CH1012
                                         L1 /   
‹#›
                                         L1 /   
12
BROMINATION
Radical reaction of bromine with propane.
                      hn or D
CH3CH2CH3 + Br2 ® CH3CH2CH2Br + CH3CH(Br)CH3
• Propane contains 8 H’s     (6 x 1o H, 2 x 2oH)
• Substitution of any of the 6 primary H’s gives 1-bromopropane while substitution of the secondary H’s gives 2-bromopropane.
• On the basis of random substitution we expect a ratio of 6:2 or  75% : 25%.
• Experimentally a ratio of 8% : 92% is found
The reaction of Br2 is selective in the order:
   3o H > 2o H > 1o H               site selectivity