THE PROTON RESONANCE SPECTRA OF BENZYL ACETONE

1963 ◽  
Vol 41 (2) ◽  
pp. 387-392 ◽  
Author(s):  
Steven S. Danyluk
Keyword(s):  
Low Temperature ◽  
High Field ◽  
Chemical Shifts ◽  
Molecular Complexes ◽  
Coupling Constant ◽  
Proton Resonance ◽  
Trans Conformation ◽  
Rapid Rotation ◽  
Aromatic Solvents ◽  
Solvent Dependence

The proton resonance spectra of benzyl acetone (4-phenyl-2-butanone) are reported in a variety of solvents at 23 °C. A marked solvent dependence is noted for the CH3 group and the methylene protons adjacent to the keto group. The shifts to high field in aromatic solvents are interpreted in terms of a specific dipole-induced interaction with solvent molecules.The signals for the two non-equivalent pairs of methylene protons show changes in coupling constant with temperature. From this it is concluded that rapid rotation occurs about the C—C bond in the temperature range investigated with an increase in population of the trans conformation at low temperature. Significant changes in relative chemical shifts are also noted with temperature change for the two pairs of methylene protons and are attributed to the formation of weak molecular complexes in aromatic solvents.

A NUCLEAR MAGNETIC RESONANCE INVESTIGATION OF MOLECULAR COMPLEXES OF POLAR MOLECULES IN AROMATIC SOLVENTS

1962 ◽  
Vol 40 (7) ◽  
pp. 1285-1290 ◽  
Author(s):  
J. V. Hatton ◽  
W. G. Schneider
Keyword(s):  
Molecular Complex ◽  
Molecular Complexes ◽  
Large Temperature ◽  
Proton Resonance ◽  
Aromatic Solvents ◽  
Temperature Coefficients ◽  
Molecular Complex Formation ◽  
Nuclear Magnetic Resonance Investigation ◽  
Polar Solutes ◽  
Magnetic Resonance Investigation

In order to confirm the existence of specific molecular complexes in solutions of polar solutes in aromatic solvents previously proposed, the temperature variation of the proton resonance shifts of the solutes acetonitrile, p-benzoquinone, and N,N-dimethylformamide in 5 mole% concentration in toluene were measured. The large temperature coefficients of the solute shifts observed strongly support molecular complex formation. For the same solutes dissolved in methylcyclohexane the temperature coefficients were negligibly small. The temperature at which onset of free rotation of the N-dimethyl group of N,N-dimethylformamide occurs is solvent and concentration dependent. These observations are consistent with the proposed geometry of the molecular complex in the aromatic solvents.

Phosphorus-31 and Mercury-199 N.M.R. studies on mercury(II) halidetributylphosphine complexes

1980 ◽  
Vol 33 (5) ◽  
pp. 955 ◽  
Author(s):  
R Colton ◽  
D Dakternieks
Keyword(s):  
Low Temperature ◽  
Time Scale ◽  
Slow Rate ◽  
Room Temperature ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Slowing Down ◽  
Halogen Exchange ◽  
And Shifts

Phosphorus-31 and mercury-199 N.M.R. studies have been carried out on HgX2P2,Hg2X4P2, mixtures thereof and the oligomers Hg2X4P3, Hg3X6P2 and Hg4X8P2 where X = Cl, Br, I and P = tributyl-phosphine. The results are consistent with exchange of both phosphine and halogen. The phosphine exchanges slowly on the N.M.R. time scale at room temperature, but rapidly on the preparative time scale. Halogen exchange is fast on both the N.M.R. and preparative time scales at room temperature; cooling to -120°C reduces exchange of terminal halogens to a slow rate on the n.m.r. time scale. Increase in the coupling constant JP,Hg at low temperature is attributed to the slowing down of halogen exchange. Exchange of bridging halogens is still fast at -120°C. ��� Mercury-199 chemical shifts span a range of over 3000 ppm and shifts have been correlated with 31P chemical shifts and with the coupling constants JP,Hg The 199Hg n.m.r. data confirm the existence of an asymmetrical isomer of Hg2I4(PBu3)2.

The chemical shifts of the methoxyl in anisole derivatives

1973 ◽  
Vol 26 (10) ◽  
pp. 2303 ◽  
Author(s):  
S Ng
Keyword(s):  
Chemical Shifts ◽  
Spin Coupling ◽  
Proton Resonance ◽  
Aromatic Solvent ◽  
Upfield Shift ◽  
Aromatic Solvents ◽  
Meta Position ◽  
Doublet Structure ◽  
Alkyl Substitution ◽  
Spin Spin Coupling

The n.m.r. spectra of anisole and 20 methyl-, t-butyl-, adamant-1-yl-, and chloro-substituted anisoles were obtained in dilute solutions in CCl4, CHCl3, and C6H6. In the non-aromatic solvents the methoxyl proton resonance shifts upfield with di-o-alkyl substitution, relative to anisole or o-alkyl substitution. However, this upfield shift is not observed in the case of di-o-chloro substitution. In benzene the methoxyl resonance exhibits the aromatic-solvent induced shift, and this shift is larger with ortho than with di-ortho substitution. Relative to anisole, alkyl substitution at the para or meta position shifts the methoxyl resonance slightly upfieid in the non-aromatic solvents, but slightly downfield in benzene. However, chloro substitution at the ortho or the para position shifts this resonance upfield in benzene. In the mono-o-substituted derivatives, the methoxyl resonance shows a doublet structure, consistent with spin-spin coupling with the o-proton (J c. 0.20 Hz).

