Comprehensive study of the thermodynamic properties for 2-methyl-3-buten-2-ol

Abstract

© 2015 Elsevier Ltd. All rights reserved. The heat capacity of 2-methyl-3-buten-2-ol over the interval T = (5 to 370) K was measured in an adiabatic calorimeter. The standard entropy and heat capacity of the liquid phase at a reference temperature 298.15 K were found to be S^o<inf>m</inf> = (232.6 ± 1.0) J·K^-1·mol^-1 and C<inf>s</inf><inf>,m</inf> = (237.4 ± 0.9) J·K^-1·mol^-1. The triple-point temperature T<inf>fus</inf> = (245.03 ± 0.03) K and the corresponding enthalpy of fusion Δ<inf>cr</inf>^lH^o<inf>m</inf> = (5.199 ± 0.012) kJ·mol^-1 were also determined. The enthalpy of vaporisation was determined with a Calvet-type calorimeter to be ΔlgHmo(305.1K) = (46.9 ± 1.6) kJ·mol^-1. The vapour pressure over the temperature interval (280 to 328) K was measured with a static technique. The standard entropy of vaporisation at T = 298.15 K was found to be Δ<inf>l</inf>^gS^o<inf>m</inf> = (132.7 ± 0.2) J·K^-1·mol^-1. The standard enthalpy of combustion for liquid 2-methyl-3-buten-2-ol ^ΔcHmo(l, 298.15 K) = -(3145.1 ± 2.7) kJ·mol^-1 was measured with two static-bomb isoperibol combustion calorimeters. From the experimental data, the standard enthalpies of formation for liquid and gaseous 2-methyl-3-buten-2-ol were found to be Δ<inf>f</inf>H^o<inf>m</inf>(l, 298.15 K) = -(251.6 ± 2.8) kJ·mol^-1 and Δ<inf>f</inf>H^o<inf>m</inf> (g, 298.15 K) = -(203.3 ± 2.8) kJ·mol^-1, respectively. The latter value was confirmed by high-level quantum chemical calculations. Molecular association in the gas phase and its effect on thermodynamic properties of the compound were discussed.