Nuclear Magnetic Resonance Spectrum of 1-Hydroxy-2,3-Epoxypropane

1968 ◽  
Vol 22 (6) ◽  
pp. 773-776
Author(s):  
A. Leifer ◽  
H. L. Goldstein
Keyword(s):  
Resonance Spectrum ◽  
Chemical Shifts ◽  
Internal Standard ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Pure Liquid ◽  
Nmr Spectrum ◽  
Hydroxyl Proton ◽  
Spin Coupling Constants ◽  
Experimental Values

The NMR spectrum of pure liquid 1-hydroxy-2,3-epoxypropane has been analyzed quantum mechanically. The analysis is greatly simplified by treating the protons on the propane chain as two separate ABX systems. The chemical shifts at 60 Mcps, relative to the internal standard tetramethylsilane (TMS), and the spin coupling constants were found to be vA = 168.1 cps, vB = 160.5 cps, vX = 188.8 cps, vA' = 232.2 cps, vB' = 212.8 cps, JAB = 5.2 cps, JA'B' = 12.7 cps, JXA = 4.5 cps, JXA' = 2.9 cps, JBX = 2.7 cps, JB'X = 5.3 cps. Using these parameters the calculated frequencies of the spectrum are in excellent agreement with the experimental values. The chemical shift of the hydroxyl proton was found to be 266.8 cps downfield from TMS.

PROTON MAGNETIC RESONANCE MEASUREMENTS OF FORMAMIDE

1960 ◽  
Vol 38 (5) ◽  
pp. 681-688 ◽  
Author(s):  
B. Sunners ◽  
L. H. Piette ◽  
W. G. Schneider
Keyword(s):  
Chemical Shifts ◽  
Water Solution ◽  
Proton Exchange ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Interaction ◽  
Pure Liquid ◽  
Kcal Mole ◽  
Screening Constant ◽  
Spin Coupling Constants

The high-resolution proton resonance spectrum of formamide has been measured and analyzed. Quadrupole broadening of the resonance signals due to the N14 nucleus was eliminated by substitution of the isotopic nucleus N15. Twenty-four lines were resolved in the spectrum, which is consistent with restricted rotation about the C—N bond. The non-equivalence of the two protons in the N15H2 group is characterized by a smaller screening constant and a greater spin–spin interaction of the proton which is in the trans position relative to the carbonyl group. It is suggested this difference in the spin coupling of the two protons may be associated with different N—H bond lengths. Pronounced changes in the chemical shifts and spin-coupling constants result when formamide is dissolved in dilute solution in water and acetone. In water solution the relative magnitudes of the spin coupling of the two protons in the NH2 group is reversed from that observed in pure formamide and the coupling of the aldehyde proton to N15 varies by nearly 50%. Heating of formamide above room temperature causes rotation of the NH2 group as well as proton exchange between neighboring molecules. The two effects could be separated. From the observed changes in the proton spectra as a function of temperature the barrier hindering rotation (measured in a 10 mole% solution of formamide in acetone) was found to be 18 ± 3 kcal/mole. The activation energy for proton exchange in pure liquid formamide was found to be 10 ± 3 kcal/mole.

73 Ge Nuclear Magnetic Resonance Studies

1971 ◽  
Vol 26 (9) ◽  
pp. 1384-1389 ◽  
Author(s):  
J . Kaufmann ◽  
W. Sahm
Keyword(s):  
Chemical Shifts ◽  
Spin Echo ◽  
Relaxation Times ◽  
Least Square ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Nmr Spectrum ◽  
Spin Coupling Constants ◽  
Spin Echo Technique ◽  
Spin Spin Coupling

Abstract The 73Ge spectra of some germanium-tetra-halides, germanium-tetra-alkyles, and of germanium-tetra-methoxide have been observed. The chemical shifts of these 73Ge NMR-lines were measured as functions of the temperature in the range up to 50 °C. In CS2-and benzene-solutions of Gel4 , two 73Ge-lines were found. The 73Ge NMR-spectrum of Ge(CH3)4 caused by indirect spin-spin-coupling between the 73Ge nucleus and the protons is well resolved. The spin-spin-coupling constants of Ge(CH3)4 and of Ge(OCH3)4, which shows an unresolved spectrum, were evaluated by an iterative least square fitting routine. The relaxation times T2 (in the range 30...740 msec) measured by the Carr-Purcell spin-echo-technique and calculated from the line widths are in good agreement. Precision measurements of the ratios of the Larmor frequencies of 73Ge in GeCl4, 41K in aqueous KF-solution and 2H in pure heavy water lead to a magnetic moment of 73Ge: μ = -(0.876 78 ± 0.000 01) μN (uncorrected).

