Extended Essays 2021

Introduction

Methyl salicylate, or the oil of wintergreen , is an aromatic ester used in pharmaceutical

drugs such as Tiger Balm. It is formed from the esterification of Salicylic acid with the chemical

formula, 8 8 3 . This investigation aims to determine the relationship between reflux duration and the concentration & yield of synthesized methyl salicylate. This was done by initially

preparing a standard ferric chloride calibration curve, in which varying concentrations (10, 20,

30, 40 & 50%) of pure methyl salicylate with a ferric chloride solution ( 3 ) was measured of its absorbance (Au) using the UV Spectrophotometer. This method was based on ferric chloride colorimetry method for methyl salicylate quantification, published by the Journal of Applied Pharmaceutical Science (Vol.4) 1 . Methyl salicylate was then synthesised under varying reflux

durations with modifications to the Vogel’s textbook of Practical Organic Chemistry . The

concentration of the product was finally determined using the ferric chloride method, comparing

absorbance at 515nm to the calibration curve.

In the pharmaceutical industry, understanding the ideal conditions for organic synthesis is

essential to maximise the yield or purity of the products while still considering the limitations of

production cost and other external factors. Hence, identifying the ideal duration of a reaction

which produces the highest concentration of the desired product is necessary to ensure optimum

atom economy and the move towards greener chemistry by reducing organic chemical waste.

Background Research The synthesis of organic compounds is vital in producing various pharmaceutical,

cosmetic, and industrial products, which are all derived from organic molecules. Specifically,

pharmaceutical drugs such the oil of wintergreen is an organic ester formed through the

esterification of salicylic acid. Salicylic acid ( 7 6 3 ) , naturally derived from the bark of willow trees, was used for pain and fever reduction during the nineteenth century. Pure salicylic acid

however, caused issues such as severe stomach irritation, digestive problems, and diarrhea.

Through esterification, the purity of salicylic acid was able to be chemically modified to

formulate milder and safer forms of medicine, such as methyl salicylate.

The oil of wintergreen, or methyl salicylate ( 8 8 3 ), is a mild analgesic used to relieve muscle aches and pain 2 , which is also naturally derived from the fermentation of wintergreen leaves. As

1 (Sajin Kattuvilakam Abbas, 2014) 2 (National Library of Medicine, 2021)

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