Essay on Ethyl Cinnamate And Ethyl Cinnamate5

1272 Words Aug 18th, 2015 null Page
The synthesised ethyl cinnamate weighed 0.56 g, which was equivalent to 140% of the theoretical yield of 0.414 g.
This excessive yield was resultant of the impurities within the product. Explicitly, the solvents, particularly the dichloromethane, were not sufficiently removed from the product. In figure 3, the peak at 5.22 ppm with a normalised intensity of 1.00 evidenced the significant proportion of the dichloromethane in the product, and the peak at 0.88 ppm with a normalised intensity of 0.25 indicated some remaining hexane.4 The unreasonably high yield was mostly attributed to these.
Additionally, there might exist other impurities elevating the value of the yield. In figure 3, the expected multiplets for the two different sets of aromatic hydrogens in ethyl cinnamate5 were not depicted, and the integrations did not match with the structure of ethyl cinnamate. Therefore, considering the abnormal large peak at 7.42 ppm, it was possible that in the product there still existed benzaldehyde that was not eluted from the column, and with its own aromatic ring, interfering with the 1H NMR measurement of the ethyl cinnamate. Similarly, the by-product triphenylphosphine oxide could be another impurity, with a chemical shift between 7.44 and 7.69 ppm that shared with aromatic hydrogens.3 Although it was not be soluble in hexane, there might exist residuals that were not fully separated from the ester product during column chromatography. These factors could potentially contribute…

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