Meta-Directing Groups
Electrophilic Aromatic Substitution of Class 12
Meta-Directing Groups
All meta-directing groups have either a partial positive charge or a full positive charge on the atom directly attached to the ring. As a typical example let us consider the trifluoromethyl group.
From above it is clear that in the resonance structures for the arenium ion arising from ortho and para attack that one contributing structure is highly unstable relative to all the others because the positive charge is located on the ring carbon that bears the electron-withdrawing group. We see no such highly unstable resonance structure in the arenium ion arising from meta attack. This means that the arenium ion formed by meta attack should be the most stable of the three.
- Introduction
- General Mechanism
- Some Important Electrophilic Aromatic Substitution Reactions
- Theory Of Substituent Effects On Electrophilic Aromatic Substitution
- Classification Of Substituents
- Ortho-Para-Directing Groups
- Meta-Directing Groups
- Ortho−Para Direction And Reactivity Of Alkylbenzenes
- Summary Of Substitutent Effects On Orientation And Reactivity
- Exercise 1
- Exercise 2
