Compound of Carbon Containing Halogen: Nomenclature of Haloalkanes (For CBSE, ICSE, IAS, NET, NRA 2022)

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Nomenclature of Haloalkanes

Rules for naming haloalkanes according to the IUPAC system are as follows:

The longest chain of the carbon atoms bearing the halogen atom is selected.

Nomenclature of Haloalkanes

The longest chain of carbon atoms in the above example is shown in the box.

Numbering of the carbon atoms in the chain is done in such a way that the carbon atom bearing the halogen atom gets the lowest number. For example,

Nomenclature of Haloalkanes

The word chloro, is prefixed to the parent hydrocarbon name. So, the correct name for the above halo compound is

Nomenclature of Haloalkanes

In alkyl substituted haloalkanes, the longest chain containing halogen atom is selected for numbering. For example,

Nomenclature of Haloalkanes
  • In structure I , both the ways of selection are correct since they include chloro group.
  • In structure II numbering shown is not correct since it does not include chloro group.

When two or more halogen atoms are present in a compound, the longest chain selected must contain the maximum number of halogen atoms . The multiplicative prefixes (di, tri, tetra, etc.) are added before the name of halogen atom to indicate the number of halogen atoms. For example,

Nomenclature of Haloalkanes
Nomenclature of Haloalkanes

Nomenclature of Haloarenes

  • Haloarenes are those aromatic halogen compounds in which the halogen atom is directly linked to an aromatic ring.
  • General formula is Ar-X where Ar- represents an aromatic ring and X denotes the halogen.
  • In naming a haloarene, the prefix chloro, bromo-or iodo- etc. is are added to name of arene according to halogen (s) present.
  • The relative positions of halogen atoms are indicated by appropriate numbers.
  • The prefixes ortho (o-) , meta (m-) and para (p-) are also commonly used respectively to indicate the relative positions i.e.. 1,2-, 1,3- and 1,4- of substituents in a benzene ring.

Examples of nomenclature of haloarenes are as follows:

Nomenclature of Haloarenes

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