Analysis Of Ethyl Cinnamate

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Discussion:
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, where 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 unreasonable yield was mostly attributed to these.
Additionally, other impurities might exist and elevate the calculated yield. In figure 3, the expected multiplets for the two different sets of aromatic …show more content…

For example, light irradiation, ionic solvents, pressure elevation, water medium, and additives.
Despite the insolubility of the reagents in water, this medium was effective for the Wittig reactions involving various ylides without affecting the isomeric ratio. The improvement was more significant with aromatic and long-chain aldehydes that induced large hydrophobic effects. Consequently, water’s ability in stabilising the polar transition state and in reducing the energy of solvation through hydrophobic associations were suggested to cause the improved reaction rates and selective yields.10
In the aqueous Wittig reaction, a combination of other factors could further improve the reaction. These included the increase of temperature to distribute aldehyde molecules for reaction and the additive LiCl that stabilised phosphoranes to prevent reactions with water.10 In general, lithium cations could catalyse the condensation step by either facilitating the nucleophilic attack, or stabilising the betaine intermediate to provide an alternative pathway with lower energy of activation, thus shortening the reaction time and improving the final

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