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Naming Straight-Chain Haloalkanes (alkyl halides)

Key Concepts

  • Compounds containing carbon (C), hydrogen (H) and one or more halogen atoms are known as haloalkanes (or as alkyl halides1).

  • The term "halogen" refers to an element that belongs to the halogen group, or Group 17, of elements in the Periodic Table.
    That is, the elements fluorine (F), chlorine (Cl), bromine (Br) and iodine (I) 2

  • In a haloalkane molecule each carbon atom forms a single covalent bond between itself and another carbon atom to form the parent alkane molecule.

  • In a haloalkane molecule some, or all, of the hydrogen atoms in the parent alkane molecule are replaced with halogen atoms.

Steps for Naming Straight-Chain Haloalkanes

The systematic IUPAC name for a straight-chain haloalkane is made up of a prefix and a stem.

halo alkane
prefix stem name

The stem is determined by the number of carbon atoms making up the longest carbon chain (which includes the halogen atoms that have substituted for hydrogen atoms).

The prefix is determined by the number and type of halogen atoms that occur along the parent alkane chain (the longest carbon chain).

Step 1: Identify and name the longest carbon chain containing the halogen atoms.
Name the carbon chain as you would for an alkane molecule:

Number of Carbon
atoms in the chain
1 2 3 4 5 6 7 8 9 10
stem
(parent alkane)
methane ethane propane butane pentane hexane heptane octane nonane decane

Step 2: Identify and name each halogen atom present in the molecule.

The name used for the halogen atom is constructed by removing the "ine" ending from the name of the element and replacing it with an "o" ending:

Symbol of Element Name of Element "Halo" Prefix to use
F fluorine fluoro
Cl chlorine chloro
Br bromine bromo
I iodine iodo

Step 3: If more than one type of halogen atom is present, list the halo prefixes in ascending alphabetical order from left to right:

order written first second third fourth
prefix bromo chloro fluoro iodo

Step 4: If more than one atom of the same halogen element is present, modify the halo prefix using the appropriate multiplier prefix:

Number of identical halogen atoms 2 3 4 5 6 7 8
multiplier prefix di tri tetra penta hexa hepta octa

Step 5: Add the multiplier prefix to the name of the halogen atom as written in the order given in Step 3 above.
If only one atom of a particular halogen atom is present, no multiplier is included for this atom.
DO NOT change the order!

order written first second third fourth
modified prefix multiplierbromo multiplierchloro multiplierfluoro multiplieriodo

Step 6: Number the carbon atoms in the parent alkane chain so that the halogen atoms are attached to the carbon atoms with the lowest set of numbers.

The lowest set of numbers is that which, when compared term by term in the order given above, has the lowest term at the first point of difference.

Example: 1-bromo-2-chloroethane NOT 2-bromo-1-chloroethane

Step 7: Use the number of the carbon atom to which each halogen is attached as an infix for that modified prefix.
Note: The modified prefix representing each halogen atom must be preceded by a number.
If the modified prefix does not include a multiplier (that is only one atom of this halogen element is present), one number will precede the prefix.
If the modified prefix includes a multipler prefix, then the number of numbers is the same as indicated by the multiplier prefix
di means there must be two numbers preceding the prefix, tri means there must be three numbers preceding the prefix, etc

Note, numbers for each halogen atom are written in ascending order.
Numbers making each infix are separated from each other by a comma (,)
Numbers making up each infix are separated from words (or word fragments) by hyphens (-)

order written first second third fourth
infix-modified prefix infix-multiplierbromo infix-multiplierchloro infix-multiplierfluoro infix-multiplieriodo

Step 8: Assemble the final name.

Write the out the string of infix-multiplierhalo prefixes in alphabetical order with a hyphen (-) between word fragments and numbers:

infix-multiplierbromo-infix-multiplierchloro-infix-multiplierfluoro-infix-multiplieriodo

Write the name of the parent alkane (determined in Step 1 above) directly after the last halogen element's prefix.
DO NOT leave a space between the name of the halogen prefix and the alkane's name.

infix-multiplierbromo-infix-multiplierchloro-infix-multiplierfluoro-infix-multiplieriodoalkane

Example: Naming Haloalkane with a Single Substitution

Name the haloalkane molecule shown below:

    H  H  H   
    | | | 
H-C-C-C-Cl
    | | | 
    H   H   H   

Step 1: Identify and name the longest carbon chain containing the halogen atoms.

