O NH Cl - University of Tulsachalker.ens.utulsa.edu/chem/Teaching_files/Problem Set 3_2.pdf · Problem Set 3 – 20 Pts Chem 3013-01 Due Oct 31 in Class Complete the 8 problems below

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Problem Set 3 – 20 Pts

Chem 3013-01 Due Oct 31 in Class Complete the 8 problems below and answer the questions in the space provided. Ensure all writing and illustrations are legible. Please write your full name on all pages and submit a stapled copy of your solutions. The point value for each question is given in brackets at the end of each exercise.

1. Match each of the following compounds to their IR spectrum. Justify your assignment. [2 pts]

Spectrum A (Nujol mull):

Spectrum B (neat film):

O

NH2

O

Cl

2

(Question 1 continued)

3

2. Design two spectroscopic experiments that could distinguish the following molecules. Explain. [2 pts]

NH2 N3

4

3. Explain how 1H NMR can be used to distinguish all three of the following compounds. [2 pts]

5

4. The following compound—from a class of materials called annulenes—has two peaks in the 1H NMR spectrum: one peak is at 9.17 ppm and the other peak is at −2.96 ppm. Which protons resonate at these frequencies? Explain your assignment and discuss the reason for the large shielding and deshielding observed in this molecule. [2 pts]

6

5. You generate an unknown compound during a reaction. The molecular formula was determined to be C10H12O2 by high resolution mass spectrometry. Propose a structure for this compound using the following IR and NMR data. Justify your proposal by labeling all diagnostic peaks in the IR spectrum. Assign 1H and 13C spectra as fully as possible and label your assignments directly on the spectra provided. [3 pts]

IR (neat film):

1H NMR (90 MHz, CDCl3): 1.16 (3H, t, J = 7.8 Hz), 2.37 (2H, q, J = 7.8 Hz), 5.11 (2H, s), 7.14-7.50 (5H, m).

7

(Question 5 continued) 13C NMR (25 MHz, CDCl3): 9.1, 27.6, 66.1, 128.2, 128.4, 128.6, 136.3, 174.1

8

6. You generate an unknown compound during a reaction. The molecular formula was determined to be C4H6O by high resolution mass spectrometry. Propose a structure for this compound using the following IR and NMR data. Justify your proposal by labeling all diagnostic peaks in the IR spectrum. Assign 1H and 13C spectra as fully as possible and label your assignments directly on the spectra provided. [3 pts]

IR (neat):

1H (90 MHz, CDCl3): 2.03 (3H, dd, J = 1.5, 6.8 Hz), 6.15 (1H, dd, J = 7.8, 15.5 Hz), 6.88 (1H, m), 9.50 (1H, d, 7.8 Hz)

9

(Question 6 continued)

13C (25 MHz, CDCl3): 18.6, 134.6, 154.3, 194.0

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7. Assign the 1H and 13C NMR spectrum for the following compound as fully as possible. Label your assignments directly on the spectra provided (see attached). COSY, DEPT-135, and HSQC spectra are provided to assist in your assignment. [3 pts]

1H (400 MHz, CDCl3): 1.03 (3H, d, J = 6.9 Hz), 1.09 (3H, d, J = 6.9 Hz), 2.27-2.34 (1H, m), 4.44 (1H, dd, J = 5.0, 8.8 Hz), 5.09 (1H, d, J = 8.8 Hz), 7.28 (2H, d, J = 9.2 Hz), 8.26 (2H, d, J = 9.2 Hz). 13C (100 MHz, CDCl3): 17.8, 19.1, 28.3, 31.0, 58.9, 80.3, 122.4, 125.3, 145.5, 155.1, 155.7, 170.4

NH O

OO

O

NO2

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8. Fully assign the 1H and 13C NMR spectrum for the following compound. Label your assignments directly on the spectra provided (see attached). COSY, DEPT-135, and HSQC spectra are provided to assist in your assignment. Assign the stereochemistry at carbon 1 with a brief justification for your assignment. [3 pts]

1H (400 MHz, CDCl3): 2.02 (3H, s), 2.06 (3H, s), 2.12 (3H, s), 2.16 (3H, s), 4.11 (1H, dd, J = 6.8, 11.4 Hz), 4.19 (1H, dd, J = 6.3, 11.4 Hz), 4.49 (1H, apparent t, J = 6.6 Hz), 5.05 (1H, dd, J = 4.0, 10.6 Hz), 5.41 (1H, dd, J = 3.3, 10.6 Hz), 5.52 (1H, dd, J = 1.4, 3.3 Hz), 6.70 (1H, d, J = 4.0 Hz). 13C (100 MHz, CDCl3): 20.52, 20.55, 20.6, 20.7, 60.8, 66.9, 67.7, 67.9, 71.0, 88.1, 169.7, 169.8, 170.0, 170.3

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For additional practice, the following problems from the Klein textbook are recommended. You do not need to hand in solutions to these problems, but working through these exercises is excellent practice for mastering the material and preparing for exams. Chapter 15: 12, 13, 14, 15, 16, 21, 22, 24, 25, 26, 27, 29, 30, 31, 33, 34, 38, 39, 40, 41, 42, 45, 46, 47, 48, 50, 53, 55, 59, 60 Chapter 16: 1, 2, 3, 4, 5, 15, 16, 17, 18, 21, 23, 25, 26, 29, 30, 31, 32, 33, 34, 36, 37, 38, 40, 44, 46, 48, 50, 53, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67 Chapter 17: 30, 31, 50, 51

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O NH Cl - University of Tulsachalker.ens.utulsa.edu/chem/Teaching_files/Problem Set 3_2.pdf · Problem Set 3 – 20 Pts Chem 3013-01 Due Oct 31 in Class Complete the 8 problems below