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What is the step-by-step procedure for the preparation of 2,4-dinitrobenzoic acid from benzoic acid and nitric acid, including the necessary reaction conditions and precautions that should be taken during the synthesis process?

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The preparation of 2,4-dinitrobenzoic acid from benzoic acid and nitric acid involves a nitration reaction. Here is a step-by-step procedure for this synthesis:1. Materials and reagents:   - Benzoic acid   - Concentrated nitric acid  HNO3    - Concentrated sulfuric acid  H2SO4    - Ice bath   - Distilled water   - Sodium bicarbonate  NaHCO3    - Vacuum filtration apparatus   - Round-bottom flask   - Separatory funnel   - Thermometer   - Stirring rod2. Precautions:   - Wear appropriate personal protective equipment  gloves, goggles, lab coat  as concentrated acids are corrosive and can cause severe burns.   - Perform the reaction in a well-ventilated area or under a fume hood, as nitrogen dioxide  NO2  gas is produced during the reaction, which is toxic and harmful.   - Keep the reaction mixture cool to avoid side reactions and formation of undesired products.3. Procedure:   a. In a round-bottom flask, mix 10 grams of benzoic acid with 30 mL of concentrated sulfuric acid. Stir the mixture until benzoic acid dissolves completely.      b. Prepare an ice bath and place the round-bottom flask in it to cool the mixture to 0-5C. Monitor the temperature with a thermometer.      c. Slowly add 15 mL of concentrated nitric acid to the cooled mixture in the round-bottom flask, drop by drop, while stirring continuously. Maintain the temperature between 0-5C during the addition. This step will form a nitrating mixture that will react with benzoic acid to form the desired product.      d. After the addition of nitric acid, continue stirring the reaction mixture for another 30 minutes while keeping it in the ice bath.      e. Carefully pour the reaction mixture into 100 mL of ice-cold distilled water in a beaker. Stir the mixture to facilitate the precipitation of 2,4-dinitrobenzoic acid.      f. Filter the precipitate using a vacuum filtration apparatus. Wash the solid product with cold distilled water to remove any remaining acid.      g. To further purify the product, dissolve the crude 2,4-dinitrobenzoic acid in a minimal amount of hot distilled water. Add a small amount of sodium bicarbonate to neutralize any remaining acid. Cool the solution to room temperature and then in an ice bath to recrystallize the product.      h. Filter the recrystallized product using vacuum filtration and let it air dry. The final product should be 2,4-dinitrobenzoic acid.4. Characterization:   - Determine the melting point of the synthesized 2,4-dinitrobenzoic acid and compare it with the literature value  242-244C  to confirm its identity and purity.   - Perform infrared spectroscopy, nuclear magnetic resonance  NMR  spectroscopy, or mass spectrometry to further confirm the structure and purity of the synthesized product.

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