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N. M. Sergeyev, S. M. Gerdov, Yu. K. Grishin, V. A. Roznyatovsky
High
Resolved 2H NMR spectroscopy at deuterium natural abundance level
Abstract
The spin-lattice relaxation times T1 for
deuterium nuclei in several deuterated compounds (methanol-d4,
ethanol-d6, benzene-d1, dimethylsulfoxide-d6)
were measured at higher temperatures (in the range 300–375 K). In all cases
almost linear increase of times T1 with
temperature was observed revealing increase of molecular mobility and decrease
of the correlation times. One may expect relaxation times of order 2–3 s for
deuteriums in small organic molecules at temperatures above 350 K. Thus for the
standard magnetic field inhomogeneity of order 0.5 Hz in NMR 1H one
can obtain linewidths of order 0.1–0.2 Hz in 2H NMR spectra. Such
“high resolved” 2H NMR spectra give the information about chemical
shifts and coupling constants J(H-D) (or J(H-H)=
(gH/gD) J(H-D))
including those between magnetically equivalent protons unobservable in 1H
NMR spectra. New or more exact data on coupling constants were obtained for
ethanol, propanol, 1,2-dichloroethane and 1,4-dioxane.
Key words: NMR 2H
spectroscopy, relaxation times, J(H-D), J(H-H), ethanol, propanol, 1,2-dichloroethane, 1,4-dioxane.
Copyright (C) Chemistry Dept., Moscow State University, 2002
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