10. HALOGEN DERIVATIVES - part 01 - Classification of halogen derivatives

10. HALOGEN DERIVATIVES - part 01 - Classification of halogen derivatives

Classification of halogen derivatives :

  • On the basis of hydrocarbon skeleton towhich halogen atom is bonded - 
  1. Haloalkanes -   CH3 - CH2 - X  
  2. Haloalkenes -   CH2 = CH - X
  3. Haloalkynes -   HC ≡ C - X
  4. Haloarenes.  -   C6H5-X 
  • On the basis of number of halogen atoms,halogen derivatives are classified as mono, di, tri or poly halogen compounds
                                                             1.Monohalogen Compounds - 


2. Dihalogen Compounds -

3. Trihalogen Compounds


Classification of monohalogen compounds : [on the basis of position of halogen atom and the type of hybridization of carbon to which halogen is attached.]
1. Alkyl halides or haloalkanes :
  • Halogen atom is bonded to sp3 hybridizedcarbon which is a part of saturated carbonskeleton. 
  • Alkyl halides may be primary, secondary or tertiary :
2. Allylic halides : 
  • Halogen atom is bonded to a sp3 hybridizedcarbon atom next to a carbon-carbon double bond.
3.Benzylic halide : 
  • Halogen atom is bonded to a sp3 hybridizedcarbon atom which is further bonded to an aromatic ring.
4. Vinylic halides : 

  • Halogen atom is bonded to a sp2 hybridizedcarbon atom of aliphatic chain. 
  • Vinylic halide is a haloalkene.
5.Haloalkyne : 

  • Halogen atom is bonded to a sp hybridizedcarbon atom.
                        HC ≡ C - X

6. Aryl halides or haloarenes : 

  • Halogen atom is directly bonded to the sp2 hybridized carbon atom of aromatic ring.
Nomenclature of halogen derivatives :

1. Common names : 
  • Derived by naming the alkyl group followed by the name of halogen as halide. 
  • For example, methyl iodide, tert-butyl chloride.
  • For dihalogen derivative of an arene, prefix o-, m-, p- are used in common name system 
2. IUPAC system  : 
  • alkyl halides are named as haloalkanes. 
  • Aryl halides are named as haloarenes in common as well as IUPAC system. 
  • For dihalogen derivative of an arene, prefix o-, m-, p- are used in common name system but in IUPAC system the numerals 1,2 ; 1,3 and 1,4 respectively are used.

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