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.

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.

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.

The Barrier to Rotation About the N—N Bond in N-Nitrosamines as Determined by Nuclear Magnetic Resonance Total Line Shape Analysis

1974 ◽  
Vol 52 (17) ◽  
pp. 3028-3036 ◽  
Author(s):  
J. D. Cooney ◽  
S. K. Brownstein ◽  
J. W. ApSimon
Keyword(s):  
Shape Analysis ◽  
Line Shape ◽  
Energy Barrier ◽  
Activation Parameters ◽  
Substantial Contribution ◽  
Resonance Structure ◽  
Bond Rotation ◽  
Line Shape Analysis ◽  
Bond Character ◽  
Nitrogen Bond

The energy barrier to internal N—N bond rotation in five cyclic and two bicyclic N-nitrosamines [Formula: see text]has been determined using high temperature 100 MHz n.m.r. spectroscopy. A substantial contribution from the ionic resonance structure of [Formula: see text] produces considerable double bond character in the nitrogen–nitrogen bond and a concomitant increase in the rotational barrier about the N—N bond. The molecules were examined in the[Formula: see text]liquid state and had ring sizes varying from five to nine atoms. The Arrhenius and Eyring activation parameters for the energy barrier were determined using total line shape analysis and the intensity ratio approximation method. The energy barrier to N—N bond rotation was found to range from 23–29 kcal/mol depending on the molecular structure and the solvent.

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.

Solvent Dependence of Cycloaddition Rates of Phenyldiazomethane and Activation Parameters

Heterocycles ◽  
1978 ◽  
Vol 11 (1) ◽  
pp. 109 ◽  
Author(s):  
Rolf Huisgen ◽  
Jochen Geittner ◽  
Hans-Ulrich Reissig
Keyword(s):  
Activation Parameters ◽  
Solvent Dependence
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