Unformatted text preview: What is a 'multiplet [m]'? 1. n+1 rule applies, but there are many neighbors Another example: d 9 Coursepack: J< '
p. 76 spectrum H
1 (m1) n t— ult' | t m’1 ( one — m Ip e ) M l | l
3 2 1 0
PPM 2. n+1 rule not enough; non-equivalent neighbors* 6.07
Another example: 5.31
p. 76 spectrum 1 H 4.04 4.04 H
1 (m4) and mi d’1 5.43 5.43
l l I I
6 4 2 0
PPM This proton has 3 different types of neighbors.
The n+1 rule cannot apply. *note: multiple peak splitting due to coupling of non-equivalent
neighbors is a multiplet. If we can distinguish the peaks we expect,
then we label them, for example the doublets of doublets above. If we
could not distinguish the dd, then that would be called a multiplet too. 3. Different NMR signals are too close to distinguish; overlapping peaks Another example:
Coursepack: p. 82: that pair 01‘ng is ’ . '7' ,,
difficult to “ distinguish, and
could be labeled EA p. 87C: the m,2 is two WWW multiplets (1 for each | ‘. , I diasteriotopic H) but 3 2 1 0
we cannot tell which , PPM is which, so we call it The green hydrogen signals are separate (2 different 1 multiplet for 2 H environments) but the signals are so close in chemical shift that the multiplets overlap. We group them
together and call it a multiplet for 3 proton signals. ...
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- Winter '07