To a RBF pour 25 mL of conc. nitric acid and 20 mL of conc. sulfuric acid, then slowly add 10 mL of chlorobenzene with stirring. The addition must be done in an ice bath since the temperature must stay below 30°C. After addition stir at room temperature for an hour. Heat the mixture again until the crude products become liquid and then stir again for an hour at room temp. Pour the mixture into ice water and add as much of sodium carbonate until no more bubbling occurs, filter and wash with 100 mL of cold water. Dissolve the product in a minimum amount of hot ethanol and cool down slowly, collect the crystals and wash 3 x 4 mL with warm ethanol. The crystals are of para isomer. Evaporate the solvent off from the filtered ethanolic solutions and then the obtained product is of ortho isomer.
The mixture after stirring and reheating
Pouring the mixture into the ice water and adding of the carbonate
Filtration of the mixture
Separating the isomers via recrystallization
The filtered para isomer
The evaporated residue consists mainly of the ortho isomer