TLC Analysis And Synthesis Of Cinnamic Acid

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The recrystallized cinnamic acid was obtained from the previous lab. It was a white and flaky powder and had a very slight sweet/spicy smell. When weighed, the recrystallized cinnamic acid was only .340 g. The starting amount was .500 g, so the percent recovery was 68.0%. ((.34g/.50g) x 100%)). The low percent recovery may have been due to the addition of too much solvent(book). Last lab, 90.0 mL of solvent was used to dissolve the cinnamic acid, which was the maximum amount directed by the instructor. The melting point range was analyzed to be 128.5 C- 131 C. This was a narrow range for the melting point, indicating purity. This melting range is close to cinnamic acid’s literature melting point of 133 C. For the esterification reaction, 1.45…show more content…
The cinnamic acid and methanol mixture was yellow and clear. .500 mL of concentrated sulfuric acid was slowly added to the mixture. The mixture was still yellow and clear. A reflux condenser was added to the flask. The mixture stirred for one hour: 3:44 pm- 4:44pm. During the hour of stirring, a TLC analysis was made. The substances compared was the recrystallized cinnamic acid, cinnamaldehyde, and aged cinnamon oil. The cinnamon oil was 6 weeks old. It was a yellow solid gel with a small amount of liquid. The oil has a slight cinnamon smell. The stationary phase was silica gel and the mobile phase was ethanol: hexane (2:6) and 2 drops of acetic acid. The cinnamic acid and cinnamaldehyde were diluted in acetone and the cinnamon oil was diluted in hexane. However, when analyzed, no compounds showed up under the UV light. It was realized by the lab professor that discarded, diluted acetone was used instead of just acetone. The cinnamic acid and cinnamaldehyde were diluted with the correct acetone and the TLC analysis was repeated. The solvent front was 4.32 cm Under the UV light, the compounds were shown and circled with a pencil. The TLC plate was dipped into a vanillin stain and heated above a hot
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