Dear Weidong,
I support all answers related to the asymmetry observed in the 19F CF3CH2OH
NMR spectrum given by Ion Ghiviriga and others.
I slightly edited the picture (see below) and showed the isotopomers that give
the satellites. (1J19F, 13C) and 2J19F, 13C).
I'm pretty sure there is an error in the JFC value because no frequency values
were specified for the main peak.
Thanks.
Novruz
Novruz G. Akhmedov, Ph.D.
NMR Research Associate
Director of NMR Facility
NMR website: http://nmr.wvu.edu
West Virginia University, Department of
Chemistry, 217 Clark Hall, PO Box 6045
Morgantown, WV 26506-6045, USA.
Phone: 304 293 0918 (Office 259, Chemistry Research Building, CRL)
304 293 0995 (NMR lab, room 422, Clark Hall)
304 293 5366 (NMR lab, room 113, Clark Hall)
Fax: 304 293 4904
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From: main_at_ammrl.groups.io<mailto:main_at_ammrl.groups.io> main_at_ammrl.groups.i=
o<mailto:main_at_ammrl.groups.io> On Behalf Of Holmes, Daniel via groups.io
Sent: Wednesday, July 12, 2023 2:03 PM
To: main_at_ammrl.groups.io
Subject: Re: [AMMRL] Unexpected peaks of 19F NMR from CF3CH2OH
The 13C satellites are not symmetric about the 19F-12C peak due to the heavy
isotope effect. See Glen Facey's excellent post about it.
http://u-of-o-nmr-facility.blogspot.com/2012/10/isotope-effects-and-19-f-13-c-hmqc.html
Dan
From: main_at_ammrl.groups.io<mailto:main_at_ammrl.groups.io> <main_at_ammrl.groups.io<mailto:main_at_ammrl.groups.io>> on behalf of Weidong Hu via groups.io <whu3Dcoh.org_at_groups.io<mailto:whu=coh.org_at_groups.io>>
Date: Wednesday, July 12, 2023 at 1:54 PM
To: main_at_ammrl.groups.io<mailto:main_at_ammrl.groups.io> <main_at_ammrl.groups.io <mailto:main_at_ammrl.groups.io>>
Subject: [AMMRL] Unexpected peaks of 19F NMR from CF3CH2OH
Hi All,
I acquired 1D-19F NMR of CF3CH2OH dissolved in CDCl3/CD3OD(2:1 v/v) on CP TCI
700 H&F-C/N-D probe (without 1H decoupling), and the spectrum is very confusing.
In addition to main triplet peaks, there are three minor triplet peaks (about
0.5% of main triplet). The positions of minor peaks are not symmetric to the
main triplet, and thus should not come from natural abundance of 13C-19F J
coupling. It is reasonable to see four minor peaks generated from one and
two-bond J couplings between 13C-19F, but they should be symmetric to the
main peak. I don't know how to explain the observed spectrum. Any
suggestions as what is going on? The spectrum is attached below.
Thank you,
Weidong
Dr. Weidong Hu
Department of Immunology & Theranostics
Beckman Research Institute
1450 E. Duarte Rd., Duarte, CA 91010
Tel: 626 256 4673, Ext: 63416
Fax: 626 301 8186
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Received on Wed Jul 12 2023 - 13:14:02 MST