Halogen Derivatives BHC Preparation and Properties
→ It has many çommon names e.g.. like gammexane. lindane, etc. It’s IUPAC name is 1, 2, 3, 4, 5, 6 : hexachiorocyclohexane. It is prepared by chlorination of benzene in the presence of UV radiations.
→ It is a mixture of many isomers (α, β, γ, δ, ε, η, ρ, θ). BHC is used in agricultural field in the form of insecticide. Insecticidal activity is highest in garna-isomer (γ-BHC).
→ in comparison to other isomers, γ-isomer is comparatively small so its penetrating power is more.
Envronmentol Impact of DDT and BHC
→ DDT and BHC are harmful and poisonous substances and they do not easily decompose. When they are used on crops in agricultural field as insecticide, they slowly accumulate in soil and water and from there they enter into the food chain of man through vegetables, eggs. crops milk etc. and give rise to many diseases.
→ Soil pollution: Chlorine containing hydrocarbon like DDT and BHC, when used frequently then large amount of chemical is left behind in soil and pollutes it due to which fertility of soil decreases.
→ Some part of BHC directly goes into soil whereas 12-30 percent of part vaporises and goes into environment from there it is bioaccumulated in food chain. In this way, it is harmful for plants and animals.
→ Due to excess of BHC, nervous system of animals, human being is also affected.