Experiment 6 Post-Lab Exercises - Part 2 Synthesis Lab I - CHEM-2380-A PDF

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CHEM 2380 Experiment 6 Post Lab Exercises Solutions...

Description

Experiment 6: Post-Lab Exercises - Part 2 Due Jun 20 at 12:30pm

Points 10

Questions 9

Available until Jun 25 at 12:30pm

Time Limit None

Instructions This "quiz" contains Part 2 of the post-lab exercises for experiment 6. Part 1 is an assignment which can be found under the same Module. For all questions, please type in your response in the corresponding boxes. For Questions 1 and 2, you will need to upload a file to answer the question. The answers that you type in or upload will save automatically. You may start the "quiz" and return to the "quiz" at any time. Do NOT press "submit" until you are fully satisfied with all your answers! Do NOT submit your assignment until you have received your NMR in lab!

This quiz is no longer available as the course has been concluded.

Attempt History LATEST

Attempt

Time

Score

Attempt 1

1,486 minutes

10 out of 10

 Correct answers are no longer available. Score for this quiz: 10 out of 10 Submitted Jun 19 at 5:13pm

This attempt took 1,486 minutes.

Question 1

1 / 1 pts

Label and attach your NMR spectra. You should include the compound's structure, your name, and label each peak on the NMR and their corresponding protons on the structure (as we did in Experiment 1.5).  NMR.jpg (https://gatech.instructure.com/files/5849863/download)

Question 2

1 / 1 pts

Label and attach your IR spectra. You should include the compound's structure, your name, and label each peak on the IR and their corresponding bonds on the structure (as we did in Experiment 1.5).  IR.jpeg (https://gatech.instructure.com/files/5850189/download)

2 / 2 pts

Question 3

Thinking about your NMR spectrum, was your product pure? Were there any peaks that were not part of the product? If so, explain what they are and how the impurities can be removed/avoid in the

future. Please answer in 50 words or less. Hint: it may be helpful to reference the common impurities in NMR paper

.

Your Answer: According to my NMR spectrum, my product was not completely pure because there were peaks around 1.6 and 2.2 ppm that did not result from the 9-10-dihydroanthracene-9,10-α,β-succinic anhydride. The peak at 1.59 was likely from water while the peak at 2.17 was likely from the acetone used to clean the NMR tubes. (These are around the values at which both show up in CDCl3.) One way to avoid having the peak from water is to make sure that the test tube is completely dry. It is difficult to avoid the peak from the acetone since that is what the NMR tubes are cleaned with but again, a way to do so is to ensure that the tubes are completely dry before the sample is put in there.

One common problem in NMR spectra is excess solvent due to insufficient drying of the sample. This can be seen by the presence of solvent peaks. You should also look for peaks corresponding to the starting material as reference to reaction progress.

Question 4

1 / 1 pts

Briefly discuss (in less than 50 words) your choice of recrystallization solvent. What factors led you to choose one over the other? Did this result in a pure, crystalline product? Your Answer:

I chose xylenes as the recrystallization solvent because the product dissolved in xylenes at high temperatures but not at room temperature. The product did not dissolve in hexanes at all, and it

dissolved in ethyl acetate at both room and high temperatures. Choosing xylenes as the solvent did result in a pure, crystalline compound.

Remember, the recrystallization solvent should be one that dissolves the compound at high temperatures only and does not dissolve the compound at room temperature. A single homogenous color and crystallinity are some indicators of a pure, crystalline product.

Question 5

1 / 1 pts

What was the mass of your product before recrystallization? This is called a crude yield. Your Answer: crude yield = 0.3016 g

As always, masses should be reported to 4 decimal places with proper units.

Question 6

1 / 1 pts

What was the mass of your product after recrystallization? Your Answer: recrystallization product = 0.3519 g

As always, masses should be reported to 4 decimal places with proper units.

Question 7

What was the percent yield of your product? Show your calculations for full credit. Your Answer: theoretical yield = 0.3727g -> anthracene: (0.2544g)(1 mol/178.23g)(1000 mmol/1 mol) = 1.427 mol -> maleic anhydride: (0.1323g)(1 mol/98.06g)(1000 mmol/1 mol) = 1.349 mol -> limiting reagent is maleic anhydride -> (1.349 mmol)(276.29g/1000 mmol) = 0.3727 g

1 / 1 pts

actual yield

0.3519 g

percent yield = (0.3519 / 0.3727) * 100 = 94 %

This should be your answer to #6 divided by the theoretical mass.

Question 8

What was the percent recovery of your product? Show your calculations for full credit. Your Answer: crude yield = 0.3016 g recrystallization product = 0.3519 g percent recovery = (0.3016/0.3519) * 100 = 86%

1 / 1 pts...