Gas chromatographic determination of liquid vapour pressure and heat of vaporization of tetrachlorobenzyltoluenes

(Subcooled) liquid vapour pressures and heat of vaporization of low-volatility isomeric organic compounds (tetrachlorobenzyltoluenes, TCBTs) were determined by two gas-liquid chromatographic (GLC) methods, By the first method vapour pressures and temperature-independent heats of vaporization of nine TCBTs were obtained at experimental temperatures (433.15-493.15 K) and linearly extrapolated to 298.15 K. By the second method vapour pressures and temperature-dependent heats of vaporization were measured for the same TCBTs and, in addition, for diphenylmethane and p,p'-DDT employing nonlinear extrapolations. It was concluded that the second method has several advantages over the first with respect to scope, sensitivity for selection of reference compounds and accuracy.