Arenes Bromination of Arenes 03 08 2015 Functional groups hydrogen s are functional groups o It s not very reactive though o Only time when we think about protons Free radical reaction with a Halogen o It is a free radical substitution o Mechanism you generate a halogen radical o Halogen radical reacts with hydrogen to generate acid o Then propagation happens Radicals are VERY REACTIVE o So many hydrogens the molecule is big When using chlorine o 3 1 but in reality it s 45 to 55 Not a random reaction Essentially 1 1 ratio so there is some selectivity going Doesn t matter what the process is When using bromine o 3 to 97 ratio markovnikov addition Very special selectivity Bromine radical is much more selective than chlorine Why is it so selective If we understand this process we can now predict the outcome of this reaction on radical Arenes o Types of hydrogens 3 Aromatics about as reactive as aliphatics Hydrogen attached to an aromatic ring Aliphatics hydrogen attached to an sp3 hybridized carbon which is also attached to sp3 hybridized carbons Primaries Secondaries Tertiaries Benzilic hydrogen that is attached to an sp3 carbon that s attached to an aromatic ring Primaries and secondaries Discussion theory behind free radical substitution o Order in which theoretically should happen o Conclusion this is what I predicted this is what happened why was it the same or different o Draw a figure and refer to it 03 08 2015 03 08 2015