In IUPAC nomenclature, when determining the priority of functional groups or substituents for naming a compound, halogens (such as fluorine, chlorine, bromine, and iodine) are generally treated as substituents rather than as functional groups.
Hydrocarbons (like alkanes, alkenes, and alkynes) are classified based on the type of bonds they contain. For example:
- Alkanes are saturated hydrocarbons.
- Alkenes contain double bonds.
- Alkynes contain triple bonds.
Typically, functional groups take precedence over halogens when it comes to determining the parent structure and the highest priority in naming. For example, if both a halogen and a functional group like an alcohol or a carboxylic acid are present in a compound, the functional group would take priority in determining the suffix and the main part of the name.
If primarily hydrocarbons are considered (such as determining the longest carbon chain), then the halogens are treated as substituents.
In summary:
- Functional groups (like alcohols, carboxylic acids) typically have a higher priority than halogens.
- Among substituents, halogens are given a priority that is generally lower than functional groups but higher than simple alkyl substituents.
So to answer your question directly: Hydrocarbons do not really "get priority" over halogens, but when naming a compound, the highest priority functional groups (if present) dictate the main structure and naming, while halogens are considered substituents.