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CHEM 344

CHEM 344. Organic Chemistry Lab. Spectroscopy of Organic Compounds Lecture 2 – More NMR Nick Hill. June 17 th 2008. 1.58. CH 3. 4.42. CH 2. SiMe 4. 3. 2. 1.12. CH 3. 12. CH. 3.64. 2. CH. 3.64. 1.18. 6.63. 7.02. 2.79. 3.51. 1.18. CH 3. 6. NH 2. CH. 3.51. 2. 2.79.

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CHEM 344

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  1. CHEM 344 Organic Chemistry Lab Spectroscopy of Organic Compounds Lecture 2 – More NMR Nick Hill June 17th 2008

  2. 1.58 CH3 4.42 CH2 SiMe4 3 2

  3. 1.12 CH3 12 CH 3.64 2

  4. CH 3.64

  5. 1.18 6.63 7.02 2.79 3.51

  6. 1.18 CH3 6 NH2 CH 3.51 2 2.79 1

  7. Ha is more shielded since closer to NH2 (activating group) Draw the resonance structures to check……. Ha Hb 6.63 7.02 CHCl3 2 2

  8. 3.91 3

  9. Hb Ha 8.18 6.97 2 2

  10. Jab Jab = Jortho= 12 – 18 Hz

  11. Jab = Jbd = Jmeta= 1 – 3 Hz Jac = Jpara= 0 - 1 Hz Jortho > Jmeta > Jpara Jbd = Jcd = Jortho= 12 – 18 Hz

  12. 3.89

  13. Ha 7.48 7.71 Hc Hb Hd 7.79 7.23 1 1 1 1

  14. 1.93 Hf 3

  15. Jab = Jcis= 6 – 12 Hz Jbc = Jgem= 1 – 3 Hz Jac = Jtrans= 12 – 18 Hz Jtrans > Jcis > Jgem

  16. 7.23 7.11 5.70 5.17 6.61 2 2 1 1 1

  17. Hd Doublet of doublets (not a 1:1:1:1 quartet!) He Ha 2 2 1

  18. Hd He 5.70 5.17 Ha 1 1

  19. Hc Hb 5.70 5.17 1 1

  20. Draw the splitting diagrams to confirm these assignments….. Hd 7.23 He 7.11 Hc Hb 5.70 5.17 Ha 6.61 2 2 1 1 1

  21. How many types of H-atom? Indicated by how many groups of signals there are in the spectrum What types of H-atoms? Indicated by the chemical shift of each signal How many H of each type are there? Indicated by the integration of the signal for each group What is the connectivity of the molecule? Indicated by the splitting pattern of each signal

  22. Spin ½ atoms 1H, 13C Carbon NMR spectroscopy No spin-spin splitting No integration Wider chem.shift range (0 – ~200 ppm) Signal/Noise ratio not great

  23. 15.34 CH3 65.94 CH2 CDCl3

  24. 128.89 Cortho C-atoms with no H-atoms attached usually give the smallest signal CH3 Cipso 20.91 CDCl3 134.61

  25. 11.66 46.98 CH2Cl 26.09 CH3CH2CH2Cl CH2CH2Cl

  26. 19.10 OCH2 C=O signal usually 150 – 180 ppm 70.42 9.22 C=O 174.48

  27. 19.10 Me2CH MeCH2 9.22 Me2CH MeCH2 27.77 27.64

  28. CH3 OCH(CH3)2 C=O

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