Lab B. Data Analysis (1)

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Feb 20, 2024

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Page 1 of 8 If turning in late, provide explanation here: ______________________________________ CHEM 3AL Lab B: Chemistry of Alpha Pinene Oxide adapted from Dr. Pete Marsden and Dr. Alexis Shusterman 1: What was your product and how did it form? a. Analyze the NMR spectra on the following pages to determine the structure of your final product. Then, draw a mechanism for its formation in the box below. MECHANISM: b. The NMR spectra will also help you identify the structure of the side product that results from the decomposition of alpha pinene oxide on the silica gel TLC plate. Draw a mechanism for the formation of this decomposition product in the box below. MECHANISM:

0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 f1 (ppm) 3.2 6.3 1.0 1.1 4.2 1.0 This is the ¹ H NMR spectrum of the alpha-pinene oxide starting material. Assign signals to the indicated (implied) hydrogens on your chosen structure using the letters provided. Since you are not assigning all of the hydrogens, not all letters will be used. Then, in your own words, explain how you differentiated between the three signals with integrals of approximately 1 (signals A, D, and E) when labeling your structure. Incomplete sentences are fine! A B/B’ + C/C’ D E F/F’ G 2

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 f1 (ppm) 6.1 1.1 5.1 1.1 1.0 1.0 1.0 1.0 1.0 (CD 3 )(CD 2 H)S=O (NMR Solvent) In your own words, share how you differentiated the true product from the other two options. Your answer must reference at least one ¹ H NMR signal and explain why this signal is unique to the true product’s structure. Incomplete sentences are fine! A B C D H I/I’ 3 Use the ¹ H NMR spectrum to identify the true product from the three options below. Once you have selected the true product, assign signals to the indicated (sometimes implied) hydrogens on your chosen structure using the letters provided. Since you are not assigning all of the hydrogens, not all letters will be used. Peaks with a * above them correspond to impurities, these should be ignored. * * E /E' + F/F’+ G

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Use the ¹ H NMR spectrum to identify the TLC decomposition product from the two options below. Once you have selected the correct structure, assign signals to the indicated (sometimes implied) hydrogens on your chosen structure using the letters provided. Since you are not assigning all of the hydrogens, not all letters will be used. In your own words, share how you identified the TLC decomposition product. Your answer must reference at least one ¹ H NMR signal and explain why this signal is unique to the true product’s structure. Incomplete sentences are fine! A B C /C' + D/D’ + E F this signal at 0 ppm is from an additive that is not part of the product G/G’ 4

14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 f1 (ppm) C + D + E + F + G + H + I/I’ A + B This is the ¹³ C NMR spectrum for the alpha-pinene oxide starting material. On the provided structure, circle the carbons associated with signals A & B. Then, in your own words, explain why these carbons exhibit a higher chemical shift. Incomplete sentences are fine! These peaks are from the NMR solvent, CDCl 3 5

15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 f1 (ppm) (CD 3 ) 2 S=O This is the ¹³ C NMR spectrum for the true product. In your own words, compare it to that provided for the alpha-pinene oxide starting material. Which signals are unique to the product? What do these unique signals tell you about the product structure? Incomplete sentences are fine! Draw the structure of the true product below. 6

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This is the ¹³ C NMR spectrum for the TLC decomposition product. In your own words, compare it to that provided for the true product. Which signals are unique to the decomposition product? What do these unique signals tell you about its structure? Incomplete sentences are fine! Draw the structure of the TLC decomposition product below. 7

Page 8 of 8 2: TLC Analysis a. Draw and label the TLC plates you developed during the lab period and use the TLC evidence to answer the following questions. 3: How much did you make? a. Convert your ACTUAL amounts into mmol: C 10 H 16 O + H 2 O → crude C 10 H 18 O 2 → final C 10 H 18 O 2 ______ mmol ______ mmol ______ mmol ______ mmol b. Based on the ACTUAL amounts above, calculate your crude % yield % c. Based on the ACTUAL amounts above, calculate your final % yield %