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