Arylation - Synthesis of m-nitrobiphenyl
The synthesis of m-nitrobiphenyl serves as an example of an arylation reaction in which the arylation is accomplished by treating a triazine with benzene in the presence of a strong acid.
A stirred solution of 1-(m-nitrophenyl)-3,3-dimethyltriazine (58.2 g, 0.3 mol) in 1.25 liters of benzene is heated to reflux. To the reaction mixture is added dropwise over a period of 4.5 hours a solution of 94% p-toluenesulfonic acid (74 g, 0.4 mol) in 375 mL of benzene. The resulting solution is refluxed for an additional 1.5 hours. The reaction is allowed to cool and 400 mL of water is added with stirring. The aqueous layer is removed and the benzene layer is washed with water (2X250 mL), 5% aqueous sodium hydroxide (3X250 mL), and 250 mL of water. The organic layer is separated and treated with calcium chloride to remove water. The benzene is removed via distillation. After most of the benzene has been removed the residue is distilled and the m-nitrobiphenyl product is collected at 115-118 °C, .1 mm. The crude distillate can be purified via recrystallization from hot methanol to afford the title compound.