Essay about Lab Report

785 WordsApr 16, 20144 Pages
Synthesis of Butyl Benzoate Using Phase Transfer Catalysis The objective of the experiment is to synthesize the butly benzoate by nucleophilic substitution and characterize it by IR spectroscopy. The percent yield of the final product is determined after the synthesis. Procedures: 2.0 mL of 1-bromobutane, 3.0 g of sodium benzoate, 5.0 mL of water, 4 drops of Aliquat 336, and a boiling stone were placed in a 50mL round-bottomed flask. The reaction mixture was refluxed for 1 hour and the flask was cooled in a beaker in the water of room temperature. The solid was formed in the mixture and the flask was shaken until it dissolved. The flash was rinsed with 15 mL dichloromethane and it was added to the separating funnel. 10 mL of…show more content…
fig) Discussion 1) Errors & discrepancy Firstly, the error of the percent yield or 18.8% yield of final product was due to the transfer of reactions of organic layers to the Erlenmeyer flask several times, which led to the lost of the final products. Besides, the excess benzoate was not entirely removed by the water and remained in the final product. For the step of adding NaCl, the water was not entirely extracted from the organic product as only several times of the extraction were done in the experiment. 2) Mechanism of the reaction The above is the mechanism of the nucleophilic substitution (SN2), which the negative O atom attacks the positive C atom and form the intermediate product in the second step. Br is replaced by the benzoate ion and Br- is formed at the end of the reaction. Conclusion Butyl benzoate is synthesized through the nucleophilic substitution and the percent yield of the final product is 18.8% from the experiment. 1) How is the phase transfer catalyst removed from product? Water and dichloromethane are used to dissolve the phase transfer catalyst to the aqueous stage. Then, the aqueous layer with the catalyst can be removed by using the separating funnel. Besides, dehydrating agent can also be used to further remove the catalyst in the aqueous layer. 2) What purpose does washing with 15% (half-saturated) NaCl solution serve? The 15% NaCl solution is to extract the water from the organic

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