Critical temperatures and pressures of some alkanes

Abstract

The critical temperatures and pressures of eleven C₉-C₁₂ alkanes were measured. Good agreement was found between the observed critical pressures and values obtained by extrapolation of two equations representing the variation of vapour pressure with temperature in the region of the normal boiling point. Good agreement was also found between the observed critical temperatures and pressures and estimates of these properties made by incremental methods based on molecular structure.

From critical and vapour-pressure data for a wide range of alkanes values of the acentric factor ω were obtained and correlated with molecular structure by incremental methods analogous to those used successfully for critical temperatures and pressures. The use of the schemes is illustrated by their application to the estimation of the critical temperature, critical pressure and acentric factor of 2,2,4,6,6-pentamethylheptane; the several methods yield a self-consistent set of values.