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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:
Alkyl halide style:

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
bromoethane 

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
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
t-butyl bromide


(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

4-bromobut-1-ene

CH2=CHCH2CH2Br




organic chemistry ©Dr. Ian Hunt, Department of Chemistry University of Calgary