Hi Weidong. There is a 12C/13C isotope effect in 19F NMR. also observed
when 19F is coupling with 35/37Cl and 10/11B
http://u-of-o-nmr-facility.blogspot.com/2012/10/isotope-effects-and-19-f-13-c-hmqc.html
Mallory Gobet
Analytical and Systems Research Group
Arkema Inc.
From: main_at_ammrl.groups.io <main_at_ammrl.groups.io> On Behalf Of Weidong Hu via groups.io
Sent: Wednesday, July 12, 2023 1:33 PM
To: 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 - 12:01:46 MST