Equilibrium and transport properties of primary, Secondary and tertiary amines by molecular simulation

Abstract

Using molecular simulation techniques such as Monte-Carlo (MC) and molecular dynamics (MD), we present several simulation results of thermodynamic and transport properties for primary, secondary and tertiary amines. These calculations are based on a recently proposed force field for amines that follows the Anisotropic United Atom approach (AUA). Different amine molecules have been studied, including n-ButylAmine, di-n-ButylAmine, tri-n-ButylAmine and 1,4-ButaneDiAmine for primary, secondary, tertiary and multi-functional amines respectively. For the transport properties, we have calculated the viscosity coefficients as a function of temperature using the isothermal-isobaric (NPT) ensemble. In the case of the pure components, we have investigated different thermodynamic properties using NVT Gibbs ensemble simulations such as liquid-vapor phase equilibrium diagrams, vaporization enthalpies, vapor pressures, normal boiling points, critical temperatures and critical densities. We have also calculated the excess enthalpies for water-n-ButylAmine and n-heptane-n-ButylAmine mixtures using Monte-Carlo simulations in the NPT ensemble. In addition, we present the calculation of liquid-vapor surface tensions of n-Butyl-Amine using a two-phase NVT simulation as well as the radial distribution functions. Finally, we have investigated the physical Henry constants of nitrous oxide (N2O) and nitrogen (N2) in an aqueous solutions of n-ButylAmine. In general, we found a good agreement between the available experimental information and our simulation results for all the studied properties, ratifying the predictive capability of the AUA force field for amines.