Haloalkanes and Haloarenes

 Haloalkanes and Haloarenes

Haloalkanes- 
The word Haloalkane is made up by the two words, -
         Halo = halogen
         Alkane= Aliphatic hydrocarbon (containing single bond only)

So, Haloalkanes are those compounds which is formed when a hydrogen atom replaced by any halogen atom from the alkanes.

               - H
   R-H  -------------->      R-X
                +X

Where ,   R  =  Alkyl group
              X  = Halogen ( F,Cl, Br, I)
For example-
   
                           - H
         CH3-H  --------------> CH3-Cl
                           +Cl


Haloarenes- 
The word Haloarene is made up by the two words, -
         Halo = halogen
   Arene= Aromatic hydrocarbon

So, Haloarenes are those compounds which is formed when a hydrogen atom replaced by any halogen atom from the arenes.

               - H
   Ar-H  -------------->      Ar-X
                +X

Where ,  Ar  =  Aromatic hydrocarbon
              X  = Halogen ( F,Cl, Br, I)
For example-
   
                           - H
         C6H5-H  --------------> C6H5-Cl
                           +Cl


Classification of Halogen derivatives of Hydrocarbon -

(A) On the basis of Nature of carbon chain - 
On this basis the Halogen derivatives of Hydrocarbons are of two types :-
(1) Aliphatic Halogen Compounds  -

Aliphatic Halogen Compounds are divided into three groups-

(a) Haloalkanes - The Halogen derivatives of the alkanes are called Haloalkanes.
These are called mono, di ,tri, tetra or polyhaloalkane on the number of hydrogen atom replaced by a halogen atom.
 For example-

         H
         |
    H-C-Cl     ( ChloroMethane)
         |
         H


         H
         |
    H-C-Cl     ( diChloroMethane)
         |
         Cl


         Cl
         |
    H-C-Cl     (tri ChloroMethane)
         |
         Cl

         Cl

         |
    Cl-C-Cl  ( tetra ChloroMethane)
         |
         Cl

Mono Halogen derivatives are also called alkyl halides or Haloalkanes.

Classification of alkyl halides-

(|) Primary (1°) alkyl halide - 

When Halogen atom is attached by 1° carbon atom is known as primary alkyl halide.
   For example-


         H
         |
    H-C-Cl     ( ChloroMethane)
         |
         H

(||) Secondary (2°) alkyl halide - 

When Halogen atom is attached by 2° carbon atom is known as secondary alkyl halide.
   For example-


             H
             |
    CH3-C-Cl  ( 2-ChloroPropane)
             |
             CH3

(|||) Tertiary (3°) alkyl halide - 

When Halogen atom is attached by 3° carbon atom is known as tertiary alkyl halide.
   For example-


             C H3
             |
    CH3-C-Cl  ( 2-Chloro 2- methyl
             |            Propane)
             CH3

(b) Haloalkenes - The Halogen derivatives of the alkenes are called Haloalkenes. 

For example-

CH2=CH-Cl    ( Chloroethene)

(c) Haloalkynes - The Halogen derivatives of the alkynes are called Haloalkynes. 

For example-

      _ 

CH=C-Cl    ( Chloroethyne)

(2) AromaticHalogen Compounds  -

Aromatic Halogen Compounds are divided into two groups-

(a) Nuclear Halogen derivatives-

When one or more hydrogen atom are replaced by one or more Halogen atom from an aromatic ring then formed compound is called nuclear halogen derivative or Haloarene or aryl halide.
For example-
  C6H5-Cl     ( chlorobenzene)


(b) Side chain  Halogen derivatives-

When one or more hydrogen atom are replaced by one or more Halogen atom from a side chain of aromatic ring then formed compound is called side chain halogen derivative or  aryl alkyl halide.
For example-
       C6H5CH2-Cl           
  ( Phenyl chloro methane )



(B) On the basis of hybridisation of the C -X bond-   




(a) Csp3--- bond containing compounds-


In this type of monohalogen Compounds , the halogen atom is attached to the directly to the sp3 hybridised carbon atom.

(1) Haloalkane or alkyl halide -
In Haloalkane , Halogen atom is attached to the alkyl group (R) . These are further divided into primary (1°), secondary (2°) , or tertiary (3°) .

For example-


         H
         |
    H-C-Cl     ( ChloroMethane)                   (1°)
         |
         H

             H
             |
    CH3-C-Cl  ( 2-ChloroPropane)               (2°)
             |

             CH3

             C H3

             |

    CH3-C-Cl  ( 2-Chloro 2- methyl             

             |            Propane)                             (3°)

             CH3

(2) Alylic halide-
In this type of halides, the halogen atom is attached to the next carbon ( sp3) of carbon - carbon double bond ( C= C).
For example -
   CH2 = CH- CH2-X

(3) Benzylic halide-

In this type of halides, the halogen atom is attached to the next carbon ( sp3) of  aromatic ring.
For example
 C6H5-CH2-Cl

(b) Csp2--- bond containing compounds-

In this type of monohalogen Compounds , the halogen atom is attached to the directly to the sp2  hybridised carbon atom(C=C).

(1) Vinylic halide-
In this type of halides, the halogen atom is attached to the sp2 hybridised carbon - carbon double bond ( C= C).
For example -
   CH2 = CH-X

(2) Aryl halide-
In this type of halides, the halogen atom is attached to the directly aromatic ring.
For example -

C6H5-Cl

(c) Csp--- bond containing compounds-

In this type of monohalogen Compounds , the halogen atom is attached to the directly to the sp  hybridised carbon atom(C-C triple bond).

For example-

       _

H-C=C-Cl