Final answer:
In IUPAC nomenclature, the suffix used for alcohol groups is '-ol'. When multiple OH groups are present, prefixes like 'di-' or 'tri-' are used before 'ol'. Optionally, the OH group can also be named as a 'hydroxy' substituent, particularly in complex molecules.
Step-by-step explanation:
In the International Union of Pure and Applied Chemistry (IUPAC) system of nomenclature, alcohols are named by substituting the ending of the parent alkane with the suffix -ol. This suffix denotes the presence of an alcohol group in the compound. For example, the simplest alcohol, methane with an OH group, is named methanol.
When the alcohol group is present on a carbon chain, the chain is numbered to ensure the alcohol group receives the lowest possible carbon number. This rule is used to prioritize the placement of the hydroxyl (-OH) group over other substituents like alkyl groups or halogens when numbering the carbon atoms in the longest chain.
If a molecule contains multiple OH groups, then prefixes like di- or tri- are added before the suffix to indicate diols or triols, keeping the parent alkane name intact. In such polyhydroxy alcohols, the -e ending of the parent alkane is retained. An example would be ethane-1,2-diol, commonly known as ethylene glycol.
Alternatively, alcohols can also be named by referring to the OH group as a hydroxy substituent, this method is particularly useful when dealing with more complex molecules. This naming convention would refer to 2-propanol as 2-hydroxypropane.