Synthesis of Salicylic Acid

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Experiment 4
Synthesis of Salicylic Acid


Introduction
Throughout history, botanical extracts have been used as medicines. Approximately 30% of all medicines have a plant origin. This number increases to 60% if you consider medicines that at one time were derived from plants, but have been synthesized in the laboratory. Salicylic acid is a white crystalline compound that can be isolated from the bark of birch trees. Since it is a valuable substance that can be isolated from nature, it is called a "natural product". Although it was used historically as an analgesic (pain reliever), today it is commonly used in ointments and plasters for the removal of warts from the skin. Salicylic acid is also a precursor to acetylsalicylic acid or aspirin. Acetylsalicylic acid (an ester derivative of salicylic acid) is much more commonly used than salicylic acid for pain relief, because the parent compound can irritate the lining of the stomach. In this experiment we synthesized salicylic acid from methyl salicylate. We converted the functional group known as an ester into a functional group known as a carboxylic acid.  Methyl salicylate is also a botanical extract. It is the major constituent of oil of wintergreen, which makes up over 90% of the essential oil from the wintergreen plant. It is also a common flavoring in candy. However, most methyl salicylate used in foods is made synthetically, a cheaper process than its extraction from wintergreen leaves or sweet birch bark. Methyl Salicylate has an alcohol and an ester group that are very important. Esters are often liquids (oils) at room temperature.  At room temperature they are volatile to varying degrees and can be quite pleasing to the nose since they smell nice.   The product of the reaction, salicylic acid was a white precipitate, the starting material, (methyl salicylate) was a liquid.  Organic synthesis involves changing part of a molecule.  This results in a different molecule often with different physical...
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