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Kcal/mol

Kcal/mol. 1.7 X 10 3. 5.7 X 10 5. 9.5 X 10 3. 4.8 X 10 2. 72. 1.2. 9.5 X 10 -3. 10 -4. EIMS. NMR. Nuclear Magnetic Resonance (NMR) Spectroscopy. To here!. From here…. The Nobel Prize in Physics 1952.

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Kcal/mol

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  1. Kcal/mol 1.7 X 103 5.7 X 105 9.5 X 103 4.8 X 102 72 1.2 9.5 X 10-3 10-4 EIMS NMR

  2. Nuclear Magnetic Resonance (NMR) Spectroscopy To here! From here…

  3. The Nobel Prize in Physics 1952 "for their development of new methods for nuclear magnetic precision measurements and discoveries in connection therewith" Felix Bloch Edward Mills Purcell

  4. Magnetic nuclei are in resonance with external magnetic field if they absorb energy and “spin-flip” from low energy state (parallel orientation) to high energy state (antiparallel orientation).

  5. atomic nuclei in absence of magnetic field atomic nuclei in presence of external magnetic field atomic nuclei can either align parallel (lower E) or antiparallel (higher E)

  6. Magnetic nuclei are in resonance with external magnetic field if they absorb energy and “spin-flip” from low energy state (parallel orientation) to high energy state (antiparallel orientation).

  7. Dependence of the difference in energy between lower and higher nuclear spin levels of the hydrogen atom

  8. Dependence of the difference in energy between lower and higher nuclear spin levels of the hydrogen atom Nuclei in different environments (i.e. with different amounts of electron density around them) will require different amounts of energy to “flip” to higher energy different spin state

  9. Magnetic: • All nuclei with odd number of protons • All nuclei with odd number of neutrons • Nonmagnetic: • Nuclei with even number of both protons and neutrons

  10. Fig. 13-4, p. 444

  11. Really Old School: Continuous wave (CW) 40 MHz NMR spectrometer 1960

  12. 1964 A little less old school: Continuous wave (CW) 60 MHz NMR spectrum

  13. Not quite so old school: 1980’s 60 MHz

  14. The Nobel Prize in Chemistry 1991 "for his contributions to the development of the methodology of high resolution nuclear magnetic resonance (NMR) spectroscopy" Richard R. Ernst

  15. State-of-the-art 900 MHz NMR spectrometer Center for Biomolecular NMR, Heinrich-Heine-Universität Düsseldorf

  16. Colchitaxel, a coupled compound made from microtubule inhibitors colchicine and paclitaxel

  17. Free-induction decay data and proton-decoupled 13C nuclear magnetic resonance spectra

  18. 13C NMR spectrum 1-pentanol : 1 scan Fig. 13-6, p. 447

  19. 13C NMR spectrum 1-pentanol : 1 scan 13C NMR spectrum 1-pentanol : 200 scans Fig. 13-6, p. 447

  20. The Nature of NMR Absorptions 1H NMR spectrum 13C NMR spectrum

  21. The Nobel Prize in Chemistry 2002 "for his development of nuclear magnetic resonance spectroscopy for determining the three-dimensional structure of biological macromolecules in solution" Kurt Wüthrich

  22. Sir Peter Mansfield Paul C. Lauterbur The Nobel Prize in Medicine 2003 "for their discoveries concerning magnetic resonance imaging"

  23. More energy to flip nucleus Less energy to flip nucleus chemical shift d, ppm

  24. Magnetically distinct 13C NMR of methyl acetate Chemically equivalent nuclei always show the same absorption

  25. Magnetically distinct hydrogens and carbons!

  26. 77 ppm CDCl3 Fig. 13-7, p. 448

  27. sp3 77 ppm CDCl3 Fig. 13-7, p. 448

  28. For each molecule below: • Determine the number of distinct carbon peaks • Assign chemical shifts for each distinct carbon

  29. Fig. 13-10a, p. 451

  30. Information in a 1H NMR spectrum 1H NMR spectrum 13C NMR spectrum

  31. Table 13-2, p. 457

  32. Table 13-3, p. 458

  33. 6.5 – 8.0 Table 13-3, p. 458

  34. 1H NMR Integration Area under each peak is proportional to number of protons causing that peak. Gives ratio, not always exact number!

  35. spin-spin splitting

  36. Spin – Spin Splitting Absorption of a proton can split into multiple peaks (multiplet) Tiny magnetic field produced by one nucleus affects magnetic field felt by neighboring nuclei Fig. 11-13, p. 424

  37. Fig. 13-13, p. 460

  38. Chemical shift – middle of multiplet 3.4130 3.4165 3.4235 3.4270 d 3.42 Fig. 13-13, p. 460

  39. Common NMR splitting patterns

  40. C3H7Br Fig. 11-15, p. 425

  41. 12 C3H7Br 2 Fig. 11-15, p. 425

  42. 1.5 C10H12O2 1 1.5 1 1 Fig. 11-16, p. 427

  43. C10H12O 4.5 4.5 3 3 3

  44. Fig. 13-19, p. 466

  45. Fig. 13-19, p. 466

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