    H  H  H   
    | | | 
H-C-C-C-Cl
    | | | 
    H   H   H   

Longest carbon chain has 3 carbon atoms.
propane is the name of the alkane with 3 carbon atoms.
Stem = propane

Step 2: Identify and name each halogen atom present in the molecule:

    H  H  H   
    | | | 
H-C-C-C-Cl
    | | | 
    H   H   H   

Cl is the symbol for the halogen element chlorine.
prefix is chloro

Step 3: If more than one type of halogen atom is present, list the halo prefixes in ascending alphabetical order from left to right:

Only one type of halogen atom is present, that is, just chlorine.

prefix is still chloro

Step 4: If more than one atom of the same halogen element is present, modify the halo prefix using the appropriate multiplier prefix:

Only one chlorine atom is present.

prefix is still chloro

Step 5: Add the multiplier prefix to the name of the halogen atom as written in the order given in Step 3 above.

No multiplier prefix is required because only one atom of chlorine is present.

prefix is still chloro

Step 6: Number the carbon atoms in the parent alkane chain so that the halogen atoms are attached to the carbon atoms with the lowest set of numbers

numbering from left to right   numbering from right to left
    H  H  H   
    | | | 
H-C1-C2-C3-Cl
    | | | 
    H   H   H   
 
    H  H  H   
    | | | 
H-C3-C2-C1-Cl
    | | | 
    H   H   H   

Numbering from right to left results in the chlorine atom being attached carbon 1 rather than carbon 3 (as when the chain is numbered from left to right).
The preferred numbering is therefore from right to left because it results in the lowest number for the infix.

Step 7: Use the number of the carbon atom to which each halogen is attached as an infix for that modified prefix.

chlorine atom attached to carbon 1 :

infix-prefix is 1-chloro

Step 8: Assemble the final name: add the prefix to the name of the parent alkane

1-chloropropane

Steps for Drawing the Structure4 of Straight Chain Haloalkanes

Step 1: Break the name of the haloalkane up into two parts: prefix and stem (the name of the parent alkane)

halo alkane
prefix stem name

Step 2: Determine the number of carbon atoms in the parent alkane from the stem.

Step 3: Draw the parent alkane showing all carbon atoms and covalent bonds.
    Remember that there are only single covalent bonds between the carbon atoms in an alkane molecule.
    Do not show hydrogen nor halogen atoms.

Step 4: Break the prefix of the haloalkane's name up into "infix-multiplierhalo" segments.

Step 5: Determine the number and type of each halogen atom present using each "multiplierhalo" segment.

Step 6: Determine the location of each halogen atom using the infix for each segment.

Step 7: Number the carbon atoms in this parent alkane molecule in ascending order from left to right.

Step 8: Position each halogen atom along the chain in the location indicated by the infix for each segment.

Step 9: Complete the structure by placing a hydrogen atom (H) at the end of any vacant covalent bond.

Example

Draw the structure for 1,2-dibromo-1-chloro-1-fluoroethane

Step 1: Break the name of the haloalkane up into two parts: prefix and stem (the name of the parent alkane)

1,2-dibromo-1-chloro-1-fluoro ethane
prefix stem name

Step 2: Determine the number of carbon atoms in the parent alkane from the stem.

stem is ethane (name of the parent alkane)

eth = 2 carbon atoms

Step 3: Draw the parent alkane showing all carbon atoms and covalent bonds.
    Remember that there are only single covalent bonds between the carbon atoms in an alkane molecule.
    Do not show hydrogen nor halogen atoms.

  |   |  
- C - C -
  |   |  

Step 4: Break the prefix of the haloalkane's name up into "infix-multiplierhalo" segments.

There are three "infix-multiplierhalo" segments in the name of this molecule:
    (i) 1,2-dibromo
    (ii) 1-chloro
    (iii) 1-fluoro

Step 5: Determine the number and type of each halogen atom present using each "multiplierhalo" segment.

    (i) 1,2-dibromo = two Br atoms (di multiplier = two atoms of this halogen)
    (ii) 1-chloro = one Cl atom (no multiplier means there is only one atom of this halogen)
    (iii) 1-fluoro = one F atom (no multiplier means there is only one atom of this halogen)

Step 6: Determine the location of each halogen atom using the infix for each segment.
    (i) 1,2-dibromo : one Br atom is located on carbon 1, one Br atom is located on carbon 2
    (ii) 1-chloro : one Cl atom is located on carbon 1
    (iii) 1-fluoro : one F atom is located on carbon 1

Step 7: Number the carbon atoms in this parent alkane molecule in ascending order from left to right.

  |   |  
- C1 - C2 -
  |   |  

Step 8: Position each halogen atom along the chain in the location indicated by the infix for each segment.

