The N.M.R. spectra of some tricyclic heterocycles related to phenothiazine

1971 ◽  
Vol 24 (2) ◽  
pp. 325 ◽  
Author(s):  
IC Calder ◽  
RB Johns ◽  
JM Desmarchelier
Keyword(s):  
High Resolution ◽  
Long Range ◽  
Solvent Effects ◽  
Substituent Effects ◽  
Coupling Constants

The high-resolution N.M.R. spectra of ten tricyclic heterocycles related to phenothiazine in which the heteroatoms are combinations of O, N, S, Se, Te, and As are reported. The coupling constants are discussed in terms of substituent effects for the heteroatoms. Long- range coupling of the NH and solvent effects are used to make assignments of the protons.

An Investigation of Substituent Effects on Coupling Constants to Vinyl Protons in Styrene Derivatives

1974 ◽  
Vol 52 (19) ◽  
pp. 3415-3423 ◽  
Author(s):  
William F. Reynolds ◽  
Ian R. Peat ◽  
Gordon K. Hamer
Keyword(s):  
Long Range ◽  
Substituent Effects ◽  
Phenyl Group ◽  
Coupling Constants ◽  
Vinyl Proton ◽  
Model Compounds ◽  
Proton Coupling ◽  
Phenyl Proton ◽  
Styrene Derivatives ◽  
Induced Changes

Experimental long-range phenyl proton–vinyl proton coupling constants in 4-substituted styrenes are substituent independent. This is also predicted by INDO–finite perturbation theory calculations of these coupling constants. Comparison with calculated and experimental long-range coupling constants for 4-substituted benzaldehydes suggests that the previously reported substituent dependence for the latter coupling constants arises from substituent-induced changes in molecular geometry.Geminal vinyl coupling constants in 4-substituted styrenes, α-methylstyrenes, and α-t-butylstyrenes are substituent dependent with substituent effects increasing as phenyl and vinyl groups are twisted out of planarity. These trends are reproduced by INDO–FPT calculations. It is concluded that the substituent effects are primarily transmitted through space.Both experimental and calculated vinyl 13C–1H coupling constants show strong stereospecific substituent effects. From the pattern of results (particularly the greater field dependence for JC(β)H(9) than JC β)H(8)) it is concluded that these coupling constants.also reflect through-space substituent effects. This is supported by calculations on model compounds with no intervening phenyl group.

Deceptive simplicity in ABMX N.M.R. spectra. III. The spectrum of benzothiophen

1972 ◽  
Vol 25 (2) ◽  
pp. 327 ◽  
Author(s):  
F Balkau ◽  
ML Heffernan
Keyword(s):  
High Resolution ◽  
Strong Coupling ◽  
Long Range ◽  
Coupling Constants ◽  
High Resolution Spectrum ◽  
Very High

The analysis of the high resolution spectrum of benzothiophen in several solvents is reported. It is noted that the conditions are close to those leading to deceptively simple spectra, but under very high resolution sufficient lines could be resolved to give an unambiguous analysis. The inter-ring, long-range coupling constants, as well as their relative signs, could be determined from these spectra as a result of the strong coupling between protons.

Proton magnetic resonance studies of non-alternant hydrocarbons. I. Some comments on the aromatic character of the fulvenes

1966 ◽  
Vol 19 (10) ◽  
pp. 1813 ◽  
Author(s):  
ML Heffernan ◽  
AJ Jones
Keyword(s):  
Magnetic Resonance ◽  
High Resolution ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Magnetic Resonance Studies ◽  
Aromatic Character ◽  
Alternant Hydrocarbons ◽  
Cyclic Dienes ◽  
Magnetic Resonance Spectra

The high-resolution proton magnetic resonance spectra of 6- phenylfulvene, 6-methyl-6-phenylfulvene, and 6-dimethylaminofulvene have been studied in detail. The aromatic character of the fulvenes is discussed in terms of the derived parameters, and observations, in general, indicate that these compounds should be regarded as cyclic dienes. Long-range coupling constants involving protons separated by five and six bonds have been observed.

High-Resolutjon nuclear-magnetic-resonance spectra of hydrocarbon groupings VI. The hydrogen spectra of carbon-13 substituted ethane, ethylene and acetylene

1962 ◽  
Vol 269 (1338) ◽  
pp. 385-403 ◽  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Long Range ◽  
Experimental Results ◽  
Coupling Constants ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

High-resolution spectra have been obtained from the hydrogen nuclei of appropriate isotopic mixtures of ethane, ethylene and acetylene containing one or two magnetic 13 C nuclei. Analysis of these spectra has yielded the magnitudes of all but one of the possible inter - nuclear coupling constants in these molecules, including those between pairs of carbon nuclei. Where a given molecule has several coupling constants between pairs of the same type of nuclei the relative signs of these have also been determined. Discussion of the experimental results in terms of current theoretical treatments shows that in nearly all cases the contact, H 3 , term is the most important one in determining the magnitude of the coupling constants. Only in the case of the J CC and the long-range J ' CH coupling constants of acetylene does it appear to be necessary to consider appreciable contributions from other terms.

Proton Magnetic Resonance Studies of Rotational Isomerism in Halotoluenes. X. Estimates of Conformational Preferences and Rotational Barriers in Benzal Fluoride and Some Dichloro Derivatives

1974 ◽  
Vol 52 (3) ◽  
pp. 481-488 ◽  
Author(s):  
J. Brian Rowbotham ◽  
Alexander Frank Janzen ◽  
James Peeling ◽  
Ted Schaefer
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Substituent Effects ◽  
Molecular Orbital Calculation ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Proton Proton ◽  
Carbon Carbon Bond ◽  
Dichloro Derivative

The synthesis of benzal fluoride and of its 2,6-, 3,5-, 3,4-, and 2,4-dichloro derivatives is followed by an analysis of their proton magnetic resonance spectra. The long-range spin–spin coupling constants are most consistent with a barrier to rotation about the sp2–sp3 carbon–carbon bond in benzal fluoride of less than 500 cal/mol, in semiquantitative agreement with an ab initio molecular orbital calculation. The 2,6-dichloro derivative has a conformation in which the C—H bond of the side chain lies in the plane of the aromatic ring. The 2,4-dichloro derivative favors a similar conformation, the C—H bond lying cis to the ring chlorine atom. In contrast to the long-range proton–proton couplings, the long-range proton–fluorine couplings are intrinsically sensitive to substituent effects from the ring chlorine atoms.

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