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Nuclear Magnetic Resonance _NMR_

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Nuclear Magnetic Resonance _NMR_ Powered By Docstoc
					  Nuclear Magnetic Resonance (NMR)
• Some atomic nuclei, but not all, have a property
  called “spin” which results in multiple energy states
  when placed in a magnetic field.
• Atoms which are in equivalent environments in a
  molecule behave equivalently.
• Anything near an electronegative element will
  appear at a larger chemical shift.
• Peak areas approximate the number of atoms in a
  particular environment.
• Hydrogen’s on adjacent carbons can affect each
  other’s environment; splitting according to n+1
  rule.
 Information From 1H-NMR Spectrum
• Number of regions of peaks equals number of
  unique hydrogen environments
• Coupling can be used to determine which sets
  of hydrogens are adjacent to other sets.
• Integrations can tell about the relative number
  of hydrogens in each environment.
• Location of peaks can indicate adjacency to
  electronegative atoms.
Information From          13C-NMR       Spectra
• Only single peaks observed (no coupling).
• No integrations possible.
• Carbon spectra interpreted strictly on the
  number of peaks and their respective locations.

				
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posted:8/27/2012
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