High‐field, high‐pressure, and low‐temperature magneto‐optical apparatus using a diamond anvil cell

1992 ◽  
Vol 63 (12) ◽  
pp. 5764-5766 ◽  
Author(s):  
Y. Matsuda ◽  
N. Kuroda ◽  
Y. Nishina
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
High Field ◽  
Diamond Anvil Cell ◽  
Diamond Anvil

The transmission of polar effects. Part VII. A proton magnetic resonance spectra study of substituted mesitylenes, durenes, anthracenes, and triptycenes

1968 ◽  
Vol 46 (24) ◽  
pp. 3903-3908 ◽  
Author(s):  
Keith Bowden ◽  
J. G. Irving ◽  
M. J. Price
Keyword(s):  
Dielectric Constant ◽  
Free Energy ◽  
Carbon Tetrachloride ◽  
Field Effect ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Linear Free Energy ◽  
Solvent Dependence ◽  
Similar Dependence ◽  
Energy Relations

The chemical shifts of the ring protons in a series of monosubstituted mesitylenes and durenes, and of the 10-protons of a series of 9-substituted triptycenes and anthracenes have been measured in dimethyl sulfoxide, acetone, 2-methoxyethanol, and carbon tetrachloride. The solvent dependence of the substituent chemical shifts has been analyzed by linear free energy relations. The systems all show similar dependence which increases with increasing dielectric constant of the solvent. This does not result from the field effect being transmitted through the medium, but appears to arise from the formation of a hydrogen-bonded interaction between the solvent and the hydrogen of the solute. The substituent chemical shifts appear to arise from contributions from substituent field, resonance, magnetic anisotropy, and solvent effects.

Circular dichroism spectra of tetraamminecobalt(III) complexes of amino alcohols

1978 ◽  
Vol 31 (11) ◽  
pp. 2399 ◽  
Author(s):  
CJ Hawkins ◽  
GA Lawrance ◽  
JA Palmer
Keyword(s):  
Circular Dichroism ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Amino Alcohols ◽  
Circular Dichroism Spectra ◽  
Chemical Shift Difference ◽  
Solvent Dependence ◽  
Cotton Effects ◽  
Circular Dichroïsm ◽  
Chiral Amino Alcohols

The circular dichroism spectra are reported for tetraamminecobalt(III) complexes with the chiral amino alcohols 2-aminopropan-1-ol, 2- aminobutan-1-ol, 1-aminopropan-2-ol, 2-amino-1-phenyl-ethanol, ψ- ephedrine and ephedrine with the alcohol groups protonated (OH) and deprotonated (O-). The solvent dependence of the chemical shifts of the NH protons was investigated to determine the effects of stereoselective solvation on the circular dichroism, but, in contrast to some other related systems, the chemical shift difference between the two NH2 protons was relatively insensitive to solvent. Consistent with this, the circular dichroism spectra of the tetraphenylborate salts of the deprotonated complexes were found not to be markedly dependent on solvent. Tetraammine-{(-)-ψ-ephedrine)cobalt(III) and tetraammine{(-)- ephedrine}cobalt(III) were found to have the same signs of Cotton effects for the various d-d transitions, whereas bis{(-)-ψ- ephedrine}copper(II) and bis{(-)-ephedrine}copper(II) had opposite signs. This has been explained in terms of different conformer populations in the cobalt(III) and copper(II) systems.

THE ANALYSIS OF NUCLEAR MAGNETIC RESONANCE SPECTRA: III. PYRIDINE AND DEUTERATED PYRIDINES

1957 ◽  
Vol 35 (12) ◽  
pp. 1487-1495 ◽  
Author(s):  
W. G. Schneider ◽  
H. J. Bernstein ◽  
J. A. Pople
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Calculated Spectrum ◽  
Proton Resonance ◽  
Nuclear Magnetic Resonance Spectra ◽  
Spin Coupling Constants

The proton resonance spectra of pyridine, 2,6-pyridine-d2, 3-pyridine-d1, and 4-pyridine-d1 have been obtained for the pure liquids under conditions of high resolution. The spectra have been analyzed as proton groupings of AB2X2, AB2, perturbed ABX, and B2X2 respectively. The spin-coupling constants obtained from analysis of the simpler spectra of the deuterated molecules were used to suggest trial solutions for the analysis of the complicated AB2X2 spectrum of pyridine. A final set of chemical shifts and spin-coupling constants derived for pyridine give satisfactory agreement between the observed and calculated spectrum.

Carbon-13/carbon-12 isotope effects on nitrogen-15 chemical shielding in some diamagnetic cyano complexes

1982 ◽  
Vol 60 (17) ◽  
pp. 2194-2197 ◽  
Author(s):  
Roderick E. Wasylishen
Keyword(s):  
Transition Metal ◽  
High Field ◽  
Chemical Shifts ◽  
Isotope Effects ◽  
Chemical Shielding ◽  
Cyanide Ion ◽  
Theoretical Formulation ◽  
Metal Cyanides ◽  
Shielding Constants ◽  
Cyano Complexes

Carbon-13/carbon-12 isotope-induced 15N chemical shifts of 0.06 to 0.10 ppm have been observed for the cyanide ion and several transition metal cyanides. In each case, the 15N resonance of the 13C labelled isotopomers is to high field of that in the corresponding carbon-12 species. The sensitivity of the 15N and 13C shielding constants in the cyanide ion to small changes in the CN bond length are evaluated using the theoretical formulation of Jameson: (∂σ(15N)/∂r)e = −872 ± 160 ppm/Å and (∂σ(13C)/∂r)e = −473 ± 90 ppm/Å. Nitrogen-15 chemical shifts in the metal complexes exhibit basically the same behaviour as do the 13C chemical shifts in these same complexes.

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