Toluene 30699 225569996 2008-07-14T10:38:23Z Nemo20000 4159109 Add use as polystyrene cement in model making. {{Chembox new | Name = Toluene | ImageFile = Toluene_chemical_structure.png | ImageFile1 = toluene-potential-upside-down.png | OtherNames = phenylmethane<br/>toluol<br/>methylbenzene | Section1 = {{Chembox Identifiers | SMILES = Cc1ccccc1 | CASNo = 108-88-3 | RTECS = XS5250000 }} | Section2 = {{Chembox Properties | Formula = C<sub>7</sub>H<sub>8</sub> (C<sub>6</sub>H<sub>5</sub>CH<sub>3</sub>) | MolarMass = 92.14 g/mol | Appearance = Clear colorless, liquid | Density = 0.8669 g/mL, liquid | Solubility = 0.47 g/l (20-25°C) | MeltingPt = −93 °C | BoilingPt = 110.6 °C | Viscosity = 0.590 c[[Poise|P]] at 20°C }} | Section3 = {{Chembox Structure | Dipole = 0.36 [[Debye|D]] }} | Section7 = {{Chembox Hazards | ExternalMSDS = [http://www.sciencelab.com/xMSDS-Toluene-9927301 ScienceLab.com] | MainHazards = highly flammable | NFPA-H = 2 | NFPA-F = 3 | NFPA-R = | FlashPt = 4 °C/ 39.2 °F | RPhrases = {{R11}}, {{R38}}, {{R48/20}}, {{R63}}, {{R65}}, {{R67}} | SPhrases = {{S2}}, {{S36/37}}, {{S29}}, {{S46}}, {{S62}} }} | Section8 = {{Chembox Related | Function = [[aromatic hydrocarbon]] | OtherFunctn = [[benzene]]<br/>[[xylene]]<br/>[[naphthalene]] | OtherCpds = [[methylcyclohexane]]}} }} '''Toluene''', also known as '''methylbenzene''' or '''phenylmethane''', is a clear, [[Water (molecule)|water]]-insoluble liquid with the typical smell of [[paint thinner]]s, redolent of the sweet smell of the related compound [[benzene]]. It is an [[aromatic hydrocarbon]] that is widely used as an industrial feedstock and as a [[solvent]]. Like other solvents, toluene is also used as an [[inhalant]] drug for its intoxicating properties.<ref>{{cite journal |author=Streicher HZ, Gabow PA, Moss AH, Kono D, Kaehny WD |title=Syndromes of toluene sniffing in adults |journal=Ann. Intern. Med. |volume=94 |issue=6 |pages=758–62 |year=1981 |pmid=7235417 |doi=}}</ref><ref>{{cite journal |author=Devathasan G, Low D, Teoh PC, Wan SH, Wong PK |title=Complications of chronic glue (toluene) abuse in adolescents |journal=Aust N Z J Med |volume=14 |issue=1 |pages=39–43 |year=1984 |pmid=6087782 |doi=}}</ref> ==History== The name ''toluene'' was derived from the older name ''toluol'', which refers to [[tolu balsam]], an aromatic extract from the tropical Colombian tree ''Myroxylon balsamum'', from which it was first isolated. It was originally named by [[Jöns Jakob Berzelius]]. ==Chemical properties== Toluene reacts as a normal [[aromatic hydrocarbon]] towards [[electrophilic aromatic substitution]].<ref>B. S. Furnell et al., ''Vogel's Textbook of Practical Organic Chemistry'', 5th edition, Longman/Wiley, New York, 1989</ref><ref>L. G. Wade, ''Organic Chemistry'', 5th ed., p. 871, Prentice Hall, Upper Saddle RIver, New Jersey, 2003</ref><ref>J. March, ''Advanced Organic Chemistry'', 4th ed., p. 723, Wiley, New York, 1992</ref> The [[methyl]] group makes it around 25 times more reactive than [[benzene]] in such reactions. It undergoes smooth [[sulfonation]] to give [[P-Toluenesulfonic acid|''p''-toluenesulfonic acid]], and [[chlorination]] by [[chlorine|Cl<sub>2</sub>]] in the presence of [[iron(III) chloride|FeCl<sub>3</sub>]] to give ortho and para [[isomer]]s of [[chlorotoluene]]. It undergoes [[nitration]] to give ortho and para [[nitrotoluene]] isomers, but if heated it can give [[dinitrotoluene]] and ultimately the explosive [[trinitrotoluene]] (TNT). With other [[reagents]] the methyl [[side chain]] in toluene may react, undergoing oxidation. Reaction with [[potassium permanganate]] leads to [[benzoic acid]], whereas reaction with [[chromyl chloride]] leads to [[benzaldehyde]] ([[Étard reaction]]). [[Halogenation]] can be performed under [[free radical]] conditions. For example, [[N-Bromosuccinimide|''N''-bromosuccinimide]] (NBS) heated with toluene in the presence of [[AIBN]] leads to [[benzyl bromide]]. Catalytic [[hydrogenation]] of toluene to [[methylcyclohexane]] requires a high pressure of [[hydrogen]] 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]] via a [[catalytic reforming|catalytic reformer]], in an [[ethylene]] [[cracking (chemistry)|cracker]] or making [[coke (fuel)|coke]] from [[coal]]. Final separation (either via [[distillation]] or [[solvent extraction]]) takes place in a [[BTX process|BTX plant]]. ==Uses== Toluene is a common [[solvent]], able to dissolve: [[paint]]s, paint thinners, silicone sealants,<ref>[http://www.freepatentsonline.com/6387487.html Dual cure, low-solvent silicone pressure sensitive adhesives - Patent 6387487<!