Molecular simulation study of hydrogen bonding mixtures and new molecular models for mono- and dimethylamine

Molecular simulation is used to study vapor–liquid equilibria of 31 binary mixtures consisting of one hydrogen bonding and one non-hydrogen bonding component. Two new pure component molecular models are presented for the hydrogen bonding fluids monomethylamine (MMA) and dimethylamine (DMA), the other models are taken from previous work. All models are of the rigid united-atom multi-center Lennard–Jones type with superimposed electrostatic sites in which hydrogen bonding is described by partial charges. The hydrogen bonding components of the studied binary mixtures are: MMA, DMA, methanol, ethanol and formic acid. The non-hydrogen bonding components are: neon, argon, krypton, xenon, methane, oxygen, nitrogen, carbon dioxide, ethyne, ethene, ethane, propylene, carbon monoxide, diflourodichloromethane (R12), tetraflouromethane (R14), diflourochloromethane (R22), diflouromethane (R32), 1,1,1,2-tetraflouroethane (R134a) and 1,1-diflouroethane (R152a). To obtain a quantitative description of the mixture vapor–liquid equilibria, one state independent binary interaction parameter is adjusted to one experimental data point of either the vapor pressure or the Henry’s law constant. The simple molecular modeling approach used here is shown to be well suited for describing the complex physico-chemical interactions in the studied mixtures.