GAS-CHROMATOGRAPHIC DETERMINATION OF LIQUID-VAPOR PRESSURE AND HEAT OF VAPORIZATION OF TETRACHLOROBENZYLTOLUENES

(Subcooled) liquid vapour pressures and heat of vaporization of low-vo latility isomeric organic compounds (tetrachlorobenzyltoluenes, TCBTs) were determined by two gas-liquid chromatographic (GLC) methods. By t he 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 vaporizati on were measured for the same TCBTs and, in addition, for diphenylmeth ane and p,p'-DDT employing nonlinear extrapolations. It was concluded that the second method has several advantages over the first with resp ect to scope, sensitivity for selection of reference compounds and acc uracy.