Before the start of this experiment, the theoretical yield was calculated. From the results, the limiting reagent is 3-nitrobenzaldehyde. The theoretical yield is determined by referring to the moles of the limiting reagent, which was calculated to be 1.3 g. However, the results obtained (Data Table 1) were greater than the theoretical yield; that is, the actual mass of the product was higher than the theoretical mass. This lead to an abnormally high yield of 320% and an impure product. Though the experiment was carried out smoothly, errors may have occurred that lead to an actual mass of 4.166 g for the crude chalcone. After the isolation of the crude product via vacuum filtration, the product was supposed to air-dry for thirty minutes.
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Data Table 2 shows the results gathered after the purification of 3-nitrochalcone. Since only half of the crude product was used, the theoretical yield for the product was determined to be 2.1 g. This led to a percent yield of 39%. The melting point of the pure product was also determined to be 142℃, which has a slight significant difference from the literature melting point of 146℃. As a result, the product, 3-nitrochalcone, is not completely pure. It probably contains water, because water lowers the melting point. Considering the fact that the crude product was not thoroughly dry before purification, water was already in the product. Even after crystallization into pure 3-nitrochalcone, the product also did not completely dry. The yield should have been much lower than 39%. Without allowing the product to dry, not only water, but methanol, would be in the product. Both the crude and pure 3-nitrochalcone were analyzed by infrared spectroscopy to test for …show more content…
There are two peaks next to each other, 2360.23 cm-1 and 2341.78 cm-1, which most likely indicated a nitrile stretch. These peaks disappeared in the spectrum for pure 3-nitrochalcone, though. Another peak at 3383.38 cm-1 indicates the presence of an OH group. As a result, water is in the impurity in the crude product. Figure 2 depicts the infrared spectrum of the pure product. The two peaks, signifying the nitrile stretch, were still on the spectrum, but smaller. However, a peak at 3380.36 cm-1 indicates that a OH stretch is present in the pure product. This means that the product is not completely, and the peak was from methanol, which was the solvent used to purify the crude product. The product was left to dry in an oven for several minutes to spur dehydration. Another IR spectrum was taken for the dried pure product (Figure 3). In this spectrum, there were no desired peaks, which indicates that the product is pure. The alcohol peak was gone and therefore, there was no methanol in the pure product. A completely dried product would cause the alcohol to disappear. This is the desired spectrum. Though performing this aldol condensation reaction did not achieve acceptable yields and resulted in impurities, drying the products resulted in better data. For future experiments on aldol condensations, allowing the product is an extremely important step that should be taken to synthesize a
Data Table 2 shows the results gathered after the purification of 3-nitrochalcone. Since only half of the crude product was used, the theoretical yield for the product was determined to be 2.1 g. This led to a percent yield of 39%. The melting point of the pure product was also determined to be 142℃, which has a slight significant difference from the literature melting point of 146℃. As a result, the product, 3-nitrochalcone, is not completely pure. It probably contains water, because water lowers the melting point. Considering the fact that the crude product was not thoroughly dry before purification, water was already in the product. Even after crystallization into pure 3-nitrochalcone, the product also did not completely dry. The yield should have been much lower than 39%. Without allowing the product to dry, not only water, but methanol, would be in the product. Both the crude and pure 3-nitrochalcone were analyzed by infrared spectroscopy to test for …show more content…
There are two peaks next to each other, 2360.23 cm-1 and 2341.78 cm-1, which most likely indicated a nitrile stretch. These peaks disappeared in the spectrum for pure 3-nitrochalcone, though. Another peak at 3383.38 cm-1 indicates the presence of an OH group. As a result, water is in the impurity in the crude product. Figure 2 depicts the infrared spectrum of the pure product. The two peaks, signifying the nitrile stretch, were still on the spectrum, but smaller. However, a peak at 3380.36 cm-1 indicates that a OH stretch is present in the pure product. This means that the product is not completely, and the peak was from methanol, which was the solvent used to purify the crude product. The product was left to dry in an oven for several minutes to spur dehydration. Another IR spectrum was taken for the dried pure product (Figure 3). In this spectrum, there were no desired peaks, which indicates that the product is pure. The alcohol peak was gone and therefore, there was no methanol in the pure product. A completely dried product would cause the alcohol to disappear. This is the desired spectrum. Though performing this aldol condensation reaction did not achieve acceptable yields and resulted in impurities, drying the products resulted in better data. For future experiments on aldol condensations, allowing the product is an extremely important step that should be taken to synthesize a