Aromatic and aliphatic hydrocarbons are formed exclusively from carbon and hydrogen, but aromatic have a special structure, the aromatic ring also called benzene ring. Aromatic hydrocarbons has strongly polar bonds, which gives them similar to those of other hydrocarbon physical properties. They are practically inmisibles water, therefore when an aromatic hydrocarbon is mixed with water two phases are formed, of which the top is organic and the lower, water. They tend to be soluble in each other and with other hydrocarbons in any ratio and tend to solubilize other apolar compounds. All compounds with benzene ring structure having at least six carbon atoms and therefore are liquid or solid at room temperature and pressure. The reactivity of the aromatic hydrocarbons is between that of alkanes and alkenes, aromatics, despite having double bonds such as alkenes, have the same reactivity.
- Aromatic hydrocarbons are more resistant to reduction and oxidation alkenes.
- Not undergo addition reactions as easily as alkenes.
- And virtually no part in polymerization reactions.
- They are more resistant to bases, even strong.
The most common reaction of these compounds is the electrophilic aromatic substitution, in which replaces one of the hydrogen atoms of the aromatic ring; why the molecules of the aromatic ring are relatively sensitive to the presence of a strong acid. This reaction occurs most commonly in the presence of inorganic acids such as sulfuric acid and concentrated nitric acid.
The great source of aromatic and aliphatic hydrocarbons is the oil. Benzene can be produced directly by catalytic reforming from n-hexane or cyclohexane for example generally occur at temperatures above 500 ° C and in the presence of specific catalysts.