Carbon-13 nuclear magnetic resonance spectrometry is used to observe changes in the spin-lattice relaxation time (T1) of the alkyl chain carbons of symmetric tetraalkylammonium salts (R4N+)X− in acetonitrile as a function of salt concentration in the range from 0.25 to 1.4 M. The T1 values of the alkyl chain carbons are observed to be differentially sensitive to salt concentration, the sensitivity being greatest at the α carbon position. These observations suggest accessibility of the cation nitrogen to solvent molecules and changing microviscosity about the salt molecule.
Tilly-MelinA.AskemarkY.WahlundK., and SchillG., Anal. Chem.51, 976 (1979).
2.
D'ApranoA.GoffrediM., and TrioloR., J. Chem. Soc. Faraday Trans1, 1188 (1975).
3.
CarmonP., J. Solution Chem.7, 845 (1978).
4.
GillD., Spectrochim. Acta24, 701 (1979).
5.
EveraertJ. and PersoonsA., J. Phys. Chem.85, 3930 (1981).
6.
ArnettE.ChawlaB., and HornungN., J. Solution Chem.6, 781 (1977).
7.
BhattacharyyaD.LeeC.SmidJ., and SzwarcM., J. Phys. Chem.69, 609 (1965).
8.
DandoN.DybowskiC., and GoldH. S., Paper 56, presented at the 15th Middle Atlantic Regional Meeting of the American Chemical Society, Washington, D.C., 8 January 1981.
9.
RimmelinP.SchwartzS., and SommerJ., Org. Magn. Res.16, 160 (1981).
10.
GoldH. S.PembertonJ., and BuckR. P., Paper 478, presented at the Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Cleveland, OH, 7 March 1979.
11.
SadekH. and FuossR., J. Am. Chem. Soc.72, 301 (1950).
12.
ParkerA., J. Chem. Soc. A, 220 (1966).
13.
LevyG., Acc. Chem. Res.6, 161 (1973).
14.
LevyG.KomoroskiR., and HalsteadJ., J. Am. Chem. Soc.96, 5456 (1974).
15.
BoppT., J. Chem. Phys.17, 3621 (1967).
16.
VoldR.WaughJ.KleinM., and PhelpsD., J. Chem. Phys.48, 3831 (1968).
17.
PitnerT. and WhidbyJ., Anal. Chem.51, 2203 (1979).
18.
SarneskiJ.SuprenantH.MolenF., and ReilleyC., Anal. Chem.47, 2116 (1975).
19.
LevyG., J. Chem. Soc. D Chem. Commun.768 (1972).
20.
KuhlmannK.GrantD., and HarrisR., J. Chem. Phys.52, 3439 (1970).
