8.2.2 Naming Alkenes
Alkenes contain carbon- carbon double bond. This is shown in their name by the ending "ene". For example 2- carbon chain containing a carbon- carbon double bond is named ethene, , 3- carbon chaining alkene is named propene, . What will be the name of alkene containing 4- carbon atoms?
With larger chains, the position of double bond is indicated by numbering the chain. Numbering is started from the end nearest to the double bond, noting which carbon the double bond starts from. For example a 4- carbon chain with a double bond starting on carbon number 1 is named as;
If the double bond is starting on the second carbon, then the alkene is named;
NOTE: How do you know from which end of the longest chain numbering is done? For this, you should remember the rule that numbering is started from the end which gives the smaller number to the name.
8.2.3 Naming Alkynes
Alkynes contain a carbon- carbon triple bond. This is shown in their name by the ending "yne". For example, 2- carbon chain containing a carbon- carbon triple bond is named ethyne,
3- carbon chaining alkyne is named propyne, . What will be the name of the alkene containing 4- carbon atoms?
With larger chains, the position of the triple bond is indicated by numbering the chain. Numbering is started from the end nearest to the triple bond, noting which carbon the triple bond starts from. For example, a 4- carbon chain with a double bond starting on carbon number 1 is named;
If the triple bond is starting on the second carbon, then the alkene is named;
But- 2- yne
Alcohols are characterized by the presence of the hydroxyl group- OH) attached to a hydrocarbon chain. This is shown by the ending "ol" in their names. While naming alcohols the "e" of alkane containing the same number of carbon atoms is replaced by the suffix "ol". For example; one carbon alkane is methane, so the name of one carbon alcohol is methanol.