Conformational studies of α-substituted ketones by nuclear magnetic resonance

1967 ◽  
Vol 45 (21) ◽  
pp. 2529-2535 ◽  
Author(s):  
T. E. Gough ◽  
W. S. Lin ◽  
R. G. Woolford
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Methyl Groups ◽  
Conformational Studies ◽  
Substituent Group ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The nuclear magnetic resonance spectra are reported for a series of α-substituted 3-pentanones. Magnetically nonequivalent methylene hydrogens are observed whenever the substituent group is diamagnetically anisotropic. The results are discussed in terms of the possible conformations of the molecules; the most stable conformations are those with the C=O bond essentially eclipsed by the terminal methyl groups.

Axial dissymmetry induced magnetic nonequivalence in the 13C nuclear magnetic resonance spectra of allenes

1980 ◽  
Vol 58 (9) ◽  
pp. 928-931 ◽  
Author(s):  
Pierre L. Beaulieu ◽  
Veronique M. Morisset ◽  
Dennis G. Garratt
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Substituent Effects ◽  
Methyl Carbon ◽  
Substituent Group ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The observation of the magnetic nonequivalence of isopropyl methyl carbon resonances as a result of axial dissymmetry in 27 appropriately substituted allenes is reported. The magnitude of the nonequivalence Δ is more dependent upon the adjacent substituent group than upon the substituents which are bonded to the remote sp2 carbon of the allene. A mechanism based upon the transmission of substituent effects from the remote substituents to the collinear π orbitals is proposed.

NUCLEAR MAGNETIC RESONANCE SPECTRA OF DURENE AND MESITYLENE DERIVATIVES

1963 ◽  
Vol 41 (3) ◽  
pp. 711-713 ◽  
Author(s):  
E. Bullock
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Aromatic Ring ◽  
Chemical Shifts ◽  
Methyl Groups ◽  
Mesomeric Effect ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The nuclear methyl groups and ring protons in nitro- and dimethylamino-durenes and -mesitylenes show considerable chemical shifts relative to the parent hydrocarbons. The shifts are generally in the direction expected from a mesomeric effect, despite the lack of coplanarity between the aromatic ring and the substituent.

SOME ASPECTS OF THE NUCLEAR MAGNETIC RESONANCE SPECTRA OF COMPOUNDS CONTAINING C-METHYL GROUPS

1961 ◽  
Vol 39 (11) ◽  
pp. 2262-2273 ◽  
Author(s):  
F. A. L. Anet
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Special Reference ◽  
Spin Coupling ◽  
Methyl Groups ◽  
Coupling Constant ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The N.M.R. spectra of compounds containing various types of C-methyl groups are discussed with special reference to the effects of spin coupling. Particular attention is given to compounds containing the CHCH3 group in saturated systems. It is pointed out that the observed splitting of the methyl band is not always equal to the coupling constant between the methyl protons and the adjacent proton, even when the chemical shift between the two groups of protons is large.

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