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Unformatted text preview: 1 Quiz Bank 7 13 H and C NMR 1. What are the 4 types of information that NMR tells us? 2. Signals in the H NMR donʼt always show up as a single peak. What is this phenomenon? 3. What do the integration values (area underneath each peak) correlate to? 4. Sometimes the integration values are not always perfect. Give an explanation for this. 5. Draw a molecule that has methyl, methylene, and methine protons on it. 6. Why is the NMR scale in chemical shift values (δ) and not in Hz? 7. A spectra was taken on a 400 MHz NMR that showed a doublet at 2500 Hz. What is the chemical shift value in ppm of this peak? 8. What influences the chemical shift value? 9. A bromine atom adjacent to a proton greatly affects the chemical shift. What happens if the bromine is placed 1 or two carbons away? 10. Describe what happens to the chemical shift value of the adjacent proton, in terms of electronegativity and deshielding effects, when you exchange an Iodine for a Fluorine. 11. Strangely, a proton adjacent to a bromine is much further upfield than a proton on an aromatic ring. In the aromatic ring, there are just hydrogen and carbon…so how can that be more electron withdrawing than a bromine? What is this phenomenon known as? 12. Analyze the following 1H NMR spectra
1 The signals from left to right are a singlet (1H), septet (1H), and a doublet (6H). The numbers in parentheses are the integrations. What is the structure of the compound? a. b. c. d. 13. Look at the following structure and identify the present splitting patterns for 1H NMR (the numbers in parentheses are not the integrations this time, but the number of the splitting in case you didnʼt know the terms). a. b. c. d. e. Doublet, septet(7), triplet, singlet Quartet, singlet, quintet(5), doublet Singlet, doublet, triplet, quartet, septet(7) Doublet, septet(7), singlet Quartet, triplet, septet, doublet 14. Identify the splitting patterns of all non-equivalent protons in the following molecules: 15. The abundance of 1H in the environment is approximately a. 0.11 % b. 1.1% c. 99% d. 99.9% e. None of the above 16. The abundance of 13C in the environment is approximately a. 0.11 % b. 1.1% c. 99% d. 99.9% e. None of the above Match the following compounds to their 1H NMR. Because these are hard to see, the splitting patterns in order from left to right are given for each spectra on the right hand side. 17. (quartet, triplet) 18. (quartet, singlet, doublet) 19. (quartet, triplet) 20. (singlet, singlet, singlet) 21. (singlet, triplet, sextet, triplet) Match the following 13C NMR to their compounds: 22. 23. 24. ...
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- Fall '07