Difference between revisions of "Benzene"

Revision as of 02:23, 14 June 2015

Structure of benzene

Benzene is an organic chemical compound with the molecular formula C₆H₆. It is the simplest aromatic hydrocarbon.

Properties

Chemical

Benzene's aromatic ring is involved in complex reactions. At standard conditions, benzene is not very reactive, but it can react with halogens, alkenes, haloalkenes, organic acid anhydrides in the presence of a Lewis acid, (anhydrous aluminium chloride, iron(III) chloride).

The nitration of benzene occurs with a solution of concentrated sulfuric acid and nitric acid.

Physical

Benzene is a colorless and highly flammable liquid with a sweet smell. It is not miscible in water, but it is in many other organic solvents, such as haloalkanes, ethers, ethanol. Benzene will dissolve certain plastic materials, such as polystyrene. It is also a good solvent for sulfur.

Availability

Benzene is available at organic chemical suppliers, but because of its environmental hazards it tends to be somewhat overpriced.

Preparation

Benzene can be prepared from the decarboxylation of sodium benzoate with sodium hydroxide, by heating the mixture and condensing the resulting benzene. You can also use calcium oxide and benzoic acid. The decarboxylation method tends to produce biphenyl as well, giving the condensate a reddish color. Distillation will remove any impurities.

Benzene can also be produced by the pyrolysis of plastic (usually polyethylene) and sodium hydroxide. This method produces benzene along with other hydrocarbons, so fractional distillation might be required.^[1]

CHROMIUM has published a pdf on Sciencemadness library about many methods of synthesizing benzene, gathered from various members.^[2]

Projects

• Napalm
• Toluene synthesis
• Chlorobenzene synthesis
• Nitrobenzene synthesis
• Sulfur extraction

Handling

Safety

Benzene is a strong carcinogen, so work must be performed in a fume hood or outside. Protection gear is required, as it can penetrate skin. If possible, use toluene or xylene, which are cheaper, safer and more widely available.

Storage

Benzene must be stored in closed bottles, away from any source of heat.

Disposal

Benzene can be destroyed using Fenton's reagent. It can also be burned, but it will give off toxic fumes, unless it's done in a waste incinerator.

References

1. ↑ http://www.youtube.com/watch?v=JhUxaNesnxs
2. ↑ http://www.sciencemadness.org/member_publications/benzene_production.pdf

Relevant Sciencemadness threads

• Benzene synthesis
• Benzene from PET