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Synthesising organic and biochemical compounds - Preparation of Aspirin.

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Unit 5: Synthesising organic and biochemical compounds Preparation of Aspirin Prepared by: Tahir Sheikh-Noor Task2: Extracting and identifying the active chemical in willow bark In this experiment we extracted some salicylic acid form willow bark twigs. We used reflux, a technique to gently heat a substance for a period of time without losing any liquid because it condenses back into the pear shape flask. Apparatus * 250 cm3 beaker * Small beaker to hold TLC plate * Reflux apparatus * Dropping tubes or melting point tubes * Clingfilm to cover beaker * UV light * Glass rod * Coffee grinder Method We took a sample of fresh twigs, form willow tree and chopped them into fine pieces using a coffee grinder. We then set up a flask with a reflux condenser as in diagram below and placed the fresh willow bark twigs in side. We added to the pear shaped flask 2 mol dm-3 sulphuric acid and 0.2 mol dm-3 potassium manganate (VII) solution. Now we were ready to reflux the mixture for 15 minutes. After the 15 minutes we poured the mixture into a 250 cm3 beaker. The same portions of a sulphuric acid and potassium manganate (VII) ...read more.


Filter the solid produced under vacuum filtration, wash with 50ml of distilled water. Re-crystallise the solid using a 50:50, which means equal quantities of distilled water and ethanoic acid as a solvent say about 10mls each. Filter, dry the product and take the melting points then store the products. We then had to work out the percentage yield and theoretical yield. Sample 1 Theoretical yield (Maximum yield possible) = 138g 180g 1g 180 138 5g 180 X5 138 Theoretical = 6.52 Percentage yield= Actual yield X 100 Theoretical yield = 0.32 X100 6.52 = 4.91g Method 2 Apparatus * Quickfit flask * 2-hydroxybenzoic acid * Phosphoric acid * Reflux apparatus * Distilled water * 250ml beaker * Glass rod * Ice * Vacuum filtration equipment * Melting point apparatus * Test tube 2-hydroxybenzoic acid and 10 ml of ethanol anhydride was added to a 100 ml quickfit flask. then add 12 drops of 85% phosphoric acid and swirl to mix. fit a reflux condenser, heat the mixture for about 10 minutes in a water bath, without cooling add 5 ml of water down the condenser. When the vigorous reaction has ended, pour the mixture into a 100 ml of cold water in a 250 ml beaker. ...read more.


Evaluation The literature value of aspirin is 1350C my sample for method 1 had a melting point of 1250C, which is quite close to the literature value, but it is not the same. Maybe this is because there were some impurities in my product or I did something wrong in the preparation stages. My sample for method 2 had a melting point of 1720C, which is very far from the literature value of aspirin this is mainly because there were some impurities in my sample making the melting point higher. Comparison with industrial processes In industrial the production aspirin will require some of the processes that require precision which does that need humans are done by automation which makes the production of aspirin very easy and quicker because the computers controlled everything that would normally done by hand The equipment and chemicals are transported on conveyor belts Advantages of automation * Made the process more efficient. * Saved more money and time in the long run. * Reduced labours costs by employing less personal. * Allows them to produce economy of scale: a continuous. process same as mass production which is cheaper than batch production that Ridley use. Disadvantages of automation * The automation would cost a lot of money * The system will consume large a amount electricity ...read more.

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