Transferable Potentials for Phase Equilibria. 7. Primary, Secondary, and Tertiary Amines, Nitroalkanes and Nitrobenzene, Nitriles, Amides, Pyridine, and Pyrimidine

Abstract

The transferable potentials for phase equilibria (TraPPE) force fields are extended to amine, nitro, nitrile, and amide functionalities and to pyridine and pyrimidine. In many cases, the same parameters for a functional group are used for both united-atom and explicit-hydrogen representations of alkyl tails. Following the TraPPE philosophy, the nonbonded interaction parameters were fitted to the vapor-liquid coexistence curves for selected one-component systems. Coupled-decoupled configurational-bias Monte Carlo simulations in the Gibbs ensemble were applied to neat (methyl-, dimethyl-, trimethyl-, ethyl-, diethyl-, or triethyl-)amine, nitromethane, nitroethane, nitrobenzene, acetonitrile, propionitrile, acetamide, propanamide, butanamide, pyridine, and pyrimidine. Excellent agreement with experimental results was found, with the mean unsigned errors being less than 1% for both the critical temperature and the normal boiling temperature. Similarly, the liquid densities at low reduced temperatures are reproduced to within 1%, and the deviation for the critical densities is about 4%. Additional simulations were performed for the binary mixtures of methylamine + n-hexane, diethyl ether + acetonitrile, 1-propanol + acetonitrile, and nitroethane + ethanol. With the exception of the methylamine/n-hexane mixture for which the separation factor is substantially overestimated, agreement with experiment for the other three mixtures is very satisfactory.

Molecular Simulation of Adsorption in Microporous Materials

“…The Transferable Potentials for Phase Equilibria forcefield (TraPPE) parameterization of this model by the group of Siepmann [9][10][11][12][13] has been used, as well as the Anisotropic United Atoms (AUA) description [14,15] with optimized parameters for hydrocarbons and functionalized compounds [16][17][18][19][20][21][22][23][24]. Both AUA and UA models use constant bond lengths.…”

A New Force Field of Formamide and the Effect of the Dielectric Constant on Miscibility

“…This has prompted the development of alternative parametrization strategies, targeting e.g. the critical temperature and liquid coexistence density [7,8]. However, very often these force fields fail to reproduce the dielectric constant of polar fluids [9].…”

Equilibrium and Transport Properties of Primary, Secondary and Tertiary Amines by Molecular Simulation

“…Green filled circles represent the Lennard-Jones force centers while red filled circles represent the partial charges. H (1°amine) +0.356 [19] H (2°amine) +0.378 [17] The Lennard-Jones parameters for the amino groups were obtained through a numerical optimization [16] while all the L-J parameters for the hydrocarbons were taken from the AUA4 potential [21]. Tables 1 and 2 summarize the partial charges and the L-J parameters used in our model respectively.…”

“…For example, Rizzo and Jorgensen [18] and Wick et al [19] proposed the OPLS-AA (Optimized Potential for Liquid Simulations -All Atom) and the TraPPE-EH (Transferable Potential for Phase Equilibria Explicit Hydrogens) respectively, both of them being based on the all atom approach. Additional attempts to model some specific amine molecules without explicitly considering transferability can also be found in the literature.…”