Determination of vaporization enthalpies of the branched esters from correlation gas chromatography and transpiration methods

The temperature dependencies of retention indices of a set of 80 eaters wit h branched molecular structures were measured on a nonpolar gas chromatogra phic column. The correlation gas chromatography method and reliable data se t of 16 esters selected from the literature were used to derive a correlati on for the prediction of the standard molar enthalpies of vaporization Delt a(l)(g)H degrees(m) at the temperature T = 298.15 K. Experimental values of Delta(l)(g)H degrees(m) for 64 branched eaters were obtained with the help of this correlation. The vaporization enthalpies of isopentyl acetate; eth yl hexanoate, and neopentyl pivalate were additionally obtained by the tran siration method from the temperature dependence of the vapor pressure measu red in a flow system and used for checking the validity of the correlation gas chromatography method.