Classification
of Halogen Derivatives

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The halogen derivative organic compounds can be classified into the following ways :

Classification on the basis of nature of aliphatic compound

The halogen derivatives of alkanes are called haloalkanes. Similarly, the halogen derivatives of alkenes and alkynes are called haloalkenes and haloalkynes respectively.

Chloroethane

Classification on the basis of aliphatic compounds example : Haloalkane

Chloroethene

Classification on the basis of aliphatic compounds example : Haloalkene

Chloroethyne

Classification on the basis of aliphatic compounds example : Haloalkyne

Classification on the basis of number of halogen atoms

Monohalgen

Classification on the basis of number of halgens example : Monohalogen

Dihalogen

Classification on the basis of number of halgens example : Dihalogen

Polyhalogen

Classification on the basis of number of halgens example : Polyhalogen

Classification on the basis of position of halogen

Alkyl halides or haloalkanes

In alkyl halides, the halogen atom is bonded to sp3 hybridised carbon atom. Alkyl halides may be primary, secondary or tertiary depending on whether the halogen is attached to 1°, 2° or 3° carbon atom.

Primary

Classification of halogen derivatives in alkyl halides example : primary

Secondary

Classification of halogen derivatives in alkyl halides example : secondary

Tertiary

Classification of halogen derivatives in alkyl halides example : tertiary

Allylic halides

In allylic halides, the halogen atom is bonded to an sp3 hybridised carbon atom and that carbon atom is attached to the carbon atom containing double bond.

The second carbon from X contains a double bond in the above compounds

Classification of halogen derivatives example : Allylic halide 1
Classification of halogen derivatives example : Allylic halide 2

Benzylic halides

In benzyl halides, the halogen atom is bonded to an sp3 hybridised carbon atom which is bonded to a benzene ring.

Benzylic halide example
Benzylic halide example

Vinylic halide

In vinyl halides, the halogen atom is bonded to an sp2 hybridised carbon atom of C=C double bond.

Vinylic halide example

Aryl halides or haloarenes

In aryl halides, the halogen atom is directly bonded to an sp2 hybridised carbon of benzene.

Chlorobenzene

Haloarene example : Chlorobenzene

1,4-Dibromobenzene

Haloarene example : 1,4-Dibromobenzene

2-Chlorotoluene

Haloarene example : 2-Chlorotoluene

Questions

Question : Name the following halides according to IUPAC system and classify them as alkyl, allyl, benzyl, vinyl or aryl halides:

  1. (CH3)2CHCH(Cl)CH3
  2. o-Br-C6H4-CH3
  3. CH3CH2C(CH3)2CH2I
  4. CH3C(C2H5)2CH2Br
  5. CH3CH=C(Cl)CH2CH(CH3)2
  6. CH3CH2CH(Cl)C6H5

Answer : The answer is written in the following table :

CompoundNameClassification
(CH3)2CHCH(Cl)CH32-Chloro-3-methylbutane2° alkyl halide
o-Br-C6H4-CH31-Bromo-2-methylbenzenearyl halide
CH3CH2C(CH3)2CH2I1-Iodo-2,2-dimethylbutane1° alkyl halide
CH3C(C2H5)2CH2Br1-Bromo-2-ethyl-2-methylbutane1° alkyl halide
CH3CH=C(Cl)CH2CH(CH3)23-Chloro-5-methylhex-2-eneVinylic halide
CH3CH2CH(Cl)C6H5(1-Chloropropyl)benzeneallyl halide

Question : Try to answer the following:

Is this halide aryl halide, vinyl halide or allyl halide?

allyl halide or vinyl halide difference

Is this halide aryl halide, vinyl halide or allyl halide?

difference between aryl allyl and vinyl halide
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