Discuss Markovnikov's rule and Kharash effect.

Explanation

Statement of Markownikoff.s rule : The rule states that when an unsymmetrical reagent adds to a double bond, the positive part of the adding reagent attaches itself to a carbon of the double bond so as to yield the more stable carbocation as an intermediate:
Mechanism: A pair of electrons from the double bond attacks the electrophilic HX to produce an achiral trigonal planar carbocation intermediate. Thehalideion X-then adds to either face of the positively charged carbon forming alkyl halide product.

Anti Mark Kownikoff.s addition or peroxide effect or Kharasch effect: In the presence of peroxide (R-0-0-R) the addition of HBr to unsymmetrical alkene like propene takes place against Markowni- koff.s rule. As per Anti Markownkoff.s rule, the addition of HBr to an unsymmetrical alkene like propene takes place in such a way that the hydrogen atom becomes attached to the carbon atom with the fewer hydrogen atoms.
`CH _(3) - CH = CH _(2) + HBr overset((C _(6) H _(5) CO ) _(2) O _(2)) to CH _(3) - CH _(2) - CH _(2) Br `
Mechanism : (ii) `overset(*) (C) _(6) H _(5) + HBr overset( " Homolytic") underset( "Cleavage") to C _(6) H _(5) + overset(*) (B)r`

(iv) `CH _(3) - overset(*) (C)H - CH _(2) Br + HBr overset("Homolytic") underset("Cleavage") to underset("Major Product") ( CH _(3) - CH _(2) - CH _(2) Br + overset(*) (B) r)`
(v) `CH _(3) - underset( Br) underset( |) (CH) - CH _(2)+ H - Br overset( " Nomohttic") underset( "Cleavage") to CH_(3) - underset( " Minor product ") (underset(Br ) underset( |) ( CH) - CH _(3) + overset(*)(B) r)`
The `2 ^(@)` fre radical is more stable than `1 ^(@).` Therefore 1- bromopropane is majeor product.