reaction of an aryl halide and alkyl halide in presence of sodium metal to give substituted aromatic compounds.

When bromobenzene and methyl bromide react with sodium metal in dry ether solution, toluene is obtained.

C6H5Br + CH3Br + 2Na → C6H5CH3 + 2NaBr

3. From toluic acid (decarboxylation
Decarboxylation
Decarboxylation is a chemical reaction that releases carbon dioxide . Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is the first chemical step in photosynthesis, is called carbonation, the addition of CO2 to...

)

When sodium salt of toluic acid (o-
O-Toluic acid
o-Toluic acid, also 2-methylbenzoic acid, is an aromatic carboxylic acid, with formula C6H4. It is an isomer of p-toluic acid and m-toluic acid. When purified and recrystallized, o-toluic acid forms needle-shaped crystals...

, m-
M-Toluic acid
m-Toluic acid, , is an aromatic carboxylic acid, with formula C6H4. It is an isomer of p-toluic acid and o-toluic acid....

, p-) is heated with soda lime
Soda lime
Soda lime is a mixture of chemicals, used in granular form in closed breathing environments, such as general anaesthesia, submarines, rebreathers and recompression chambers, to remove carbon dioxide from breathing gases to prevent CO2 retention and carbon dioxide poisoning.It is made by treating...

, toluene is obtained.

C6H4CH3COONa (sodium toluate) + NaOH → C6H5CH3 (toluene) + Na2CO3

4. From cresol
Cresol
Cresols are organic compounds which are methylphenols. They are a widely occurring natural and manufactured group of aromatic organic compounds which are categorized as phenols . Depending on the temperature, cresols can be solid or liquid because they have melting points not far from room...



When cresol (o-, m-, p-) is distilled with zinc dust, toluene is obtained.

C6H4CH3OH (cresol) + Zn → C6H5CH3 (toluene) + ZnO

5. From toluenesulfonic acid

When toluenesulfonic acid is treated with superheated steam or boiled with HCl, toluene is obtained.

CH3C6H4SO3H (toluenesulfonic acid) + HOH (steam) → C6H5CH3 (toluene) + H2SO4 (sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

)

6. From toluidine
Toluidine
There are three isomers of toluidine, which are organic compounds. These isomers are o-toluidine, m-toluidine, and p-toluidine. The o- stands for ortho- , m- stands for meta- , and p- stands for para-...



Toluidine is first diazotized with sodium nitrite
Sodium nitrite
Sodium nitrite is the inorganic compound with the chemical formula NaNO2. It is a white to slight yellowish crystalline powder that is very soluble in water and is hygroscopic...

 (NaNO2) and HCl at low temperature. The diazonium compound thus obtained is heated with alkaline stannous chloride (SnCl2). This reaction gives toluene.

7. From Grignard reagent

When phenyl magnesium bromide (C6H5)MgBr is reacted with methyl bromide, toluene is obtained.

8. From aromatic
Aromaticity
In organic chemistry, Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. The earliest use of the term was in an article by August...

 ketones

Using a Friedel–Crafts reaction, when an acid chloride is reacted with an aromatic hydrocarbon in the presence of anhydrous aluminium chloride (AlCl3), a mixed aliphatic/aromatic ketone is obtained. The ketone is then reduced with amalgamated zinc and concentrated HCl.

C6H6 + ClCOCH3 → C6H5COCH3 (acetophenone) + HCl

C6H5COCH3 + 4H → C6H5CH2CH3 (ethyl benzene)

This method is used to produce alkyl benzenes other than toluene.

Uses


Toluene is a common solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...

, able to dissolve paint
Paint
Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...

s, paint thinners, silicone sealants, many chemical reactants, rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...

, printing
Printing
Printing is a process for reproducing text and image, typically with ink on paper using a printing press. It is often carried out as a large-scale industrial process, and is an essential part of publishing and transaction printing....

 ink, adhesive
Adhesive
An adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...

s (glues), lacquer
Lacquer
In a general sense, lacquer is a somewhat imprecise term for a clear or coloured varnish that dries by solvent evaporation and often a curing process as well that produces a hard, durable finish, in any sheen level from ultra matte to high gloss and that can be further polished as required...

s, leather tanners, and disinfectants. It can also be used as a fullerene
Fullerene
A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs, and they resemble the balls used in association football. Cylindrical ones are called carbon nanotubes or buckytubes...

 indicator, and is a raw material for toluene diisocyanate
Toluene diisocyanate
Toluene diisocyanate is an aromatic diisocyanate. It is produced for reaction with polyols to form polyurethanes. It exists in two isomers, 2,4-TDI and 2,6-TDI . 2,4-TDI is produced in the pure state, but TDI is often marketed as 80/20 and 65/35 mixtures of the 2,4 and 2,6 isomers respectively...

 (used in the manufacture of polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...

 foam) and TNT. In addition, it is used as a solvent to create a solution of carbon nanotubes. It is also used as a cement for fine polystyrene
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...

 kits
Plastic model
thumb|300px||4-year-old boy starts painting a plastic model he has assembled of the South Goodwin LightshipPlastic models, often called scale models, are models manufactured as kits which are assembled by hobbyists, and intended for static display....

 (by dissolving and then fusing surfaces) as it can be applied very precisely by brush and contains none of the bulk of an adhesive.

