What are the functional group names of halogenoalkanes?
They don't have a functional group name similar to that of hydroxyl/phenyl/etc. Instead, you've to name them as if they were an alkyl branch - "haloalkyl" - and that too within parentheses.



Have a look at this simple comparison:



Notice that both 2,3-dimethylbutyl and chloromethyl are both within parentheses, whereas phenyl isn't. Therefore don't mistake "haloalkyl" to be a short name as "phenyl" is. There simply is no such short name, and you've to name it as an alkyl chain instead.