Toluene
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| Toluene | |
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| General | |
| Systematic name | Toluene |
| Other names | Methylbenzene Phenylmethane Toluol |
| Molecular formula | C7H8 |
| SMILES | CC1=CC=CC=C1 |
| Molar mass | 92.14 g/mol |
| Appearance | clear, colourless liquid |
| CAS number | [108-88-3] |
| Hazards | |
| MSDS | Wikisource MSDS |
| Main Hazards | Highly flammable |
| Flash point | 7 °C |
| R/S statement | R: 11, 20 S: 16, 25, 29, 33 |
| RTECS number | XS5250000 |
| Properties | |
| Density and phase | 0.8669 g/mL, liquid at 20 °C |
| Solubility in water | 0.053 g/100 mL (20-25 °C) |
| Solubility in ethanol, acetone, hexane, dichloromethane | Fully miscible |
| Melting point | -93 °C (180 K) |
| Boiling point | 110.6 °C (383.8 K) |
| Viscosity | 0.590 cP at 20 °C |
| Dipole moment | 0.36 D |
| Supplementary data page | |
| Structure and properties | n, εr, etc. |
| Thermodynamic data | Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related aromatic hydrocarbons | benzene xylene naphthalene |
| Related compounds | Methylcyclohexane |
| Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references | |
Toluene, also known as methylbenzene or phenylmethane is a clear water-insoluble liquid with the typical smell of paint thinners, reminiscent 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. Toluene is listed as a Table II precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances[1] (http://www.incb.org/pdf/e/list/red.pdf).
| Contents |
History
The name toluene was derived from the older name toluol that refers to tolu balsam, an aromatic extract from the tropical American 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. The methyl group makes it around 25 times more reactive than benzene in such reactions. It undergoes smooth sulfonation to give p-toluenesulfonic acid, and chlorination by Cl2 in the presence of FeCl3 to give ortho and para isomers 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. Potassium permanganate leads to benzoic acid, whereas chromyl chloride leads to benzaldehyde. Halogenation can be performed under free radical conditions, for example NBS leads gives benzyl bromide.
Hydrogenation of toluene to methylcyclohexane requires a high pressure of hydrogen to go to completion, because of the stability of the aromatic system.
Preparation
Toluene occurs naturally at low levels in crude oil and usually produced in the process of making gasoline via a catalytic reformer, in an ethylene cracker or making coke from coal. Final separation (either via distillation or solvent extraction) will take place in a BTX plant.
Uses
Toluene is used as an octane booster in fuel, as a solvent in paints, paint thinners, chemical reactions, rubber, printing, adhesives, lacquers, leather tanning, disinfectants, and to produce phenol and TNT. It is also used as a raw material for toluene diisocyanate, which is used in the manufacture of polyurethane foams.
Precautions
Inhaling of toluene fumes can be intoxicating, but in larger doses nausea-inducing. Chronic or frequent inhalation of toluene over long time periods leads to irreversible brain damage; lower levels can cause damage to teeth[4].
Suppliers/Manufacturers
- Lancaster (http://www.lancastersynthesis.com/homecatsearch.htm) (now part of Alfa)
- Fisher (https://www1.fishersci.com/index.jsp)
- VWR (http://www.vwr.com/index.htm)
- Alfa (http://www.alfa.com/alf/index.htm)
- Aldrich (http://www.sigmaaldrich.com)
- Aurora Fine Chemicals (http://www.aurora-feinchemie.com)
See also
- External solubility data (http://144.16.93.203/energy/HC270799/HDL/ENV/enven/vol364.htm)
- NIST WebBook (http://webbook.nist.gov/)
References
- B. S. Furnell et al., Vogel's Textbook of Practical Organic Chemistry, 5th edition, Longman/Wiley, New York, 1989.
- (a) L. G. Wade, Organic Chemistry, 5th ed., p. 871, Prentice Hall, Upper Saddle RIver, New Jersey, 2003.
- J. March, Advanced Organic Chemistry, 4th ed., p. 723, Wiley, New York, 1992.
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