Extended Essays 2021

by only using the solutions prepared by the lab technicians and by ensuring that the mass of

salicylic acid used was 28g (0.2mol, Appendix #2 ) when measured on the electronic balance.

Any changes would directly affect the data. This is as sulfuric acid is the limiting regent

( Appendix #3 ), as methanol needs to be in excess, and as varying the concentration/volume

of the sulfuric acid catalyst would directly affect the rate of the reaction and hence final

concentration/yield.

 Heating mantle voltage was set to 100Volts: Ensured that the reacting mixture wouldn’t

‘spit’ due to overheat ed liquid. If the voltage were to be changed throughout the experiment,

the variation of heat energy would directly the reaction rate and hence the concentration/yield

of the product.

 Concentration of the ferric chloride solution (0.01%): Kept the same by controlling the

dilution of ferric chloride to ethanol ( Appendix #4 ) to ensure that the absorbance values of

the synthesised solutions could be comparable to the calibration curve, accurately

determining the percentage concentration of the methyl salicylate.

Methodology Development of the method:

Through initial research, it was found that there were numerous reported methods for the

synthesis and refinement of methyl salicylate which all varied significantly. The greatest

difference was the time required for the reaction mixture to undergo reflux (salicylic acid,

methanol & con. Sulfuric acid). Through careful evaluation of the numerous methods, the

procedure which required the greatest duration of reflux and included both the synthesis and

refinement of the methyl salicylate was chosen for this investigation. Published in the Vogel’s textbook of Practical Organic Chemistry, 15 the procedure was amended considering the

limitations of the school laboratory to allow adequate independent variables as outlined in Table

#1 . The considerable safety considerations were also assessed, and appropriate modifications

made as appropriate to the school laboratory setting (Appendix #5).

15 (Vogel's Textbook of Practical Organic Chemistry, 1989)

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