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Synthesis Of Methyl Benzoate Lab Report

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Recommended: Laboratory procedure for synthsis of methyl benzoate

Lance Feig
CH 128L
Experiment Report

Purpose

The purpose of this lab was to synthesize methyl benzoate from benzoic acid and methanol through Fischer esterification. The identity of the product was verified through IR, GC, and 1H-NMR analysis, where the experimental readings were compared to known readings of methyl benzoate. Furthermore, a percent yield of the product was calculated.
In Fischer esterification, a carboxylic acid is converted to an ester by replacing the carboxyl alcohol group (-OH) with an ether (-OR). The acid catalyst protonates the carbonyl oxygen, making the carbonyl carbon more electrophilic. This promotes the attack of the alcohol nucleophile. Fischer esterification is an equilibrium reaction because the water product …show more content…

Then, the product was filtered over cotton to remove the solids. Some of the product was absorbed by the cotton, which decreased the percent yield. The product was a thick liquid, so some remained stuck to the side of the decanted beaker, which also decreased the percent yield. For future experimentation, the amount of cotton used could be reduced or the sample could be decanted without the use of filtering. In addition, a pipette could be used to transfer the sample to reduce the amount of sample left behind. Second, the product was separated from an aqueous layer in the separatory funnel twice. It was probable that some organic solvent was left in the aqueous layer, which would reduce the percent yield as it was discarded. For future experimentation, an additional separation could be performed on the collected aqueous layers to maximize the extracted organic solvent. However, the yield of methyl benzoate was likely lower than the calculated 47.40% since a majority of the product was diethyl ether solvent. As noted in the GC analysis, over 90% of the product was diethyl ether according to the peak areas. Due to an external situation, the solvent was evaporated by heating the product on the hot plate. This was less effective than the preferred method of blowing air over the top of the

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