THE PROTON MAGNETIC RESONANCE SPECTRA OF CHRYSANTHEMUM ETHYL ESTER AND THE RELATED cis- AND trans-CHRYSANTHEMUMIC ACIDS

1962 ◽  
Vol 40 (5) ◽  
pp. 875-881 ◽  
Author(s):  
H. M. Hutton ◽  
T. Schaefer
Keyword(s):  
Magnetic Resonance ◽  
Ethyl Ester ◽  
Proton Magnetic Resonance ◽  
Acid Ethyl Ester ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Magnetic Resonance Spectra

The high-resolution proton magnetic resonance spectra of a mixture of the cis and trans isomers of chrysanthemum monocarboxylic acid ethyl ester have been studied. The cis-chrysanthemumic and trans-chrysanthemumic acids spectra were obtained to facilitate the interpretation of the complex spectra of the ester. The percentage of the trans isomer in the chrysanthemum ester was measured to be 62.0 ± 1.1%. The cyclopropane proton spin coupling constants were found to be Jcis = 8.7 c.p.s. and Jtrans = 5.4 c.p.s., in reasonable agreement with Karplus' calculations of the dependence of coupling constants on the dihedral angle.

THE PROTON RESONANCE SPECTRA OF SOME SUBSTITUTED FURANS AND PYRROLES

1961 ◽  
Vol 39 (4) ◽  
pp. 905-914 ◽  
Author(s):  
R. J. Abraham ◽  
H. J. Bernstein
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Proton Resonance ◽  
Spin Coupling Constants ◽  
Substituted Furans ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of some substituted furans and pyrroles have been analyzed for spin coupling constants and chemical shifts.The relative insensitivity of the spin coupling constants to the nature of the substituent makes it possible to estimate their values in the parent molecules furan and pyrrole. The magnitude of the spin coupling constants is correlated with the angles made by the CH bonds with the CC bonds of the ring.The chemical shifts are interpreted in terms of an effect due to the electronegativity of the substituent together with the effect due to conjugation with the ring.

Nuclear magnetic resonance spectra of some aryl derivatives of mercury

1971 ◽  
Vol 24 (2) ◽  
pp. 317 ◽  
Author(s):  
PJ Banney ◽  
PR Wells
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Proton Spin ◽  
Spin Coupling ◽  
Methyl Groups ◽  
Conformational Effects ◽  
Nuclear Magnetic Resonance Spectra ◽  
Spin Spin Coupling ◽  
Derivatives Of ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of a series of arylmercury chlorides containing methyl groups or a single polar substituent have been determined paying particular attention to mercury-proton spin-spin coupling. This is readily observed for protons or methyl groups ortho or meta to mercury but rarely for the para derivatives. The ortho coupling is relatively insensitive to structure whereas the meta coupling shows considerable variations that appear to be associated with conformational effects.

Morpholines: stereochemistry and preferred steric course of quaternization

1976 ◽  
Vol 54 (1) ◽  
pp. 126-135 ◽  
Author(s):  
Alan J. Jones ◽  
C. P. Beeman ◽  
M. U. Hasan ◽  
A. F. Casy ◽  
M. M. A. Hassan
Keyword(s):  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Deuterium Nmr ◽  
Free Energies ◽  
Trans Isomers ◽  
Methyl Substitution ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Magnetic Resonance Spectra

The 13C magnetic resonance spectra of a series of methyl and phenyl substituted morpholines, their hydrochlorides, and methiodides have been determined. The effects of methyl substitution adjacent to oxygen and nitrogen are reasonably equivalent and substituent induced chemical shift parameters derived for the series show favorable agreement with those previously observed in both alicyclic and heterocyclic systems. Results for the cis and trans isomers of phendimetrazine (3,4-dimethyl-2-phenylmorpholine), confirm the preferred chair conformations and configurations cis-3-CH3, cis-2-phenyl (cis) and trans-3-CH3, cis-2-phenyl (trans) for these isomers. The preferred course of quaternization of nitrogen in these systems was determined as axial, using deuteriomethyliodide as a label. This 13C–2H technique relies on the observation of the γ-syn-axial effect and is clearly unambiguous and superior to other methods used in evaluating this mechanism. Product ratios and consequently free energies of this reaction were measured from proton and deuterium nmr spectra.

Proton magnetic resonance spectra of some benzo[b]thiophens. An investigation of substituent effects in a heteroaromatic system

1968 ◽  
Vol 21 (7) ◽  
pp. 1853 ◽  
Author(s):  
B Caddy ◽  
M Martin-Smith ◽  
RK Norris ◽  
ST Reid ◽  
S Sternhell
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Spin Coupling ◽  
Heteroaromatic System ◽  
Spin Spin Coupling ◽  
Magnetic Resonance Spectra

N.m.r. data for 19 5-substituted and 13 polysubstituted benzo[b]thiophens are tabulated. The influence of the substituents at C5 on the chemical shifts of H4 and H6 is discussed. Long-range interproton spin-spin coupling between H3 and H7, and between H2 and H6, is general in benzo[b]thiophens. The vicinal coupling J6,7 in 5-substituted benzo[b]thiophens varies directly and linearly with the electronegativity of the substituents at C5.

Protonenresonanz-Spektroskopie ungesättigter Ringsysteme I

1965 ◽  
Vol 20 (10) ◽  
pp. 948-956 ◽  
Author(s):  
Harald Günther
Keyword(s):  
Magnetic Resonance ◽  
Concentration Dependence ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Electron System ◽  
Coupling Constants ◽  
Resonance Signal ◽  
Aromatic Character ◽  
Additional Support ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of 1.6-methano- and 1.6-oxido-cyclodecapentaene are described and analyzed in terms of chemical shifts and coupling constants. The results are discussed in connection with the structure and possible aromatic character of these compounds. Measurements of the concentration dependence of the chloroform resonance signal in solutions of both compounds give additional support for the presence of a delocalized 10 π-electron system.

A proton magnetic resonance determination of the small rotational barriers about the C—Si bond in phenyl derivatives of chloro and methyl silanes

1977 ◽  
Vol 55 (3) ◽  
pp. 557-561 ◽  
Author(s):  
William J. E. Parr ◽  
Ted Schaefer
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Molecular Orbital Calculations ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Derivatives Of ◽  
Low Energy Conformations

The long-range spin–spin coupling constants between protons bonded to silicon and ring protons in C6H5SiH3, C6H5SiH2Cl, C6H5SiH2CH3, C6H5SiHCl2, and C6H5SiH(CH3)2 are determined from the proton magnetic resonance spectra of benzene solutions. A hindered rotor treatment of the barrier to internal rotation about the C—Si bond, in conjunction with the coupling constants over six bonds, allows the deduction of the low-energy conformations for C6H5SiH(CH3)2 and for C6H5SiHCl2, as well as of barriers of 1.0 ± 0.2 kcal/mol. The approach becomes less reliable for C6H5SiH2CH3 and for C6H5SiH2Cl and, particularly for the latter compound, the derived barrier is very likely an upper limit only. Ab initio molecular orbital calculations of the conformational energies are reported for C6H5SiH3, C6H5SiH2Cl, and for C6H5SiHCl2.

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