Methylamine-Deuterium Isotope Exchange Equilibria in the Gaseous and Liquid Phases

Article abstract of DOI:10.1021/j100454a013

The deuterium-protium separation factor, α, between molecular hydrogen and liquid methylamine in the presence of potassium methylamide catalyst has been measured at low deuterium concentrations over the temperature range -50 to +5 deg C.The separation factor is about 10 percent larger than that for liquid ammonia, and its dependence upon absolute temperature, T, is given by lnα = 0.1135 + (240.05/T) + (43989/T²).The equilibrium constant, K₁, for deuterium-protium exchange between hydrogen and the amino group of methylamine vapor has been calculated for all deuterium concentrations at temperatures between 150 and 400 K with partition functions for methylamine derived from an internal rotation-inversion-normal vibration model of methylamine based on spectroscopic data.Conversion of K₁ into α values, by inclusion of vapor-liquid fractionation effects, shows that the discrepancy between theory and experiment is less than the combined tolerances (+/- 5 percent) of the two approaches.The dependence of α on deuterium atom fraction is discussed.