8.1 Donation of electrons into a benzene ring by resonance

1.1 A Resonance Picture of Benzene
1.2 The Stability of Benzene
1.3 The Resonance Explanation of the Structure of Benzene
1.4 Bond lengths and angles in benzene
1.5 Hückle’s Rule: The $\left( {4n{\text{ }} + {\text{ }}2} \right)\pi $ Electron Rule

2.1 A General Mechanism for Electrophilic Aromatic Substitution

7.1 Limitations of Friedel - Crafts Reactions

8.1 Donation of electrons into a benzene ring by resonance
8.2 Withdrawal of electrons from a benzene ring by resonance

9.1 Directive influence of the groups during substitutions in benzene ring
9.2 Mechanism of o and p-directing groups
9.3 Mechanism of o- and p-directing groups not have unshared pair of electrons
9.4 Mechanism of o- and p-directing gps having unshared pair of electron(s)
9.5 Mechanism of m-directing groups
9.6 Competitive orienting effect of two substituents

10.1 Halogenation of the side chain
10.2 Oxidation of side chain

If a substituent is attached to the benzene ring by an atom that is doubly or triply bonded to a more electronegative atom, $\pi $ the electrons of the ring can be delocalized on to the substituent. Such substituents are said to withdraw electrons by resonance. Substituents such as $ - C = O,{\text{ - }}C \equiv N,$, and $N{O_2}$ withdraw electrons by resonance. These substuents also withdraw electrons inductively because the atom attached to the benzene ring is more electronegative than a hydrogen.