OH
Ortho: ~6-9 Hz
Meta: ~2-3 Hz
Para: ~0-1 Hz
(or pk. broadening)
Y
2495.45
J=8.85 Hz
EXPECTED PEAK:
doublet
a
X
•split by b (J ~2,
characteristic
meta)
EXPECTED PEAK:
doublet
EXPECTED PEAK:
doublet of doublets
J=2.20 Hz
2214.59
2212.55
•split by a (J ~9
Hz, characteristic
ortho)
•split by c (J ~2,
characteristic meta)
J=9.14 Hz
J=2.04 Hz
2223.73
2221.43
b
c
2259.64
for:
Characteristic J constants
Z
2257.44
In aliphatic organic
compounds, the only coupling that
you need to worry about is from
adjacent protons (J =0 between any
non-adjacent protons)...
In aromatic compounds,
however, significant splitting
does not only come from ortho
protons coupled to each other, but
also from meta (even para) protons
due to conjugated π bonds.
Thus, coupling constants are
a helpful tool for deciphering
complicated aromatic regions, and
are especially vital when the
chemical shifts (δ ) between
aromatic protons are uncertain or
overlapping.
2486.60
•split by b (J ~9
Hz, characteristic
ortho)
NMR AROMATIC PROTON COUPLING