Answer to Question #189505 in Organic Chemistry for Sam

Question

How does pi bonding help to explain the structure of benzene?

Answer 1

The structure of benzene is best described in terms of the molecular orbital theory. All the six carbon atoms of benzene are  $sp^2$ hybridized. Six  $sp^2$ hybrid orbitals of carbon linearly overlap with six one is orbitals of hydrogen atoms to form six C−H sigma bonds. Overlap between the remaining  $sp^2$  hybrid orbitals of carbon forms six C-C sigma bonds.

All the bonds in benzene lie in one plane with bond angle $120\degree$ . Each carbon atom in benzene possess an un hybridized p-orbital containing one electron. The lateral overlap of their p-orbital produces $3π$ bond The six electrons of the p-orbitals cover all the six carbon atoms and are said to be delocalized.

Due to delocalization, strong -bond is formed which makes the molecule stable. Hence unlike alkenes and alkynes benzene undergoes substitution reactions rather addition reactions under normal conditions.

 benzene has a planar hexagonal structure in which all the carbon atoms are $sp^2$ hybridized, and all the carbon-carbon bonds are equal in length. As shown below, the remaining cyclic array of six p-orbitals ( one on each carbon) overlap to generate six molecular orbitals, three bonding and three antibonding.