Specific Dispersion of Pure Hydrocarbons

Thorpe, Ryan; Larsen, R. G.

doi:10.1021/ie50391a019

Cited by 10 publications

(8 citation statements)

References 6 publications

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“…In none of the references consulted was an explanation of the high dispersion of tung oil suggested. During the last 10 years much work has been done on the specific dispersion of hydrocarbons (2,6,8,9,13,17,18,20), and this work has brought out very clearly that the value of the specific dispersion of hydrocarbons depends largely on their structure. The value for a saturated hydrocarbon is very nearly constant regardless of its molecular weight.…”

Section: Refractive Indices and Dispersions Of Tung Oil And Related Smentioning

confidence: 99%

Studies on the refractive index and dispersion of American tung oil

Holmes¹,

Pack²

1948

J Americ Oil Chem Soc

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Conclusions Tung oil has a refractive index and a dispersion so far above those of any other common oil that both are valuable criteria for identification purposes. With proper equipment the dispersion, in addition to the refractive index, can be determined with little extra effort and would confirm the conclusions drawn from the refractive index. Mixtures of tung oil with another vegetable oil (except oiticica and other rare conjugated oils) can be analyzed to within 0.5% from the refractive index for either the sodium or the mercury line if the refractive indices of the separate oils are known. The mixtures can be analyzed from the dispersion to within about 1% of the correct composition if the dispersions of the separate oils are known. If the adulterating oil is not known the adulteration can be more closely estimated from the depression of the dispersion than from the depression of the refractive index. When tung oil is bodied by heat the refractive indices for the sodium and mercury lines and the dispersion fall rapidly and continuously to the point of gelation, but the changes are so similar that no worth‐while additional information is obtained by determining more than one refractive index. The fact that refractive index decreases as viscosity increases suggests the use of the refractive index in controlling the bodying of tung oil. Other things being equal, the refractive index for the mercury line should give more accurate information on tung oil than that for the sodium line because of the greater changes in the refractive index for the mercury line upon adulteration or heating. A correlation coefficient of 0.83 was found for refractive index with the diene number of tung oil. A lower correlation coefficient was found for refractive index with the iodine number, but the latter would probably be higher if a more accurate method for the determination of the iodine number of tung oil were available.

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Section: Refractive Indices and Dispersions Of Tung Oil And Related Smentioning

confidence: 99%

Studies on the refractive index and dispersion of American tung oil

Holmes¹,

Pack²

1948

J Americ Oil Chem Soc

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“…RECENT research in hydrocarbon analysis has been directed toward the determination of quantity (8,8,9,15,16,26) and type (6,14,18,27,81, 82) of olefins and aromatics in petroleum. For this purpose specific dispersion has been a most useful property because it is nearly constant for paraffins and naphthenes, increases with increasing unsaturation, and varies considerably depending on the position of the double bonds relative to each other.…”

mentioning

confidence: 99%

“…These methods are limited to gasolines of low end point which contain no dicyclic aromatics. Many investigators (6,14,27,81,82) have recommended the use of specific dispersion for the identification of type of hydrocarbon because of its dependence on the number of double bonds and the configuration of the molecule, Thorpe and Larsen (27) have developed a simple system for the calculation of specific dispersion from a knowledge of structure, which enables one to calculate accurate specific dispersions for most olefins and aromatics and to explain the wide differences in specific dispersion between types such as anthracenes and phenanthrenes, which are both condensed tricyclic aromatics. Specific dispersion itself and the constants developed by Thorpe and Larsen are both particularly useful for identification of pure compounds but of limited value for mixtures such as petroleum fractions.…”

mentioning

confidence: 99%

Double Bond Index

Lipkin¹,

Martin²

1948

Anal. Chem.

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“…d = density at 20°C. For hydrocarbons specific dispersion is a unique physical property because it is nearly constant for paraffins and naphthenes and is variable with the number of double bonds and their position in an unsaturated hydrocarbon molecule (2,8,17). Accurate determination of specific dispersion requires considerable skill and precision apparatus.…”

mentioning

confidence: 99%

“…It is emphasized that the correction term is only approximate and intended for the types of hydrocarbon fractions normally Table III. Agreement of Aromatic Extracts, Pulfrich Refractometer Data sidered to be the average specific dispersion of paraffin and naphthene hydrocarbons (2,17).…”

mentioning

confidence: 99%