Halogen Derivatives Preparation and Properties

Halogen Derivatives Preparation and Properties

Introduction :

→ The replacement of one or more hydrogen atoms of a aliphatic or aromatic, hydrocarbon by an equal number of halogen atoms results in the formation of haloalkane (or alkyl halide) and haloarene (or aryl halid) respectively.

  • Haloalkane : RX where R is alkyl group
  • Haloarne : ArX where Ar ja aryl group.

X is halogen atom (P, Cl, Br, I).
Thus, haloalkanes and haloarenes are halogen derivatives of aliphatic and aromatic hydrocarbons.
The general formula of haloalkane is Cn H2n+1X or RX,
where X = halogen atom (F, Cl, Br, I) and n = 1, 2, 3

Halogen Derivatives Preparation and Properties 1

Haloalkanes contain halogen atom(s) attached to the sp3 hybridised carbon.

Halogen Derivatives Preparation and Properties

Summary of the chapter and glossary

→ Classification of halogen derivation:

Halogen Derivatives Preparation and Properties 2

  • Due to difference in electronegativity of carbon and halogen, C-X bond is polar (C-X) in halogen derivatives.
    Main reactions of alkyl halides are nucleophilic substitution reactions which are classified as SN1 and SN2.
  • Aryl halides mainly gives electrophilic and nucleophilic substitution reactions.
  • Due to resonance in aryl halide there is partial double bond character in C-X bond. Therefore, nucleophilic substitution reaction does not take place easily.
  • In electrophilic substitution reactions of aryl halides, halogen atom is ortho (o-) and para (p.) directing.
  • Most of the polyhalogen compounds like freon, DDT, BHC have main industrial applications but they do not decompose easily therefore they are harmful for environment also.
  • In chlorai hydrate yet there are two —OH group on one carbon only yet it is stable due to intramolecular hydrogen bonding.

Halogen Derivatives Preparation and Properties 3

→ Main chemical reactions of alkyl halides are as follows:

Halogen Derivatives Preparation and Properties 4
Halogen Derivatives Preparation and Properties 5

→ Main chemical properties of chloroform are as follow:

Halogen Derivatives Preparation and Properties 6

→ Main chemical properties of halobenzene can be explained by taking example of chioro benzene.

Halogen Derivatives Preparation and Properties 8Halogen Derivatives Preparation and Properties 9

Chemistry Notes

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