  Cl      
  |   |  
Br- C1 - C2 -Br
  |   |  
  F      

Step 9: Complete the structure by placing a hydrogen atom (H) at the end of any vacant covalent bond.

  Cl   H  
  |   |  
Br- C - C -Br
  |   |  
  F   H  

Animated Tutorial

Summay Table 1: Name and Structure of Some Single Substitution Haloalkanes

No. Carbon atoms bromoalkane chloroalkane fluoroalkane
1
    H
|
   
Br - C - H
    |
H
   

bromomethane

    H
|
   
Cl - C - H
    |
H
   

chloromethane

    H
|
   
F - C - H
    |
H
   

fluoromethane


2
    H
|
  H
|
   
Br - C - C - H
    |
H
  |
H
   

bromoethane
(1-bromoethane)

    H
|
  H
|
   
Cl - C - C - H
    |
H
  |
H
   

chloroethane
(1-chloroethane)

    H
|
  H
|
   
F - C - C - H
    |
H
  |
H
   

fluoroethane
(1-fluoroethane)


3
    H
|
  H
|
  H
|
   
Br - C - C - C - H
    |
H
  |
H
  |
H
   

1-bromopropane

    H
|
  H
|
  H
|
   
Cl - C - C - C - H
    |
H
  |
H
  |
H
   

1-chloropropane

    H
|
  H
|
  H
|
   
F - C - C - C - H
    |
H
  |
H
  |
H
   

1-fluoropropane

    H
|
  Br
|
  H
|
   
H - C - C - C - H
    |
H
  |
H
  |
H
   

2-bromopropane

    H
|
  Cl
|
  H
|
   
H - C - C - C - H
    |
H
  |
H
  |
H
   

2-chloropropane

    H
|
  F
|
  H
|
   
H - C - C - C - H
    |
H
  |
H
  |
H
   

2-fluoropropane


Summay Table 2: Name and Structure of Some dihaloalkanes (same halogen type)

No. Carbon atoms dibromoalkane dichloroalkane difluoroalkane
1
    H
|
   
Br - C - Br
    |
H
   

dibromomethane

    H
|
   
Cl - C - Cl
    |
H
   

dichloromethane

    H
|
   
F - C - F
    |
H
   

difluoromethane


2
    Br
|
  H
|
   
Br - C - C - H
    |
H
  |
H
   

1,1-dibromoethane

    Cl
|
  H
|
   
Cl - C - C - H
    |
H
  |
H
   

1,1-dichloroethane

    F
|
  H
|
   
F - C - C - H
    |
H
  |
H
   

1,1-difluoroethane

    H
|
  H
|
   
Br - C - C - Br
    |
H
  |
H
   

1,2-dibromoethane

    H
|
  H
|
   
Cl - C - C - Cl
    |
H
  |
H
   

1,2-dichloroethane

    H
|
  H
|
   
F - C - C - F
    |
H
  |
H
   

1,2-difluoroethane


3
    Br
|
  H
|
  H
|
   
Br - C - C - C - H
    |
H
  |
H
  |
H
   

1,1-dibromopropane

    Cl
|
  H
|
  H
|
   
Cl - C - C - C - H
    |
H
  |
H
  |
H
   

1,1-dichloropropane

    F
|
  H
|
  H
|
   
F - C - C - C - H
    |
H
  |
H
  |
H
   

1,1-difluoropropane

    H
|
  Br
|
  H
|
   
Br - C - C - C - H
    |
H
  |
H
  |
H
   

1,2-dibromopropane

    H
|
  Cl
|
  H
|
   
Cl - C - C - C - H
    |
H
  |
H
  |
H
   

1,2-dichloropropane

    H
|
  F
|
  H
|
   
F - C - C - C - H
    |
H
  |
H
  |
H
   

1,2-difluoropropane

    H
|
  H
|
  H
|
   
Br - C - C - C - Br
    |
H
  |
H
  |
H
   

1,3-dibromopropane

    H
|
  H
|
  H
|
   
Cl - C - C - C - Cl
    |
H
  |
H
  |
H
   

1,3-dichloropropane

    H
|
  H
|
  H
|
   
F - C - C - C - F
    |
H
  |
H
  |
H
   

1,3-difluoropropane

    H
|
  Br
|
  H
|
   
H - C - C - C - H
    |
H
  |
Br
  |
H
   

2,2-dibromopropane

    H
|
  Cl
|
  H
|
   
H - C - C - C - H
    |
H
  |
Cl
  |
H
   

2,2-dichloropropane

    H
|
  F
|
  H
|
   
H - C - C - C - H
    |
H
  |
F
  |
H
   

2,2-difluoropropane


Summay Table 3: Name and Structure of Some dihaloalkanes (different halogen type)

