Virial Coefficients of Methanol from 150 to 300°C and Polymerization in the Vapor

The second and third virial coefficients of methanol have been determined from 150 to 300°C. At most temperatures the estimated standard error of the second is less than 1%. These values of the second virial coefficient are less negative than results in which the third and higher virial coefficients were neglected. The virial coefficients are interpreted in terms of equilibria between monomer, dimer, and trimer; the enthalpies and entropies of dimerization and trimerization are in line with those found for steam.