Predicting Boiling Points and Flash Points of Monochloroalkanes from Structure

Boiling points (<i>T</i>_B) of acyclic monochloroalkanes are predicted from their boiling point numbers (<i>Y</i>_BP) with the relationship previously established for hydrocarbons, <i>T</i>_B (K) = −16.802 <i>Y</i>_BP^2/3 + 337.377 <i>Y</i>_BP^1/3 – 437.883. The <i>Y</i>_BP values are determined from molecular structure through the relationship <i>Y</i>_BP = 1.726 + <i>I</i>_Cl + 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> + 0.574<i>S</i>. Here <i>I</i>_Cl is a contribution to the <i>Y</i>_BP value resulting from the substitution of Cl for H on an alkane, while the other parameters are the same as those reported earlier for calculating <i>Y</i>_BP values of alkanes. For a data set of 82 acyclic monochloroalkanes having from 4 to 20 carbon atoms, the average absolute deviation between reported <i>T</i>_B values and those predicted with these equations was 1.39 K, and the <i>R</i>² of the correlation was 0.999. In addition, the calculated <i>Y</i>_BP values provide a useful means to predict the flash points of monochloroalkanes through the relationship <i>T</i>_FP (K) = 150.5 ln­(<i>Y</i>_BP) – 185.6