No. Carbon atoms n-bromo-n-chloroalkane n-bromo-n-fluoroalkane n-chloro-n-fluoroalkane
1
    H
|
   
Br - C - Cl
    |
H
   

bromochloromethane

    H
|
   
Br - C - F
    |
H
   

bromofluoromethane

    H
|
   
Cl - C - F
    |
H
   

chlorofluoromethane


2
    Cl
|
  H
|
   
Br - C - C - H
    |
H
  |
H
   

1-bromo-1-chloroethane

    F
|
  H
|
   
Br - C - C - H
    |
H
  |
H
   

1-bromo-1-fluoroethane

    F
|
  H
|
   
Cl - C - C - H
    |
H
  |
H
   

1-chloro-1-fluoroethane

    H
|
  H
|
   
Br - C - C - Cl
    |
H
  |
H
   

1-bromo-2-chloroethane

    H
|
  H
|
   
Br - C - C - F
    |
H
  |
H
   

1-bromo-2-fluoroethane

    H
|
  H
|
   
Cl - C - C - F
    |
H
  |
H
   

1-chloro-2-fluoroethane


3
    Cl
|
  H
|
  H
|
   
Br - C - C - C - H
    |
H
  |
H
  |
H
   

1-bromo-1-chloropropane

    F
|
  H
|
  H
|
   
Br - C - C - C - H
    |
H
  |
H
  |
H
   

1-bromo-1-fluoropropane

    F
|
  H
|
  H
|
   
Cl - C - C - C - H
    |
H
  |
H
  |
H
   

1-chloro-1-fluoropropane

    H
|
  Cl
|
  H
|
   
Br - C - C - C - H
    |
H
  |
H
  |
H
   

1-bromo-2-chloropropane

    H
|
  F
|
  H
|
   
Br - C - C - C - H
    |
H
  |
H
  |
H
   

1-bromo-2-fluoropropane

    H
|
  F
|
  H
|
   
Cl - C - C - C - H
    |
H
  |
H
  |
H
   

1-chloro-2-fluoropropane

    H
|
  H
|
  H
|
   
Br - C - C - C - Cl
    |
H
  |
H
  |
H
   

1-bromo-3-chloropropane

    H
|
  H
|
  H
|
   
Br - C - C - C - F
    |
H
  |
H
  |
H
   

1-bromo-3-fluoropropane

    H
|
  H
|
  H
|
   
Cl - C - C - C - F
    |
H
  |
H
  |
H
   

1-chloro-3-fluoropropane

    H
|
  Br
|
  H
|
   
Cl - C - C - C - H
    |
H
  |
H
  |
H
   

2-bromo-1-chloropropane

    H
|
  Br
|
  H
|
   
F - C - C - C - H
    |
H
  |
H
  |
H
   

2-bromo-1-fluoropropane

    H
|
  Cl
|
  H
|
   
F - C - C - C - H
    |
H
  |
H
  |
H
   

2-chloro-1-fluoropropane

    H
|
  Cl
|
  H
|
   
H - C - C - C - H
    |
H
  |
Br
  |
H
   

2-bromo-2-chloropropane

    H
|
  F
|
  H
|
   
H - C - C - C - H
    |
H
  |
Br
  |
H
   

2-bromo-2-fluoropropane

    H
|
  F
|
  H
|
   
H - C - C - C - H
    |
H
  |
Cl
  |
H
   

2-chloro-2-fluoropropane


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1The term alkyl halide refers to the functional naming of this group of organic compounds and is no longer preferred by IUPAC.

2Astatine (At) is also a halogen element, but not one you are likely to meet during your chemistry course.

3IUPAC is the abbreviation for the International Union of Pure and Applied Chemistry

The preferred IUPAC systematic name places the infix for the locant immediately before that part of the name to which it relates, except when the preferred IUPAC name is the traditional contracted name in which case the infix is placed at the front of the name.
The systematic IUPAC name is derived from a set of general "rules" designed to ensure that each organic molecule can be given an unambiguous name.
The rules for naming organic compounds are still being developed. The most recent document for referral is "Preferred names in the nomenclature of organic compounds" (Draft 7 October 2004).

4"Structure" here will refer to a valence structure, which can be used to represent the 2-dimensional structural formula.

Once you have drawn the valence structure or 2-dimensional structural formula you can use this to draw

a condensed (semi) structural formula

or a skeletal structure

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