NMR Folks,
Does anyone know what the chemical shift of a bare proton would be on the
ppm scale? I would like this number for my organic NMR interpretation course.
A NIST web page gives the gyromagnetic ratios (units =10^8 rad s-1 T-1) of
the proton (2.67522212) and the "shielded proton" (2.67515341). I believe
the "shielded proton" is that of water at 25 deg. Since these numbers
differ by 25.7 ppm and since the chemical shift of water is about 4.5 ppm,
can I estimate the chemical shift of a bare proton to be about 30.2 ppm or
am I making some fundamental physics mistake?
The matter is confused by the IUPAC recommendations of last year where TMS
was continued at the standard (of course) but a gyromagnetic ratio
of 2.67522128 was given. If this is for TMS, I'm really confused because
it would place TMS very close to the bare proton.
Thanks for any help you might give.
Ed Waali
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Edward E. Waali
Department of Chemistry
University of Montana
Missoula, MT 59812
Voice: (406) 243-4992
FAX: (406) 243-4227
E-mail: waali_at_selway.umt.edu
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Received on Thu May 02 2002 - 18:37:34 MST