Explain electrophilic addition reactions of ethylene with mechanism.

Explanation

Electrophilic addition reactions of ethylene :
1. Addition of Hydrogen : Ethylene react with hydrozen in the presence of Pt, Pd or Ni catalyst ot form ethane.
`underset("ethylene") ( CH _(2) = CH _(2)) + H _(2) overset( PL) to underset( " ethane") ( CH _(2) - CH _(3))`
`CH _(2) = CH _(2) + Br _(2) overset( C Cl _(4)) to overset( Br ) overset( |) (CH _(2)) - underset( Br ) underset(|) (CH _(2)) 1,2` dibromo ethane

3. Addition of hydrogen halldes : Ethylene reacts with HBr to form ethyl bromide
`CH _(2) = CH _(2) + HBr to underset( " ethyl bromide") ( CH _(3) - CH _(2) - Br)`
mechanism `: HBr to H ^(+) + Br ^(-)`
(i) `CH _(2) = CH _(2) + H ^(+) to CH _(3) - C overset( o+) (H) z`
(ii) (ii) `CH _(3) - C overset( o+ ) (H) z+ Br^(o+ ) to CH _(3) - CH _(2) - Br `
4. Addition of water : In presence of feq drops of conc. `H _(2) SO _(4)` water adds to ethylene to form alcohol.
`CH _(2) = CH _(2) + H _(2) O overset (H ^(+)) to underset( " Alcohol") ( CH _(2) CH _(2) OH)`
Mechanism :
`CH _(2) = CH _(2) underset("from" H _(2) SO _(4)) overset ( H ^(o+))to CH _(3) overset( o+) (C) H _(2) overset( H _(2) O)to H _(3) C - underset(|) ( CH _(2))`
`CH _(3) - underset( OH) underset(|) (CH_(2)) overset( - H ^(o+))larr underset(H) underset(|) overset(o+) (O) - H`