The most effective method to prepare 2,4-dinitrophenol from phenol and nitric acid is through a two-step nitration process. Here are the steps involved in the synthesis:1. Preparation of reagents and materials: Before starting the synthesis, ensure that you have the following reagents and materials: phenol, concentrated nitric acid HNO3 , concentrated sulfuric acid H2SO4 , an ice bath, a round-bottom flask, a dropping funnel, a magnetic stirrer, and a separatory funnel.2. First nitration step: In a round-bottom flask, dissolve an appropriate amount of phenol in a small volume of concentrated sulfuric acid. The sulfuric acid acts as a catalyst and dehydrating agent, promoting the nitration reaction. Place the flask in an ice bath to maintain a low temperature and prevent side reactions.3. Slowly add concentrated nitric acid to the flask using a dropping funnel while stirring the mixture with a magnetic stirrer. The nitric acid will react with phenol to form ortho- and para-nitrophenol. The low temperature and slow addition of nitric acid help to control the reaction and minimize the formation of unwanted byproducts.4. After the addition of nitric acid is complete, let the reaction mixture warm to room temperature and stir for an additional hour to ensure complete nitration.5. Quench the reaction by pouring the mixture into a large volume of ice water. The nitrophenol products will precipitate out of the solution.6. Collect the precipitate by filtration and wash it with water to remove any remaining acid. The crude product will be a mixture of ortho- and para-nitrophenol.7. Second nitration step: To obtain 2,4-dinitrophenol, the para-nitrophenol needs to be nitrated again. Dissolve the crude product in concentrated sulfuric acid and cool the mixture in an ice bath.8. Slowly add concentrated nitric acid to the mixture, as in the first nitration step. The second nitration will selectively occur at the para position, forming 2,4-dinitrophenol.9. Quench the reaction by pouring the mixture into a large volume of ice water. The 2,4-dinitrophenol will precipitate out of the solution.10. Collect the precipitate by filtration and wash it with water to remove any remaining acid. The crude 2,4-dinitrophenol can be further purified by recrystallization from a suitable solvent, such as ethanol or water.11. Dry the purified 2,4-dinitrophenol and store it in a suitable container.By following these steps, you can effectively prepare 2,4-dinitrophenol from phenol and nitric acid. Always remember to follow proper safety precautions and work in a well-ventilated area when handling hazardous chemicals.