A carbon-13 nuclear magnetic resonance study of a series of 5-substituted benzimidazoles

1982 ◽  
Vol 60 (24) ◽  
pp. 2987-3092 ◽  
Author(s):  
Barry J. Blackburn ◽  
Douglas W. Ankrom ◽  
Harold M. Hutton
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Excess Charge ◽  
Chemical Shift Assignments ◽  
Magnetic Resonance Study ◽  
Nmr Chemical Shift Assignments ◽  
Density Values

Carbon-13 nmr chemical shift assignments are reported for a series of 5-substituted benzimidazoles, 2-methylbenzimidazole, and 5,6-dimethylbenzimidazole. By employing the three-parameter equation of Smith and Proulx, the chemical shifts of all the ring carbons of the 5-substituted compounds are correlated with F and R of Swain and Lupton and Q of Schaefer; only the ipso carbon, C-5, has chemical shifts with a correlation coefficient less than 0.953. These correlations are compared with those obtained from the Swain–Lupton and Taft relationships; in general those from the latter two approaches are found to be less satisfactory. Correlations of the same chemical shifts with excess charge density values, calculated at the INDO level of approximation, are also presented.

Nuclear Magnetic Resonance Study of Caesium-133 in Binary Molten Trifluoroacetate Salt Mixtures

2001 ◽  
Vol 56 (3-4) ◽  
pp. 288-290 ◽  
Author(s):  
V. N. Mirny ◽  
V. V. Trachevski ◽  
T. A. Mimaya
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Sodium Potassium ◽  
Salt Mixtures ◽  
Nuclear Magnetic

Abstract The chemical shifts of Cs+ in binary melts of caesium trifluoroacetate with lithium, sodium, potassium or thallium trifluoroacetates have been studied as a function of composition. An influence of added foreign cations on chemical shift of caesium nuclei has been found. The nature of the intra-and intermolecular paramagnetic contributions into the shifts of 133Cs is discussed.

A Nuclear Magnetic Resonance Study of some 4-X-Substituted-2,6-Dinitroanisoles and Related Meisenheimer 1,3- and 1,1-Complexes

1972 ◽  
Vol 50 (21) ◽  
pp. 3558-3565 ◽  
Author(s):  
M. P. Simonnin ◽  
M. J. Lecourt ◽  
F. Terrier ◽  
C. A. Dearing
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Linear Relationship ◽  
Negative Charge ◽  
Inductive Effect ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Methoxide Ion

The structures of transient 1,3-complexes 2 and stable 1,1-complexes 3 formed by the reaction of methoxide ion with various 4-X-2,6-dinitroanisoles in DMSO-d6 are confirmed by n.m.r. spectroscopy. 13C satellites in the proton spectra of anisoles and 1,1-complexes have been used to obtain [Formula: see text] as well as 4JH–H in these symmetrical compounds.The chemical shifts of the ring protons in 1,3- and 1,1-complexes give some information concerning the influence of the substituent X on the delocalization of the negative charge. In anisoles and 1,1-complexes, [Formula: see text] of the ring protons are mainly dependent on the inductive effect of X. Furthermore, a linear relationship is observed in anisoles between the chemical shift as well as [Formula: see text] of the methoxyl protons and the Hammett σP constant of X, thus suggesting an identical geometry of these molecules at C-2,-1, and -6.

Sesquiterpene alkaloids from Tripterygiumwilfordii (Hook): a nuclear magnetic resonance study of 1-desacetylwilfordine, 1-desacetylwilfortrine, and 2-debenzoyl-2-nicotinoylwilforine

1990 ◽  
Vol 68 (3) ◽  
pp. 371-374 ◽  
Author(s):  
Li Ya ◽  
George M. Strunz ◽  
Larry A. Calhoun
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Chemical Shift Assignments ◽  
Magnetic Resonance Study ◽  
Root Extracts ◽  
C Nmr ◽  
Nuclear Magnetic

1-Desacetylwilfordine, 8, 1-desacetylwilfortrine, 9, and 2-debenzoyl-2-nicotinoylwilforine, 10, have been isolated from root extracts of the Chinese medicinal and insecticidal plant Tripterygiumwilfordii. Analysis of the 1H and 13C NMR spectra of 8 and 10, with the aid of COSY, HCCOSY, and COLOC experiments, has allowed unambiguous chemical shift assignments of all protons and carbons of these alkaloids. Keywords: alkaloids, sesquiterpene, Celastraceae, Tripterygium, NMR.

Fe(CO)3 and Rh(acac) complexes of ergosteryl and 7-dehydrocholesteryl acetates: A high field nuclear magnetic resonance study

1988 ◽  
Vol 66 (12) ◽  
pp. 3003-3011 ◽  
Author(s):  
Richard E. Perkier ◽  
Michael J. Mcglinchey
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Field ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Two Dimensional ◽  
Magnetic Resonance Study ◽  
Anisotropic Properties ◽  
Diene System ◽  
Nmr Techniques

The 500 MHz 1H and 125 MHz 13C spectra of ergosteryl and 7-dehydrocholesteryl acetate were recorded in C6D6 and CDCl3 and assigned using two-dimensional NMR techniques. It is shown that incorporation of an Fe(CO)3 or a Rh(acac) moiety onto the ring B diene system affects the chemical shifts of neighbouring protons and carbons. These changes are discussed in terms of the anisotropic properties of the organometallic fragments.

A nitrogen-15 nuclear magnetic resonance study of N-aryl phosphoramidates and phosphorimidates

1980 ◽  
Vol 58 (23) ◽  
pp. 2442-2446 ◽  
Author(s):  
G. W. Buchanan ◽  
F. G. Morin ◽  
R. R. Fraser
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Aromatic Ring ◽  
Chemical Shifts ◽  
Lone Pair ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Nuclear Magnetic

15N nuclear magnetic resonance chemical shifts and one-bond 15N—31P couplings are reported for a series of five N-arylphosphoramidates and four N-arylphosphorimidates. Results are interpreted in terms of an extensively delocalized N lone pair in the phosphoramidates, with pπ–pπ donation into the aromatic ring being dominant over pπ–dπ donation from nitrogen to phosphorus.

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