Long-range coupling in substituted coumarins

1968 ◽  
Vol 21 (10) ◽  
pp. 2445 ◽  
Author(s):  
MW Jarvis ◽  
AG Moritz
Keyword(s):  
Magnetic Resonance ◽  
High Resolution ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Very High ◽  
Substituted Coumarins ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of some substituted coumarins and furanocoumarins have been examined under very high resolution (0.1 Hz). Trans-annular long-range spin-spin couplings across four, five, six, and seven bonds are reported.

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.

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.

Identification of Polychlorobiphenyls by High Resolution Proton Magnetic Resonance

1972 ◽  
Vol 55 (5) ◽  
pp. 1101-1103
Author(s):  
K D Bartle
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Proton Magnetic Resonance ◽  
Chlorine Atoms ◽  
Magnetic Resonance Spectra

Abstract Mass spectrometry allows the number of chlorine atoms per polychlorobiphenyl molecule to be determined but not the positions of substitution. A method of identifying PCB components from high resolution proton magnetic resonance spectra is illustrated by application to 2,5,2′,5′-tetrachloro- and 2,3,4,2′,4′,- 5′-hexachlorobiphenyls separated by gas chromatography from a commercial PCB mixture.

An Abnormal Saturation Behavior in High Resolution Proton Magnetic Resonance Spectra

1959 ◽  
Vol 14 (5) ◽  
pp. 679-679 ◽  
Author(s):  
Michihiko Nagumo ◽  
Yoshinobu Kakiuchi
Keyword(s):  
Magnetic Resonance ◽  
High Resolution ◽  
Proton Magnetic Resonance ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of N-nitroso derivatives of sarcosine, proline and iminodiacetic acid

1971 ◽  
Vol 24 (9) ◽  
pp. 1949 ◽  
Author(s):  
FHC Stewart
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Iminodiacetic Acid ◽  
Conformational Isomerism ◽  
Nitroso Group ◽  
Restricted Rotation ◽  
Derivatives Of ◽  
Shielding Effects ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of various N-nitroso derivatives of sarcosine, L-proline, and iminodiacetic acid, including some protected dipeptides, have been obtained. Magnetic non-equivalence and conformational isomerism arising from restricted rotation of the nitroso group are discussed in relation to the reported behaviour of other nitrosamines. Long-range shielding effects on protons at a considerable distance from the anisotropic nitrosamino centre were readily detected with these compounds.

The proton magnetic resonance spectra of phenol in the absence of intermolecular proton exchange

1976 ◽  
Vol 54 (23) ◽  
pp. 3666-3671 ◽  
Author(s):  
Ted Schaefer ◽  
J. B. Rowbotham ◽  
Kalvin Chum
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Proton Exchange ◽  
Associated Species ◽  
Hydroxyl Protons ◽  
Model Support ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra in the absence of intermolecular proton exchange for 0.27, 0.59, and 0.79 M solutions of phenol in CCl4 are analyzed. The long-range coupling over five bonds between the hydroxyl and ring protons is estimated as 0.33 Hz in the monomer and as 0.20 Hz in the trimer of a monomer–trimer model. Support for the decrease in the coupling on trimerization is found in CNDO/2 and INDO MO FPT calculations. The long-range coupling over six bonds is unobservable, consistent with conformations of the trimer in which the phenol molecules remain planar. Water catalyzes the intermolecular proton exchange and, in its absence, the transfer of hydroxyl protons from molecule to molecule within the associated species is inefficient.

The analysis of the proton magnetic resonance spectra of heteroaromatic systems. V. Diazanaphthalenes

1965 ◽  
Vol 18 (5) ◽  
pp. 707 ◽  
Author(s):  
PJ Black ◽  
ML Heffernan
Keyword(s):  
Carbon Tetrachloride ◽  
Magnetic Resonance ◽  
Long Range ◽  
Iterative Procedure ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Direct Calculation ◽  
Coupling Constants ◽  
Dilute Solutions ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of the four isomeric diazanaphthalenes, quinoxaline, phthalazine, quinazoline, and cinnoline, all as dilute solutions in carbon tetrachloride and acetone, have been investigated at 100 Mc/s. The chemical shifts and coupling constants have been obtained by direct calculation or, where appropriate, by an iterative procedure. Long-range coupling constants between protons separated by five and six bonds have been observed.

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