The Dielectric Properties of Binary Systems of Ketones and Hydrocarbons

1949 ◽  
Vol 2 (3) ◽  
pp. 405
Author(s):  
RL Meakins
Keyword(s):  
Relaxation Time ◽  
Dielectric Properties ◽  
Chain Length ◽  
Binary Systems ◽  
Dipole Interaction ◽  
Polar Compounds ◽  
Electrical Measurements ◽  
Cooperative Effects ◽  
Dielectric Absorption ◽  
Long Chain

Experimental work on the dielectric properties of solid systems of long-chain polar and non-polar compounds has been performed by Jackson(l), Sillars(2), and Pelmore(3) with dilute solutions of esters in paraffin wax. In subsequent theoretical studies in this field Fr�hlich(4) adopted, as a model, a crystalline long-chain paraffin in which a small proportion of the molecules were assumed to be replaced by long-chain polar molecules. Taking Debye's theory of dielectric absorption in polar solids as a basis, this led to the derivation of a relationship between the relaxation time and the number of links in the polar molecule. In order to obtain experimental results more closely related to the theory, electrical measurements have now been made with symmetrical long-chain ketones in pure crystalline hydrocarbon solvents. The variation of dielectric constant and loss angle with frequency for these systems is found to be approximately in agreement with the Debye theory of dielectric absorption. For ketones of chain-length shorter than that of the hydrocarbon solvent the relationship between relaxation time and chain-length is of the type expected from Fr�hlich's theory, but displaced towards lower frequencies. The results show that, in applying the theoretical relationship to systems of long-chain polar and non-polar compounds, it would be necessary to determine new constants for each different type of polar compound and for each different solvent. The results of electrical measurements of ketone-hydrocarbon systems with ketones of varying chain-length (both less and greater than that of the solvent) are in accordance with conclusions from previous X-ray studies of long-chain hydrocarbons. The effects of dipole interaction on the dielectric absorption of systems of laurone and n-hexacosane, are discussed in relation to the solid-liquid phase diagram. The results of dielectric measurements with pure crystalline compounds suggest that dipole interaction and electrical cooperative effects are larger in ketones than in esters of similar chain-length.

The Dielectric Properties of a Series of dl-n-Eicosanols

1951 ◽  
Vol 4 (3) ◽  
pp. 359
Author(s):  
RJ Meakins ◽  
HK Welsh
Keyword(s):  
Dielectric Properties ◽  
Low Frequency ◽  
Polar Compounds ◽  
Carbon Chain ◽  
Hydroxyl Groups ◽  
Secondary Alcohols ◽  
Polar Group ◽  
Dielectric Absorption ◽  
Ready Availability ◽  
Long Chain

Initial investigations of the dielectric properties of normal long-chain secondary alcohols were made with the symmetrical compounds because of their ready availability. The properties of long-chain polar compounds are known to vary considerably, however, with the position of the polar group in the carbon chain and it therefore seemed desirable to make dielectric measurements with some unsymmetrical alcohols. The present paper describes such an investigation of a series of dl-n-eicosanols having the hydroxyl groups in the 2-, 4-, 6-, 8-, and 10-positions, respectively. The results for the melted forms show that slight asymmetry, as in the 10-compound, has little effect on the dielectric properties, but with the more unsymmetrical 4-, 6-, and 8-compounds a considerable enhancement of the dielectric absorption is observed. This is accompanied by increased dispersion of the dielectric constant which, for the 8-compound, reaches a low frequency value of 15. Both ε" and ε' decrease during storage at room temperature. Anomalous results are obtained with dl-n-eicosan-2-ol, probably due to the molecules in the crystal lattice being alternately reversed, end-to-end. As with the symmetrical secondary alcohols, the recrystallized forms give comparatively little dielectric absorption.

