Dipole moment aliphatic compounds

The use of dipole moments p [296, 316] in QSAR studies was proposed by Lien [316 — 318] group dipole moments of 311 aromatic [317] and 214 aliphatic substituents [318] are tabulated in literature. A certain problem of the use of dipole moments is their directionality. Vector addition has to be used to estimate the dipole moment of compounds having more than one site of substitution. 

Sulfonates, aliphatic la 388, 389 Sulfones lb 321,360 Sulfonic acids la 91 Sulfonylurea derivatives lb 204 Sulfoxides lb 321,358,360,372,373,374 Sulfur compounds lb 338 Sulfur-containing compounds lb 301,339 Sulfur dioxide vapor la 86 -, dipole moment la 97 Sulfur, divalent lb 302 Sulfuric acid la 87,195,333,411,426 Sulfur ions lb 302 Sulfutyl chloride vapor la 86 Sulpyrid lb 268 Sunflower seed oil lb 286 Surfactant-TLC plates la 89 Sweeteners la 44, 388-390 Swep la 108... 

Compounds with high dielectric constants such as water, ethanol and acetonitrile, tend to heat readily. Less polar substances like aromatic and aliphatic hydrocarbons or compounds with no net dipole moment (e. g. carbon dioxide, dioxane, and carbon tetrachloride) and highly ordered crystalline materials, are poorly absorbing. 

In compounds like soap, the aliphatic portion is soluble in oil. while the end group (sulphonic acid etc.) called a polar group (because its unsym-metrical grouping contributes a dipole moment to the compound) is soluble in water. The soap molecules get concentrated at the interface between water and oil in such a way that their polar end (-COONa) and hydrocarbon chain (R-) dip in water and oil, respectively as shown in figure 11. This allows the two liquids to come in close contact with each other. 

The dipole moment of the nitro group alone, present in an aliphatic nitro compound is ... 

With the only exception of thiourea, all aliphatic compounds are characterized by positive dl/dE values.54 Within the limits in which we can exclude an appreciable reorientation of the aliphatic molecules with a change in the applied potential E, the increase of l with an increase in E is to be ascribed to a gradual reorientation of the adsorbed water molecules. Water molecules have a particularly high dipole moment per unit volume, and are known to be readily orientable under the influence of an electric field. A progressive shift of E towards more positive values causes to pass gradually from negative to positive values. Consequently, the contribution to aM required to keep E constant upon removing v adsorbed water molecules by one... 

Some relationships between the dipole moment and molecular structure have also been found in the case of aliphatic compounds. In the first instance we may mention the two methyl esters of a- and 8-aminovaleric acid. We should expect from the results for the aminobenzoic acids that in an open chain the moment of the 8-ester would be greater than that of the a-ester, while in a chain joined into a ring the moments should be about the same. The values obtained... 

The dipole moments of various aliphatic compounds containing one or more polar groups have been determined, but it seemed advisable to study the effect on the moment of the position of the polar group in an aliphatic compound. 

In the chlorides and bromides it is seen that in the 2-, 3-, 4-positions the dipole moment is practically independent of the position in the chain. In i-bromo-heptane the dipole moment is slightly smaller than for the other bromides. The i-chloro-heptane will be investigated for comparison. The dipole moment is the same for the chloro- and bromo-derivatives of the aliphatic compounds, as... 

For disubstituted chlorides and bromides of benzene and of ethylene, one of us f has found that the moment of the chloro-derivatives is larger than that of the bromo-derivatives. In these aliphatic compounds the dipole moment of the chloro- and bromo-derivatives is greater than for the hydroxyl-derivative, in contradistinction to the aromatic compounds, where the dipole moment of the hydroxyl derivative is greater than that of the chloro- and bromo-derivatives. 

The Dipole Moment and Intramolecular Motions in large Molecules, especially in those of Aliphatic Compounds. ... 

Table XCVI. Dipole Moments of Aliphatic and Aromatic Compounds...

The experimental data on the dipole moments of aliphatic and aromatic compounds clearly indicate the existence of molecular resonance in the latter. The resonance, which produces either positive or negative charges on the carbon atoms in the ortho and para positions, determines the specificity, which has been observed in the substitution of the benzene nucleus. The substituent groups may be divided into two classes depending... 

Derivatives of durene and mesitylene— In Chapter 9 it was pointed out that in derivatives of durene and mesitylene stcric factors due to the methyl groups may hinder the resonance of the substituent group with the ring system. In Tables Cl and C//the dipole moments of these compounds are compared with the corresponding aromatic and aliphatic derivatives. The dipole moments of the acetyl derivatives of durene and mesitylene are very similar to the value for acetone but lower than that for acetophenone, where resonance with the ring occurs. In aldehydes, on the other hand, where apparently there is no steric hindrance, the moment is almost identical with that of benzaldehyde. 

Dipole Moments of Durene and Mesitylene Compounds with Corresponding Aliphatic and Aromatic Derivatives... 

Aliphatic compounds are oriented with the hydrocarbon end with negligible dipole moment towards the electrode, whereas the hydrophilic dipolar group, e.g., OH, CHO COOH, protrudes outside of the field. 

---