The IUPAC rules permit alkyl halides to be named in two different ways, called
functional class nomenclature and substitutive nomenclature. In functional class nomenclature the alkyl group and the halide (fluoride, chloride, bromide, or iodide) are designated as separate words. The alkyl group is named on the basis of its longest continuous chain beginning at the carbon to which the halogen is attached.
Substitutive nomenclature of alkyl halides treats the halogen as a halo-(fiuoro-, chloro-, bromo-, or iodo-) substituent on an alkane chain. The carbon chain is numbered in the direction that gives the substituted carbon the lower number.
When the carbon chain bears both a halogen and an alkyl substituent, the two are considered of equal rank, and the chain is numbered so as to give the lower number to the substituent nearer the end of the chain.
IUPAC Nomenclature Rules
Functional group suffix = halide (i.e. fluoride, chloride, bromide, iodide)
Substituent name = halo– (i.e. fluoro, chloro, bromo, iodo)
Structural unit: haloalkanes contain R-X where X = F, Cl, Br, I
Notes :
- Haloalkanes can also be named as alkyl halides despite the fact that the halogens are higher priority than alkanes.
- The alkyl halide nomenclature is most common when the alkyl group is simple.
