Conformation around several equivalent bonds. Polymethoxy derivatives of benzene

1983 ◽  
Vol 48 (4) ◽  
pp. 1030-1041 ◽  
Author(s):  
Otto Exner ◽  
Václav Jehlička
Keyword(s):  
Dipole Moment ◽  
Crystalline Phase ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Graphical Comparison ◽  
Methoxy Groups ◽  
Derivatives Of

Dipole moments of benzene methoxy derivatives I-IX were measured in benzene solution and discussed in terms of the conformation around the Car-O bonds, exploiting the method of graphical comparison and systematic introduction of substituents. In the case of 1,2-dimethoxybenzene several explanations are in accord with the dipole moment data. However, considering all available evidence, most probable seems to be the presence of two conformers, one of which is non-planar with two non-equivalent methoxy groups (IC). The conformation of 1,2,3-trimethoxybenzene is similar to that found for many derivatives in the crystalline phase (VC), only the outer methoxy groups are probably slightly deviating from the coplanar position.

Dipole moment studies of some derivatives of 4-pyridone

1972 ◽  
Vol 25 (12) ◽  
pp. 2605 ◽  
Author(s):  
BD Batts ◽  
AJ Madeley
Keyword(s):  
Dipole Moment ◽  
Dipole Moments ◽  
Phenyl Group ◽  
A Value ◽  
Derivatives Of

The dipole moments of 13 derivatives of 4-pyridone were measured. Attempts to obtain a value for 4-pyridone were unsuccessful but a value of 6.O D is compatible with other evidence. Dipole moment and n.m.r, evidence indicated that for N-phenyl-4-pyridone the phenyl group is inductively electron-repelling (in contrast to that reported)1,2 for N-phenylpyrrole) and that the rings are probably collinear.

Hydrogen bonding, configuration and conformation of substituted α-oxo oximes and hydrazones

1979 ◽  
Vol 44 (8) ◽  
pp. 2494-2506 ◽  
Author(s):  
Otto Exner ◽  
Jorga Smolíková ◽  
Václav Jehlička ◽  
Ahmad S. Shawali
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Carbonyl Group ◽  
Intramolecular Hydrogen Bond ◽  
Benzene Solution ◽  
Dipole Moments ◽  
H Nmr ◽  
Intramolecular Hydrogen ◽  
Derivatives Of ◽  
Configuration And Conformation

Substituted 2-bromo-1-phenylglyoxal 2-phenylhydrazones IIIa-f exist in tetrachloromethane or benzene solutions prevailingly in E-configuration and in conformation A with an intramolecular hydrogen bond. The latter was evidenced by the N-H valence frequency at 3 290 cm-1 and by 1H NMR shifts with reference to derivatives without a carbonyl group - α-chlorobenzaldehyde phenylhydrazones V. From dipole moments of IIIa-d, measured in benzene solution, the contribution of the hydrogen bond (μH) was evaluated to 17 . 10-30 C m. This quantity is twice larger than in any other reported compound but the direction of the vector is as usual: approximately from H to N. In structurally similar derivatives of hydroxylamine, substituted 2-phenylglyoxylhydroximoyl chlorides IVa-d, no intramolecular hydrogen bond was detected; the dipole moments found were interpreted in terms of the Z-configuration and the prevailing conformation G.

A Study of d-Orbital Effects in Esters of Trifluorothiolacetic Acid. A Comparison of Evidence from Dipole Moment and Kinetic Data

1974 ◽  
Vol 52 (17) ◽  
pp. 3113-3118 ◽  
Author(s):  
E. Bock ◽  
A. Queen ◽  
S. Brownlee ◽  
T. A. Nour ◽  
M. N. Paddon-Row
Keyword(s):  
Dipole Moment ◽  
Trifluoroacetic Acid ◽  
Kinetic Data ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Aqueous Acetone ◽  
Electron Release ◽  
Hydrolysis Of ◽  
D Orbitals

The dipole moments of a series of esters of trifluoroacetic acid and trifluorothiolacetic acid have been determined in benzene solution at 25 °C. The results are consistent with conjugative and hyperconjugative electron release by the hydrocarbon groups to the d-orbitals of sulfur. This conclusion is supported by data for the hydrolysis of these compounds in water or aqueous acetone.

Dipole moments of some ethylene derivatives

1967 ◽  
Vol 45 (10) ◽  
pp. 1097-1100 ◽  
Author(s):  
E. Bock ◽  
E. F. Dojack
Keyword(s):  
Dipole Moment ◽  
Carbon Tetrachloride ◽  
Solvent Effect ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
Methyl Vinyl ◽  
Vinyl Bromide ◽  
Reported Data

The dipole moments of the ethylene derivatives acrylonitrile, chloroacrylonitrile, methyl vinyl ketone, vinyl bromide, 1,1-dichloroethylene, and tribromoethylene were determined in benzene solution at 20 °C. The measured dipole moments were corrected for the solvent effect by the method of Looyenga. In addition the applicability of the Looyenga equation for the solvent effect was tested on earlier reported data for 20 different molecules, whose dipole moments were derived from dilute benzene and carbon tetrachloride solutions, respectively. The corrected dipole moment values were compared with earlier corrected values calculated according to the method of Le Fevre and Le Fevre and with reported gas values. It was found that for most compounds both methods of correction yielded dipole moment values which differed by 0–10% from the gas values.

