Exploration of the vapour-liquid phase equilibria and critical points of triacontane isomers

Direct configurational-bias Monte Carlo simulations in the Gibbs ensemble have been used to determine the vapor-liquid coexistence curves and critical points of three C30H62 isomers: n-triacontane (Tc = 851 K, pc = 0.202 g cm−3), 11-nonylheneicosane (Tc = 835 K, pc = 0.208 g cm−3), and 2,6,10,15,19,23-hexamethyl-tetracosane, also called ‘squalane’ (Tc = 807 K, pc = 0.244 g cm−3). The calculations show that the molecular shape can have a substantial influence on the phase diagrams of isomeric alkanes and that, in particular, squalane deviates significantly from the principle of corresponding states.