1 / 60

NMR N uclear M agnetic R esonance

NMR N uclear M agnetic R esonance. Heteronuclear NMR:. Index. NMR-basics. H-NMR. NMR-Symmetry. Heteronuclear-NMR. Proton with Carbon-13 coupling. Proton with Fluorine-19 coupling. Fluorine-19: Fluoroacetone. Phosphorus-31. Phosphorus-31: Coupling with 1 H.

omer
Download Presentation

NMR N uclear M agnetic R esonance

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NMRNuclear Magnetic Resonance HeteronuclearNMR: Index NMR-basics H-NMR NMR-Symmetry Heteronuclear-NMR

  2. Proton with Carbon-13 coupling

  3. Proton with Fluorine-19 coupling

  4. Fluorine-19:Fluoroacetone

  5. Phosphorus-31

  6. Phosphorus-31: Coupling with 1H

  7. Phosphorus-31 Coupling with 13C

  8. Phosphorus-31

  9. AQ: P31 AQ: P31 Phosphorus-31 28 Hz 8Hz dt H1 decoupling

  10. AQ: P31 39 Hz Phosphorus-31 9 Hz H1 decoupling NMR – From Spectra to Structures An Experimental approachSecond edition (2007) Springler-Verlag Terence N. Mitchellm Burkhard Costisella

  11. Silicon, Mercury, Carbon

  12. N15 NMR 10 mm tube 25% in CDCl3 Inverse gated D1=15 s Total time 12 hrs NMR – From Spectra to Structures An Experimental approachSecond edition (2007) Springler-Verlag Terence N. Mitchellm Burkhard Costisella

  13. C-13 NMR

  14. C-13 NMR: Quantitative?? • In C-13, some carbons can have long relaxation time: If the relaxation delay is not long enough, the long relaxation carbons will not achieve full amplitude • NOEs varies for the various carbons • Number of data points used to record the data might not be sufficient • The efficiency of the pulse vary depending if a signal is in the center of the window or on the side.

  15. NMR – From Spectra to Structures An Experimental approachSecond edition (2007) Springler-Verlag Terence N. Mitchellm Burkhard Costisella AQ: C13 Normal C13 measure time 1.5 hrsNOE present, no integration possible 2 C2 3 1 H1 decoupling 3JCP = 2.3 3JCP = 5.5 2JCP = 7.2 1JCP = 201.3 C3 PCHO2 C1 1JCP OCH2 CH3

  16. NMR – From Spectra to Structures An Experimental approachSecond edition (2007) Springler-Verlag Terence N. Mitchellm Burkhard Costisella AQ: C13 AQ: C13 C13-NMR 2 d 1 3 C13, H-coupled H1 decoupling dd t q C2 PCHO2 C3 1JCP C1 OCH2 CH3

  17. NMR – From Spectra to Structures An Experimental approachSecond edition (2007) Springler-Verlag Terence N. Mitchellm Burkhard Costisella C13 coupling to proton 2 1 3 3JC3-H2 = 7.9 2JC3-H2’ = 5.4 C3-Cl

  18. AQ: C13 AQ: C13 AQ: C13 C13 extracting J values Me 3JPC = 5.5 Hz H1 decoupling CH2selective dec. Quartet : CH3 split by P (doublet) Split by CH2 triplet 1JCH = 127.7 Hz

  19. NMR – From Spectra to Structures An Experimental approachSecond edition (2007) Springler-Verlag Terence N. Mitchellm Burkhard Costisella AQ: C13 C13 inverse gated: integrationMeasuring time: 28 hoursD1=120 s H1 decoupling D1 off

  20. Multiplicity detection DEPT : CH, CH3 CH2 APT : CH, CH3 C , CH2 Normal C13

  21. NOE and decoupler

  22. Carbon-13 Shift

  23. Carbon-13 Shift Acid Amide Ester Ketone Aldehyde O C = O C – O C – O = C = C  C C – C C=C 200 150 100 50 0

  24. Alkanes d = -2.5 + SnA 1 2 3 4 5 CH3-CH2-CH-CH2-CH3 6 CH3 dC1 = -2.5 + 1a + 1b + 2g + 1d dC1 = -2.5 + 9.1 + 9.4 + 2(-2.5) + .3 = 11.3 dC2 = -2.5 + 2a + 2b + 1g + 2o(3o) (Secondary carbon bound to tertiary) dC2 = -2.5 + 18.2 + 18.8 + (-2.5) + (-2.5) = 29.5 dC3 = -2.5 + 3a + 2b + 2{3o(2o)} dC3 = -2.5 + 27.3 + 18.8 + (-7.4) = 36.2 dC6 = -2.5 + 1a + 2b + 2g + 1o(3o) = 19.3

  25. Alkanes dC1 = -2.5 + 1a + 1b + 2g + 1d = 11.3 dC2 = -2.5 + 2a + 2b + 1g + 2o(3o) = 29.5 dC3 = -2.5 + 3a + 2b + 2{3o(2o)} = 36.2 dC6 = -2.5 + 1a + 2b + 2g + 1o(3o) = 19.3 C2 C1 C3 C6 2 3 1 6

  26. Substituted Alkanes CH3-CH2-CH2-CH2-CH3 13.9 – 22.8 – 34.7 g b a CH3-CH2-CH-CH2-CH3 OH CH = 34.7 + 41 = 75.7 ppm CH2 = 22.8 + 8 = 30.0 ppm CH3 = 13.9 + (-5) = 8.9 ppm

