Determination of Ambient Temperature Vapor Pressures and Vaporization Enthalpies of Branched Ethers

The standard molar enthalpies of vaporization of 11 branched tert -butyl alkyl ethers, tert -amyl alkyl ethers, and tert-octyl alkyl ethers have been determined from the temperature dependence of the vapor pressure measured by the transpiration method. The temperature dependences of retention indices for a set of 31 ethers with branched molecular structures were measured using a nonpolar gas chromatographic column. Values of for 13 ethers obtained from the transpiration method in this work (as well as some values selected from the literature) together with data for these ethers obtained from the correlation gas-chromatography method were used to derive a correlation for the prediction of the standard molar enthalpies of vaporization for branched ethers at the temperature T = 298.15 K. Experimental values of for 19 branched ethers were obtained with the help of this correlation. The procedure of the correlation gas-chromatography method was modified and substantially simplified by introduction of the Kovat's index for the correlation of the retention indices with the experimental .