Conversion of Salicylic Acid into Ch3ch2coo(c6h4)cooh

CHM1022 PRAC 3

TASK: Devise a method to synthesise the unknown compound you identified from last week’s lab session. The method must be in full sentences and contain the correct measurements your group calculated last lab session. A list of apparatus and chemicals available to you is available online or a copy can be obtained from your TA. A copy of this method must be submitted to your TA at the beginning of the lab session, it is your responsibility to retain a copy to guide you during the synthesis.

Conversion of Salicylic Acid into CH3CH2COO(C6H4)COOH

**Method**

Weigh 1.45 g of salicylic acid on a top loading balance and transfer to a clean, dry 125 mL conical flask. Add 1.6 mL of propionic anhydride and 3.8 mL of concentrated H3PO4. Swirl the flask until all the salicylic acid is dissolved. Float the conical flask in an 800 mL beaker containing 250 mL of distilled water. Heat this beaker to 85 °C in a water bath and maintain between 85 and 90 °C for ten minutes. Once heated, remove flask using a wooden peg, and place straight into an ice bath until crystals begin to form. Scratch the walls of flask with glass rod to promote crystallization. Add 50 mL of deionised water to the flask and swirl. Isolate the product via vacuum filtration. Rinse the conical flask with 15 mL of iced deionized water, pour over the precipitate, and continue suction for about 10 minutes. Transfer to a clean, dry watch glass and weigh on a top loading balance (using difference of mass method).

If time permits, perform a second vacuum filtration to increase chance of purity of the product. Then transfer the solid to a clean, dry crucible and dry on hotplate (at 80 °C) in the fume cupboard until constant mass is achieved. Remove, cool, and weigh the final product.

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