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CHEM 3780 Orgo II, S12, Exp 9 (Lab #11) (REAC721 Wittig)

LAB REPORT INSTRUCTIONS

Synthesis of trans-9-(2-Phenylethenyl)anthracene: A Wittig Reaction

Carefully read all instructions and complete Section I on page 2 before you come to the lab.

Experimental Notes

1. Please read and be familiar with the background information before coming to lab (p. 209-111) 2. Please read and be familiar with the experimental procedure described on p. 212-114 before coming to

lab. 3. Obtain a TLC for the reaction. 4. Obtain a melting point of the product. 5. You will analyze the product by 1H NMR, see last page.

Lab Report Notes

(written in your lab notebook, 50 pts total)

You may work with a lab partner for the in-lab portion. The lab report is due at the beginning of the next lab session and it needs to reflect the student’s own work, no group work for lab report entries.

Section I Introduction (prepare this section before coming to the lab, 17 pts)

1. (1 pt) Date and Title of Experiment

2. (2 pts) Objective (2 sentences)

3. (2 pts) Prepare a table that lists the properties of all chemicals. List separately all hazards that are

involved in this experiment.

4. (2 pts) Which precautions are you taking for working with the harmful chemicals in this experiment?

5. (3 pts) Give a balanced equation for the overal transformation.

6. (5 pts) Give a detailed mechanism for the reaction beginning with PhCH2PPh3Cl and NaOH to form the

ylide; and form the betaine and oxaphosphatene intermediates. Show curved arrows for each step.

7. (2 pts) Give a bulleted outline of the procedure. **************************************************************************************************

Section II Observations and Calculations (data recorded during the lab, 12 pts)

8. (2 pts) Include observations that you make during the experiment.

9. (4 pts) Show the calculation of the theoretical yield and percent yield of your Wittig product.

10. Recrystallize your product from 2-propanol, and obtain a TLC.

11. (4 pts) Sketch your TLC plate in your notebook and calculate the Rf of your product and starting material.

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12. (2 pts) Determine the melting point of your dried product. Section III Results and Discussion (analysis after the experiment is completed, 19 pts)

13. (4 pts) What does the melting point tell you about the product trans-9-(2-phenylethenyl)anthracene?

14. (3 pts) Give two key IR stretches you would expect to see for your starting material.

15. (3 pts) Give two key IR stretches you would expect to see for your product.

16. (6 pts) Using the 1H NMR, identify the double bond 1H peaks (note the chemical shift) and calculate the coupling constant.

17. (2 pts) What evidence supports the synthesis of the trans-isomer instead of the cis-isomer?

18. (1 pt) What is the chemical shift of the aldehyde proton? Section IV Conclusions (2 pts)

19. (2 pts) List two new things you learned in doing this experiment or something that you now understand better than before you did the lab. Explain.

_____________________________ Sign & date your lab report

The lab report is due at the beginning of the next lab session and it needs to reflect the student’s own work, no group work

for lab report entries. Print clearly in your lab notebook so that the carbon copies are legible. Label everything when you hand in the duplicate

pages with your name, date, and experiment number.

Final Exam

Your final exam will take place during the week of April 16, 2012.

You must take the final exam during your regularly scheduled lab period.

You are NOT permitted to use any lose notes or textbooks.

You are allowed to use your lab notebook(s), a calculator and a ruler.

Handouts and PreLabs may be stapled to the lab notebook(s).

You are permitted to use molecular models. Sharing of models is not allowed.

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1. Identify the two olefin hydrogens—they should have identical coupling constants and will integrate to 1 H each.

2. Determine the coupling constant (J) in millimeters (x mm). 3. Determine how many mm are in 1 ppm (y mm). Then, assume that

1 ppm = 400 Hz = y mm. 4. Set up a ratio and solve for J. This is the coupling constant between

the olefin hydrogens. x mm = _y mm_ J 400 Hz