Functional Group : Single covalent bond
Definition : The aliphatic, unsaturated, hydrocarbons containing carbon - carbon single bond is called alkanes.
General formula : CnH2n +2 {n = 1,2,3,.....}
i) Common name system :
The common names of former four alkanes are derived from their sources such as methane, ethane, propane and butane.
The common names of remaining alkanes are derived on the basis of number of carbon atoms representing in greek numericals followed by the suffix 'ane' as below.
Alkane with five carbon atoms called pentane.
C5H12 Pent+ane = pentane
C6H14 Hex+ane = Hexane
C7H16 Hept+ane = Heptane
C8H18 Oct+ane = Octane
C9H20 Non+ane = Nonane
C10H22 Dec+ane = Decane
Further more use the prefixes n, Iso & Neo when ever neccessary.
ii) IUPAC system :
IUPAC means International Union of Pure & Applied Chemistry.
In this system with common names of first four members of alkanes are selected as it is such as methane, ethane, propane & butane.
Do not use the prefixes n, Iso & Neo in IUPAC system.
Following are the IUPAC rules used as determine the IUPAC names of alkanes.
Rule 1 : Select the longest carbon chain.
Count the number of carbon atoms in normal chain only.
Find the name of parent alkane.
Rule 2 : Give the numbering to normal carbon atom from that terminal carbon atom nearest to branched carbon atom (alkyl group).
Rule 3 : Give name and position (location) of branched groups (alkyl groups).
Rule 4 : It alkane contains 2,3,4 similar alkyl groups, use the prefixes di, tri & tetra respectively.
Rule 5 : If alkane contains dissimilar branched alkyl groups, suggest their names by alphabetical order.
| SL. No | Formula | Common name | IUPAC name | ||
| 1 | CH4 | Methane | methane | ||
| 2 | CH3-CH3 | Ethane | ethane | ||
| 3 | CH3-CH2-CH3 | Propane | propane | ||
| 4 | CH3-CH2-CH2-CH3 | n Butane | butane | ||
| 5 |  |
Iso Butane | 2− methylpropane | ||
| 6 | CH3-CH2-CH2-CH2-CH3 | n Pentane | pentane | ||
| 7 |  |
Iso Pentane | 2− methylbutane | ||
| 8 |  |
Neo Pentane | 2,2− dimethylpropane | ||