-- Bot generated title -->]</ref> many [[chemical reactant]]s, [[rubber]], [[printing]] ink, [[adhesive]]s (glues), [[lacquer]]s, [[leather tanning|leather tanners]], and [[disinfectant]]s. It can also be used as a [[fullerene]] indicator, and is a raw material for [[toluene diisocyanate]] (used in the manufacture of [[polyurethane]] foam) and [[trinitrotoluene|TNT]]. It is also used as an adhesive for fine [[polystyrene]] [[plastic model|kits]] (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 to a mixture of benzene and [[xylene]] 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]]s. Toluene can be used to break open [[red blood cells]] in order to extract [[hemoglobin]] in biochemistry experiments. Toluene can be used as an [[octane rating|octane booster]] in [[gasoline]] fuels used in [[internal combustion engine]]s. Toluene at 86% by volume fueled all the turbo Formula 1 teams in the 1980s. ==Toxicology and metabolism== {{main|Toluene (toxicology)}} Inhalation of toluene fumes can be intoxicating, but in larger doses nausea-inducing. Toluene may enter the human system not only through vapour inhalation from the liquid evaporation, but also following [[soil contamination]] events, where human contact with soil, ingestion of contaminated groundwater or soil vapour off-gassing can occur. The toxicity of toluene can be explained mostly by its metabolism. As toluene has very low water solubility, it cannot exit the body via the normal routes (urine, feces, or sweat).{{Fact|date=March 2007}} It must be metabolized in order to be excreted. The methyl group of toluene is more easily oxidized by [[cytochrome P450]] than the benzene ring. Therefore, in the metabolism of toluene, 95% is oxidized to become [[benzyl alcohol]].<ref>{{cite journal |author=Nakajima T, Wang R, Elovaara E, Gonzalez F, Gelboin H, Raunio H, Pelkonen O, Vainio H, Aoyama T |title=Toluene metabolism by cDNA-expressed human hepatic cytochrome P450 |journal=Biochem Pharmacol |volume=53 |issue=3 |pages=271–7 |year=1997 |pmid=9065730 | doi = 10.1016/S0006-2952(96)00652-1 <!--Retrieved from CrossRef by DOI bot-->}}</ref> The toxic metabolites are created by the remaining 5% that are oxidized to [[benzaldehyde]] and [[cresol]]s.<ref>{{cite journal |author=Chapman D, Moore T, Michener S, Powis G |title=Metabolism and covalent binding of [14C]toluene by human and rat liver microsomal fractions and liver slices |journal=Drug Metab Dispos |volume=18 |issue=6 |pages=929–36 |year= |pmid=1981539}}</ref><ref>{{cite journal |author=Hanioka H, Hamamura M, Kakino K, Ogata H, Jinno H, Takahashi A, Nishimura T, Ando M |title=Dog liver microsomal P450 enzyme-mediated toluene biotransformation |journal=Xenobiotica |volume=25 |issue=11 |pages=1207–17 |year=1995 |pmid=8592870}}</ref> Most of the reactive products are [[detoxification|detox]]ified by conjugation to [[glutathione]] but the remainder may severely damage cells.<ref>{{cite journal |author=van Doorn R, Leijdekkers C, Bos R, Brouns R, Henderson P |title=Alcohol and sulphate intermediates in the metabolism of toluene and xylenes to mercapturic acids |journal=J Appl Toxicol |volume=1 |issue=4 |pages=236–42 |year=1981 |pmid=6764216 |doi=10.1002/jat.2550010411}}</ref> [[Image:Toluene Metabolism Scheme.png|500px|center|The metabolism of toluene]] Toluene is mainly excreted as [[benzoic acid]] and [[hippuric acid]], both formed by further metabolic oxidation of benzyl alcohol. [[Image:Benzyl Alcohol Metabolism Scheme.png|500px|center|The metabolism of benzyl alcohol]] ==See also== * [[Organic chemistry]] * [[Water pollution]] * [[Isotoluene]]s are toluene isomers ==Footnotes== {{reflist}} ==External links== {{commons|Toluene|Toluene}} * [http://www.atsdr.cdc.gov/csem/toluene/ ATSDR - Case Studies in Environmental Medicine: Toluene Toxicity] U.S. Department of Health and Human Services (public domain) * [http://144.16.93.203/energy/HC270799/HDL/ENV/enven/vol364.htm External solubility data] * [http://www.compchemwiki.org/index.php?title=Toluene Computational Chemistry Wiki] [[Category:Aromatic hydrocarbons]] [[Category:Hazardous air pollutants]] [[Category:Soil contamination]] [[Category:Hydrocarbon solvents]] [[Category:Antiknock agents]] [[Category:DEA List II chemicals]] [[ar:تولوين]] [[bs:Toluen]] [[ca:Toluè]] [[cs:Toluen]] [[de:Toluol]] [[es:Tolueno]] [[eo:Tolueno]] [[fa:تولوئن]] [[fr:Toluène]] [[gl:Tolueno]] [[ko:톨루엔]] [[hr:Toluen]] [[he:טולואן]] [[id:Toluena]] [[it:Toluene]] [[lv:Toluols]] [[lt:Toluenas]] [[hu:Toluol]] [[mk:Толуен]] [[nl:Tolueen]] [[ja:トルエン]] [[no:Toluen]] [[pl:Toluen]] [[pt:Tolueno]] [[ro:Toluen]] [[ru:Толуол]] [[sk:Toluén]] [[fi:Tolueeni]] [[sv:Toluen]] [[ta:தொலுயீன்]] [[vi:Toluen]] [[tr:Toluen]] [[zh:甲苯]]