Proton magnetic resonance line shapes of water and ammonium ions in type-Y zeolites

1976 ◽  
Vol 80 (12) ◽  
pp. 1350-1356 ◽  
Author(s):  
E. B. Whipple ◽  
P. J. Green ◽  
M. Ruta ◽  
R. L. Bujalski
Keyword(s):  
Magnetic Resonance ◽  
Resonance Line ◽  
Proton Magnetic Resonance ◽  
Ammonium Ions ◽  
Y Zeolites ◽  
Line Shapes

The Proton Magnetic Resonance Line in Liquid Crystals

1953 ◽  
Vol 21 (2) ◽  
pp. 380-380 ◽  
Author(s):  
R. D. Spence ◽  
H. A. Moses ◽  
P. L. Jain
Keyword(s):  
Liquid Crystals ◽  
Magnetic Resonance ◽  
Resonance Line ◽  
Proton Magnetic Resonance

Application of proton magnetic resonance to rotational isomerism in halotoluene derivatives. III. α,α-Dichloro-2,4,6-tribromotoluene

1970 ◽  
Vol 48 (18) ◽  
pp. 2839-2842 ◽  
Author(s):  
J. Peeling ◽  
T. Schaefer ◽  
C. M. Wong
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Room Temperature ◽  
Proton Magnetic Resonance Spectrum ◽  
Methine Proton ◽  
Proton Spectrum ◽  
Kcal Mole ◽  
Ring Proton ◽  
Line Shapes ◽  
Carbon Carbon Bond

At room temperature the proton magnetic resonance spectrum of α,α-dichloro-2,4,6-tribromotoluene is ABX where the methine proton in the sidechain is X and is lying in the plane of the aromatic ring. At higher temperatures the ring proton spectrum, AB, broadens and eventually collapses to yield an A2X spectrum. From an analysis of the ring proton line shapes the barrier to rotation of the dichloromethyl group about the sp2–sp3 carbon–carbon bond is obtained; ΔG* = 17.5 ± 0.1 kcal/mole at 304°K, ΔH* = 15.67 ± 0.08 kcal/mole, ΔS* = −7 e.u., Ea = 16.38 ± 0.08 kcal/mole, log A = 11.78 ± 0.23 where the least squares errors given should probably be multiplied by a factor of from 3 to 5 to take possible systematic errors into account. The barrier is about 2 kcal/mole higher than in α,α,2,4,6-pentachlorotoluene. The barrier to rotation arises from the conformation in which chlorine and bromine atoms are eclipsed.

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