Ochem lab 2 EAS Full Lab Report PDF

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Full lab report for ochem lab 2 taught by Dr. Z...

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EAS Full Lab Report Abstract: The experiment that was performed was the preparation of p-Nitroaniline from acetanilide. The purpose was to display how an Electrophilic Aromatic Substitution reaction proceeds. The techniques of vacuum filtration, recrystallization, and TLC testing were used in this experiment to accomplish this. With 86.52% of the final product recovered, a TLC test with similar Rf values ranging from 0.818 cm to 0.909 cm, and a melting point range of 171-172 degrees Celsius, it was concluded that the preparation of nitroaniline from acetanilide proceeded successfully but the purification of p-Nitroaniline from o-nitroaniline did not properly proceed. Synthetic Equations:

Chemical Properties:

Acetanilide1 ● Molar mass: 135.16 g/mol ● Boiling point: 304.0 degrees C ● Melting point: 114.3 degrees ● Density: 1.219 g/mol ● Hazards: irritant

N-(4-Nitrophenyl)acetamide2 ● Molar mass: 180.16 g/mol ● Melting point: 216 degrees C ● Hazards: irritant

o-Nitroaniline3 ● Molar mass: 180.16 g/mol ● Melting point: 94 degrees C ● Hazards: irritant

Sulfuric acid4 ● Molar mass: 98.08 g/mol ● Boiling point: 337 degrees C ● Melting point: 10.31 degrees C ● Density: 1.84 g/mL ● Hazards: corrosive

1 Acetanilide. https://pubchem.ncbi.nlm.nih.gov/compound/Acetanilide#section=Melting-Point (accessed Apr 9, 2020). 2 N-(4-Nitrophenyl)acetamide. https://pubchem.ncbi.nlm.nih.gov/compound/N-_4-Nitrophenyl_acetamide (accessed Apr 9, 2020). 3 2-Nitroaniline. https://pubchem.ncbi.nlm.nih.gov/compound/2-Nitroaniline (accessed Apr 9, 2020). 4 Sulfuric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Sulfuric-acid (accessed Apr 9, 2020). 5 Nitric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Nitric-acid (accessed Apr 9, 2020). 6 Sneden, A. T. Experiment 6: Electrophilic Aromatic Substitution: Preparation Of p-Nitroaniline. Electrophilic Aromatic Substitution: Preparation Of pNitroaniline (accessed Apr 9, 2020).

Nitric acid5 ● Molar mass: 63.013 g/mol ● Boiling point: 83 degrees C ● Melting point: -41.6 degrees C ● Density: 1.38 g/mL ● Hazards: corrosive

Procedure6: A nitrating reagent was prepared in the hood by slowly adding 1.7 mL of cold concentrated sulfuric acid to 0.6 mL of cold concentrated nitric acid in a 50 mL Erlenmeyer flask. The mixture was swirled in an ice bath to make sure they were mixed thoroughly together. 1.06 g of acetanilide in 1.5 mL of concentrated sulfuric acid was slowly mixed together in a second 50 mL Erlenmeyer flask (slowly pouring the acid into the acetanilide) and then swirled after. The mixture was heated with a hot plate to further dissolve the acetanilide. The flask was then cooled in an ice bath once all of the acetanilide was dissolved. While still being immersed in an ice bath, the cold nitrating reagent was then slowly added to the cold acetanilide mixture dropwise, while swirling in between each addition. The flask was kept in an ice bath with intermittent swirling for 20 minutes after. A 10 mL ice-water mixture was added to dilute the acids. The mixture was swirled to thoroughly dilute and then left to stand for 5 minutes with swirling. Solid nitroaniline formed. The solid was then collected by vacuum filtration and the solid was rinsed with cold water. Using a Buchner funnel, the solid was allowed to dry in a stream of air for several minutes. A small amount of the solid was saved in a small test tube. The filter flask was then rinsed out with a small amount of water. Taking the remainder of the solid, it was recrystallized from hot ethanol. The recrystallized solid was then collected by vacuum filtration. A TLC test (eluted with ethyl acetate) was run on the crude solid, the recrystallized solid, and the filtrate from the recrystallization. The solid was allowed to dry until next lab period and the weight and melting point of the product was taken. 1 Acetanilide. https://pubchem.ncbi.nlm.nih.gov/compound/Acetanilide#section=Melting-Point (accessed Apr 9, 2020). 2 N-(4-Nitrophenyl)acetamide. https://pubchem.ncbi.nlm.nih.gov/compound/N-_4-Nitrophenyl_acetamide (accessed Apr 9, 2020). 3 2-Nitroaniline. https://pubchem.ncbi.nlm.nih.gov/compound/2-Nitroaniline (accessed Apr 9, 2020). 4 Sulfuric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Sulfuric-acid (accessed Apr 9, 2020). 5 Nitric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Nitric-acid (accessed Apr 9, 2020). 6 Sneden, A. T. Experiment 6: Electrophilic Aromatic Substitution: Preparation Of p-Nitroaniline. Electrophilic Aromatic Substitution: Preparation Of pNitroaniline (accessed Apr 9, 2020).

