There are three types of alcohol molecules. The type of alcohol is determined by the position of the hydroxyl functional group.
A primary alcohol is one in which the hydroxyl group (–OH) is attached to a carbon atom with at least two hydrogen atoms.
This will only occur when the hydroxyl group is at the end of the molecule chain.
Propan-1-ol is a primary alcohol.
A secondary alcohol is one in which the hydroxyl group (-OH) is attached to a carbon with only one hydrogen atom attached.
This can happen somewhere in the middle of a carbon chain.
Propan-2-ol is a secondary alcohol.
A tertiary alcohol is one in which the hydroxyl group is attached to a carbon with no hydrogen atoms attached.
This will normally mean that the hydroxyl group is joined to the same carbon atom as a branch.
2-methylpropan-2-ol is a tertiary alcohol.
Alcohols can have more than one hydroxyl group: