منابع مشابه
Dissecting the hindered rotation of ethane.
The existence of a rotational barrier of ca. 3 kcalmol 1 around the C C single bond in ethane has been known since the early studies of Ebert, Wagner, Eucken and Weigert and Pitzer done in the 1930s. Even the simplest ab initio methods are able to reproduce this fundamental result. However, the physical origin of this hindered rotation is still under controversy in the literature. There are two...
متن کاملHindered rotation in N-methylformamide. A peptide-bond model system.
Barriers to rotation about the C-N bond in the cis and trans isomers of N-methylformamide have been determined by n.m.r. spectroscopy. Representative values are 20.7 and 22.0 kcal/mole. Arrhenius parameters have also been determined. These results are compared with C-N barriers for N,N-dimethylformamide and unsubstituted formamide. The data suggest that C-N rotational barriers for N-methyl amid...
متن کاملHindered Rotation in Poly(N-acyl)iminoalkylenes - A 13C Nuclear Magnetic Resonance Study
Poly(N-acetyl)iminoethylene. poly(N-propionyl)iminoethylene and poly(N-acetyl)-2,2-dimethyliminoethylene were prepared by cationic polymerization in solution of 2-methyl2-oxazoline, 2-ethyl-2-oxazoline, and 2,4,4-trimethyl-2-oxazoline respectively. The 13C NMR spectra of the polymers obtained showed different sets of shifts for the carbon atoms of the backbone as well as for the N-acylimino sid...
متن کاملHindered rotation in ion-neutral molecular complexes: The n1 vibration of H2–HCO
Infrared spectra of the mass selected ionic complexes H2–HCO 1 and D2–DCO 1 have been recorded in the vicinity of their n1 vibrations ~H2 /D2 stretch! by means of photofragmentation spectroscopy. The anomalous rotational constants obtained by fitting the observed line positions to a semirigid Watson A-type Hamiltonian reflect the appreciable zero-point excursions of the H2 /D2 molecule. Barrier...
متن کاملHindered Transport in Composite Hydrogels
The ultimate goal of this research was to develop a greater understanding of the structural components needed to describe transport within the glomerular basement membrane (GBM). Specifically, dimensionless diffusive and convective hindrance factors were investigated by measuring macromolecular permeability through synthetic, two-fiber, agarose-dextran hydrogels at very small or very high Pe, r...
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ژورنال
عنوان ژورنال: Bulletin of the Chemical Society of Japan
سال: 1972
ISSN: 0009-2673,1348-0634
DOI: 10.1246/bcsj.45.1562