Extended Essays 2021

In addition, the percentage yield in table #5 , shows that the range of the yield increased from 37-

41%, showing that the significant increase didn’t occur in the first 3 hours. This also shows that

the 4& 5-hour reflux time, did not make any different in terms of percentage yield. This result

does not fully support my hypothesis, however, can be justified by random and systematic errors

associated in the methodology (see evaluation).

The trends found are supported by the background research. When an esterification reaction is in

a reflux system for a longer duration, as outlined by the mechanism of the reaction, more water

molecules are liberated from the alcohol-acid mixture due to the high energy provided by the reflux system. This produces a higher concentration and yield of the desired methyl salicylate 18 .

Conclusion: The purpose of this experiment was to explore the relationship between the increasing duration

of the reflux and the concentration of the synthesized methyl salicylate, using the controlled

concentrations of salicylic acid (0.2mol), methanol (2.1mol) and conc. sulfuric acid (~18mol).

The synthesis was performed by increasing the duration of reflux using the 100V heating mantle

by 1 hour for 5 variations (1, 2, 3, 4 & 5 hours). Prior to the methyl salicylate synthesis, the ferric

chloride colorimetric method was used to determine the relationship between the concentration

of methyl salicylate and the 0.01% ferric chloride solution. Through the investigation, it was

found that the relationship between reflux time and concentration was directly proportional,

forming a linear relationship which validates the hypothesis. The yield with a range of 37-41%,

showed an increasing pattern, however not in a linear trend. This indicates that increasing reflux

time may not be the most economical method for producing greater quantities. Instead, shorter

reflux durations for a quicker turnover for overall yield is more effective. Therefore, this

experiment provided data that is strongly supported by the background research presenting

relevant information regarding the industrial processes of methyl salicylate synthesis, thus

proving the investigation reliable and valid.

18 (Barnes, 2017)

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