Calculations: Rf values from TLC: Solvent front = 5.5 cm Crude solid: 4.6 cm/5.5 cm = 0.836 cm 5.0 cm/5.5 cm = 0.909 cm Recrystallized solid: 4.5 cm/5.5 cm = 0.818 cm 4.9 cm/5.5 cm = 0.891 cm Filtrate from recrystallized solid: 4.5 cm/5.5 cm = 0.818 cm 4.9 cm/5.5 cm = 0.891 cm Percent yield: Theoretical yield calculation1.06 g acetanilide x (1 mol/135.16 g) = .0078 mol x (180.16 g/1 mol) = 1.41 g (1.22 g / 1.41 g) x 100 = 86.52% recovered

1 Acetanilide. https://pubchem.ncbi.nlm.nih.gov/compound/Acetanilide#section=Melting-Point (accessed Apr 9, 2020). 2 N-(4-Nitrophenyl)acetamide. https://pubchem.ncbi.nlm.nih.gov/compound/N-_4-Nitrophenyl_acetamide (accessed Apr 9, 2020). 3 2-Nitroaniline. https://pubchem.ncbi.nlm.nih.gov/compound/2-Nitroaniline (accessed Apr 9, 2020). 4 Sulfuric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Sulfuric-acid (accessed Apr 9, 2020). 5 Nitric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Nitric-acid (accessed Apr 9, 2020). 6 Sneden, A. T. Experiment 6: Electrophilic Aromatic Substitution: Preparation Of p-Nitroaniline. Electrophilic Aromatic Substitution: Preparation Of pNitroaniline (accessed Apr 9, 2020).

Results: 1.06 g of acetanilide was measured in the beginning. The final mass taken of the solid (nitroaniline) at the end was 1.22 g. This gave a percent yield of 86.52% of nitroaniline recovered. The TLC plate test gave the following results shown below.

The melting point taken of final solid came out with a range of 171-172 degrees Celsius. Discussion: The TLC plate we got does not parallel the predicted TLC plate from this experiment. Shown below is what the TLC should look like if the entirety of the experiment were to be successful.

The crude solid’s results came out correct, with it being a combination of both ortho-nitroaniline and para-nitroaniline. Hence, the two dots. However, the recrystallized and 1 Acetanilide. https://pubchem.ncbi.nlm.nih.gov/compound/Acetanilide#section=Melting-Point (accessed Apr 9, 2020). 2 N-(4-Nitrophenyl)acetamide. https://pubchem.ncbi.nlm.nih.gov/compound/N-_4-Nitrophenyl_acetamide (accessed Apr 9, 2020). 3 2-Nitroaniline. https://pubchem.ncbi.nlm.nih.gov/compound/2-Nitroaniline (accessed Apr 9, 2020). 4 Sulfuric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Sulfuric-acid (accessed Apr 9, 2020). 5 Nitric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Nitric-acid (accessed Apr 9, 2020). 6 Sneden, A. T. Experiment 6: Electrophilic Aromatic Substitution: Preparation Of p-Nitroaniline. Electrophilic Aromatic Substitution: Preparation Of pNitroaniline (accessed Apr 9, 2020).

filtrate did not show the anticipated results. The recrystallized solid should have shown one dot at the top, symbolizing the para-nitroaniline. (Due to para-nitroaniline being less polar than ortho-nitroaniline). Instead, we see two dots, signifying that both ortho- and para- were conserved in the recrystallized. This is further proven when we look at the filtrate as well. The filtrate should have only shown one dot at the bottom, symbolizing ortho-nitroaniline. Instead, we see two dots again, showing that both ortho- and para- were still present. This error in our results shows that the purification steps failed. Besides just looking at the visible locations of the spots, the calculated Rf values also contribute to this argument. The Rf values of each of the three components are all extremely close in range, showing that they all contain the same polarities and the same components. However, the reaction itself of the preparation of nitroaniline from acetanilide still proceeded successfully. This is proven true due to the fact that acetanilide is nowhere to be found on the TLC plate (which would have appeared at the very top above all the other dots, due to it being the least polar). The recrystallization step is what failed. The recrystallized product was impure, as was the filtrate. This is further proven when we look at the percent recovery. As seen from our calculations, there was a percent recovery of 86.52%. This is a much higher yield than expected. This high yield is due to the fact that both o-nitroaniline and p-nitroaniline were collected, instead of just p-nitroaniline alone. The collected melting point of the final product also aligns with this. A melting point range of 171-172 degrees Celsius was taken. The literature melting point of just p-nitroaniline is 216 degrees Celsius. This further proves that the final product was not purified correctly.

