Mechanism:- halogenations reaction take place by free radical mechanism. The reaction proceeds in the following steps:
Initiation( i) Chain initiation step:-
Cl— Cl h
2Cl
( ii) Chain Propagation step:-
CH4 Cl CH3 HCl
CH3 Cl2 CH3Cl Cl
( iii) Chain Termination step:-
Cl Cl Cl2
CH3 |
CH3 |
CH3 CH3 |
CH3 |
Cl |
CH3Cl |
Nitration:
The reaction takes places by free radicals mechanism at high temp( 450 0 C).
At high temp C— C bond is also broken so that mixture of nitro alkanes is obtained.
CH3CH2CH3
450 ° C Conc. HNO3
The reaction occurs as: HO-NO2
CH3CH2CH2NO2 + CH3CHCH3 + CH3CH2NO2 + CH3NO2
450 0 C Homolytic fission
HO o + o NO2
RH + 0 OH R o + o NO2
R o + HOH RNO2