L1 /
4
CH1012
SPIN-SPIN SPLITTING
II
Consider
the 1H NMR spectrum of:
methyl acetate CH3-C(=O)-OCH3
methyl acetate CH3-C(=O)-OCH3
da = 2.0, singlet, CH3 db = 3.6, singlet, CH3
• These absorptions
are singlets as they
are due to isolated
groups of
equivalent hydrogens
are singlets as they
are due to isolated
groups of
equivalent hydrogens
• Coupling is only
observed when the Hs are £ 3 bonds apart
eg. H-C-C-H 3J or H-C-H 2J coupling
observed when the Hs are £ 3 bonds apart
eg. H-C-C-H 3J or H-C-H 2J coupling
