Steric Effects. Internal-Rotation of 1-Aryl-8-Phenylnaphthalenes

1987 ◽  
Vol 40 (6) ◽  
pp. 1107 ◽  
Author(s):  
R Cosmo ◽  
S Sternhell
Keyword(s):  
Internal Rotation ◽  
Activation Parameters ◽  
Steric Effects

A general, albeit low-yielding, synthesis of 1-aryl-8-phenylnaphthalenes was devised and used to prepare three l-(3'-X-5'-isopropylphenyl)-8-phenylnaphthalenes (X = H, F, Br). Activation parameters for the rotation of the 3'-X-5'4sopropylphenyl group were determined by dynamic m.m.r. spectroscopy.

c. Internal rotation of the nitroso group in p-substituted nitrosoanilines by the density matrix line-shape method

1974 ◽  
Vol 27 (1) ◽  
pp. 21 ◽  
Author(s):  
PD Buckley ◽  
AR Furness ◽  
KW Jolley ◽  
DN Pinder
Keyword(s):  
Density Matrix ◽  
Internal Rotation ◽  
Line Shape ◽  
Matrix Theory ◽  
Activation Parameters ◽  
Nitroso Group ◽  
Approximate Methods ◽  
Density Matrix Theory

Density matrix theory has been applied to study the barrier to internal rotation about the Ar-NO bond in N,N-dimethyl-p-nitrosoaniline and N,N-diethyl-p-nitrosoaniline. Theoretical fits to experimental n.m.r. spectra have been obtained in the range - 30°C to +40°C. Activation parameters have been determined and compared with those obtained by more approximate methods.

Thermolysis of 3-methyl-3-alkyl-1,2-dioxetanes: steric effects on the activation parameters

1983 ◽  
Vol 48 (21) ◽  
pp. 3713-3716 ◽  
Author(s):  
Alfons L. Baumstark ◽  
Tambra Dunams ◽  
Luiz H. Catalani ◽  
Etelvino J. H. Bechara
Keyword(s):  
Activation Parameters ◽  
Steric Effects

Nuclear Magnetic Resonance Studies of Enantiomeric Internal Rotational Isomers of 1- and 3-Arylhydantoins in Achiral and Chiral Solvents

1975 ◽  
Vol 53 (11) ◽  
pp. 1556-1562 ◽  
Author(s):  
Lawrence D. Colebrook ◽  
Siddik Icli ◽  
Frank H. Hund
Keyword(s):  
Internal Rotation ◽  
Shape Analysis ◽  
Chemical Shifts ◽  
Activation Parameters ◽  
Methyl Groups ◽  
Solvent Interactions ◽  
Rotational Isomers ◽  
Line Shape Analysis ◽  
Solvent Dependence ◽  
Normal Probe

1H and 13C n.m.r. spectra have been determined for a number of 1- and 3-arylhydantoins in achiral and chiral solvents. These compounds, which have enantiomeric rotational isomers, show restricted internal rotation about the aryl C—N bond at normal probe temperatures. Chemical shifts between corresponding protons on the pairs of rotamers, induced by diastereomeric solute–solvent interactions in the chiral solvent, are strongly dependent on the location of the protons in the solute molecules. In conjunction with 1H and 13C chemical shifts, these data provide information on the geometry of the solvated species. No splitting of signals resulting from the presence of diastereomeric solvates was observable in the 13C spectra. Activation parameters for hindered internal rotation, determined by complete p.m.r. line shape analysis using signals of the diastereotopic methyl groups in the 5-position, show some solvent dependence.

ChemInform Abstract: THERMOLYSIS OF 3-METHYL-3-ALKYL-1,2-DIOXETANES: STERIC EFFECTS ON THE ACTIVATION PARAMETERS

1984 ◽  
Vol 15 (11) ◽  
Author(s):  
A. L. BAUMSTARK ◽  
T. DUNAMS ◽  
L. H. CATALANI ◽  
E. J. H. BECHARA
Keyword(s):  
Activation Parameters ◽  
Steric Effects

The effect of solvent on the barrier to internal rotation in p-substituted nitrosoanilines

1975 ◽  
Vol 28 (10) ◽  
pp. 2303 ◽  
Author(s):  
AR Furness ◽  
PD Buckley ◽  
KW Jolley
Keyword(s):  
Internal Rotation ◽  
Line Shape ◽  
Activation Parameters ◽  
Effect Of Solvent ◽  
Solvent Dependence

The solvent dependence of the barrier to internal rotation about the Ar-NO bond in N,N-dimethyl-p-nitrosoaniline and N,N-diethyl-p- nitrosoaniline has been investigated by a complete N.M.R. line-shape method. Activation parameters are reported for the nitrosoanilines in solution in acetone[D6], chloroform[D], and toluene[D8]. The effect of solvent has been found to be small.

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