1 Acetanilide. https://pubchem.ncbi.nlm.nih.gov/compound/Acetanilide#section=Melting-Point (accessed Apr 9, 2020). 2 N-(4-Nitrophenyl)acetamide. https://pubchem.ncbi.nlm.nih.gov/compound/N-_4-Nitrophenyl_acetamide (accessed Apr 9, 2020). 3 2-Nitroaniline. https://pubchem.ncbi.nlm.nih.gov/compound/2-Nitroaniline (accessed Apr 9, 2020). 4 Sulfuric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Sulfuric-acid (accessed Apr 9, 2020). 5 Nitric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Nitric-acid (accessed Apr 9, 2020). 6 Sneden, A. T. Experiment 6: Electrophilic Aromatic Substitution: Preparation Of p-Nitroaniline. Electrophilic Aromatic Substitution: Preparation Of pNitroaniline (accessed Apr 9, 2020).

Questions: 1. What product (or products) may form if the reaction is not kept on ice during the addition of the acid mixture to the acetanilide? If the addition of the acid mixture to the acetanilide is not kept cold, a di-nitro substituted product can possibly be produced. 2. If compound A is more polar than compound B, which compound will have the highest Rf value on a TLC plate that is eluted with ethyl acetate? Which compound will have the highest Rf value if the plate is eluted with dichloromethane? If compound A is more polar than compound B, then compound B will have the highest Rf value using either ethyl acetate or dichloromethane. While dichloromethane is not as polar as ethyl acetate, it is still a polar solvent that can be used for TLC.

3. What compound (or compounds) would form if aniline was used instead of acetanilide using the same reaction conditions? Since aniline is a strong ortho-para director due to the fact that is a strong activator, we would still see both ortho and para products from the reaction.

1 Acetanilide. https://pubchem.ncbi.nlm.nih.gov/compound/Acetanilide#section=Melting-Point (accessed Apr 9, 2020). 2 N-(4-Nitrophenyl)acetamide. https://pubchem.ncbi.nlm.nih.gov/compound/N-_4-Nitrophenyl_acetamide (accessed Apr 9, 2020). 3 2-Nitroaniline. https://pubchem.ncbi.nlm.nih.gov/compound/2-Nitroaniline (accessed Apr 9, 2020). 4 Sulfuric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Sulfuric-acid (accessed Apr 9, 2020). 5 Nitric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Nitric-acid (accessed Apr 9, 2020). 6 Sneden, A. T. Experiment 6: Electrophilic Aromatic Substitution: Preparation Of p-Nitroaniline. Electrophilic Aromatic Substitution: Preparation Of pNitroaniline (accessed Apr 9, 2020).

References: 2-Nitroaniline. https://pubchem.ncbi.nlm.nih.gov/compound/2-Nitroaniline (accessed Apr 9, 2020). Acetanilide. https://pubchem.ncbi.nlm.nih.gov/compound/Acetanilide#section=Melting-Point (accessed Apr 9, 2020). N-(4-Nitrophenyl)acetamide. https://pubchem.ncbi.nlm.nih.gov/compound/N-_4-Nitrophenyl_acetamide (accessed Apr 9, 2020). Nitric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Nitric-acid (accessed Apr 9, 2020). Sneden, A. T. Experiment 6: Electrophilic Aromatic Substitution: Preparation Of p-Nitroaniline. Electrophilic Aromatic Substitution: Preparation Of pNitroaniline (accessed Apr 9, 2020). Sulfuric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Sulfuric-acid (accessed Apr 9, 2020).

1 Acetanilide. https://pubchem.ncbi.nlm.nih.gov/compound/Acetanilide#section=Melting-Point (accessed Apr 9, 2020). 2 N-(4-Nitrophenyl)acetamide. https://pubchem.ncbi.nlm.nih.gov/compound/N-_4-Nitrophenyl_acetamide (accessed Apr 9, 2020). 3 2-Nitroaniline. https://pubchem.ncbi.nlm.nih.gov/compound/2-Nitroaniline (accessed Apr 9, 2020). 4 Sulfuric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Sulfuric-acid (accessed Apr 9, 2020). 5 Nitric acid. https://pubchem.ncbi.nlm.nih.gov/compound/Nitric-acid (accessed Apr 9, 2020). 6 Sneden, A. T. Experiment 6: Electrophilic Aromatic Substitution: Preparation Of p-Nitroaniline. Electrophilic Aromatic Substitution: Preparation Of pNitroaniline (accessed Apr 9, 2020)....