Synthesis of Aspirin and Oil of Wintergreen

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Synthesis of Aspirin and Oil of Wintergreen

Janelle Alyssa P. Prudente

De La Salle University-Dasmariñas
Dasmariñas City, Cavite, Philippines

ABSTRACT

In this experiment, acetylsalicylic acid commonly known as aspirin and methyl salicylate, commonly known as oil of wintergreen, was synthesized from salicylic acid. This study will show that it is possible to show two very different organic compounds from the same common starting material. For the synthesis of aspirin, salicylic acid was mixed with one drop of 85% H2SO4 and 0.3mL of acetic anhydride. The collected aspirin was obtained by means of vacuum filtration. For the synthesis of methyl salicylate, 0.25g of salicylic acid was mixed with 2.0mL of methanol and ten drops of concentrated H2SO4. The collected products were tested with FeCl3 test, both resulting to a positive reaction.

INTRODUCTION

Organic molecules are distinguished by the difference in the structure of atoms, such as how alcohols contain a carbon atom bond to an OH group, e.g. methyl alcohol in CH3OH. Both aspirin and oil of wintergreen are esters. Esters are organic compounds which contain the molecular connectivity that expresses the pleasant fragrances and aromas they have, which can be observed in fruits and flowers. In modern times, the cosmetic industry has employed the use of esters in the production of self-care and vanity products such as perfumes and make-ups. This can also be noted in food and pharmaceutical industries that make use of esters in flavouring agents both in solid and liquid products.

Aspirins, known chemically as acetylsalicylic acid, are the most widely utilized medical compound worldwide used as pain relievers and anti-pyretics. A regular strength tablet contains 325mg of acetylsalicylic,held together with an inert binder. The compounds present in aspirins are said to inhibit the production of rostaglandins that are used in the perception of pain. Common aspirins found in drugstores are Tylenol, advil and biogesic.

Oil of wintergreen is used widely as a flavouring agaent as well as a rubbing compound. Methyl salicylate causes a mild burning sensation when it is applied to the skin, which in effect creates a counter irritant effect for sore muscles. A popular example of this is Ben Gay.

MATERIALS AND METHODS

For the synthesis of aspirin, water bath maintaining a temperature between 70-90˚c was maintained. Salicylic acid amounting to 0.150g was obtained and placed in a test tube added with one drop of 85% H2SO4 and 0.3mL of acetic anhydride using a pipet. The content of the test tube was mixed thoroughly by swirling and was placed in the water bath until the salicylic acid dissolved in a colourless solution. The reaction mixture was then removed from the water bath to add 0.2mL of deionized water using a syringe. If no reaction was observed, another 0.3mL of the same sample was added. The test tube was then placed over an ice bath to re-crystalize the product. The collected aspirin was obtained by means of vacuum filtration and was washed with cold water and was left to completely dry before weighing.

For the synthesis of methyl salicylate, approximately 0.25g of salicylic acid was placed in a test tube with 2.0mL of methanol, which was mixed in a swirling motion until the methyl salicylate completely dissolves and then added ten drops of concentrated H2SO4. The reaction mixture was placed in a heated water bath for 15 minutes. The test tube was then allowed to cool over running water. The product formed was identified by determining its aroma.

Lastly, a ferric chloride test was done for the synthesized aspirin and methylsalicytate. This was performed by dissolving the sample with 5.0mL distilled H2O added with 1 drop of 1% FeCl3.

RESULTS AND DISCUSSION

Aspirin and wintergreen are both organic esters. An ester is a compound that is formed when a carboxylic group containing acid reacts with an alcohol group containing compound. This...
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