  27. CH = 34.7 + 41 = 75.7 ppm g b a CH3-CH2-CH-CH2-CH3 CH2 = 22.8 + 8 = 30.0 ppm OH CH3 = 13.9 + (-5) = 8.9 ppm

  28. Shift Calculation: • Select a suitable model • Use proper substituent effects to predict the shifts of the various carbonsThis gives a crude estimate without taking into account the geometry • For cyclohexanes, substituents effects are compiled in terms of axial/equatorial orientation

  29. Cycloalkanes: Cyclohexane

  30. Alkenes: Additivity rules

  31. d- d+ CH2 CH OMe CH2 CH OMe 84.2 153.2 CH2 CH2 C C C d- d+ OEt CH C CH OEt C Unsaturated compounds: Electronic Effects Alkenes d- 129.3 d+ 157 Allenes 75-97 200-215 Alkynes 65-90 ppm 23.2 89.4

  32. Benzene Calculation

  33. Nitro-4-Aniline

  34. Example: Benzene Calculation => distinguish isomers

  35. H-NMR: isomers

  36. Example: Benzene Calculation => distinguish isomers Experimental shifts 152.5, 136.6, 131.7, 126.3, 121.9, 116.3 Subst. C1 ortho meta para Me 9.2 0.7 -0.1 -3.0 CH(Me)2 20.2 -2.2 -0.3 -2.8 OH 26.9 -12.8 1.4 -7.4 C1 = 128 + 9.2 – 2.8 +1.4 = 135.8 C2 = 128 + .7 - 0.3 –7.4 = 121.0 C3 = 128 – 0.1 – 2.2 + 1.4 = 127.1 C4 = 128 – 3.0 + 20.2 – 12.8 = 132.4 C5 = 128 – 0.1 – 2.2 + 26.9 = 152.6 C6 = 128 + 0.7 – 0.3 – 12.8 = 115.6 C1 = 128 + 9.2 – 2.8 – 12.8 = 121.6 C2 = 128 + .7 - 0.3 + 1.4 = 129.8 C3 = 128 – 0.1 – 2.2 - 7.4 = 118.3 C4 = 128 – 3.0 + 20.2 + 1.4 = 146.6 C5 = 128 – 0.1 – 2.2 - 12.8 = 112.9 C6 = 128 + 0.7 – 0.3 + 26.9 = 155.3

  37. C1 = 128 + 9.2 – 2.8 +1.4 = 135.8 C2 = 128 + .7 - 0.3 –7.4 = 121.0 C3 = 128 – 0.1 – 2.2 + 1.4 = 127.1 C4 = 128 – 3.0 + 20.2 – 12.8 = 132.4 C5 = 128 – 0.1 – 2.2 + 26.9 = 152.6 C6 = 128 + 0.7 – 0.3 – 12.8 = 115.6 C2 C6 C3 C5 C1 C4

  38. C1 = 128 + 9.2 – 2.8 – 12.8 = 121.6 C2 = 128 + .7 - 0.3 + 1.4 = 129.8 C3 = 128 – 0.1 – 2.2 - 7.4 = 118.3 C4 = 128 – 3.0 + 20.2 + 1.4 = 146.6 C5 = 128 – 0.1 – 2.2 - 12.8 = 112.9 C6 = 128 + 0.7 – 0.3 + 26.9 = 155.3 C3 C2 C5 C6 C4 C1

  39. CarbonylsC=O Acid Ester

  40. CarbonylsC=OEsters, Acid chlorides, Anhydrides, Amides, Carbamates

  41. CarbonylsC=O : Ketones, Aldehydes

  42. Coupling between 1H and 13C1JCH One bond coupling is proportional to % s charactersp3 : ~125 Hzsp2: ~ 165 Hzsp : ~ 250 Hz Electronegative subst. Increase JCH-OR => J ~ 140 HzCH-Cl => J ~ 150 Hz

  43. Coupling between 1H and 13C sp3: 1JCH Increase of coupling values with the electronegativity of the substituant : CHZ Z : Li1JCH = 98 Hz Z : C1JCH = 125-129 Hz Z : NR1JCH = 131-134 Hz Z : S1JCH = 138 Hz Z : OR1JCH = 140 Hz Z : Cl1JCH = 150 Hz Z : (OR)21JCH = 162 Hz Z : Cl2 1JCH = 178 Hz 1JCH = 161 Hz 1JCH = 180 Hz 1JCH = 134 Hz 1JCH = 137 Hz 1JCH = 150 Hz

  44. Coupling between 1H and 13C sp2: 1JCH Increase of coupling values with the electronegativity of the substituant : =CHZ =C-H 1JCH = 157 Hz 1JCH = 238 Hz 1JCH = 172 Hz 1JCH = 250 Hz 1JCH = ~200 Hz 1JCH = 182 Hz 1JCH = 202 Hz

  45. Use of 1JCH Extremely useful for molecules where 1JCHlarger than usual Diagnostic for alkynes (250 Hz) , epoxides (180 Hz) , hemiacetal (162 Hz) and cyclopropane (161 Hz)

  46. Coupling between 13C and 13C : 1JCC Measurable only on enriched compound Useful for setting up pulse sequences like INADEQUATE sp3 R-CH2-CH31JCC = 35 Hz 1JCC = 48 Hz sp2 1JCC = 44 Hz 1JCC = 56 Hz 1JCC = 54 Hz 1JCC = 74 Hz 1JCC = 74 Hz 1JCC = 123 Hz

  47. Coupling between 1H and 13C2JCH Usually small and difficult to predict Typical values: -8 to +4 Hz

More Related