Resonance in Benzene

Benzene is a six-membered, cyclic hydrocarbon possessing a delocalized pi-electron system. The delocalization of π-electrons is responsible for the stability of benzene. The carbon-carbon bond length in benzene is intermediate between a single bond and a double bond. The stability of benzene is due to the resonance of its π-electrons in the ring. The resonance in benzene is explained by the following points:

- The six carbon atoms of benzene are sp2 hybridized and are in the same plane.
- Each carbon atom is attached to a hydrogen atom, and there are alternating double bonds between the carbon atoms.
- The double bonds in benzene are not localized; instead, they are delocalized over the six carbon atoms.
- The delocalization of the π-electrons results in the formation of a ring of electrons above and below the plane of the molecule.
- The delocalization of the π-electrons in benzene creates a resonance hybrid that is more stable than any of the possible contributing structures.

Stability of Benzene

The stability of benzene is due to the delocalization of its π-electrons. The delocalization of the π-electrons leads to the following points:

- The delocalized π-electrons in benzene are more stable than the localized π-electrons in other compounds.
- The delocalization of the π-electrons results in a uniform distribution of electron density throughout the ring, which makes the molecule more stable.
- The delocalized π-electrons lead to a decrease in the energy of the molecule, making it more stable.

Conclusion

The resonance in benzene is due to the delocalization of its π-electrons, which results in the formation of a resonance hybrid that is more stable than any of the possible contributing structures. The stability of benzene is due to the uniform distribution of electron density throughout the ring, which makes the molecule more stable. The delocalization of the π-electrons leads to a decrease in the energy of the molecule, making it more stable.

Resonance of benzene

The oscillating double bonds in the benzene ring are explained with the help of resonance structures as per valence bond theory. All the carbon atoms in the benzene ring are sp2 hybridized. One of the two sp2 hybridized orbitals of one atom overlaps with the sp2 orbital of adjacent carbon atom forming six C-C sigma bonds. Other left sp2 hybridized orbitals combine with s orbital of hydrogen to form six C-H sigma bonds. Remaining unhybridized p orbitals of carbon atoms form π bonds with adjacent carbon atoms by lateral overlap.

This explains an equal possibility for the formation of C1 –C2, C3 – C4, C5 – C6 π bonds or C2 – C3, C4 – C5, C6-C1 π bonds. The hybrid structure is represented by inserting a circle in the ring as shown below in the figure. Hence, it explains the formation of two resonance structures proposed by Kekule.

Stability of benzene

Resonance and delocalization of electrons leads to stability of any molecule .
since, in benzene all the six π- electrons of the three double bonds are completely delocalized to form one lowest energy molecular orbital which surrounds all the carbon atoms of the ring , therefore it is extraordinarily stable.