CH1012
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7
1H & 13C NMR II
Nature of NMR
absorptions
• Fortunately 1H nuclei in different
chemical environments absorb energy at slightly different frequencies. 13C nuclei do the
same
downfield
or lowfield
or lowfield
upfield
or highfield shift
or highfield shift
• Hence we expect
to see different
NMR signals for
each different type
of 1H (or 13C)
nucleus in a
molecule.
to see different
NMR signals for
each different type
of 1H (or 13C)
nucleus in a
molecule.
• Frequency scale
in ppm ® chemical shift
