Calculation of Boiling Points of Aliphatic Hydrocarbons

Abstract

The boiling points of the aliphatic hydrocarbons of any known type may be calculated readily from their molecular boiling point numbers by means of the boiling point equation. The molecular boiling point number of the molecule is obtained by summing up the boiling point numbers representing the various atoms and structural groupings in the molecule. THE calculation of the boiling points of the aliphatic hydrocarbons may be accomplished by the use of the boiling point equation developed previously (1). The method is empirical and depends upon obtaining sufficient accurate boiling point data so that the boiling point number (b. p. n.) may be obtained for the various structural groupings. From the existing data for the aliphatic hydrocarbons it is possible to obtain the necessary boiling point numbers and to calculate the boiling points of these hydrocarbons, including the naphthenes, from their structures with an accuracy of better than 5 per cent in most cases. The structure of a hydrocarbon may also be calculated from its boiling point and molecular formula, but for the higher hydrocarbons which have large numbers of isomers, several structures have the same molecular boiling point number (B. P. N.) and it is impossible to make a further limitation. In spite of this difficulty, the use of boiling point data limits definitely the possible structures which a hydrocarbon boiling at a particular temperature may have and should, therefore, be a valuable tool for the petroleum chemist.The calculation of the boiling points of the aliphatic hydrocarbons depends upon the following equation:

Detailed Chemical Composition of Straight-Run Vacuum Gas Oil and Its Distillates as a Function of the Atmospheric Equivalent Boiling Point

“…The value of the boiling point number is determined by the aromatic ring structures and side chains of the molecules. For the compounds containing a monoaromatic structure and n -alkyl side chain, there exists a relationship described in empirical formula where N b,n is the boiling point number of the molecule with a n -alkyl side chain, N b,0 is the boiling point number of the monoaromatic ring without any side chains, and n is the carbon number of the side chain.…”

Relationships between Analgous Organic Compounds of Silicon and Carbon.

“…It is seen that there is a reasonably good linear relationship represented by the equation S = 0.118 + 0.878C, where S is the density of a silicon compound and C is that of its carbon analog. Lewis and Newkirk (123) have shown that an additive system of atomic and group boiling-point numbers developed by Kinney (101)(102)(103)(104)(105) for carbon compounds can be extended to organosilicon compounds. This suggests that a linear relationship like that for densities should apply to the boiling points of silicon and carbon analogs, and such is found to be the case.…”

A simple method to evaluate, correlate and predict boiling and flash points of alkynes

“…Our initial investigation of the relationship between Y BP values and molecular structure was carried out with acyclic alkanes (this work was based on an early report by Kinney,4 who introduced the concept of a boiling point number, Y, as a measure of T B values). Their Y BP values could be predicted quite accurately from molecular structure, as is shown in equation 2.…”