Module 2

Lesson 1.3  Naming Halogenated Hydrocarbons 



Key Concepts


Naming halogenated hydrocarbons (alkyl halides) is similar to naming branched hydrocarbons. Simply consider the halogen atoms to be branches (i.e. "halide" branches). Keep the following points in mind:

  1. When identifying the main or parent chain, keep in mind that the parent chain must contain the carbon to which the halide branch is attached.


  2. When numbering the carbons of the parent chain, assign the alkyl branches and halide branch(es) the lowest possible number(s).  Halide branches do not receive priority.


  3. If more than one type of halide branch is present, list the halide branches alphabetically. The halide branches are named by shortening the halogen names.

    Chemical symbol prefix
    -F fluoro
    -Cl chloro
    -Br bromo
    -I iodo

  4. If more than one atom of the same halide is present, use the prefixes di, tri, tetra, etc. Realize that these prefixes do not affect the alphabetical listing of the halides.



Examples of Halogenated Hydrocarbons


1,2-dichloro-1,2-difluoroethane


2,2-dichloro-1,1,1,4,4,4-hexafluorobutane


1,1-difluorocyclopentane


tetrafluoroethene


1,4-dibromo-2-chlorobenzene

Learning Tip

When writing molecular formulae for halogenated hydrocarbons, list halogen atoms in ascending order of electronegativity (i.e. I, Br, Cl, F)

Examples:

C4H2Cl2F6, C4H4Br2ClF3, C5H8F2, C8H8F8I2, C3Br2F4, C6H3Br2Cl


Check Your Understanding


Complete Practice Question 2 on page 419 of the textbook.

Check your work by clicking the link below.

Page 419 Practice Question 2

  1. triiodomethane
  2. 3-chloromethylpropene
  3. dichloromethane
  4. 1,2,3-tribromopropane
  5. chlorobenzene
  6. phenylethene

You might have used names that contain redundancies; these are still correct. For example, 3-chloro-2-methylprop-1-ene is acceptable for question b) above.