Determination of vapor pressures and vaporization enthalpies of the aliphatic branched C5 and C6 alcohols

The standard molar enthalpies of vaporization Delta (g)(l) H degrees (m) of the 14 branched C-5 and C-6 alkanols 2,2-dimethyl-1-propanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 2-ethyl-1-butanol, 3,3-dimethyl-1-butanol, 2-hexanol, 3-hexanol, 3-methyl-2-pentanol, 4-methyl-2-pentanol, 2-methyl-3-pentanol, 3,3-dimethyl-2-butanol, 2-methyl-2-butanol, 3-methyl-3-pentanol, and 2,3-dimethyl-2-butanol have been determined. The data were obtained from the temperature dependence of the vapor pressure measured by the transpiration method. A linear correlation of enthalpies of vaporization of the secondary alcohols with the number of C atoms has been found. The effect of self-association of aliphatic alcohols in the liquid phase is discussed in terms of the difference of Delta (g)(l) H degrees (m) (298.15 K) between associating alcohols and their nonassociating alkane homomorphs.