Group Contribution Method To Predict Boiling Points and Flash Points of Alkylbenzenes

Abstract

Boiling point numbers (<i>Y</i>_BP) of alkylbenzenes are predicted directly from the molecular structure with the relationship <i>Y</i>_BP = <i>Ar</i>_<i>i</i> + 1.726 + 2.779<i>C</i> + 1.716<i>M</i>₃ + 1.564<i>M</i> + 4.204<i>E</i>₃ + 3.905<i>E</i> – 0.329<i>D</i> + 0.241<i>G</i> + 0.479<i>V</i> + 0.967<i>T</i> + 0.574<i>S</i>. Here, <i>Ar</i>_<i>i</i> is a parameter that depends upon the substitution pattern of the aromatic ring, while the remainder of the equation is the same as that reported earlier for calculating the <i>Y</i>_BP values of alkanes. The boiling points (<i>T</i>_B) of the alkylbenzenes are then calculated from the relationship <i>T</i>_B (K) = −16.802<i>Y</i>_BP^2/3 + 337.377<i>Y</i>_BP^1/3 – 437.883. For a data set consisting of 130 alkylbenzenes having 7–40 carbon atoms, the average absolute deviation between the literature and predicted <i>T</i>_B values was 1.67 K and the <i>R</i>² of the correlation was 0.999. In addition, <i>Y</i>_BP values calculated with this method can be used to predict the flash points of the alkylbenzenes