Hydrocarbons:
Hydrocarbons are compounds containing carbon and hydrogen only. Depending upon the type of carbon—carbon bonds present, hydrocarbon can be classified into three main categories viz,
- Saturated Hydrocarbons
- Unsaturated Hydrocarbons
- Aromatic Hydrocarbons
1) Saturated Hydrocarbons:
The hydrocarbons which contain only carbon—carbon single bonds are called saturated hydrocarbons. These include open chain hydrocarbons as well as closed chain (cyclic) hydrocarbons. For examples, alkanes and cycloalkanes.
CH4 CH3—CH3 CH3—CH2—CH3 CH3—CH2—CH2—CH3 Methane Ethane Propane Butane
2) Unsaturated Hydrocarbons:
The hydrocarbons which contain carbon-carbon multiple bonds (double or triple bonds or both) are called unsaturated hydrocarbons. Depending upon the multiple bonds (double or triple bonds) they are classified as alkenes and alkynes.
Alkenes are hydrocarbons which contain at least one carbon—carbon double bond. e.g.
CH2 = CH2 CH2 == CH—CH3 CH3—CH = CH—CH3
Ethene Propene Butene
Alkynes are hydrocarbons which contain at least one carbon—carbon triple bond. e.g.
CH ≡ CH CH ≡≡C—CH3 CH3—C ≡ C—CH3
Ethyne Propyne Butyne
3) Aromatic Hydrocarbons:
Aromatic hydrocarbons are those which contain at least one special type of hexagonal ring of carbon atoms with three double bonds in the alternate positions. The ring is called aromatic ring or benzene ring. For examples,
