Dear Weidong,
This is common behavior in 19F NMR and it puzzled me too in my younger days.
Isotopical shift in fluorine is much bigger than in proton, so satellites
than in 1H NMR appear symmetrical, in 19F NMR appear asymmetrical.
Hope that helps. Best wishes,
[Descripción: logoICIQ]
Dr. Gabriel González Ferrer
Responsable RMN / NMR Manager
Institut Català d’Investigació Química (ICIQ) /
Institute of Chemical Research of Catalonia (ICIQ)
The Barcelona Institute of Science and Technology
Av. Països Catalans 16 – 43007 Tarragona (Spain)
Phone +34 977920207 / +34 686669420 – Fax +34 977920224
ggonzalez_at_iciq.es<mailto:ggonzalez_at_iciq.es> -
http://www.iciq.es
From: main_at_ammrl.groups.io <main_at_ammrl.groups.io> On Behalf Of Weidong Hu via groups.io
Sent: Wednesday, July 12, 2023 7:33 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 - 12:01:48 MST