Rule 1. The longest chain that contains the -OH group is chosen as the main chain.
![nomenclature-alcohols nomenclatura-alcoholes](/images/stories/organica-i/alcoholes/nomenclatura/nomenclatura-alcoholes-01.png)
Rule 2. The main chain is numbered so that the -OH group takes the lowest locant. The hydroxyl group has preference over carbon chains, halogens, double and triple bonds.
![nomenclature-alcohols nomenclatura-alcoholes](/images/stories/organica-i/alcoholes/nomenclatura/nomenclatura-alcoholes-02.png)
Rule 3. The name of the alcohol is constructed by changing the ending -o of the alkane with the same number of carbons to -ol
![alcohol nomenclature 03](/images/stories/organica-i/alcoholes/nomenclatura/nomenclatura-alcoholes-03.png)
[1] 3-Ethylheptan-2-ol
[2] 2-Propyloctan-1-ol
Rule 4. When there are functional groups of higher priority in the molecule, the alcohol becomes a mere substituent and is called hydroxy- . They have priority over alcohols: carboxylic acids, anhydrides, esters, alkanoyl halides, amides, nitriles, aldehydes and ketones.
![alcohol nomenclature 04](/images/stories/organica-i/alcoholes/nomenclatura/nomenclatura-alcoholes-04.png)
[3] 3-Chloro-4-hydroxypentanoic acid
[4] 5-Hydroxy-4-methylheptan-2-one
[5] 3-Hydroxycyclohexanone
Rule 5 . The -OH group has priority over alkenes and alkynes. The numbering gives the lowest locant to -OH and the name of the molecule ends in -ol.
![alcohol nomenclature 05](/images/stories/organica-i/alcoholes/nomenclatura/nomenclatura-alcoholes-05.png)
[6] Hex-5-en-2-ol
[7] Hex-3-in-5-in-1-ol
[8] 6-Methylcyclohex-2-en-1-ol