Structural Characterization of Natural Products By Means of Quantum Chemical Calculations of NMR Parameters: New insights

2021 ◽  
Author(s):  
Fabio Luiz Paranhos Costa ◽  
Ana Carolina Ferreira de Albuquerque ◽  
Rodolfo Goetze Fiorot ◽  
Luciano Morais Lião ◽  
Lucas Haidar Martorano ◽  
...  
Keyword(s):  
Natural Products ◽  
Structural Characterization ◽  
Quantum Chemical ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Nmr Parameters ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The calculation of NMR parameters for natural products was pioneered by Bifulco and coworkers in 2002. Since then, modelling 1H and 13C chemical shifts and spin-spin coupling constants for this...

THE ANALYSIS OF NUCLEAR MAGNETIC RESONANCE SPECTRA: III. PYRIDINE AND DEUTERATED PYRIDINES

1957 ◽  
Vol 35 (12) ◽  
pp. 1487-1495 ◽  
Author(s):  
W. G. Schneider ◽  
H. J. Bernstein ◽  
J. A. Pople
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Calculated Spectrum ◽  
Proton Resonance ◽  
Nuclear Magnetic Resonance Spectra ◽  
Spin Coupling Constants

The proton resonance spectra of pyridine, 2,6-pyridine-d2, 3-pyridine-d1, and 4-pyridine-d1 have been obtained for the pure liquids under conditions of high resolution. The spectra have been analyzed as proton groupings of AB2X2, AB2, perturbed ABX, and B2X2 respectively. The spin-coupling constants obtained from analysis of the simpler spectra of the deuterated molecules were used to suggest trial solutions for the analysis of the complicated AB2X2 spectrum of pyridine. A final set of chemical shifts and spin-coupling constants derived for pyridine give satisfactory agreement between the observed and calculated spectrum.

The planar conformation of 2-methylthiobenzaldehyde in solution

1983 ◽  
Vol 61 (1) ◽  
pp. 26-28
Author(s):  
Ted Schaefer ◽  
Rudy Sebastian
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spectral Parameters ◽  
H Nmr ◽  
Heavy Atoms ◽  
Planar Conformation ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Infrared Data

The 1H nmr spectral parameters are extracted for a 4 mol% solution of 2-methylthiobenzaldehyde in CCl4 at 305 K. The long-range spin–spin coupling constants involving the aldehydic and methyl protons are consistent only with a preferred conformation in which all heavy atoms are coplanar, as are the chemical shifts of the ring and methyl protons. This conclusion contradicts previous interpretations of the dipole moment, the nmr parameters, and of the infrared data for CCl4 solutions. The present data show that the O-syn and O-anti forms of the compound are present in roughly equal proportions.

Zur Struktur des Enols von Benzoylaceton / On the Structure of the Enol of Benzoylacetone

1979 ◽  
Vol 34 (11) ◽  
pp. 1606-1611 ◽  
Author(s):  
W. Winter ◽  
K.-P. Zeller ◽  
S. Berger
Keyword(s):  
Structural Model ◽  
Chemical Shifts ◽  
Ring System ◽  
Coupling Constants ◽  
Spin Coupling ◽  
X Ray ◽  
Wide Range ◽  
Spin Coupling Constants ◽  
C Nmr ◽  
Oxygen Atoms

Abstract A low temperature X-ray study of the enol of benzoylacetone indicates fixed positions of the C and O atoms within the enolic ring system and an extensive bond delocalisation over these atoms. The distribution of electron density between the two oxygen atoms shows that the enolic hydrogen is spread over a wide range. This is in accordance with a structural model proposed by de la Vega, whereupon the C and O atoms are kept fixed in their average positions during a tunneling process of the hydrogen between the two oxygen atoms. With this conception, the chemical shifts in the 17O and 13C NMR spectra, the 13C13C spin coupling constants and the temperature independance of these values can be explained.

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