Halogenated compounds are omnipresent in our daily life: forniture, pipes, solvents, insecticides, synthetic intermediates, etc.
It is not common to find natural products only containing halogens but it is with other organic functions in addition. Here you are an important example.
Tyroxine
Substance released by the tyroid gland: it controls the growing, the development and matureness of organisms, the regulation of the basal metabolism, etc.
In the IUPAC nomenclature, an halogen is considered, within the main cahin, as a substituent with its localizer number.
Only in very simple molecules the compounds can be named as alkyl halides.
