Post Lab 6 chm 2211L PDF

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Post Lab 6: Nitration of Methyl Benzoate Breana Barnes TA: Maryam Arif Partner: Summer 6/17/19

Data: Melting point: 79-80 °C Mass: 0.288 g Percent Yield: Actual Yield Theoretical Yield

x100= Percent Yield

0.3 g methylbenzoat e x

1 mol methyl benzoate =0.002 mol (limiting reagent) 136.15 g methyl benzoate

0.002 mol Methyl benzoate

x

1 mol 3−nitro methyl benzoate = 0.002 mole 3-nitro methyl 1 mol methyl benzoate

benzoate Mass = moles x mass (0.002 mol 3- nitro methyl benzoate) x (181.15 g/mol 3-nitro methyl benzoate) = 0.362 grams 3nitro methyl benzoate (theoretical yield) 0.288 g 0.362 g

x 100 = 79.56 % yield

Discussion: This lab consisted of several quantitative results. The melting point of our sample of 3-nitro methyl benzoate was found to be 79-80°C. The expected melting point was 78°C (Pubchem, 2018). The obtained melting point was within close range of the expected theoretical melting point. The obtained melting point was slightly different than the expected melting point, this could be due to cross contamination from glassware that was not properly cleaned after previous experiments. The obtained mass of the product was found to be 0.22 g, which produced a percent yield of 79.56 percent. The percent yield was obtained by finding the number of moles of the limiting reagent ( LibreTexts, 2019). This was

done by taking the grams of methyl benzoate used, and then dividing by the molar mass of methyl benzoate, this produced a value of 0.002 mol. The number of moles of methyl benzoate was then converted to moles of 3-nitro methyl benzoate by using a mole to mole conversion between methyl benzoate and 3- nitro methyl benzoate. This produced a value of 0.002 moles of 3- nitro methyl benzoate. The mass was then calculated by multiplying the number of moles by the molar mass. This resulted in a theoretical value of 0.362 g. Our actual mass of 0.288 g was then divided by the theoretical mass of 0.362 and multiplied by 100 to obtain the overall percent yield of 79.56 percent. There could be a number of experimental and human caused errors that could have contributed to a loss of product. To start, there was a large quantity of product in the bottom of the flask after the process of vacuum filtration which contributed to a loss of product. Experimental errors could have also contributed to the lower percent yield. In this experiment, we did not recrystallize our solution, so all of the product that was in the bottom of the flask after vacuum filtration was lost. I hypothesized that if we followed all experimentally procedures properly, then we would obtain a melting point within close range of the expected melting point, as well as a percent yield between 80 and 100 percent. Overall, my hypothesis proved to be true. Our melting point was within close range of the expected melting point. Our percent yield was found to be 79.56 percent, which rounds to 80%. This experiment was overall successful, as it accomplished what it set out to do. The main goal of the experiment was to perform a nitration reaction on methyl benzoate in order to make 3-nitro methylbenzoate starting from methyl benzoate (Weldegirma, 2019). This was done successfully.

Post Lab Questions 1)

Give detailed mechanism of Nitration of Methyl Benzoate (5)

2)

Which caution was used in the handling of sulfuric acid and nitric acid? (3)

These chemicals should be used underneath the fume hood, they also require special measuring tools. Specific containers and pipettes must be used. After each transfer of chemicals, gloves were replaced due to the risk of skin corrosion. Proper PPE was required at all times in this lab.

3)

Describe recrystallization process. (2)

The solvent was boiling in a beaker with the crude sample as solvent was added to force it all to completely dissolve. The solution is then cooled and separated using vacuum filtration. This produced crystals from the impure compound. These crystals are then dried. These crystals can be used to obtain the melting point.

References:

1) “Methyl 3-Nitrobenzoate.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, pubchem.ncbi.nlm.nih.gov/compound/Methyl-3nitrobenzoate#section=Experimental-Properties. 2) Libretexts. “12.9: Theoretical Yield and Percent Yield.” Chemistry LibreTexts, Libretexts, 5 June 2019, chem.libretexts.org/Bookshelves/Introductory_Chemistry/Book %3A_Introductory_Chemistry_(CK12)/12%3A_Stoichiometry/12.9%3A_Theoretical_Yield_and_Percent_Yield. 3) Weldegirma, s., PhD, &PandeY, M., PhD. (2019) Organic Chemistry II Laboratory Manual. St. Petersburg, FL: USF....