In naming the compounds containing double or triple bonds, the following rules are followed:
Rule 1. Select the longest continuous chain containing the carbon atoms carrying multiple bonds (double or triple). This gives the parent name of alkene or alkyne.
Rule 2. Once the longest chain is selected, the carbon atoms of the chain are numbered as 1,2,3......from one end to the other keeping in mind that the carbon atoms involved in multiple bonds should get a lowest possible number. For example
Rule 3. If the organic compound contains only one double bond or the triple bond, its locant on the positional number is always placed before its suffix, e.g.
Rule 4. All the rules for naming side chains or substituents are then followed as in alkanes. e.g.
Rule 5. If there are more than one double bond in the molecule, their positions are indicated separately and the prefix (word root) is followed by a diene, a triene etc. e.g.
Rule 6. If there are more than one triple bond in the molecule, their positions are indicated separately and the prefix (word root) is followed by a diene, triene, etc. e.g.
Rule 7. If both double and triple bonds are present, the numbering of the parent chain should always be done from that end which is nearer to the double or the triple bond (lowest sum for the multiple bonds must be followed).
Rule 8. If the double bond and the triple bond are present at equal distances from the end of the chain, then double bond is always given the first preference over the triple bond in numbering, e.g.
