Haloalkanes

Basic IUPAC Organic Nomenclature

Haloalkanes / Alkyl halides

Nomenclature	Formula	3D structure
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 etc. 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.

Haloalkane style:

The root name is based on the longest chain containing the halogen.
This root give the alkane part of the name.
The type of halogen defines the halo prefix, e.g. chloro-
The chain is numbered so as to give the halogen the lowest possible number

Alkyl halide style:

The root name is based on the longest chain containing the halogen.
This root give the alkyl part of the name.
The type of halogen defines the halide suffix, e.g. chloride
The chain is numbered so as to give the halogen the lowest possible number.

Haloalkane style: Functional group is an alkane, therefore suffix = -ane The longest continuous chain is C2 therefore root = eth The substituent is a bromine, therefore prefix = bromo No locant is required since the -Br location is unambiguous (i.e. substitution at either carbon gives the same molecule) bromoethane Alkyl halide style: The alkyl group is C2, it's an ethyl The halogen is a bromine, therefore suffix = bromide ethyl bromide	CH₃CH₂Br
Haloalkane style: Functional group is an alkane, therefore suffix = -ane The longest continuous chain is C3 therefore root = prop The substituent is a chlorine, therefore prefix = chloro The first point of difference rule requires numbering from the right as drawn, the substituent locant is 1- The locant is required to distinguish between 1- and 2-chloropropane 1-chloropropane	CH₃CH₂CH₂Cl
Alkyl halide style: The alkyl group is C4, it's a tert-butyl The halogen is a bromine, therefore suffix = bromide tert-butyl bromide Haloalkane style: Functional group is an alkane, therefore suffix = -ane The longest continuous chain is C3 therefore root = prop The substituent is a bromine, therefore prefix = bromo There is a C1 substituent = methyl The substituent locants are both 2- 2-bromo-2-methylpropane	(CH₃)₃CBr
Haloalkane style: Functional group is an alkene, therefore suffix = -ene The longest continuous chain is C4 therefore root = but The substituent is a bromine, therefore prefix = bromo Since bromine is named as a substituent, the alkene gets priority The first point of difference rule requires numbering from the left as drawn to make the alkene group locant 1- Therefore the bromine locant 4- 4-bromobut-1-ene	CH₂=CHCH₂CH₂Br

©Dr. Ian Hunt, Department of Chemistry