Temperature Dependence of the Dielectric Properties of Long-Chain Aliphatic Alcohols in the Solid State

1952 ◽  
Vol 5 (4) ◽  
pp. 661 ◽  
Author(s):  
JS Dryden
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Temperature Dependence ◽  
Aliphatic Alcohols ◽  
Experimental Results ◽  
Secondary Alcohols ◽  
Primary Alcohols ◽  
Dielectric Absorption ◽  
Apparent Activation Energies ◽  
Long Chain

The dielectric properties of three primary and three secondary long-chain aliphatic alcohols have been investigated within the temperature range of -20 to 70 �C. The experimental results are discussed in relation to the theory of Sack on dielectric absorption in linear polar chains and to the conclusions reached in earlier papers on the dielectric properties of these compounds. The apparent activation energies in the primary alcohols are approximately three times those in the secondary alcohols. This indicates either different mechanisms of absorption in the two types of alcohols or, if the mechanisms are the same, significant differences in the energy barriers involved.

Dielectric Behaviour in the MHz range of cis-bis (glycynato)Cu(II) monohydrate and (glycylglycinato)Cu(II) trihydrate in Water

1976 ◽  
Vol 31 (9) ◽  
pp. 1085-1088 ◽  
Author(s):  
P. U. Sakellaridis ◽  
E. K. Karageorgopoulos
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Dipole Moment ◽  
Relaxation Time ◽  
Dielectric Properties ◽  
Charge Separation ◽  
Rotational Relaxation ◽  
Kcal Mole ◽  
Dielectric Absorption ◽  
Molecular Radius

Abstract The dielectric properties of Cu(gly)2 and Cu(glygly) in diluted aqueous solution were examined in the MHz range at 273 to 313 K. The complexes exhibit dielectric absorption in the ranges 5.09X107 to 9.34X107 Hz and 4.63X107 to 8.01X107 Hz, respectively, depending on concentration and temperature. This absorption was attributed to rotational relaxation of the unhydrated and monohydrated complexes. The following data for the two complexes in solution at 293 K have been obtained, respectively: dipole moment 19.3 D and 34.0 D, charge separation 2.01 A and 3.54 Å, relaxation time 2.3X10-9 sec and 2.6X10-9 sec, molecular radius 6.36 Å and 6.47 Å, activation energy for the relaxation process 5.6 kcal mole-1 for both complexes.

The Dielectric Properties of Crystalline Long-Chain n-Primary Alcohols at Low Frequencies

1951 ◽  
Vol 4 (3) ◽  
pp. 365
Author(s):  
RJ Meakins ◽  
JW Mulley
Keyword(s):  
Dielectric Properties ◽  
Primary Alcohol ◽  
Dielectric Constants ◽  
Double Layers ◽  
Significant Feature ◽  
Hydroxyl Groups ◽  
Secondary Alcohols ◽  
Primary Alcohols ◽  
Dielectric Absorption ◽  
Long Chain

In a previous paper it was reported that certain crystalline forms of long-chain secondary alcohols show abnormally large dielectric absorption and dispersion of the dielectric constant at audio and radio frequencies. The present paper describes an extension of the investigation to n-primary alcohols and discusses the results in terms of the previously suggested theory of dielectric absorption due to the presence of hydrogen-bonded chains of hydroxyl groups. The most significant feature of the results is that the absorption is larger and occurs at much lower frequencies than for the secondary alcohols. This is considered to be due to the end-to-end arrangement of the molecules in n-primary alcohol crystals, which gives double layers of hydroxyl groups and enables the formation of more extensive hydrogen-bond chains. The dielectric constants at the lowest frequencies are almost as large as those previously reported by Hoffmann and Smyth (1949) for the " waxy " forms of n-primary alcohols. Further aspects described are the changes in dielectric properties during storage, the differences between the melted and recrystallized forms, and the effect of dispersing the molecules in an inert solid solvent. In each of these aspects the observed behaviour is similar to that previously reported for the secondary alcohols.

