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(More) NMR practice problems

(More) NMR practice problems. Sources: http://www.chem.ucla.edu/~webspectra/ http:// www.aist.go.jp/RIODB/SDBS/cgi-bin/cre_index.cgi. Ch14C, Spring 2012 Prof. Dong. Rough 13 C-NMR guidelines. ketone 210 ppm aldehyde 200 (this is a nice even number to remember) carboxylic acid 180

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(More) NMR practice problems

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  1. (More) NMR practice problems Sources: http://www.chem.ucla.edu/~webspectra/ http://www.aist.go.jp/RIODB/SDBS/cgi-bin/cre_index.cgi • Ch14C, Spring 2012 • Prof. Dong

  2. Rough 13C-NMR guidelines • ketone 210 ppm • aldehyde 200 (this is a nice even number to remember) • carboxylic acid 180 • ester/amide 170 • C=C 120 • C≡C 80 • C-O 60 (note that CHCl3 appears at 77 ppm) • C-C 0-30 • CH4 -2.3 • Neobutane25.0 • TMS Si(CH3)4 0 ppm (set as reference)

  3. For each structure:1. Calculate the number of peaks you would expect on 13C-NMR for each of these structures. 2. Using the molecular formula, calculate the number of DBEs expected and compare it to the actual structure Answers. Number of equivalent carbons (from left to right): 5, 6, 9, 3, 1, 5

  4. Beginner #7, C14H14 Solvent: CHCl3

  5. Beginner #10, C10H10O2 194.452 158.166 148.135 132.603 128.900 128.740 122.796 120.738 111.175 55.4332 Solvent: CHCl3

  6. Beginner #12 C6H12O2 Solvent: CHCl3

  7. Beginner #27, C3H7OCl Solvent: CHCl3

  8. Beginner #25, C4H8O Solvent: CHCl3

  9. Int1 #1, C3H4O Solvent: CHCl3 0 200

  10. Int1 #16, C6H10O Solvent: CHCl3

  11. Int1 #2, C8H12O2 2H,sextet 3H,t 2H, t 2H,p 3H, s 1H-NMR 3H,t 2H, t 2H,sextet 2H,p 13C-NMR Solvent: CHCl3

  12. Int2 #13, C10H15N Example of a DEPT 13C-NMR spectra (four 13C-NMR spectra) Solvent: CHCl3 The normal, “standard” 13C-NMR Up: CH, CH2, CH3 Up: CH Up: CH and CH3 Down: CH2

  13. Int#12, C7H9NO Solvent: CHCl3 The normal, standard 13C-NMR Up: CH, CH2, CH3 Up: CH Up: CH and CH3 Down: CH2 160 50

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