Synthesis of o-Chlorobenzoic Acid

Two solutions are prepared and numbered as 1 and 2. Solution 1 is made by refluxing a mixture of 9.2 g of copper dichloride dihydrate, 9.4 g of sodium chloride, 45 mL of 20% HCl and 8g of copper powder until the mixture becomes clear, then the solution is cooled down to 5°C in an ice bath. Solution 2 is made by combining and heating until complete dissolution 7 g of anthranilic acid, 24 mL of 20% HCl and 50 mL of water, then the solution is cooled down in an ice bath and 3.5 g of sodium nitrite dissolved in 15 mL of water is added to the solution while maintaining the temperature below 5°C. The number 2 solution carefully added with stirring to the number 1 solution while maintaining the temperature below 5°C in an ice bath, thereafter stir the solution for 2h at 15°C, filter and wash with some water. Combine the green residue with 100 mL of water and add as much of sodium carbonate until only insoluble green copper salts remain in the solution, boil 5 minutes with some decolorizing carbon, filter and acidify the filtrate with some HCl. Filter and wash with some water, recrystallize the crude product from 300 mL of water 20 mL of EtOH solution.

Source

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Refluxing the copper solution

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The refluxed copper solution

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The second solution

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Combining the solutions

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The mixture ready to be filtered

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Decolorizing and filtering the mixture

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The crude product

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