Measurement and correlation of excess molar enthalpy HmE for (1,2-propanediol, or 1,3-propanediol, or 1,4-butanediol + water) at the temperatures (298.15, 323.15, and 343.15) K

The excess molar enthalpies for (1,2-propanediol, or 1,3-propanediol, or 1,4-butanediol + water) have been measured at three different temperatures under atmospheric pressure over the whole composition range using a modified 1455 Parr solution calorimeter. For the temperature range studied all the mixtures exhibit negative values for HmE being less negative with increasing temperature. The obtained values have been correlated by a model [M.Y. Nagamachi, Ph.D. Thesis, Universidade Estadual de Campinas, Brazil, 2001.] in which hydrophobic effects are considered. The calculated values are in good agreement with the experimental ones. The influence of methyl group of alkanediol on hydrophobic hydration as well as the influence of the position of OH groups on hydrophilic hydration is discussed.