Naming Alcohols

Alcohols are named using IUPAC rules, with the suffix -ol replacing the final -e of the parent alkane.Step 1. Find the longest carbon chain that contains the carbon bonded to the -OH group. This gives the stem: meth-, eth-, prop-, but-, pent-, hex-.Step 2. Number the chain from the end that gives the carbon bearing the -OH group the lowest possible number. Put this number just before -ol, for example propan-1-ol and propan-2-ol.Step 3. Name any alkyl side chains as prefixes (methyl, ethyl) with their position numbers, in alphabetical order.Step 4. If there is more than one -OH group, keep the -e of the alkane and use di- or tri-, for example ethane-1,2-diol and propane-1,2,3-triol.Worked example: name (CH₃)₂C(OH)CH₂CH₃.
The longest chain containing the C-OH carbon has 4 carbons, so the stem is butan-. Numbering from the left puts the -OH on carbon 2 (from the right it would be carbon 3). There is a methyl group on carbon 2. The name is 2-methylbutan-2-ol.Other examples:
CH₃OH is methanol
CH₃CH₂CH₂CH₂OH is butan-1-ol
CH₃CH(OH)CH₂CH₃ is butan-2-ol
(CH₃)₃COH is 2-methylpropan-2-olMethanol and ethanol need no number, because the -OH group can only be on carbon 1.