THERMODYNAMIC PROPERTIES OF 1-METHYLCYCLOPENTANOL AND 1-CHLORO-1-METHYLCYCLOPENTANE IN THE IDEAL-GAS STATE

The enthalpies of evaporation, the saturated vapor pressures of 1-meth ylcyclopentanol (I) and 1-chloro-1-methylcyclopentane (II) and the ene rgy of combustion of crystal I were measured. IR and Raman spectra of both compounds were recorded and vibrational analyses were made. Therm odynamic functions of I and II in the ideal gas state were calculated by the statistical thermodynamics methods. In order that the experimen tal and calculated entropies of gaseous 1,1-CIMeCP agree, it is necess ary to determine the contribution of pseudorotation as the contributio n of motion with potential function V(phi) = {5800 - 3060 cos(phi) - 2 740 cos(2 phi)} J mol(-1) and pseudorotational moment of inertia 15.24 x 10(-40) g cm(2). The molecular rotation in the plastic crystal stat e of II is discussed. (C) 1997 Elsevier Science B.V.