Industrial uses of toluene include dealkylation to benzene, and the disproportionation
Disproportionation
Disproportionation, also known as dismutation is used to describe a specific type of redox reaction in which a species is simultaneously reduced and oxidized so as to form two different products....

 to a mixture of benzene and xylene
Xylene
Xylene encompasses three isomers of dimethylbenzene. The isomers are distinguished by the designations ortho- , meta- , and para- , which specify to which carbon atoms the two methyl groups are attached...

 in the BTX process. When oxidized it yields benzaldehyde and benzoic acid, two important intermediates in chemistry. It is also used as a carbon source for making Multi-Wall Carbon Nanotube
Carbon nanotube
Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material...

s. Toluene can be used to break open red blood cells in order to extract hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...

 in biochemistry experiments.

Toluene can be used as an octane booster
Octane rating
Octane rating or octane number is a standard measure of the anti-knock properties of a motor or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating...

 in gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

 fuels used in internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

s. Toluene at 86% by volume fueled all the turbo Formula 1 teams in the 1980s, first pioneered by the Honda team. The remaining 14% was a "filler" of n-heptane, to reduce the octane to meet Formula 1 fuel restrictions. Toluene at 100% can be used as a fuel for both two-stroke and four-stroke engines; however, due to the density of the fuel and other factors, the fuel does not vaporize easily unless preheated to 70 degrees Celsius (Honda accomplished this in their Formula 1 cars by routing the fuel lines through the muffler system to heat the fuel). Toluene also poses similar problems as alcohol fuels, as it eats through standard rubber fuel lines and has no lubricating properties, as standard gasoline does, which can break down fuel pumps and cause upper cylinder bore wear.

In Australia, toluene has been found to have been illegally combined with petrol in fuel outlets for sale as standard vehicular fuel. Toluene attracts no fuel excise, while other fuels are taxed at over 40%, so fuel suppliers are able to profit from substituting the cheaper toluene for petrol. This substitution is likely to affect engine performance and result in additional wear and tear. The extent of toluene substitution has not been determined.

Toluene is another in a group of fuels that have recently been used as components for jet fuel
Jet fuel
Jet fuel is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is clear to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1 which are produced to a standardized international specification...

 surrogate blends. Toluene is used as a jet fuel surrogate for its content of aromatic compounds.

Toluene has also been used as a coolant for its good heat transfer capabilities in sodium cold traps used in nuclear reactor system loops.

Toluene had also been used in the process of removing the cocaine
Coca-Cola formula
The Coca-Cola formula is The Coca-Cola Company's secret recipe for Coca-Cola. As a publicity, marketing, and intellectual property protection strategy started by Robert W...

 from coca leaves in the production of Coca-Cola syrup.

Biology


Similar to many other solvents such as 1,1,1-trichloroethane
1,1,1-Trichloroethane
The organic compound 1,1,1-trichloroethane, also known as methyl chloroform, is a chloroalkane. This colourless, sweet-smelling liquid was once produced industrially in large quantities for use as a solvent...

 and some alkylbenzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

s, toluene has been shown to act as a non-competitive NMDA receptor antagonist
NMDA receptor antagonist
NMDA receptor antagonists are a class of anesthetics that work to antagonize, or inhibit the action of, the N-methyl d-aspartate receptor . They are used as anesthesia for animals and, less commonly, for humans; the state of anesthesia they induce is referred to as dissociative anesthesia...

 and GABAA receptor positive allosteric modulator
Positive allosteric modulator
A positive allosteric modulator is a drug which increases the activity of a receptor indirectly via activation of an allosteric site on the protein. PAMs are similar to agonists in that they contribute to overall receptor activation, but they are different because they do so in a functionally...

. It is abused as an inhalant
Inhalant
Inhalants are a broad range of drugs whose volatile vapors are taken in via the nose and trachea. They are taken by volatilization, and do not include drugs that are inhaled after burning or heating...

 likely on account of the euphoric
Euphoriant
A euphoriant is a type of psychoactive drug which tends to induce feelings of euphoria, the effects of which may include relaxation, anxiolysis, stress relief, mood lift, pleasure, and a rush although these effects are not necessary for a drug to be a euphoriant. Many euphoriants are notorious for...

 and dissociative effects these actions produce. Additionally, toluene has been shown to display antidepressant
Antidepressant
An antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. According to Gelder, Mayou &*Geddes people with a depressive illness will experience a therapeutic effect to their mood;...

-like effects in rodents in the forced swim test (FST) and the tail suspension test
Tail suspension test
The tail suspension test is an experiment used to assay mood levels in rodents in scientific research. Changes in immobility time indicate changes in mood. It is widely used to detect potential antidepressant effects of drugs....

 (TST).

Toxicology and metabolism



Toluene should not be inhaled due to its health effects. Low to moderate levels can cause tiredness, confusion, weakness, drunken-type actions, memory loss, nausea, loss of appetite, and hearing and color vision loss. These symptoms usually disappear when exposure is stopped. Inhaling high levels of toluene in a short time may cause light-headedness, nausea, or sleepiness. It can also cause unconsciousness, and even death.

Toluene is, however, much less toxic than benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

, and has, as a consequence, largely replaced it as an aromatic solvent in chemical preparation.

External links