Dipole moments of substituted chloroformates in dilute benzene solutions

1967 ◽  
Vol 45 (24) ◽  
pp. 3177-3179 ◽  
Author(s):  
E. Bock ◽  
D. Iwacha
Keyword(s):  
Chlorine Atom ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Experimental Results ◽  
Methyl Ethyl ◽  
Hydrocarbon Group

The dipole moments of methyl, ethyl, n-propyl, n-butyl, amyl, and phenyl chloroformate as well as n-butyl formate in dilute benzene solution at 25 °C were determined. The experimental results suggest that the configuration of the chloro-esters differs from the configuration of the unchloroinated esters, viz. the ester hydrocarbon group and the chlorine atom are cis to each other.

Electric moments and conformation of substituted fluoroformates in benzene solutions

1968 ◽  
Vol 46 (10) ◽  
pp. 1645-1648 ◽  
Author(s):  
E. Bock ◽  
D. Iwacha ◽  
H. Hutton ◽  
A. Queen
Keyword(s):  
Dipole Moment ◽  
Long Range ◽  
Fluorine Atom ◽  
Dipole Moments ◽  
Experimental Results ◽  
Spin Coupling ◽  
Coupling Mechanism ◽  
Methyl Ethyl ◽  
Hydrocarbon Group ◽  
Spin Spin Coupling

The dipole moments of methyl-, ethyl-, n-propyl-, n-butyl-, n-amyl-, and phenyl-fluoroformate were determined in dilute benzene solutions at 25 °C. The experimental results suggest that the conformation of the fiuoro-esters is similar to the conformation of the chloro-esters and differs from the conformation of the normal esters; viz. the ester hydrocarbon group and the fluorine atom are cis to each other. Results of fluorine and proton n.m.r. measurements on these molecules support the conclusions based on the dipole moment data if a "through-space" coupling mechanism is assumed for the long range spin–spin coupling JH–F1−5.

Electric moments, sulfur bonding, and conformations of substituted thiochloroformate esters in benzene solutions

1969 ◽  
Vol 47 (2) ◽  
pp. 343-348 ◽  
Author(s):  
A. Queen ◽  
T. A. Nour ◽  
E. Bock
Keyword(s):  
Sulfur Atom ◽  
Halogen Atom ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Vector Model ◽  
Hydrocarbon Group ◽  
Electron Release ◽  
D Orbitals

The dipole moments of a series of aryl and alkyl thiochloroformate esters have been determined in benzene solution at 25 °C and compared with the corresponding values for chloroformate and fluoroformate esters. The results have been interpreted in terms of conjugative and hyperconjugative electron release by the hydrocarbon group to the d-orbitals of the sulfur atom in the thio compounds. Vector model, bond moment calculations indicate that, as in the cases of the chloroformate and fluoroformate esters, the preferred conformations of the thiochloroformates are those in which the hydrocarbon group and the halogen atom are cis to each other.

Dipole moments induced in larger molecule. Long-chain aliphatic esters

1982 ◽  
Vol 47 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Otto Exner ◽  
Ayfer Bapçum
Keyword(s):  
Benzene Solution ◽  
Dipole Moments ◽  
Straight Chain ◽  
Basic Assumptions ◽  
Donor Acceptor ◽  
Eyring Theory ◽  
Aliphatic Esters ◽  
Long Chain

Dipole moments of straight-chain aliphatic esters Ia-Ic and IIa-IIf were measured in benzene solution. The observed trends are poorly reproduced by the classical Smith-Eyring theory; the reason may be partly the unknown conformation, partly even donor-acceptor complexes with the solvent. No deviations were observed with the highest members of the series, attributable to violation of some basic assumptions of the theory of dielectrics.

A Novel SN1 Displacement: The Reaction of Tertiary Amines with Acetic Anhydride

1971 ◽  
Vol 49 (20) ◽  
pp. 3348-3351 ◽  
Author(s):  
R. P. Mariella ◽  
K. H. Brown
Keyword(s):  
Acetic Anhydride ◽  
Experimental Results ◽  
Methyl Ethyl ◽  
Tertiary Amines

The action of actic anhydride on tertiary amines at reflux may cause the displacement of one of the R groups from the amine. The groups which are displaced are benzyl, t-butyl, benzhydryl, trityl, and cinnamyl; the groups which are not displaced are methyl, ethyl, n-butyl, phenyl, α-naphthyl, iso-propyl, allyl, and propargyl. An SN1 mechanism with special steric requirements is consistent with the experimental results.

Dipole moments and conformation of α-disulphones. The gauche effect

1985 ◽  
Vol 50 (10) ◽  
pp. 2245-2251 ◽  
Author(s):  
Otto Exner ◽  
Václav Jehlička
Keyword(s):  
Dihedral Angle ◽  
Graphical Method ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Statistical Treatment ◽  
X Ray ◽  
Gauche Effect

The dipole moments of substituted diphenyl disulphones I-III were measured in benzene solution and interpreted by the previously described graphical method. The results suggest an equilibrium of the ap and sc conformations in the ratio 3 : 1, at variance with various empirical rules and theories of the so-called gauche effect. A statistical treatment of X-ray data of various sulphonyl derivatives revealed essentially two preferred conformations: the more stable sc, with a broadened dihedral angle, and the less stable ap.

PHOSPHONITRILIC COMPOUNDS: PART I. THE MECHANISM OF PHOSPHONITRILIC CHLORIDE POLYMERIZATION CAPACITANCE, CONDUCTANCE, AND ELECTRON-SPIN RESONANCE STUDIES

1964 ◽  
Vol 42 (2) ◽  
pp. 447-455 ◽  
Author(s):  
H. R. Allcock ◽  
R. J. Best
Keyword(s):  
Free Radicals ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Ring Cleavage ◽  
Preliminary Step ◽  
Polymerization Mechanism ◽  
Spin Resonance ◽  
Nitrogen Ring

Capacitance and conductance measurements were carried out with molten (NPCl2)3 and [NP(OC6H5)2]3 and dipole moments were determined in benzene solution. Attempts to detect free radicals in molten samples of the same compounds were unsuccessful. Evidence was obtained that homolytic or heterolytic phosphorus–nitrogen ring cleavage is not involved in the primary initiation process. The results favor, instead, a polymerization mechanism for (NPCl2)3 in which phosphorus–chlorine ionization is a preliminary step.

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 dipole moments of substituted isothiocyanates of 1,3-diphenyl-2-propen-1-one

1984 ◽  
Vol 49 (10) ◽  
pp. 2382-2386 ◽  
Author(s):  
Gejza Suchár ◽  
Milan Dzurilla ◽  
Pavol Kristian
Keyword(s):  
Electronic Structure ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Vector Addition

The dipole moments have been measured of various substituted isothiocyanates of 1,3-diphenyl-2-propen-1-one in benzene solution. The measured values have been compared with the dipole moments obtained by the vector addition of the bond dipole moments, and the comparison has been used for a discussion of their electronic structure and interactions of the NCS group.

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