scholarly journals The barrier to the conformational interconversion of 1,4-dimethylenecyclohexane and related compounds

1969 ◽  
Vol 47 (15) ◽  
pp. 2911-2913 ◽  
Author(s):  
Maurice St-Jacques ◽  
Michel Bernard
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Kcal Mole ◽  
Temperature Dependent ◽  
Conformational Interconversion ◽  
Spectral Changes ◽  
Related Compounds ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of 1,4-cyclohexanedione, 1,4-dimethylenecyclohexane, and 1,4-difluoromethylenecyclohexane have been studied at various temperatures; the spectra of the last two compounds were found to be temperature dependent. ΔF≠ values of 7.5 and 6.5 kcal/mole, respectively, were estimated from the spectral changes.

Conformational interconversion of 3,3,5,5-tetramethylmethylenecyclohexane and related compounds

1970 ◽  
Vol 48 (15) ◽  
pp. 2386-2392 ◽  
Author(s):  
Maurice St-Jacques ◽  
Michel Bernard ◽  
Cambyse Vaziri
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Conformational Interconversion ◽  
Spectral Changes ◽  
Related Compounds ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of compounds 1 to 4 have been studied at various temperatures. The spectral changes observed for 2, 3, and 4 are interpreted in terms of interconverting chair conformations.

Aza-analogues of pteridine. III. Some monomethoxy-1,2,4,6,8-pentaazanaphthalenes and related compounds

1971 ◽  
Vol 24 (3) ◽  
pp. 633 ◽  
Author(s):  
DJ Brown ◽  
T Sugimoto
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Triethyl Orthoformate ◽  
Ionization Constants ◽  
Reductive Cyclization ◽  
Ultraviolet Spectra ◽  
Chloro Derivative ◽  
Related Compounds ◽  
Magnetic Resonance Spectra

4-Hydrazino-2-methoxy-6-methyl-5-nitropyrimidine reacted with triethyl orthoformate to give the ethoxymethylenehydrazino analogue or 4-methoxy-6-methyl-7-nitro-1,2,3a,5-tetraazaindene according to conditions. The first of these products was converted by reductive cyclization and subsequent dehydrogenation into 7-methoxy-5-methyl- 1,2,4,6,8-pentaazanaphthalene. Attempts to hydrolyse this and related compounds to the corresponding 7-hydroxypentaazanaphthalenes failed and direct approaches via appropriate 2-hydroxypyrimidines gave only 4- hydroxy-7-nitrotetraazaindenes. ��� 5-Alkoxypentaazanaphthalenes were prepared via 1,2-dihydropentaaza- naphthalene or its 5-chloro derivative. Nucleophilic displacements were used to make the 5-hydroxy, 5-methylthio, 5-diethylamino, and other analogues from 5-methoxy-3-methylpentaazanaphthalene. ��� The ionization constants, ultraviolet spectra, and proton magnetic resonance spectra of members of both bicyclic series are tabulated and discussed.

REACTIONS OF AMIDES AND RELATED COMPOUNDS: III. N.M.R. INVESTIGATION OF THE PROTONATION OF N,N-DIMETHYLNITROSOAMINE, N,N-DIETHYLNITROSOAMINE, AND N-NITROSOPIPERIDINE

1966 ◽  
Vol 44 (2) ◽  
pp. 105-109 ◽  
Author(s):  
Stephen J. Kuhn ◽  
John S. McIntyre
Keyword(s):  
Sulfuric Acid ◽  
Magnetic Resonance ◽  
Perchloric Acid ◽  
Trifluoroacetic Acid ◽  
Proton Magnetic Resonance ◽  
Acid Solutions ◽  
Concentrated Sulfuric Acid ◽  
Related Compounds ◽  
Equimolar Solution ◽  
Magnetic Resonance Spectra

Protonation of N,N-dimethylnitrosoamine has been investigated by dissolving the nitrosoamine in different acids and recording the proton magnetic resonance spectra of these solutions. Concentrated sulfuric acid, sulfuric acid monohydrate, perchloric acid (72%), trifluoroacetic acid, and fluorosulfuric acid have been used in this study. Only in fluorosulfuric acid near 0 °C and lower was a new signal observed for the protonated nitrosoamine molecule. Integration of the peaks has shown that only one proton is captured by the nitrosoamine. The following structure is suggested for the protonated nitrosoamine.[Formula: see text]The n.m.r. spectra of fluorosulfuric acid solutions of N,N-diethylnitrosoamine and N-nitrosopiperidine also show separate signals for the captured proton.The n.m.r. spectrum of an equimolar solution of N,N-dimethylnitrosoamine, N,N-dimethylformamide, and trifluoroacetic acid in 2-nitropropane indicates that N,N-dimethylnitrosoamine is a weaker base.

The analysis of the proton magnetic resonance spectra of heteroaromatic systems. IV. Benzofuran, indole, and related compounds

1965 ◽  
Vol 18 (3) ◽  
pp. 353 ◽  
Author(s):  
PJ Black ◽  
ML Heffernan
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Spectral Parameters ◽  
Related Compounds ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of benzofuran, dibenzofuran, indole, 7-azaindole, carbazole, and 4-azacarbazole (α-carboline) have been investigated at 100 Mc/s, and the spectral parameters for these molecules have been obtained. The presence of cross-ring coupling constants involving the NH proton of indole and carbazole is reported.

Intramolecular hydrogen bonding in some ortho-nitrodiphenylamines and related compounds. A proton magnetic resonance study

1972 ◽  
Vol 25 (10) ◽  
pp. 2145 ◽  
Author(s):  
DJ Gale ◽  
JFK Wilshire
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Intramolecular Hydrogen Bonding ◽  
Temperature Dependent ◽  
Polar Solvents ◽  
Chemical Shift Data ◽  
Intramolecular Hydrogen ◽  
Related Compounds

.Proton magnetic resonance spectra of a wide variety of substituted 2-nitro- and 2,4-dinitro-diphenylamines and related compounds reveal that long-range coupling occurs between the NH proton and the 5-proton of the nitrophenyl ring in non-polar or weakly polar solvents. However, in the case of the 2,4-dinitrodiphenyl- amines, this coupling is absent in highly polar solvents, except when the non-nitrated ring carries powerful electron-donating substituents, e.g. methoxyl or dimethylamino, ortho or para (but not meta) to the NH group. An examination of these phenomena leads to the conclusion that such long-range coupling provides evidence that intramolecular hydrogen bonding occurs between the NH and the 2-nitro groups. N-Benzyl-2,4-dinitroaniline also exhibited similar long-range coupling but, in dimethyl sulphoxide solut'ion, this coupling was temperature-dependent. The chemical shift data of the ortho-nitrodiphenylamines suggest that they adopt a non-planar skew conformation in solution. A six-bond H-F coupling was observed between the fluorine atom and the 6-proton of 2'-fluoro-2,4-dinitrodiphenylamine.

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