Why are allylic and benzylic radicals always more stable?
1 Answer
Jul 25, 2015
Benzylic and allylic radicals are more stable because they are stabilized by resonance.
Explanation:
Resonance involves a delocalization of electron density, and any process that delocalize electrons lowers the energy of a system.
(from www.mhhe.com)
We can write two equivalent resonance structures for the allyl radical, so its energy is lower than that of, say, a propyl radical.
The resonance energy of the allyl radical is about 45 kJ/mol.
The benzyl radical has even more resonance structures.
(from chemistry.stackexchange.com)
Its resonance energy is about 100 kJ/mol.