scholarly journals The behaviour of polar molecules in solid paraffin wax

1940 ◽  
Vol 175 (961) ◽  
pp. 253-254
Keyword(s):  
Relaxation Time ◽  
Chain Length ◽  
National Physical Laboratory ◽  
Paraffin Wax ◽  
Polar Molecules ◽  
Solid Paraffin ◽  
Physical Laboratory ◽  
Chain Compounds ◽  
Long Chain

A paper by R. W. Sillars of the National Physical Laboratory was published under the above title in 1938. Sillars showed how the relaxation time of long-chain esters embedded in a paraffin wax medium depended upon the chain length of the ester. It is well known that many properties of long-chain compounds alternate according as the number of carbon atoms is odd or even. Accordingly, Sillars was careful to use only esters with an even number of carbon atoms in order to reduce the number of possible variables affecting his investigations. He hoped the esters with an odd number would be examined later, and accordingly the work described in this paper was undertaken for the purpose of filling in an obvious gap in Sillars’s experiments and to be complementary to them.

scholarly journals On the mechanism of boundary lubrication. II. Wear prevention by addition agents

1940 ◽  
Vol 177 (968) ◽  
pp. 103-118 ◽  
Keyword(s):  
High Pressures ◽  
Preceding Paper ◽  
Accurate Method ◽  
Polar Compounds ◽  
Experimental Conditions ◽  
Group V ◽  
Highly Sensitive ◽  
Local Pressures ◽  
Steel Balls ◽  
Long Chain

If two metal surfaces slide over each other in the presence of a lubricant and under high load, high pressures and temperatures prevail a t those isolated spots which actually carry the load, leading to wear and possibly to breakdown. The action of wear preventing agents under these conditions has been studied in detail and it has been found that such agents are effective through their chemical polishing action, by which the load becomes distributed over a larger surface and local pressures and temperatures are decreased. Especially effective are compounds containing phosphorus or other elements of group V of the periodic system. These have been found to form a metal phosphide or homolog on the surface which is able to alloy with the metal surface, lowering its melting point markedly, and by this action aiding greatly in maintaining a polish. The wear experiments were carried out with a highly sensitive and accurate method which uses metal-plated steel balls as its sliding elements. Under the experimental conditions additions of 1.5% triphenyl phosphine or triphenyl arsine in white oil gave wear prevention factors of 7.2 and 12.2 respectively (relative to pure white oil). A further addition of 1% of a long chain polar compound is able to double the wear prevention factor obtained with the polishing agents and wear prevention factors as high as 17.6 have been observed. The specifically physical action of the long-chain polar compounds is discussed in the preceding paper.

The Use of N-alkanes for Estimating Intake and Passage Rate in Horses

1996 ◽  
Vol 1996 ◽  
pp. 98-98
Author(s):  
B M L McLean ◽  
R W Mayes ◽  
F D DeB Hovell
Keyword(s):  
Recent Work ◽  
Chain Length ◽  
Carbon Chain ◽  
Carbon Chain Length ◽  
Passage Rate ◽  
Forage Crops ◽  
Carbon Chains ◽  
Naturally Occurring ◽  
Chain Lengths ◽  
Long Chain

Alkanes occur naturally in all plants, although forage crops tend to have higher alkane contents than cereals. N-alkanes have odd-numbered carbon chains. They are ideal for use as markers in feed trials, because, they are inert, indigestible and naturally occurring, and can be recovered in animal faeces. Synthetic alkanes (even-numbered carbon chains) are available commercially and can also used as external markers. Dove and Mayes (1991) cite evidence indicating that faecal recovery of alkanes in ruminants increases with increasing carbon-chain length. Thus the alkane “pairs” (e.g. C35 & C36, and C32 & C33) are used in calculating intake and digestibility because they are long chain and adjacent to each other. However, recent work by Cuddeford and Mayes (unpublished) has found that in horses the faecal recovery rates are similar regardless of chain lengths.

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