Dissolve 55 g of sodium dichromate in 200 mL of water with stirring, all of it won’t dissolve, then add 80 mL of conc. sulfuric acid. Allow the solution to cool down to about 50°C, pour it into an addition funnel which is connected to a 3-neck RBF. Pour 50 mL of cyclohexanol and 100 mL of water to the RBF, start stirring. Then start slowly add the chromic acid mixture to the solution over 2 h, make sure that the temperature stays below 65°C, cooling might be required. Then add 10 g of oxalic acid dihydrate. Start to distill vigorously, distill for about an hour, collect about 200 mL of distillate. Pour the distillate into a separatory funnel, add 30 g of coarse sodium chloride and shake, let the mixture stand for 30 minutes and discard the bottom layer. Dry the upper cyclohexanone layer with anhydrous magnesium sulfate.
Dissolving the sodium dichromate in water
After the addition of sulfuric acid
The solution was cooled down to 50°C and it was transferred to an addition funnel
Suspension of water and cyclohexanol
The acid mixture was slowly added to the suspension with stirring
The solution turned very deep green and the reaction was complete
The pure cyclohexanone after distillation