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Tutorial on 2D-NMR: Using COSY & HSQC to Assist in Assigning 1 H & 13 C NMR Spectra

Tutorial on 2D-NMR: Using COSY & HSQC to Assist in Assigning 1 H & 13 C NMR Spectra. 1 H NMR. Chemical shift ( δ ) depends on molecular structure and solvent 1 H nuclei sensitive to hybridization of atom to which H is attached and electronic effects

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Tutorial on 2D-NMR: Using COSY & HSQC to Assist in Assigning 1 H & 13 C NMR Spectra

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  1. Tutorial on 2D-NMR:Using COSY & HSQC to Assist in Assigning 1H & 13C NMR Spectra

  2. 1H NMR • Chemical shift (δ) depends on molecular structure and solvent • 1H nuclei sensitive to hybridization of atom to which H is attachedandelectronic effects • EDG’s shield nuclei  shift upfield  lower δ • EWG’s deshield nuclei  shift downfield  higher δ Downfield Deshielded Upfield Shielded 0 ppm 10 ppm

  3. 1H NMR • Spin-spin coupling effects: interaction between nuclei through bonds • Causes splitting in observed peak (s, d, dd, t, m…) • Coupling constants: magnitude of splitting (Hz) • Hz (not ppm) since effect is independent of applied mag. fld. • Caused by mag. fld. of another nuclei

  4. 2-D NMR • Determine structure (especially for molecules too complicated for 1-D NMR) • Involves series of 1-D NMR experiments • Doesn’t need to use the complicated coupling constants

  5. Correlation Spectroscopy (COSY) • Homonuclear: plots 1H NMR on both x and y-axis • Diagonal divides the spectrum into 2 equal halves • Cross-signals: symmetrical to diagonal; contain the relevant info • FAB-FOUR • 1H NMR (~5 min) • COSY (~30 min) • 13C NMR (depends…) • HSQC (~30 min)

  6. H4 H2 H3 H3 3 H4 4 H2 2

  7. H8 H6 H4 H2 H7 H3 H3 3 H7 7 H4 4 H8 8 H2 2 H6 6

  8. H1 H8 H6 H4 H2 H7 H3 H3 3 H7 7 H4 4 H8 8 H2 2 H6 6 H1 1

  9. H5 H1 H8 H6 H4 H2 H7 H3 H3 3 H7 7 H4 4 H8 8 H2 2 H6 6 H1 1 H5 5

  10. H9 H11 H10 H5 H1 H8 H6 H4 H2 H7 H3 H3 3 H7 7 H4 4 H10 10 H8 8 H2 2 H6 6 H9 9 H11 11 H1 1 H5 5

  11. H9 H11 H10 H5 H1 H8 H6 H4 H2 H7 H3 H3 3 H7 7 H4 4 H10 10 H8 8 H2 2 H6 6 H9 9 H11 11 H1 1 H5 5

  12. LONG-RANGE COUPLING H9 H11 H10 H5 H1 H8 H6 H4 H2 H7 H3 H3 3 H7 7 H4 4 H10 10 H8 8 H2 2 H6 6 H9 9 H11 11 H1 1 H5 5

  13. Heteronuclear Single Quantum Coherence (HSQC) • Plots 1H NMR on x-axis and 13C NMR on y-axis • Utilizes 1 bond coupling between H and C • Eliminating all the H containing C’s eliminates many C’s assignments • Leaves only on-H containing C’s to assign

  14. HSQC Spectrum

  15. H9 H11 H10 H5 H1 H8 H6 H4 H2 H7 H3 1 5 10 3 7 11 2 6 8 4 9

  16. H9 H11 H10 H5 H1 H8 H6 H4 H2 H7 H3 1 5 10 3 7 11 2 6 8 4 9

  17. # of total peaks: 5 1 3 1 4 2 # of non-H C peaks: 2 1 1 0 1 0 ?????????? C12, C13, C14, C15, C17 ?????????? C14, C15, C17 C6 C7 C1 C8 C2 C3 C9 C5 C11 C10 C4 C13 C12

  18. Thank YouAny Questions?

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