Describe any two methods of preaparation of benzene with corresponding equtions. Benzene does not behave like an alkene, why? How do we mthyl benzene from benzens?

Explanation

Preparation of Benzene:
1. Laboratory Method: Sodium benzoate on distillation with soda lime gives benzene.
`underset("Sod. benzoate")(C_(6)H_(5)COONa)+NaOH underset(Delta)overset(CaO)to underset("Benzene")(C_(6)H_(6))+Na_(2)CO_(3)`
A mixture of NaOH and CaO is called soda lime.
2. Polymerisation of acetylene: When acetylene gas is passed through red hot copper tube, it undergoes polymerisation forming benzene.
`underset("Acetylene")(3C_(2)H_(2)) underset(600^(@)C)overset("Red hot Cu")to underset("Benzene")C_(6)H_(6))`
Reason for not behaving as an alkene: Benzene has a number of resonance sturcutres.

Because of resonance benzene has more stability. The resonance energy of benzene is also very high. It also indicates more stability to the benzene molecule. Hence, stability of a molecule is due to saturation. Hence, from these two points it is evident that benzene exhibits more the properties of a saturated compound (alkane) rather than the properties of an unsaturated compound (alkene).
Methyl benzene from benzene: In presence of anhydrous `AlCl_(3)` benzene reacts with methyl chloride and formes methyl benzene (Toluence).