Transferable Potentials for Phase Equilibria. 10. Explicit-Hydrogen Description of Substituted Benzenes and Polycyclic Aromatic Compounds

The explicit-hydrogen version of the transferable potentials
for
phase equilibria (TraPPE-EH) force field is extended to various substituted
benzenes through the parametrization of the exocyclic groups F,
Cl, Br, CN, and OH and to
polycyclic aromatic hydrocarbons through the parametrization of the
aromatic linker carbon atom for multiple rings. The linker carbon
together with the TraPPE-EH parameters for aromatic heterocycles constitutes
a force field for fused-ring heterocycles. Configurational-bias Monte
Carlo simulations in the Gibbs ensemble were carried out to compute
vapor–liquid coexistence curves for fluorobenzene; chlorobenzene;
bromobenzene; di-, tri-, and hexachlorobenzene isomers; 2-chlorofuran;
2-chlorothiophene; benzonitrile; phenol; dihydroxybenzene isomers;
1,4-benzoquinone; naphthalene; naphthalene-2-carbonitrile; naphthalen-2-ol;
quinoline; benzo­[b]­thiophene; benzo­[c]­thiophene; benzoxazole; benzisoxazole; benzimidazole; benzothiazole;
indole; isoindole; indazole; purine; anthracene; and phenanthrene.
The agreement with the limited experimental data is very satisfactory,
with saturated liquid densities and vapor pressures reproduced to
within 1.5% and 15%, respectively. The mean unsigned percentage errors
in the normal boiling points, critical temperatures, and critical
densities are 0.9%, 1.2%, and 1.4%, respectively. Additional simulations
were carried out for binary systems of benzene/benzonitrile, benzene/phenol,
and naphthalene/methanol to illustrate the transferability of the
developed potentials to binary systems containing compounds of different
polarity and hydrogen-bonding ability. A detailed analysis of the
liquid-phase structures is provided for selected neat systems and
binary mixtures.