Dipole moments and conformation of some aromatic benzamidoximes

1986 ◽  
Vol 51 (7) ◽  
pp. 1444-1449 ◽  
Author(s):  
Otto Exner ◽  
Nedelko Motekov
Keyword(s):  
Aromatic Ring ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Mutual Position ◽  
Methoxy Groups

Dipole moments of aromatic benzamidoximes I - VI were measured in benzene solution. Assuming the Z configuration as established previously on another set of similar derivatives, some details of conformation could be determined, e.g. the position of an unsymmetrically substituted aromatic ring or mutual position of several methoxy groups.

The conformation of aryl carbonates. A dipole moment study

1981 ◽  
Vol 46 (4) ◽  
pp. 856-860 ◽  
Author(s):  
Otto Exner ◽  
Václav Jehlička
Keyword(s):  
Dipole Moment ◽  
Benzene Solution ◽  
Dipole Moments

The dipole moments of diaryl carbonates I-V in benzene solution are consistent with the Z,Z-conformation (A) in which the conformation of simple esters is repeated in the two moieties. The E,Z-form (B) was not detected; it may be either present as a quite small fraction or only with specific, overcrowded structures.

Determination of dipole moment values of anisotropic molecules using Brot's formalism

1990 ◽  
Vol 68 (9) ◽  
pp. 1523-1526
Author(s):  
P. Brito ◽  
M. Mechetti
Keyword(s):  
Molecular Structure ◽  
Dipole Moment ◽  
Dipole Moments ◽  
Dilute Solutions ◽  
Molecular Anisotropy ◽  
Derivatives Of ◽  
Best Parameters

A method for the determination of dipole moment values based on Brot's theory is proposed. It takes into account the influence of the molecular anisotropies of shape and polarizability on the permittivity of a mixture. Starting from measurements performed on dilute solutions and from the knowledge of the molecular structure of some chlorinated derivatives of α-cyanostilbene and 1,3 derivatives of benzene, the best parameters of an ellipsoid used for the representation of a polar anisotropic molecule are determined. The dipole moments obtained, using benzene and tetrachloromethane as solvents, are finally compared to values from the literature. Keywords: dipole moment, Brot's formalism, molecular anisotropy.

A physical Study on the Aromaticity of 4H-Pyran-4-one, 9H-Xanthen-9-one, and related sulphur Compounds

1986 ◽  
Vol 41 (10) ◽  
pp. 1250-1257 ◽  
Author(s):  
Henri Lumbroso ◽  
Jacqueline Curé ◽  
Michel Evers
Keyword(s):  
Dipole Moment ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Moment Analysis ◽  
Sulphur Compounds ◽  
Physical Study

Dipole moment analysis of 4H-pyran-4-one and 9H-xanthen-9-one, and their sulphur analogues, and of 9H-selenoxanthen-9-one, enables a discussion on their aromaticities. In the present work, the dipole moments of tetrahydro-4H-pyran-4-one, tetrahydrothio-4H-pyran-4-one, tetrahydroseleno- 4H-pyran-4-one, 9(10H)-anthracen-9-one, 9H-xanthen-9-one, 9H-thioxanthen-9-one and 9H-selenoxanthen-9-one were measured in benzene solution at 30.0 °C.

scholarly journals The Solution-State Conformations of 2,4,6-Tri-t-butyl-benzaldehyde and -thiobenzaldehyde

1985 ◽  
Vol 40 (11) ◽  
pp. 1157-1161
Author(s):  
Henri Lumbroso ◽  
Jacqueline Curé ◽  
Renzo Okazaki ◽  
Akihiko Ishii ◽  
Naoki Inamoto
Keyword(s):  
Dipole Moment ◽  
Chemical Shift ◽  
Electric Dipole ◽  
Crystalline Phase ◽  
Electron Distribution ◽  
Inductive Effect ◽  
Benzene Solution ◽  
Formyl Group ◽  
Rotational Angle ◽  
X Ray

Formyl-ring conjugation has been examined in benzaldehyde, 2,4,6-trimethyl- and 2,4,6-tri t- butyl-benzaldehyde, and the ab initio STO-3G π-electron distribution in benzaldehyde has been analysed in terms of the mesomeric and π-inductive effect of the formyl group. The electric dipole moment determined in benzene solution at 30.0 °C, and formyl-carbon n.m.r. chemical shift, recorded in deuterochloroform, of 2,4,6-tri-t-butylbenzaldehyde indicate a nonplanar conformation with a formyl-group rotational angle (ϕ) of about 65°. The dipole moment of 2,4,6-tri- t-butylthiobenzaldehyde, also in benzene solution at 30.0 °C, is consistent with a nearly orthogonal model [ϕ ~ 90°), in agreement with the X-ray structure in the crystalline phase giving ϕ = 89.1 ° .

Dipole moments and conformation of peroxy esters

1981 ◽  
Vol 46 (2) ◽  
pp. 490-497 ◽  
Author(s):  
Božo Plesničar ◽  
Otto Exner
Keyword(s):  
Dipole Moment ◽  
Dihedral Angle ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Ester Group ◽  
Model Compounds ◽  
Tert Butyl ◽  
Butyl Esters

Dipole moments of sixteen substituted peroxybenzoic esters III, IV were measured in benzene solution and interpreted in terms of the conformation around the O-O bond. The dipole moment of the CO3R group is different for R = methyl and R = tert-butyl, viz. 9.0 and 10.4 . 10-30 C m, respectively. Its solution into components was carried out making reference to the dipole moments of substituted benzoic esters as model compounds. As a result the dihedral angle τ = C-O-O-C was estimated to 160-180° in the case of tert-butyl peroxy esters IV and to 110-150° in the case of methyl peroxy esters III. The mesomeric dipole moment expressing the conjugation within the ester group was estimated to 0.8 or 1.5 . 10-30 C m for methyl or tert-butyl esters, respectively.

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