Hi all:
A question about multiplet reporting comes up in our NMR class
regularly. I'm not sure it's a very important issue, but the question
is common enough to have me searching NMR textbooks, author guidelines,
googling, etc. for info addressing the issue. I haven't been able to
find anything. So I'm hoping the AMMRL group can help.
Today was typical. We were reviewing vinyl multiplets, e.g., a compound
of type:
H2C=CH-CH2-R
The cis-proton often shows up as a doublet of quartets, and would be
reported as something like:
dq J=10,1.6
I.e., the cis proton couples to its gem partner and the two protons on
the methylene with similar enough J values to produce a small "quartet".
The student asks, should one report this multiplet as a dq, or rather as
a ddt (or equivalently dtd; or even as a dddd)? Stated another way,
they're asking whether one should report the multiplet according to its
appearance in the observed spectrum, or relative to the assigned
structure.
We teach to report according to the appearance in the spectrum, i.e., as
dq J=10,1.6. If you are aware of guidelines that address this, I'd
appreciate your letting me know.
Cheers,
Charlie
~~~~~~~~~~~~~~~~~~~~~~~
Charles G. Fry, Ph.D. Tel: (608)262-3182
Director, MR Facility Fax: (608)262-0381
Chem. Dept., 1101 University Ave, Univ. Wisconsin-Madison
Madison, WI 53706 USA email: fry_at_chem.wisc.edu
Received on Wed Feb 04 2009 - 14:07:49 MST