Lab 6 - Lab Report PDF

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Preston Kummer No Lab Partner Songyi Xue “Nitration of Methyl Benzoate”IntroductionIn this lab we performed a standard electrophilic aromatic substitution reaction with methyl benzoate. An aromatic compound is a planar, cyclic compound where all p orbitals are parallel to each other. In addition to ...

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Preston Kummer No Lab Partner Songyi Xue “Nitration of Methyl Benzoate”

Introduction

In this lab we performed a standard electrophilic aromatic substitution reaction with methyl benzoate. An aromatic compound is a planar, cyclic compound where all p orbitals are parallel to each other. In addition to this, there needs to be a specific amount of pi electrons equal to 4n+2 where n is a whole number. This is known as The Hückel Rule. This being said, an electrophilic aromatic substitution reaction involves substituting an atom that is attracted to an aromatic system, usually hydrogen, with an electrophile like nitrogen dioxide in the case of our experiment. Activating and deactivating groups are used to describe the groups attached to an aromatic ring, typically activating groups are more likely to donate electrons and deactivating groups are more likely to withdraw electrons. During electrophilic aromatic substitution reactions, substituents regulate where the substitution will transpire. The ortho product predominates at (1,2), the meta product (1,3), and the para product (1,4). The substituent in methyl benzoate is a withdrawing group, which automatically makes in meta, creating a (1,3) product.

Figure 1. Reaction and side reactions Experimental Prepare a mixture with 0.2 mL of sulfuric acid and 0.2 mL of nitric acid, adding it to the test tube dropwise, keeping the reaction in ice.

Add 0.6 mL of sulfuric acid and 0.3 g of methyl benzoate to a medium sized test tube, swirling it gently

Let the reaction get to room temperature before adding it to a 50 mL flask with ice

Keep swirling in minutes, lettin reaction go to co

Recrystallize th with an equal a methanol, thi produce large which can be again

Wash the product with water, then ice cold methanol, then weigh the crude product.

Table of Chemicals Dissolve the product and obtain a C-NMR and HNMR

Calculate the p yield and obtain point

Name of Chemical

Sulfuric Acid

Methyl Benzoate Nitric Acid

Methanol

Formula

H2SO4

C8H8O2

HNO3

CH4O

Molar Mass

98.08 g/m

136.15 g/m

63.013 g/m

32.042 g/m

Melting Point

51 Co

10 Co

-41.6 Co

-97.6 Co

Boiling Point

337 Co

388 Co

83 Co

64.7 Co

Properties

Corrosive

Irritant

Oxidizer Corrosive

Flammable Acute Toxic Health Hazard

Results Physical Properties

Beige crystalline powder

Melting Point

78-80 Co

Appearance

Beige crystals

Color

Beige

Percentage Yield

64.16%

Rate of Reaction

Fast

Percentage Yield Calculation: Theoretical Yield = (0.3 grams of methyl benzoate / 136.15 grams of methyl benzoate) x 181.145 grams of 3-nitromethyl benzoate= 0.399 grams of 3-nitromethyl benzoate Actual Yield = 0.256 grams of 3-nitromethyl benzoate Percentage Yield = 0.256 / 0.399 x 100 = 64.16%

Discussion

The percentage yield of our reaction was fairly mediocre, being just barely above 60% which is low, but our melting point was exactly at the literature value. This means that despite having a low percentage yield, our product was more than likely pure. When comparing our HNMR spectrum to the theoretical H-NMR spectrum there are some differences which might be cause for concern. The H-NMR we got has the large peak at around 4, and two smaller peaks at around 7.5 and 8 which are all present in the theoretical graph, however, the theoretical graph also has a singlet peak around 8.5 which is absent from the graph that we got from our experiment. This result is concerning largely because that H-NMR spectrum would coincide with the reactant, methyl benzoate. Generally, H-NMR is useful for identifying whether or not the product you got was accurate because even a minor change in a chemicals composition will show on an H-NMR graph. Confusingly enough, our H-NMR graph is on par with the graph of our reactant, but our melting point value is on par with our product. I would say it is inconclusive whether or not we got the final product we were hoping for. Conclusion The data from this experiment was conflicting, the H-NMR and melting point both point to opposing conclusions as to whether or not the reaction occurred, but I am more inclined to believe the melting point was accurate and that the reaction did occur. The main technique present in this lab was the usage of ice to maintain a low temperature for the reaction. This technique can be applied to any reaction that only occurs at low temperatures. Overall I don’t think this lab did what it set out to do, it left me questioning whether or not the reaction actually occurred, but I did learn that it is possible to receive conflicting results. References Methanol. National Center for Biotechnology Information. PubChem Compound

Database Available at: https://pubchem.ncbi.nlm.nih.gov/compound/Methanol Methyl Benzoate. National Center for Biotechnology Information. PubChem Compound Database Available at: https://pubchem.ncbi.nlm.nih.gov/compound/Methyl-benzoate Nitric Acid. National Center for Biotechnology Information. PubChem Compound Database Available at: https://pubchem.ncbi.nlm.nih.gov/compound/Nitric-acid Sulfuric Acid. National Center for Biotechnology Information. PubChem Compound Database Available at: https://pubchem.ncbi.nlm.nih.gov/compound/Sulfuric-acid Weldegirma, Solomon. "Experimental Organic Chemistry." Department of Chemistry. Organic Chemistry Lab Manual...