Heat Capacities and Derived Thermodynamic Functions of 1-Octadecanol, 1-Nonadecanol, 1-Eicosanol, and 1-Docosanol between 10 K and 370 K

Abstract

The molar heat capacities of the linear alcohols 1-octadecanol (C 18 H 38 O), 1-nonadecanol (C 19 H 40 O), 1-eicosanol (C 20 H 42 O), and 1-docosonol (C 22 H 46 O) were measured from 10 K to 370 K. The derived absolute entropies were fitted as a function of the carbon number ( n ) in the linear chain. At 360 K the function is S °(360 K, n ) = {117.52 + 38.328 n } J·K - 1 ·mol - 1 . A simple function was found for the heat capacity of the liquids. From the melting point to 370 K the liquid heat capacities can be represented within the measuring error with C p,l ( n, T ) = {−450.41 + 36.4968 n + 1.47317 T } J·K - 1 ·mol - 1 . The solid−solid phase transition in 1-octadecanol was investigated in more detail, and the relative Gibbs energy curves of both solid phases and the liquid phase are presented.