Synthesis of o-Nitrotoluene and p-Nitrotoluene

Slowly combine 150 mL of 68% nitric acid with 180 mL of sulfuric acid. Pour 156 mL of toluene into a reflux apparatus with open pressure equalized addition funnel, place the flask in salt-ice slush. Pour the acid mixture to the addition funnel. Start adding the acid mixture very slowly with vigorous stirring, the temperature should stay below 10°C. Balance the acid addition for 2h. After all of the acid has been added stir for 1h, then allow to warm up slowly to room temperature. Pour the mixture into a separatory funnel and discard the bottom acid layer. Then wash the product with 100 mL of water, then with 100 mL of 10% sodium carbonate solution in two portions and finally with 200 mL of water in two portions. Always shake the mixture and discard the upper layers when washing. After washings collect the bottom cloudy mixed nitrotoluene solution, add some anhydrous calcium chloride to remove the water. Remove the dehydrating agent and place the solution in a freezer to freeze it to -11°C, then filter and get as much of the liquid out from the crystals repeat once and then leave it to crystallize for a week in the freezer to get all of the para isomer out. Nitration of toluene gives 63% of the ortho product, 3% meta and 34% of the para product, so with freezing the liquid down and collecting the crystals, you can remove the meta and para-nitrotoluenes, which gives you almost isomerically pure products. The crystals will start to melt slowly, so put them into a storage container fast. You can also distill the remaining ortho isomer, in order to make it purer.

Source

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Toluene was added to the RBF

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Acid mixture

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Slowly adding the acid mixture over 2h

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The solution will turn yellowish after some time

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Pour into separatory funnel and discard the bottom layer

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Wash with water and discard the upper layer

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Wash with sodium bicarbonate solution  and discard the upper layer

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Collect the bottom layer and add some anhydrous calcium chloride

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Calcium chloride removed all of the water

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Freeze down to -11°C, and filter

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Try to remove as much of the liquid as possible

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ortho-Nitrotoluene

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para-Nitrotoluene

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